JPH0792017B2 - Engine controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control type engine control device having a backup function, and more particularly to an engine control device suitable for a gasoline engine for automobiles.

[Conventional technology]

In order to satisfy various requirements for automobiles such as sufficient exhaust gas purification, energy saving, and excellent drivability, in recent years, various control signals necessary for engine control have been created using a microcomputer. However, so-called electronic engine control devices that perform engine control have been widely adopted.

By the way, in any case, engine failure is not desirable, but especially in automobiles, engine failure may cause it to become inoperable and may even jeopardize safety on highways. Therefore, it is not particularly desirable.

On the other hand, in the electronic engine control device described above, the reliability of the microcomputer used there is still a little uncertain, and the occurrence of failures due to initial failure and aging is stochastically inevitable. Then, for example, JP-A-61-2320
As disclosed in Japanese Patent Publication No. 3, a control device using a microcomputer is provided with a backup function so that even when the control device fails, only the minimum control function required for maintaining engine rotation is maintained. As a result, it was possible to travel only to the extent necessary to move the vehicle to ensure safety and repair the trouble.

[Problems to be solved by the invention]

In the above-mentioned conventional technology, the minimum functions necessary for maintaining the rotation of the engine, for example, only the backup for the creation of the ignition signal, the other functions are not considered, the ease of restarting the engine, There was a problem in maintaining an appropriate number of revolutions when idling.

In particular, in recent years, there is a tendency to integrate bypass control of the intake air flow rate of the engine, and from this viewpoint, a large-diameter solenoid valve is often used to control the bypass air flow rate. If the control of this solenoid valve is left unattended as in the conventional example, it may cause a high-speed rotation state of the engine and even cause danger at times, and the maintenance of the above-described rotation speed becomes a serious problem.

An object of the present invention is to provide an engine control device capable of maintaining a sufficiently high level of safety even in a backup state, without fear of difficulty in restarting the engine, and always obtaining high reliability. .

[Means for solving problems]

The above-mentioned object is to detect the control operation state of the engine, for example, that the engine is in the start operation state or the idle operation state when switching to the backup control, and control the intake air flow rate of the engine based on the detection result. Will be achieved.

[Work]

Even in the backup control state, the intake air flow rate of the engine is appropriately controlled according to the operating state of the engine at that time, so the startability at the time of restarting the engine and the controllability of the rotation speed at the time of idling deteriorate Can be suppressed.

〔Example〕

Hereinafter, an engine control device according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the present invention. In the figure, reference numeral 1 denotes a rotation detector called a crank angle sensor or the like, which generates a rotation reference position signal 1a of an engine and a rotation angle signal 1b.

On the other hand, the input / output device 2 and the CPU 3 constitute a control signal calculation device, and the rotation reference position signal 1a and the rotation angle signal 1b, the start signal 8a from the start switch 8 and the idle signal 9a from the idle switch 9 are shown. Based on signals from various sensors that indicate other operating conditions of the engine, the optimum ignition timing, the optimum energization time, the fuel injection time, etc. are calculated, and the ignition signal 2a, the fuel injection signal 2b, IS
C (idle speed control) signal 2c, etc.
Generates various control signals and backs them up 4
Are typing in. From the CPU3, the fuel pump signal 3a
Has been generated and is also input to the backup device 4.

Next, 10 is a reset circuit, which has a so-called watchdog timer function, monitors the state of the CPU 3 by the program run signal 2d supplied from the input / output device 2, and
When the abnormal condition is detected, the abnormal condition is removed, and until the program run signal 2d is output again, for example, 20
It functions to generate the reset signal 10a at a predetermined constant cycle of 0 mS.

The backup device 4 inputs the rotation reference position signal 1a, the rotation angle signal 1b, the start signal 8a, and the idle signal 9a, and independently of the CPU 3, generates various minimum control signals necessary for maintaining the rotation of the engine. Ignition signal 2a, which has a function and is normally input from the input / output device 2, a fuel injection signal
2b, ISC signal 2c, and fuel pump signal 3a are directly sent to the ignition device 6, fuel injection device 7, ISC valve 11, fuel pump 5, and ignition signal 4a, fuel injection signal 4b, ISC signal 4c, fuel pump signal 4d. Is in the so-called normal mode, but when an abnormality is detected, the ignition signal 4a generated independently by the control signal generating function of its own, as described above,
Fuel injection signal 4b, ISC signal 4c, and fuel pump signal 4d
External ignition device 6, fuel injection device 7, ISC valve 11,
The fuel pump 5 operates in a so-called backup mode in which the fuel pump 5 is switched and supplied.

