JPH0629597B2 - Electric governor for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an actual injection amount detector for detecting an actual injection amount to an engine for an injection pump in which a fuel injection amount to an internal combustion engine is feedback-controlled. The present invention relates to an electric governor that prevents an engine from over-rotating or stopping even if an abnormality should occur, and allows emergency running in the case of a vehicle.

(Prior Art) The engine operating condition is detected by various operating condition detectors, the target injection amount of the engine is calculated by a microcomputer, and the fuel adjusting member of the injection pump is used as a positioning servo means to realize the target injection amount. The so-called electric governor, which controls positioning by means of the above, is a means to achieve both fuel consumption improvement and exhaust gas purification by utilizing flexibility and high controllability such as high accuracy and high responsiveness to various parameters required for engine injection amount control. Is seen as promising.

However, if an error occurs in the actual injection amount detector that detects the actual injection amount to the engine, the feedback control of the appropriate injection amount cannot be performed and the injection amount control function is lost, so the engine stops or the engine overruns. There is a problem that leads to.

Therefore, it is considered that the actual injection amount detector is switched to the open loop control to ensure the minimum function when it is abnormal (for example, JP-A-57-2123).
No. 37).

However, this is one that always makes the value of the final injection amount with respect to the target injection amount smaller than the value at the normal time,
The engine output during emergency operation may not be sufficient and the engine may stop.

Further, Japanese Utility Model Application Laid-Open No. 57-53040 discloses that in an emergency, a target rotational speed is determined according to the accelerator opening degree and feedback control is performed to this target rotational speed. It is not shown to control with such injection amount characteristics.

Further, Japanese Unexamined Patent Publication (Kokai) No. 57-210133 discloses that the second injection amount characteristic is used in an emergency, but the rotational speed range controlled by this injection amount characteristic is unknown. It is also unknown whether such excellent emergency driving can be performed.

(Problems to be Solved by the Invention) The present invention improves the injection amount control performance during open loop control more than the above-described conventional device, and more reliably prevents engine hunting, stop, overrun, and the like, In the case of a vehicle, the purpose is to enable emergency travel.

(Means for Solving Problems) The present invention, in an electric governor that feedback-controls an injection amount, monitors an output signal of an actual injection amount detector that detects an actual injection amount, and performs feedback control of the injection amount when an abnormality occurs. The control of the injection amount is switched to the open loop control using an injection amount pattern different from the injection amount pattern at the time of the feedback control, and the injection amount is determined according to the rotation speed as the injection amount pattern for this open loop control. An injection amount pattern having a speed characteristic and having a controllable maximum rotation speed set to a value lower than that of the injection amount pattern for feedback control is used.

(Operation) With this configuration, the second injection amount pattern, which has the speed control characteristic of determining the injection amount according to the fluctuation of the actual rotation speed signal, is more than the first injection amount pattern that is normally used. Since the maximum controllable rotation speed is set low, the control range of the rotation speed becomes a condensed injection amount pattern. Therefore, in the second injection amount pattern, not only is the maximum value of the rotation speed suppressed to a low value, but the speed control characteristic is that the injection amount change with respect to the change in the rotation speed when the accelerator is constant is greater than that in the first injection amount pattern. Since the injection amount suddenly changes abruptly with a short operation of the accelerator, it is possible to surely make the driver aware of the emergency operation and prevent hunting, overrun or stop of the engine.

(Examples) The present invention will be described in detail below with reference to the examples shown in the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention, in which a target injection amount of a column injection pump A of a diesel engine is calculated by a microcomputer, and a positioning servo circuit controls a fuel adjustment member of the column injection pump ( Control rack). In this figure, 1a to 1
h is a group of operating condition detectors that detect various operating conditions of the engine,
Reference numeral 2 is a central processing unit (CPU) for calculating the injection amount, and 3 is its program memory and data memory (ROM, RAM). The CPU 2 inputs the starter switch state and the key switch state from the starter switch 1g and the key switch 1h, and the rack position sensor 1b, the intake pressure sensor 1c, the intake air temperature sensor 1d, the engine cooling water temperature sensor 1e, which is the actual injection amount detector. , The actual injection amount signal, the intake pressure signal, the intake temperature signal from the accelerator sensor 1f,
An engine cooling water temperature signal and an accelerator operation amount signal are input via the A / D converter 9, and a rotation speed signal is input from the rotation sensor 1a via the waveform shaping circuit circuit 10,
The target injection amount is calculated and output to the D / A converter 11, and at the same time, the accelerator operation amount signal and the actual injection amount detection signal (rack position signal) are monitored to detect and process the abnormality. The rack position sensor 1b and the fuel adjustment member 8 are connected via a link.

Next, the processing procedure of the CPU 2 will be described according to the flowcharts shown in FIGS. 2 (A), (B), and (C). In the main routine shown in (A), 200 is a program initialization step, which makes various preparations necessary for processing. Reference numeral 201 is a step for determining the starter signal. When the key switch of the vehicle is turned to the starter-on side, the processing is 202
Go to step. Reference numeral 202 denotes a step of taking in signals of the operating condition detector group into the microcomputer, and intake pressure,
The intake air temperature, the engine cooling water temperature, and the analog signal from the accelerator sensor are taken in through the A / D converter 9.

Reference numeral 203 denotes a step of determining whether or not the accelerator operation amount signal Vα from the accelerator sensor captured at 202 is normal, and detects a voltage (Vα <Vα0, Vα> Vα100) in a range that cannot be obtained by a normal accelerator device. If (according to the shaded area in FIG. 3), it is judged that the accelerator sensor is abnormal and 20
In 4 steps, the abnormal accelerator operation amount sensor input value is replaced and fixed by the sensor input value at a certain set opening (10% in this embodiment). Reference numeral 205 denotes a step of calculating the basic injection amount Q _BASE from the accelerator operation amount signal and the engine speed N, and the memory stores a map of the governor pattern as shown in FIG. 4, which is referred to. By Q
_{Get BASE} . Reference numerals 206 and 207 denote steps for correcting the engine cooling water temperature to calculate the cooling water temperature corrected injection amount Q _B by adding the water temperature correction amount Q _T to the basic injection amount Q _BASE when the temperature is low. 208 derives the intake air amount β of the engine from the intake air temperature and the intake pressure, calculates the target injection amount Qf by adding a correction to the cooling water temperature correction injection amount after Q _B in 209 steps.

Reference numeral 210 denotes a step for determining whether or not a rack position sensor 1b for detecting an actual injection amount, which is a feedback signal of a positioning servo circuit described later, is normal and cannot be obtained at a normal position of the control rack 8 which is a fuel adjusting member. range of the voltage _{(V P <V PMAX, V} P> V PMIN) when detecting a (FIG. 5 shaded area), it is determined that the rack position sensor abnormality, switching to open-loop control. When the rack position sensor 1b is normal, the routine proceeds to step 211, where the target injection amount command voltage V _S is calculated from the characteristics shown in FIG.
Output to the D / A converter 11 in 13 steps. If the rack position sensor is abnormal, the process proceeds to step 214, and as shown in FIG. 7, the current command voltage V _S ′ during open loop control in which the rotation speed and the accelerator opening rapidly change with respect to the rotation speed.
To calculate. Further, in step 212, the feedback of the rack position in the positioning servo circuit 4 which will be described later is stopped, and the selector is controlled so that only the feedback of the current flowing through the actuator is controlled, and the command voltage V _S ′ is set to D /.
Output to the A converter 11.

Reference numeral 215 is a step for determining the key switch state. If the key switch is in the on state, steps 202 to 213 are repeated, and if it is in the off state, step 216.
At 217, the injection amount is set to 0, the engine is stopped, and the process returns to the starter state determination step 201.

Further, the CPU 2 has two interrupt processing routines.
One of them is a rotation speed interrupt processing routine shown in (B), in which a gear and an electromagnetic pickup incorporated in the injection pump interrupt the rotation speed signal to start the processing.
In step 218, the number of revolutions is calculated by counting the time from interrupt to interrupt with a clock of a constant frequency and taking the reciprocal of the count value. The other interrupt is called the scheduled interrupt shown in FIG.
An interrupt is issued at regular intervals, and in step 219, processing such as engine stall determination and constant time counting is performed.

Returning to FIG. 1, when the rack position sensor 1b is normal, the positioning servo circuit 4 detects the target injection amount command voltage V _S output from the CPU 2 through the D / A converter and the actual position detector of the fuel adjusting member 8 ( The output from the rack position sensor) 1b is compared to detect an error, the error signal is processed, and the electromagnetic actuator 7 as an electric servo means is driven so as to correct the error. The electromagnetic actuator 7 moves the fuel adjusting member 8 by a link mechanism in response to a signal from the positioning servo circuit 4. If the rack position sensor is abnormal, the feedback from the rack position sensor output signal is stopped by the signal from the CPU, and the selector is switched to control by the open loop control current command voltage V _S ′. In this embodiment, a variable inductance type position sensor is used as the rack position sensor.

FIG. 8 shows an electric circuit diagram of the positioning servo circuit. 8a
The injection amount command voltage V _S calculated by the CPU is the actual position signal (rack position sensor output signal) from the position sensor at 8b.
V _P is applied. Injection amount command voltage V _S and the target injection quantity Q
FIG. 6 shows the relationship with f, and FIG. 5 shows the relationship between the actual position signal V _P and the actual injection amount Q. The block 80 adds V _S and V _P for amplification, and adds the offset voltage V ₀ f ₁ with the variable resistor R ₁ . Further, differential compensation and integral compensation are added by the capacitors C ₁ and C ₂ and the resistor R ₂ . V _S, V
_P is Figure 6, the error amplification value of V _S and V _P is obtained as the output voltage of the block 80 to have a polarity opposite characteristics with the same inclination with respect to the injection amount as shown in Figure 5. 82 is CP
A gate for controlling the selector rack position sensor abnormality detection signal by 81 from U, 81 when it detects an abnormality of the rack position sensor, when open-loop control error signal of the V _S and V _P of the block 80 Current command voltage V
_This is a selector for switching to _S '.

