JPS61292709A - Signal storage device - Google Patents

Abstract

PURPOSE:To secure the storage of the signal data for a fixed period until an abnormal state is detected by stopping the data writing action to a storage circuit when the change a working state which causes a system fault is detected and monitoring the change of the working state for a fixed period of time. CONSTITUTION:When the number N of revolutions of an engine exceeds the prescribed value N0, an operation is started to write the signal data obtained from the action signals of an engine control system to a storage circuit 32. This data writing action is stopped when the number N of revolutions is reduced less than the prescribed level N1. Then the signal data obtained by a time point preceding by a fixed period from the time point when said data writing is stopped is written to the circuit 32. The number N of revolutions N is monitored for a fixed period of time and the state where the data writing is stopped to the circuit 32 is released as long as the number N of revolutions is not reduced less than a prescribed number N2 of revolutions. Thus the data writing action is started again. While the stoppage of the engine is decided when the number N of revolutions is reduced less than N2. Thus the control processing is carried out for preservation of the data stored in the circuit 32.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a signal storage device, and in particular, it stores signals necessary for diagnosing the causes of abnormalities in various control systems of vehicles, etc., and determines the causes of system abnormalities from the stored contents. The present invention relates to a signal storage device for diagnosing.

(Prior Art) Conventionally, the following methods are mainly known as methods for monitoring the operating state of a vehicle control system and diagnosing system abnormality.

First, the deviation between the operating signal used for abnormality determination in the control system and a preset reference value for abnormality determination is detected, and when this deviation reaches a certain size, a system abnormality is determined. Second, a method of issuing a warning etc.
This is a method of separating the sensors, actuators, etc. that make up the control system from the system and using a diagnostic checker individually to determine whether or not they are defective.

However, with the first method, it is fine if the system becomes completely abnormal, but if a change that does not lead to a failure occurs but temporarily or intermittently causes an abnormality, this abnormal state can be considered. It was difficult to determine the cause of the failure because it could not be detected, and even if it eventually occurred, the situation during the process was unknown. On the other hand, even with the second method, because it only checks individual sensors, actuators, etc., it is not possible to detect abnormalities in the entire system, and of course it is not possible to check for temporary or intermittent failures. Ta.

Therefore, we have solved the problems of conventional failure diagnosis methods, and we have developed a system that can detect system failures in the installed state, especially continuous failures, as well as intermittent failures and temporary failures. A diagnostic device is being considered that allows the cause of failure to be determined from records (Japanese Patent Application No. 130846/1986).
No. etc.).

FIG. 4 schematically shows such a conventional diagnostic device, which includes a sensor 1, a control circuit 2, an actuator 3, and connectors 4 and 5 as a control system, and input/output signals of the control circuit 2 are connected to a signal line 17. .18 to the memory circuit 15, the write control circuit 16 writes and stores the control system signals in time series at a predetermined timing in the memory circuit, and later reproduces the memory contents of the memory circuit 15. This allows for fault diagnosis when a system abnormality occurs.

However, as a practical matter, the memory capacity of the memory circuit 15 is limited, so a circuit equipped with a timer 21 as shown in FIG. I am trying to remember only the data for the period.

For example, when the engine start switch 20 is turned on, the timer 21
The timer output obtained over T time is given to the AND gate 23, and the write clock 24 by the generator 22 is output for a certain period of time from the AND gate 23, and the memory circuit 15 is
I am trying to write data to .

However, even such a diagnostic device using signal storage has the following problems.

First, in order to accurately detect abnormalities in the control system, it is necessary to capture stored data at a timing shorter than the sampling interval of the control data used for control calculations, but normally, it is extremely fast timing of 1 ms or less. Therefore, storing it as time series data requires an enormous amount of storage capacity.

Further, even if data is stored only for a predetermined period, an abnormality does not necessarily occur during that period, and stored data for fault diagnosis may not always be obtained after all.

Furthermore, even if data is stored for a sufficient period of time by reducing the sampling rate of stored data due to storage capacity constraints, the abnormal data needed for fault diagnosis usually exists in only a small portion of the stored data, making it difficult to reproduce. Searching for abnormal data from data takes time, and at the same time, considering the amount of abnormal data stored, a large amount of memory capacity is wasted.