Therefore, the backup device 4 monitors the reset signal 10a generated from the reset circuit 10, and when this signal is inverted a predetermined number of times within a predetermined time, for example, three times within one second, It is considered that the control signal arithmetic unit including the input / output device 2 and the CPU 3 has a permanent error for some reason, and the backup signal 4e is generated to stop the operation of the reset circuit 10 at the same time. It is configured to take a backup mode.

By the way, as described above, in the conventional technique, no control is performed on the ISC valve 11 in this backup mode, and it is simply left as it is.

However, in this embodiment, the backup device 4
2 is provided with the ISC signal generation circuit shown in FIG. 2, to which the start signal 8a from the start switch 8 and the idle signal 9a from the idle switch 9 are input, whereby the engine is started. ISC to the optimum state at the time of, and when it is in the idle state, and when the control operation is performed to a state other than these.
The valve 11 is adapted to be controlled. As a result, according to this embodiment, even when an abnormality occurs in the control signal arithmetic unit composed of the input / output device 2 and the CPU 3, the fuel pump 5,
The ignition device 6 and the fuel injection device 7 include a backup device 4
The minimum necessary control signal is supplied from the engine to maintain the rotation of the engine, and not only the minimum running required to secure the safety of the car and repair the trouble is secured,
Further, control that facilitates restart of the engine and positively maintains the stabilization of the idle speed of the engine can be obtained. This point will be described in more detail below.

Returning to FIG. 2, this ISC signal generating circuit is composed of a frequency dividing circuit 12,
The counter circuit 13, the decoder circuit 14, the oscillation circuit 15, the AND circuit 16, the OR circuit 17, and the mode selection switch 19 are included.

The counter circuit 13 has a programmable 4-bit down counter configuration with 4-bit data inputs D _{0 to} D ₃ , and the basic clock 15a generated from the oscillator circuit 15a.
Acts to count.

The frequency divider circuit 12 functions to divide the basic clock 15a into ^1/4 .

The decoder circuit 14 functions to generate 4-bit data 14a to 14d according to the input state of the start signal 8a from the start switch 8 and the idle signal 9a from the idle switch 9.

The mode selection switch 19 is provided to allow the control mode of the ISC valve 11 in the backup mode to be selected in advance.

Next, the operation of this ISC signal generation circuit will be described.

In the embodiment of FIG. 1, the ISC valve 11 composed of a solenoid valve is driven and controlled by the pulse signal type ISC signal 4c (= 2c), and at this time, the intake air flow rate is controlled by the duty ratio of the pulse signal. Therefore, the second
In the ISC signal generation circuit in the figure, the basic clock 15a generated from the oscillation circuit 15 is frequency-divided by the counter circuit 13 programmed by the decoder circuit 14, thereby obtaining a pulse signal of a predetermined duty ratio, which is It is designed to output as ISC signal 4c.
There are the following two types of C signal generation modes.

Selection Mode Mode Selection Switch 19: Contact A Selection Mode Mode Selection Switch 19: Contact B First, in the selection mode, the switch signal 19a becomes "H", and as a result, the AND circuit 16 remains activated. .

Then, the start switch 8 is operated and the start signal
When 8a becomes "H", it becomes the signal 16a through the AND circuit 16 as it is, and further passes through the OR circuit 17 to the ISC signal 4c.
Becomes

Independently of this, when the carrier signal 13a appears from the counter circuit 13, this also passes through the OR circuit 17 and the ISC signal.
It becomes 4c.

Next, in the selection mode, since the switch signal 19a is set to "L", the AND circuit 16 is closed, and as a result, the ISC signal 4c becomes the carrier signal 13c from the counter circuit 13.
Will only depend on it.

Now, the operation of generating the carrier signal 13c by the counter circuit 13 will be described with reference to the time chart of FIG.

First, the load signal 12a obtained by dividing the basic clock 15a by 16
Is input to the counter circuit 13 from the frequency dividing circuit 12, and the data 14a to 14d from the decoder circuit 14 is input in the next basic block 15a.
Is read into the counter circuit 13, and at the same time the carrier signal 13a
Becomes “H”. Therefore, the carrier signal 13a is also input to the EN terminal of the counter circuit 13 to permit the start of counting.