The characteristic of the voltage V _S ′ is as shown in FIG. 7, and is obtained from the rotation speed and the accelerator opening. This is because even if the characteristics of the electromagnetic actuator during open loop control have a relationship between the current and the injection amount as shown in Fig. 10, a slight change in the rotational speed is performed to prevent stalling and overrun. Also, the pattern is such that V _S ′ is greatly changed. Further, the maximum rotational speed of the pattern of FIG. 7 is set lower than the maximum rotational speed of the governor pattern in the normal state shown in FIG. 4 to allow a large margin for overrun.

Reference numeral 8c is a coil of the electromagnetic actuator 7, resistance 8d is a resistance for detecting a current value flowing through the coil 8c,
A voltage proportional to the current value is generated at both ends.

The amplification stage 8b amplifies the voltage proportional to this current value, and applies the offset voltage V ₀ f ₂ by the variable resistor R ₃ .
_{V S} and V-block 83, which is select in block 81
The error signal of _P or the current command voltage V _S ′ during open loop control and the electromagnetic actuator current feedback voltage obtained in block 86 are compared and output. In block 85, the comparative value in block 83 is chopped using the charge / discharge waveform of the constant frequency obtained by the oscillator circuit in block 84, and the electromagnetic actuator drive circuit 87 is controlled.

The voltage waveform in block 85 is shown in FIG. The oscillation waveform of FIG. 9 (i) a is applied to point 8e. If the output voltage of the block 83 applied to the 8f point is V _S f ₁ , then 8
The output waveform at point g is chopped as shown in (ii) and V _S
In the case of f ₁ , it becomes like (iii). The electromagnetic wave 7 is controlled by this rectangular wave. That is, the current flowing through the electromagnetic actuator coil 8c is, on average, proportional to the pulse width of the rectangular wave to control the position of the electromagnetic actuator. The current flowing through the coil 8c of the electromagnetic actuator is converted into a voltage and fed back by the current detecting resistor 8d and the amplification stage 86 because the voltage of the battery is directly supplied to the coil 8c of the electromagnetic actuator. This is for the purpose of correcting the fluctuation and the purpose of correcting that the resistance value of the coil 8c changes due to self-heating or a change in the thermal environment.

(Advantages of the Invention) As described above, the present invention monitors the output signal of the actual injection amount detector and, when an abnormality is detected, stops the feedback control of the injection amount and determines the injection amount according to the rotational speed. The open loop control is performed by using the injection amount pattern for open loop control, which has characteristics and the maximum controllable rotation speed is set to a value lower than the injection amount pattern for feedback control. In this case, the change in the injection amount with respect to the change in the rotation speed becomes rapid, which allows the driver to recognize an emergency, and it is possible to reliably prevent the engine hunting overrun and stop. It has an excellent effect of being able to drive.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
The flowchart which shows the processing procedure in the central processing unit in the figure, FIG. 3 is the characteristic view which shows the accelerator sensor output,
FIG. 4 is a governor pattern showing the basic injection amount of fuel, and FIG.
FIG. 6 is a characteristic diagram showing the position detection signal of the fuel adjusting member, FIG. 6 is a characteristic diagram showing the relationship between the injection amount command voltage and the target injection amount, and FIG. 7 is a current from the rotational speed and accelerator opening during open loop control FIG. 8 is a characteristic diagram for obtaining the command voltage, FIG. 8 is an electric circuit diagram of the positioning servo circuit in FIG. 1, FIG. 9 is a timing diagram showing the operation of the circuit shown in FIG. 8, and FIG. It is a characteristic view which shows the characteristic of an actuator. 1a ... Revolution sensor, 1b ... Actual injection amount detector, 1c
Intake pressure sensor, 1d Intake temperature sensor, 1e Engine cooling water temperature sensor, 1f Accelerator sensor, 1g
...... Starter switch, 1h …… Key switch, 2 ……
Central processing unit, 3 ... Memory, 4 ... Positioning servo circuit, 7 ... Actuator, 8 ... Fuel adjusting member,
A: In-line injection pump.

Claims (1)

[Claims] 1. An actuator for controlling a fuel injection amount, an actual injection amount detector for generating an actual injection amount signal corresponding to an actual fuel injection amount, and a rotation for generating an engine speed signal corresponding to an engine speed. It has a number detector and an accelerator detector that generates an accelerator signal corresponding to the accelerator operation amount, and receives a signal from each detector to calculate the target injection amount of the engine based on the first injection amount pattern. Then, in the electric governor for an internal combustion engine that compares the target injection amount with the actual fuel injection amount and feedback-controls the fuel injection amount so as to correct the error, a state where the actual injection amount signal is abnormal is detected. And the feedback control is stopped when the actual injection amount signal is abnormal, and the fuel injection amount is opened by using a second injection amount pattern different from the first injection amount pattern. And an open loop control means for controlling, wherein the second injection amount pattern has a controllable maximum rotational speed with the speed control characteristic that determines the injection amount according to the rotational speed signal from the first injection amount pattern. An electric governor for an internal combustion engine, which is also set to a low value.