The way to solve this problem is to input data sequentially into a rewritable memory circuit with a predetermined memory capacity.
When the storage capacity is reached, the oldest data is sequentially rewritten with the latest data, and when a system error occurs, data writing is stopped and the data is retained, so that data can be stored in the event of an error. Conceivable.

Figure 6 shows the data writing state of the memory circuit at this time, and the memorizable area of the memory is 1vl from address MO0.
If it is address n, time-series data is stored sequentially from time to as shown by the arrow, and if storage is stopped at time tx, the data stored at that time is stored at time tx-ty. The data is from address MX-1 to address Mn and from address MO0 to M
They are stored in the order of address X.

For example, if we take the engine stall of the engine control system as a condition for stopping writing, -tm is when the engine speed N drops below the predetermined speed No while the ING switch is on.

That is, as shown by the dotted line in Fig. 7 (A>), the engine speed N decreases over time and becomes below the predetermined speed NO, and finally, when the engine speed N becomes zero. be.

(Problems to be Solved by the Invention) However, in some cases, as shown by the solid line in FIG. 7 (A>), the rotation often returns after an instantaneous drop in rotation.

Therefore, in order to reliably determine whether the engine has stalled, the engine speed should be sampled multiple times, and all of the engine speeds should be at the predetermined speed No.
It is conceivable to take time to determine engine stalling, such as determining engine stalling when the following conditions occur.

However, if the engine stall determination takes time, data writing continues as shown in Figure 6, so if the time required to determine the engine stall is ΔO, then ΔT time is wasted. Data is written, and a memory capacity that takes T into account for this engine stall determination time is required.

In addition, as shown in FIGS. 4(B) and 4(C), the pattern of decrease in engine speed varies over time depending on the driving conditions of the vehicle, and the engine stall determination time ΔT may also change. It has been difficult to always secure data for a certain period of time related to the cause of failure after the engine stalls.

(Means for solving the problems) The present invention was made in view of the above problems, and
When a system abnormality is detected, do not increase the storage capacity even if it takes time to determine the abnormality. It is an object of the present invention to provide a signal storage device in which the cause of a failure can be easily investigated.

In order to achieve this purpose, the present invention must first stop writing data to the memory circuit when a change in the operating state that causes a system abnormality is detected, and then monitor the change in the operating state for a certain period of time after stopping the data writing. However, if a system error does not occur, the write stop is canceled and data writing is resumed, but if a system error occurs, the data at the time the write was stopped is retained as is. .

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention.
A vehicle engine control system will be taken as an example of a control system, and engine stall will be taken as an example of an abnormality in the control system.

First, the configuration will be described. Reference numeral 1 indicates sensors used in the engine control system, such as an air amount sensor, a crank angle sensor, a water temperature sensor, an oil pressure sensor, and a negative pressure sensor. A control circuit 2 performs control processing to obtain optimal combustion conditions for the engine based on various detection signals obtained from the sensor 1. Reference numeral 3 denotes an actuator, which includes, for example, a spark plug for engine ignition control, an injector for fuel injection, and the like. Further, the sensor 1 and the control circuit 2 are connected through a connector 4, and the control circuit 2 and the actuator 3 are connected through a connector 5.

Reference numeral 30 denotes an input interface that receives signals from the engine control system consisting of a sensor 1, a control circuit 2, and an actuator 3 to investigate the cause of engine stall failure through signal lines 40 and 41; It takes in the sensor signal of the engine condition, and also the signal line 41
The control signal from the control circuit 2 at the time of engine stall is taken in from.

The signal from the input interface 30 is given to the storage control circuit 31 via the signal line 42, and
After write control by , the data is written into the memory circuit 32 as time-series data. This storage control circuit 31 starts and stops writing to the storage circuit 32 based on control commands from a microcomputer, which will be explained later.

A backup power supply 33 is connected to the memory circuit 32,
The memory contents of the memory circuit 32 can be retained even when the ignition switch is turned off. Of course, memory circuit 3
If a non-volatile memory is used as the power source 2, the backup power source 33 is not required.

36 is a CPU that executes stopping and restarting data writing to the storage circuit 32 according to the present invention under program control, and is connected to a ROM 37 that permanently stores a control program and a RAM 3B that temporarily stores data necessary for control processing. ing.