Therefore, the counter circuit 13 starts down counting by the basic clock 15a from the read data value. When the count value reaches zero, the carrier signal 13
Since "a" becomes "L", which causes "L" to be input also to the EN terminal, counting is stopped, the counter circuit 13 holds this state, and as a result, the next load signal 12a is input, The carrier signal 13a holds "L" until the next data is read from the decoder circuit 14 by the basic clock 15a.

Then, thereafter, each time the load signal 12a is input, the above operation is sequentially repeated.

Therefore, the period during which the carrier signal 13a is "H" is the period during which the ISC valve 11 is on, and the cycle is determined by the cycle of the load signal 12a.

In addition, 4-bit data read from the decoder circuit 14
If the value of 14a to 14d is X (= 0 to 15), ISC valve 11
The on-duty Don of is Don = X / 16 × 100 (%), and can take a value of 0% to 93.75%.

As described above, the data 14a to 14d from the decoder circuit 14
Is determined according to the input states of the start signal 8a and the idle signal 9a, the decoding characteristics of the decoder circuit 14 are preset to predetermined characteristics when the start signal 8a is input and when the idle signal 9a is input. By doing so, as ISC signal 4c, at start and idle,
Each of them can have a duty ratio that gives an optimum intake air flow rate.

Therefore, according to this embodiment, the ISC valve 11 is constituted even when the operation mode is switched to the backup mode due to the occurrence of an abnormality in the part which is composed of the input / output device 2 and the CPU 3 and which is normally operating as the main control signal arithmetic device. It is possible to give different control during start operation and idle state, and not only control that can maintain the rotation of the engine as in the conventional example, but more positively Since the control of the intake air flow rate can also be obtained, the restart of the engine can be facilitated and the stable rotation speed control at the time of idling can be sufficiently obtained.

Further, in this embodiment, the mode selection switch is set as the on-duty value of the ISC valve 11 in the backup mode.
The following two types of selection modes are provided by switching 19 so that the applicable range can be sufficiently widened.

Selection mode Start: On-duty 100% Idle: On-duty 0-93.75% Selection mode Start: On-duty 0-93.75% Idle: On-duty 0-93.75% By the way, in the above embodiment, in the engine of the automobile, The present invention is applied to an engine system using an ISC valve provided in a bypass passage bypassing a throttle valve as a means for controlling the intake air flow rate of the engine when the accelerator pedal is not depressed and in an idle state. However, the present invention is not limited to this and is applicable, for example, the present invention is applied to an engine system that performs ISC using an actuator that controls the return opening position of the throttle valve. Needless to say, this may be carried out.

〔The invention's effect〕

According to the present invention, in an electronically controlled engine system having a backup device to improve reliability, a signal necessary for controlling the intake air flow rate of the engine during backup is obtained by a simple hardware configuration such as a counter circuit. Since this is done, there is no risk of failure, backup can be reliably obtained, and sufficient reliability can be ensured.

Further, according to the present invention, different intake air flow rate control is provided even at the time of backup even at the time of starting the engine and at the time of idling, so the engine can be easily started even at the time of backup, and a large capacity ISC valve Also in the system used, it is possible to eliminate the risk of an abnormal increase in the idle speed and easily obtain high reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an engine control device according to the present invention, FIG. 2 is a block diagram showing an embodiment of an ISC signal generating circuit, and FIG. 3 is a timing chart for explaining the operation. 1 ... Rotation detector, 2 ... Input / output device, 3 ... CPU, 4
…… Backup device, 5 …… Fuel pump, 6 …… Ignition device, 7 …… Fuel injection device, 8 …… Start switch,
9 ... Idle switch, 10 ... Reset circuit, 11 ...
ISC valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-49154 (JP, A) JP-A-59-28030 (JP, A) JP-B-58-19851 (JP, B2)

Claims (2)

[Claims] 1. An engine control device comprising a backup device for backing up a signal for controlling an engine by a control signal arithmetic device, wherein the backup device indicates a signal indicating an operating state of an engine starter and an idle state. A decoder circuit that receives two kinds of signals as decode inputs, and a clock signal that is programmed by the decode data output from the decoder circuit and has a predetermined cycle is counted to control the duty ratio determined by the decode data. A programmable counter circuit for generating a signal is provided, and a control signal for backup of an intake air flow rate control actuator of the engine is supplied from the counter circuit. 2. The electromagnetic actuator for controlling the opening of a bypass passage bypassing the throttle valve, and the return opening position of the throttle valve in an idle state according to claim 1. One of the actuators for controlling the engine is controlled, and the control state by the control signal at the time of backup for these actuators is at least two states of intake air flow rate control at engine start and intake air flow rate control at idle. An engine control device characterized in that: