JPH02112649A - Controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To secure a fail-safe function by selecting either of two types of large and small speeds according to an output signal of an idle position detecting means at a time when detecting something wrong in an accelerator position detecting means, and thereby controlling and engine. CONSTITUTION:At normal time, a target injection quantity is operated by a target injection quantity operational means A of an electronic control fuel injection system A on the basis of each output signal of an engine speed detecting means D, a fuel injection quantity detecting means E and an accelerator position detecting means F. Then, a fuel injection system B is controlled via an actuator A2, whereby speed of an engine C is controlled. At this time, when something wrong in the accelerator position detecting means F is detected by a trouble detecting means H, the target injection quantity detecting means F is selected by a control selector means I, inputting an output signal of an idle detecting means G. According to a fact of whether an accelerator is in an idle position or not, either of two types of large and small speeds is selected, thereby operating the target injection quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device for an internal combustion engine that has a fail-safe function in the event that an accelerator position sensor fails.

<Prior Art> A fuel injection system for an internal combustion engine that uses an electronically controlled governor to control the fuel injection amount is well known, and generally detects the actual rotation speed of the engine and a target set rotation speed, and calculates the difference between the two. The amount of fuel injection is controlled to eliminate this. The set rotation speed is set by an operator's accelerator operation, and its detection is performed by an accelerator position sensor that operates in conjunction with an accelerator pedal or the like, and a potentiometer is used as the accelerator position sensor, for example.

<Problems to be Solved by the Invention> The accelerator position sensor as described above is essential for an electronically controlled governor, and if it should fail, the engine will not be able to operate. Therefore, one solution to this problem is to set a certain rotation speed in advance, and if the accelerator position sensor fails, this rotation speed can be used as a temporary set rotation speed, and the engine can be operated without interrupting control. Fail-safe control that continues the process is known.

However, in this type of control, only one type of rotation speed is used as the temporary setting rotation speed, so if that rotation speed is, for example, the idle rotation speed, the engine output will be insufficient and it will be impossible to climb or work on a steep slope. Moreover, if the rotational speed is too high, there are problems such as difficulty in running and increased danger, which is inconvenient.

This invention focuses on these problems and makes it possible to select two types of rotation speed, low speed and high speed, as a temporary setting speed by using an idle switch that is always provided in ordinary devices. .

This was done with the aim of solving the problems mentioned above.

Means for Solving the Problems> In order to achieve the above object, the present invention provides an abnormality detecting means for detecting an abnormality in the accelerator position detecting means for detecting the set rotation speed. If an abnormality in the accelerator position detection means is detected, one of two predetermined rotation speeds, large and small, is selected according to the output signal of the idle detection means that detects the idle position of the accelerator, and Control is performed using the selected rotation speed as a temporary set rotation speed.

FIG. 1 is a diagram showing the configuration of the present invention. A is an electronically controlled fuel injection device that includes a fuel target injection amount calculation means A, a governor section consisting of an actuator A2, etc., and a fuel injection device B, C is an engine, D is a rotation speed detection means, and E is a fuel injection amount. The detection means F is an accelerator position detection means, and these constitute a normal internal combustion engine control device using an electronically controlled governor. A switching mechanism is incorporated into the system.

<Function> During normal operation, the target injection amount calculation means A1 detects each detection means,
The target fuel injection amount is calculated using the output signals of E and F, and the rotation speed of one engine C is controlled by controlling the fuel injection device B via the actuator A2. Then, when the abnormality detection means H detects an abnormality in the accelerator position detection means F.

In response to a signal from the control switching means, the target injection amount calculation means A0 outputs a rotational speed signal used for calculation to the idle detection means G.
The output signal is switched to the output signal of , and depending on the 2a status of this signal, that is, the signal indicating whether the accelerator is at the idle position or at a position beyond the idle position, two preset types of large and small are output. Select one of the rotation speeds.

The target fuel injection amount is calculated using the selected rotation speed as a temporary set rotation speed. Therefore, it is possible to continue the control by the electronically controlled governor A, and for example, it is possible to drive a working machine or a car to a repair shop on its own by using either high or low engine speed depending on the accelerator operation. You can do some work.

<Example> Hereinafter, an illustrated example in the case of a diesel engine will be described. Figure 2 is a block diagram.

FIG. 3 is a flowchart of the control procedure, and FIG. 4 is a diagram showing an example of a map defining the relationship between the accelerator position and the set rotation speed.

In FIG. 2, 1 is an engine, 2 is a fuel injection pump attached to the engine 1, 3 is a rack actuator, 4 is a rotation sensor, and 5 is a rack position sensor.

6 is an accelerator position sensor, 7 is an idle switch, 8 is another sensor such as a cooling water temperature, and 9 is a control section.