The CPtJ 36 is supplied with an output from a rotation speed processing circuit 34 that detects the engine rotation speed N, and is also supplied with a signal indicating whether the ignition switch is on or off from a processing circuit 35. The rotation speed processing circuit 34 is given a number of pulse signals 44 proportional to the engine rotation speed, so the rotation speed processing circuit 34 calculates the engine rotation speed N based on the cycle of the engine rotation pulses, and the CPU 36
give to Further, a signal 45 on a signal line branched from the output side of the ignition switch is input to the processing circuit 35.

Writing control of the sensor signal and the control signal of the control circuit 20 for diagnosing the cause of the engine stall by the CPU 36 is performed according to the following conditions.

Continuation of writing; (a) Make sure the ignition switch is on (b)
) The engine speed N is equal to or higher than the specified speed N1 Writing stop: <a > The ignition switch is on (b
) Resume writing that the engine speed is below the predetermined speed N1; (a > The ignition switch is on (b)
) Writing has been stopped. (C) The number of rotations has not fallen below the predetermined number N2 (N2<N1) within a certain period of time after stopping writing. Data retention based on engine stall determination after stopping writing; (a
> Make sure the ignition switch is on (b) &i
The control process according to the embodiment of FIG. 1 will be explained with reference to the flowchart of FIG. 2. In addition, in Fig. 2, [A]
shows the main flow of write control based on engine stall determination,
[81 shows a flow for calculating the engine rotation speed from the engine rotation pulse.

First, when the power to the control system is turned on, an initial reset is applied to the microcomputer 36, and as shown in FIG.
A] main flow is executed.

Of course, the engine control system is turned on by turning on the ignition switch.

First, in step (1), the system is initialized, constants are initialized, etc., and in the next step (2), it is determined whether the engine rotation speed N is equal to or greater than a predetermined value No.

Here, the engine rotation speed N can be detected, for example, as shown in Fig. 2 [8].
It is determined by the process shown in the flow below. That is, since the engine rotation pulse 44 is input to the rotation speed processing circuit 34 in FIG. Execute the flow.

That is, as shown in the time chart of FIG. 3, a sufficiently high-speed clock pulse of a predetermined frequency is used for the engine rotation pulse 44, and the counter that counts this clock pulse is stopped in step (12). In the next step (13), the count value when the counter is stopped is read, and in step (14), the read count value is stored at a predetermined address in the memory. Further, in step (15), the counter is reset, and the process returns to the main flow of FIG. 2 [A].

If the flow shown in [8] is executed every time an engine rotation pulse is obtained, the pulse interval T1. of the engine rotation pulse shown in FIG. T2. ... can be counted as the number of clock pulses each time, and since this number of pulses is a value proportional to the reciprocal of the engine rotation speed,
At the time the count value is stored, data corresponding to the engine rotation speed N is stored. - Referring again to the main flow in FIG. 2 [A], in step (2), the engine speed N is the predetermined value N.

If it is below, proceed to step (3) and determine whether the ignition switch is on or off. If the ignition switch is on, return to step (2) again; at this time, the engine is in a state immediately after starting and before the rotation has increased, so step (2) is performed.

Repeat the process in (3) until the engine speed N reaches the predetermined value N0.
Wait until it reaches above.

On the other hand, if the ignition switch is off in step (3), it is assumed that the engine has stopped due to cranking only even if the ignition switch is turned on, and control is stopped.

Next, in step (2), the engine speed N is set to N.

In the above case, the process proceeds to step (4), and writing of signal data obtained from the operation signal of the engine control system to the storage circuit 32 is started.

Next, the process proceeds to step (5), where a determination process is performed to check for the occurrence of an engine stall. Meanwhile, the flow for calculating the engine rotation speed N shown in FIG. 2 [B] is repeated every time an engine rotation pulse is obtained, and in step (5), the engine rotation speed calculated every time an engine rotation pulse is obtained. Compare N with a predetermined rotational speed N1, and determine the engine rotational speed N
If the rotation speed is equal to or higher than the predetermined rotation speed N1, it is assumed that the engine is rotating normally and data writing in step (4) is continued.

