JPS61164053A - Electric governer for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurence of a hunting or the like in an electric governer for the feedback control of the quantity of fuel injection by permitting the feedback control, to be stopped, if abnormality is detected, so that an open- loop control is carried out by the use of a pattern of the quantity of fuel injection prepared for the open-loop control. CONSTITUTION:This electric governer adjusts the quantity of fuel injection in such a way as controlling the operation of a control rack 8 in an in-line injection pump A through an electromagnetic actuator 7. In addition, CPU2 calculates a desired value of the quantity of fuel injection in accordance with an output signal from operating condition detectors including a rotational speed sensor 1a and a rack position sensor 1b, and obtains a deviation by comparing the desired value with a measured value of the actual quantity of fuel injection, and then feedback controls the actuator 7 in such a manner that the deviation can be eliminated. In this case, when abnormality is detected by the rack position sensor 1b, said feedback control is stopped so that an open-loop control is to be carried out by the use of a pattern of the quantity of fuel injection prepared for the open-loop control, in which a driving signal from the actuator 7 is quickly change in response to a change in the number of revolutions.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an actual injection amount detector that detects the actual injection amount to the engine, for an injection pump in which the amount of fuel injection to the internal combustion engine is feedback-controlled. This relates to an electric governor that prevents the engine from overspeeding or stopping even in the event of an abnormality, and in the case of a vehicle, enables emergency running.

(Prior art) The operating conditions of the engine are detected by various operating condition detectors, the target injection amount of the engine is calculated by a microcomputer, and the fuel adjustment member of the injection pump is positioned by servo means to achieve the target injection amount. The so-called electric governor, which performs positioning control using
It is seen as a promising means of achieving both fuel efficiency improvement and exhaust purification by taking advantage of its excellent controllability, including its flexibility, high precision, and high responsiveness.

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

Therefore, a system has been considered in which when the actual injection amount detector is abnormal, it switches to open-loop control to ensure the minimum functionality (for example, Japanese Patent Laid-Open No. 57-2123
Publication No. 37).

(Problems to be Solved by the Invention) The present invention further improves the injection amount control performance during open loop control than the conventional device described above, more reliably prevents engine hunting, stopping, overrun, etc. In the case of vehicles, the purpose is to enable emergency running.

(Means for Solving the Problems) The present invention provides an electric governor that performs feedback control of the injection amount, monitors the output signal of an actual injection amount detector that detects the actual injection amount, and performs feedback control of the injection amount in the event of an abnormality. is stopped, and the injection amount control is switched to open-loop control that uses an injection amount pattern different from the injection amount pattern during feedbank control, and the injection amount pattern for feedback control is used as the injection amount pattern for this open-loop control. An injection amount pattern is used in which the actuator drive signal changes more rapidly with respect to changes in rotational speed.

(Example) The present invention will be described in detail below according to an example shown in the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, in which a microcomputer calculates the target injection amount of the in-line injection pump A of a diesel engine, and a positioning servo circuit controls the fuel consumption of the in-line injection pump A. It controls the adjustment member (control rack). In this figure, ■a to 1h
2 is a group of operating condition detectors that detect various operating conditions of the engine;
is the central processing unit (CPU) that calculates the injection amount.

3 is its program memory and data memory (ROM, RAM).The CPU 2 manually inputs the starter switch state and key switch state from the starter switch Ig and key switch 1h, and also controls the rack which is the actual injection amount detector. The actual injection amount signal, intake pressure signal, intake temperature signal, engine cooling water temperature signal, and accelerator operation amount signal from the position sensor 1b, intake pressure sensor lc, intake temperature sensor ld, engine coolant temperature sensor 1es, and accelerator sensor 1f are converted to an A/D converter. The target injection amount is calculated by inputting the rotation speed signal from the rotation sensor 1a via the waveform shaping circuit 10 and outputting it to the D/A converter 1).At the same time, the accelerator operation amount signal, The actual injection amount detection signal (rank position signal) is monitored, and abnormalities are detected and processed. Note that the rack position sensor 1b and the fuel adjustment member 8 are coupled via a link.

Next, the processing procedure of the CPU 2 will be described according to the flowcharts shown in FIGS. 2(A), 2(B), and 2(C).

In the main routine shown in (A), 200 is a program initialization step, in which various preparations necessary for processing are made. 201 is a step for determining the starter signal, and when the key switch of the vehicle is turned to the starter ON side, the process advances to step 202. Reference numeral 202 denotes a step in which signals from the operating condition detector group are taken into the microcomputer, in which intake pressure, intake air temperature, engine coolant temperature, and analog signals from the accelerator sensor are taken in through the A/D converter 9.

Step 203 is a step for determining whether the accelerator operation amount signal Vα from the accelerator sensor acquired in step 202 is normal, and when a voltage in a range that cannot be obtained with a normal accelerator device (■α〈VαO1Vα〉Vα100) is detected. (Shaded area in Figure 3), it was determined that the accelerator sensor was abnormal, and 20
In four steps, the abnormal accelerator operation amount sensor input value is replaced with a sensor input value at a certain set opening degree (10% in this embodiment) and fixed. 205 is the basic injection amount QIA3! based on the accelerator operation amount signal and the engine rotation speed N! In the step of calculating QIA, a governor pattern map as shown in FIG. 4 is stored in the memory, and QIA is obtained by referring to it. 206 and 207 are steps for correcting the engine cooling water temperature, and the basic injection amount QllAsE is set at low temperature.
The injection amount QB after cooling water temperature correction is calculated by adding the water temperature correction amount Qa to . Step 208 derives the intake air amount β of the engine from the intake temperature and intake pressure, and in step 209, the target injection amount Q is determined by adding correction to the injection amount Q8 after correcting the cooling water temperature.
Calculate f.

210 is a step for determining whether or not the rack position sensor 1b for detecting the actual injection amount, which is a feed bank signal of the positioning servo circuit to be described later, is normal; No range of voltage (V.

If <VPM□,y,>vwork,) is detected (the shaded area in FIG. 5), it is determined that the rack position sensor is abnormal, and the control is switched to open loop control. If the rack position sensor 1b is normal, proceed to step 21), calculate the target injection amount command voltage ■ from the characteristics shown in Fig. 6, and set D in step 213.
/A converter 1). If the rack position sensor is abnormal, the process proceeds to step 214, where the current command voltage v, l during open loop control, which changes rapidly with respect to the rotation speed, is calculated from the rotation speed and the accelerator opening as shown in FIG. Further, in step 212, the selector is controlled so that the feedback of the rank position in the positioning servo circuit 4, which will be described later, is stopped and only the feedback of the current flowing to the actuator is performed, and the command voltage V3' is outputted to the D/A converter 1).

215 is a step for determining the state of the key switch; if the key switch is in the on state, steps 202 to 213 are repeated; if the key switch is in the off state, steps 216,
At step 217, the injection amount is set to O, the engine is stopped, and the process returns to step 201 for determining the starter state.

Furthermore, the CPU 2 has two interrupt processing routines.

One of them is a rotational speed interrupt processing routine shown in (B), in which an interrupt is generated by a rotational speed signal using a gear and an electromagnetic pickup built into the injection pump to start processing.

In step 218, the time from one interrupt to another is counted using a clock of a constant frequency, and the number of revolutions is calculated by taking the reciprocal of the counted value. The other interrupt is called a scheduled interrupt as shown in Figure (C).
An interrupt is generated at regular intervals, and in step 219, processes such as engine stall determination and fixed time counting are performed.

Returning to FIG. 1, when the rack position sensor 1b is normal, the positioning servo circuit 4 receives the target injection amount command voltage V output from the CPU 2 through the D/A converter and the actual position detector ( An error is detected by comparing the outputs from the rack position sensor (rack position sensor) lb, and an electromagnetic actuator 7 as an electric servo means is driven to process the error signal and correct the error. The electromagnetic actuator 7 moves the fuel adjustment 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 selector is switched in response to a signal from the CPU so that feedback based on the rack position sensor output signal is stopped and control is performed using the current command voltage v,° during open loop control.

In this embodiment, a variable inductance type position sensor is used as the rack position sensor.

FIG. 8 shows an electrical circuit diagram of the positioning servo circuit. 8a
The injection amount command voltage is calculated by the CPU.

However, the actual position signal (rack position sensor output signal) Vp from the position sensor is applied to 8b. Injection amount command voltage■,
The relationship between the actual position signal (2) and the target injection amount Qf is shown in FIG. 6, and the relationship between the actual position signal (2) and the actual injection amount Q is shown in FIG. Block 80 is ■,
and (2) are added for amplification, and an offset voltage V, f is added by a variable resistor R8. Furthermore, capacitor ct +
C! +Resistor R2 adds differential compensation and integral compensation.

As shown in FIGS. 6 and 5, V,, V, have the same slope and opposite positive and negative characteristics with respect to the injection amount, so the output voltage of the block 80 is the error amplification value of V and vP. It will be done. 8
2 is a gate that controls the selector 81 by the rack position sensor abnormality detection signal from the CPU, and 81 is a gate that outputs the error signals of V$ and This is a selector that switches the current command voltage during control between ■ and °.

The characteristics of voltage ■3" are as shown in Figure 7, and are determined from the rotation speed and accelerator opening. This is because the characteristics during open loop control of the electromagnetic actuator are the relationship between current and injection amount as shown in Figure 10. In order to prevent engine stalling and overruns, the pattern is such that Vs'' changes significantly even with a slight change in rotational speed.

Further, by setting the maximum rotation speed of the pattern shown in FIG. 7 lower than the maximum rotation speed of the governor pattern during normal operation shown in FIG. 4, a large margin for overrun is provided.

8C is a coil of the electromagnetic actuator tough, and resistor 8d is a resistor for detecting the current value flowing through the coil 8e.
Generates a voltage proportional to the current value at both ends.

The amplification stage 8b amplifies the voltage proportional to this current value, and offset voltage (2) is generated by the variable resistor R3. f2 is added.

Block 83 is selected by block 81.
, or the current command voltage V5'' during open-loop control, and the electromagnetic actuator current feedback voltage obtained by the program 86 are compared and output. The comparison value of the block 83 is chopped using the frequency charging/discharging waveform, and the electromagnetic actuator drive circuit 87 is controlled.

FIG. 9 shows the voltage waveform at block 85.

The oscillation waveform shown in FIG. 9(i)a is applied to 80 points.

The output voltage of block 83 applied to point 8f is Vsrt
In the case of , the output waveform at point 8g is chopped as shown in (ii), and in the case of V, f, it becomes as shown in (iii). The electromagnetic actuator 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, and controls the position of the electromagnetic actuator. The current flowing through the coil 8C of the electromagnetic actuator is converted into a voltage by the current detection resistor 8d and the amplification stage 86 and fed back.
Since the battery voltage is directly supplied to the coil 8C of the electromagnetic actuator, the purpose is to compensate for this voltage fluctuation and to compensate for changes in the resistance value of the coil 8C due to self-heating and changes in the thermal environment. It is.

(Effects of the Invention) As described above, the present invention monitors the output signal of the actual injection amount detector, stops feedback control of the injection amount when an abnormality is detected, and adjusts the actuator drive signal in response to changes in the rotation speed. Since open-loop control is performed using an injection quantity pattern for open-loop control that rapidly changes, it is possible to reliably prevent engine hunting, overrun, and stoppage, and in the case of vehicle engines, emergency running is possible. It has an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
A flowchart showing the processing procedure in the central processing unit in the figure, FIG. 3 is a characteristic diagram showing the accelerator sensor output,
Figure 4 shows the governor pattern showing the basic injection amount of fuel.
The figure is a characteristic diagram showing the position detection signal of the fuel adjustment member, Figure 6 is a characteristic diagram showing the relationship between the injection amount command voltage and the target injection amount, and Figure 7 is a characteristic diagram showing the relationship between the injection amount command voltage and the target injection amount. Characteristic diagram for determining the command voltage, Figure 8 is an electrical circuit diagram of the positioning servo circuit in Figure 1, Figure 9 is a timing diagram showing the operation of the circuit shown in Figure 8, and Figure 10 is the diagram during open loop control. FIG. 3 is a characteristic diagram showing the characteristics of an actuator. 1a... Rotation speed sensor, 1b... Actual injection amount detector,
1c...Intake pressure sensor, 1d...Intake temperature sensor, 1
e... Engine coolant temperature sensor, If... Accelerator sensor, 1g... Starter switch, 1h... Key switch, 2... Central processing unit, 3... Memory, 4... Positioning servo Circuit, 7... Actuator, 8... Fuel adjustment member, A... Size type injection pump.

Claims (1)

[Claims] (1) An actuator that operates the fuel adjustment member of the fuel injection pump of the internal combustion engine to adjust the fuel injection amount, an actual injection amount detector that generates an actual injection amount signal corresponding to the actual fuel injection amount, and engine rotation. an operating condition detector that detects the operating conditions of the engine as an electrical signal, including a rotational speed detector that generates a rotational speed signal corresponding to the number of rotations; an electric control circuit that calculates a target injection amount of the engine based on the target injection amount, compares the target injection amount with the actual injection amount signal, and controls the drive of the actuator to correct the error. In the electric governor, the control circuit monitors the output signal of the actual injection amount detector, stops feedback control of the injection amount in case of an abnormality, and controls the injection amount using an injection amount pattern different from the injection amount pattern. In addition to switching to open loop control using
An electric governor for an internal combustion engine, characterized in that the injection amount pattern for open loop control uses an injection amount pattern in which the actuator drive signal changes more rapidly with respect to a change in the rotational speed than the injection amount pattern for feedback control.