The main part of the control unit 9 uses a microcomputer, and includes an input port 91, an output port 92, a CPU 93 that provides control calculations and input/output instructions, a ROM 94 that stores control programs and various data necessary for control calculations, It is composed of RAM 95 and the like used for calculations. Signals from the one rotation sensor 4, rack position sensor 5, accelerator position sensor 6, idle switch 7, other sensors 8, etc. are input to the input port 91, and the output from the output port 92 is sent to the rack actuator 3. , to drive a fuel rack (not shown) of the fuel injection pump 2. Although not shown, an A/D converter or the like may be inserted before the input port 91 if necessary.

Further, a driver circuit is inserted into the output side of the output port 92 as necessary.

Next, the control procedure will be explained using the flowchart of FIG. 3 and the map of FIG. 4.

First, in step S1, the detection signal of the accelerator position sensor 6, that is, the amount of accelerator operation is input, and in step S2, it is determined whether or not there is an abnormality in the accelerator position sensor 6. This determination is made, for example, based on whether the input signal is within a normal value range, and if it is determined to be abnormal, the process moves to step S3.

The idle switch 7 is configured to be turned on when the accelerator is below the idle position, and turned off when the accelerator is over the idle position. Under normal conditions, the set rotation speed is
As shown by the broken line in Figure 4, when the accelerator is below the idle position, a constant idle rotation speed is set, and when the accelerator is beyond the idle position, it increases depending on the position, and is finally set to be constant. . In addition, in the event of an abnormality, as shown by the solid line, when the idle switch 7 is on, the accelerator is assumed to be at the position corresponding to the idle speed and the idle speed is selected, and when it is off, the accelerator is set to the rated speed. The rated rotation speed is selected based on the assumption that the position corresponds to .

Therefore, in step S3, the state of the idle switch 7 is first input and its on/off is determined, and if the idle switch 7 is on, the idle rotation speed is selected;
If it is off, the rated rotation speed is selected. On the other hand, if it is determined in step S2 that the accelerator position sensor 6 is normal, the set rotation speed determined from the broken line in FIG. 4 is selected in accordance with the accelerator operation amount detected by the accelerator position sensor 6. .

The next step S4 is the operation of a general electronically controlled governor. First, the actual rotational speed of the engine 1 is determined by the rotation sensor 4, the fuel injection amount is determined by the rack position sensor 5, and other operating conditions are determined by the sensor 8, such as the cooling water temperature. are input, and using these data, a target injection amount for obtaining the set rotation speed selected in the above procedure is calculated. A signal corresponding to the result is output to the rack actuator 3, and the rack is driven to inject the target amount of fuel. Therefore,
Of course, normal control is performed using the map shown by the broken line in Fig. 4 during normal conditions, but control using the map shown using the solid line is performed even during abnormal conditions, so that even if the accelerator position sensor 6 fails, the engine cannot be operated. This makes it possible to do so.

In addition, in the above example, the idle speed and the rated speed are used as the two types of speeds that are provisionally set speeds, but this is just an example and other values can be changed as necessary. You can also set it.

<Effect of the invention> As is clear from the above description, this invention has the following features.

When an abnormality in the accelerator position detection means is detected, one of two types of rotation speeds, large and small, is selected according to the output signal of the idle detection means, and the selected rotation speed is controlled as a temporary set rotation speed. It was designed to do this.

Therefore, there is no need to stop the engine, and while selecting either high or low engine speed depending on the accelerator operation, if it is a work machine or a car, it can run on its own to a garage or repair shop, or just for the time being. In the case of ships, it is possible to sail at high or low speeds without the risk of drifting, compared to conventional systems where only one rotation speed could be selected. A more practical fail-safe function can be obtained. In addition, since idle detection means is always provided in general control devices, a fail-safe function in the event of a failure of the accelerator position detection means can be easily achieved by simply modifying the control procedure without adding new parts. It is possible.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of the present invention, Fig. 2 is a block diagram of an embodiment of the invention, Fig. 3 is a flowchart of the control procedure, and Fig. 4 defines the relationship between the accelerator position and the set rotation speed. FIG. 3 is a diagram showing an example of a map. ]... Engine, 2... Fuel injection pump, 3... Rack actuator, 4... Rotation sensor, 5... Rack position sensor, 6... Accelerator position sensor (accelerator position detection means) , 7... Idle switch (idle detection means), 9... Control unit, 91... Input port, 92... Output port, 93... CPU, 94...
・ROM.

Claims (1)

[Claims] (1) In a control device for an internal combustion engine equipped with an electronically controlled fuel injection device, an abnormality detection means is provided to detect an abnormality in the accelerator position detection means for detecting the set rotation speed, and the abnormality detection means detects the accelerator position. If an abnormality in the means is detected, one of two predetermined rotation speeds, large and small, is selected according to the output signal of the idle detection means that detects the idle position of the accelerator, and the selected A control device for an internal combustion engine, characterized in that control is performed using a rotational speed as a temporary set rotational speed.