On the other hand, when the engine speed N1 falls below the predetermined speed N1, the process proceeds to step (6) and data writing is stopped. Therefore, the memory circuit 32 is in a state in which signal data from the time when data writing was stopped until a certain period of time ago has been written.

Next, in step (7), it is again determined whether the ignition switch is on or off. If the ignition switch is off at this point, the engine is not stalled, but the ignition switch is simply turned off to stop the engine, which is the normal state, so the process ends with the write stopped.

On the other hand, if the ignition switch is on,
Since there is a possibility that the engine stalls, the process proceeds to step (8), and the progress of the engine rotational speed N is further monitored for a certain period of time. For example, during a certain period of time, the engine speed N calculated by the flow shown in FIG.
It is determined whether the engine is stalled or not.

In step (9), the average value & is the predetermined rotation speed N2 (however, N
2<N1> or less, and if the engine speed does not fall below the predetermined number N2, it is a temporary drop in engine speed as shown by the solid line in FIG. 7 [A]. Since there is no need to record data for engine stalls,
Proceeding to step (10), the stoppage of data writing to the memory circuit 32 stopped in step (6) is canceled, and the process returns to step (4) again to restart data writing.

On the other hand, when the average value N falls below the predetermined rotation speed N2 in step (9), it is certain that the engine has stalled, so the process proceeds to step (11), and the writing is stopped in step (6). Control processing is performed to save the remaining data, and the series of processing ends.

As soon as the engine speed decreases, which is a symptom of engine stalling, data writing to the memory circuit is immediately stopped, and the progress of the engine speed is monitored from the time data writing is stopped to ensure that Only when the engine stalls, the remaining memory data in the writing stopped state is retained, so the memory circuit is sure to store the signal data for a certain period of time that causes the engine stall. By reproducing the data stored in the memory circuit after the engine stalls, the cause of the engine stall failure can be known reliably and quickly.

Although the above-mentioned embodiment takes an engine control system as an example, the present invention is not limited thereto, and can be applied to an automatic air conditioning system, an automatic transmission control system, which requires data storage for failure diagnosis, The present invention can be applied as is to any appropriate vehicle control system such as an anti-skid control system.

(Effects of the Invention) As described above, according to the present invention, when a change in the operating state leading to a system abnormality is detected, data writing to the memory circuit is first stopped, and after this data writing is stopped, the change in the operating state is detected. Abnormal phenomena are detected by monitoring for a certain period of time, and when a system error does not occur, the write stop is canceled and data writing is restarted, and when a system error occurs, the data at the time of writing stop is retained as is. Even if it takes a long time to determine whether an abnormality is detected, data writing is stopped at the time of the first abnormality determination, so data is not written in vain during the abnormality determination time. In addition, there is no need to secure memory capacity corresponding to the abnormality determination period, and signal data for a certain period that always leads to the cause of failure can be efficiently and reliably stored, allowing for quick and reliable investigation of the cause of failure by reproducing the stored data. becomes possible.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a flowchart showing signal storage control processing according to the embodiment of Fig. 1, and Fig. 3 is an engine rotation used to calculate the engine rotation speed. A time chart showing pulses and counting clock pulses, Fig. 4-5 is a block diagram showing a conventional example, Fig. 6 is an explanatory diagram showing conventional time-series signal storage,
FIG. 7 is a time chart showing changes over time in the engine speed when the engine stalls. 1: Sensor 2: Control circuit 3: Actuator 4.5: Connector 30: Input interface 31: Memory control circuit 32 2 Memory circuit 33: Backup power supply 34: Rotation speed processing circuit 35: Processing circuit 36: CPU 37: ROM 38 :RAM

Claims (1)

[Claims] A signal storage device that records signals necessary for diagnosing the cause of a system abnormality in a time-series manner in a storage circuit with a predetermined storage capacity, which monitors the operating state of the system and detects system abnormalities. A write stop means that stops writing data to the memory circuit when a change in the falling control state is detected, and a write stop means that monitors a change in the operating state after the stop of the write for a certain period of time, and stops the write when a system abnormality does not occur. A write restart means cancels the write stop and restarts the write, and a memory retention means holds the data at the time the write was stopped when a control abnormality occurs within a certain monitoring time after the write stop. A signal storage device characterized by: