JP2000274300A - Electronic control unit for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the problem of errors in calculation, regardless of the unexpected change of data showing an execution state of the calculation, from happening. SOLUTION: A thermostat 13 is provided between an engine 11 and a radiator 15 which is in the midstream of a circulation passage of engine cooling water. A water temperature sensor 20 detects the engine cooling water temperature, and an ECU 30 takes in the detected value. The ECU 30 decides that an abnormal decision condition of the thermostat 13 is satisfied only at cold start of the engine 11, and decides the presence of abnormality of the thermostat 13 according to the temperature change in the engine cooling water. The ECU 30 individually sets a state variable comprising plural bits according to the states before, during and after the abnormality decision of the thermostat 13. When abnormality occurrence in the state variable is detected, the ECU 30 rewrites the state variables to data showing abnormality decision completion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control unit for a vehicle that determines whether a thermostat is abnormal, for example, when the engine is cold started.

[0002]

2. Description of the Related Art Conventionally, a vehicle electronic control unit of this type has a function of determining an abnormality of various sensors, actuators, and the like, and performs an abnormality determination process according to a vehicle driving state. In particular, in recent years, thermostat abnormality determination has been legally regulated (US law, OBDII), and techniques for easily realizing normal / abnormal determination and abnormal location identification are being studied.

As an outline of the abnormality determination of the thermostat, a change in the temperature of the engine cooling water is monitored for a predetermined period after the engine is started, and the abnormality is determined only once based on the monitoring result. That is, when the thermostat is abnormal (for example, when the thermostat is open and fixed), the engine cooling water is cooled by the radiator even during the cold start. Therefore, the rate of rise in water temperature is slower than when the thermostat is normal. Using this characteristic, the presence or absence of an abnormality is determined based on the temperature change of the engine cooling water.

[0004]

As another abnormality determination process performed by the vehicle electronic control device, there is an abnormality (deterioration) determination process of the exhaust gas purifying catalyst.
If an abnormality determination is made during one trip of the vehicle traveling, the subsequent abnormality determination is not performed. That is,
At the time of such an abnormality determination, a flag indicating a state before and after the operation is operated, and it is determined from the state of the flag whether or not to execute the abnormality determination. Normally, one bit of one byte data is allocated to the flag, and when 1 is set to the flag after the abnormality determination, it is determined that the abnormality determination has already been completed based on the flag information thereafter. Had become.

[0005] If the flag inversion is not detected when the flag is inverted due to noise or the like, it is recognized that the abnormality determination has not been performed although the abnormality determination has been performed. It is considered that the determination process is performed again. In such a case, the possibility of erroneous determination is small because the catalyst abnormality can be re-determined in a normal vehicle operation state, the abnormality determination is re-executed without any problem, and the flag information is stored in the memory along with the determination result.

However, similar to the above-described catalyst abnormality determination, when the flag is operated at the time of abnormality determination of the thermostat and the abnormality determination is performed based on the flag information, the following problems can be considered. That is, if the flag is inverted from the value after the abnormality determination to the value before the abnormality determination during the operation of the vehicle, it is recognized that the abnormality determination of the thermostat has not been performed, and the abnormality determination is performed again. The determination is performed based on a change in the temperature of the engine cooling water immediately after the engine is started. Therefore, if the abnormality determination is performed after the engine is warmed up, there is a possibility that an erroneous determination is made.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to execute arithmetic processing erroneously even if data indicating the state of execution of arithmetic processing changes unexpectedly. It is an object of the present invention to provide a vehicular electronic control device capable of preventing such a problem.

[0008]

According to the first aspect of the present invention, at least two state data before and after execution of the arithmetic processing in a specific period are defined by a plurality of bits, and the state data of the plurality of bits is defined. A storage unit for storing, a detection unit for detecting an abnormality of the stored state data, and a prohibition unit for prohibiting the execution of the arithmetic processing when the state data abnormality is detected.

When some bit data in the status data is inverted due to data corruption (data destruction) or the like, a data abnormality is detected, and further execution of arithmetic processing is prohibited. In this case, since the status data is composed of a plurality of bits instead of 1-bit flag information as in the conventional device, an abnormality in the data can be appropriately detected when the bits are inverted. As a result, even if the data indicating the execution state of the arithmetic processing (state data) unexpectedly changes, it is possible to prevent a problem that the arithmetic processing is erroneously performed.

[0010] In the above invention, as described in claim 2,
When it is detected that the state data is abnormal, the state data may be used as data indicating that the arithmetic processing has been performed. When the state data is abnormal, if the data is changed to a value indicating “after execution” of the arithmetic processing, thereafter, the execution of the arithmetic processing is prohibited. As a result, as described above, it is possible to prevent a problem that the arithmetic processing is erroneously performed.

According to the third aspect of the present invention, at least two status data before and after the execution of the thermostat abnormality determination are defined by a plurality of bits, and storage means for storing the plurality of bits of status data; A detection unit for detecting an abnormality of the stored state data, and a prohibition unit for prohibiting the execution of the thermostat abnormality determination when the state data abnormality is detected.

When some bit data in the status data is inverted due to data corruption (data destruction) or the like, it is detected that the data is abnormal, and the subsequent execution of the thermostat abnormality determination is prohibited. In this case, the status data is
Since it is composed of a plurality of bits instead of 1-bit flag information as in the conventional device, an abnormality in the data can be appropriately detected when the bits are inverted. As a result, even if the data indicating the execution state of the abnormality determination processing (state data) unexpectedly changes, it is possible to prevent a problem that the determination processing is erroneously performed.

[0013] According to the present invention, as described in claim 4,
When the state data abnormality is detected, the state data may be data indicating that the thermostat abnormality determination has been performed. When the status data is abnormal, if the data is changed to a value indicating “after execution” of the abnormality determination process, the execution of the determination process is prohibited thereafter. As a result, as described above, it is possible to prevent a problem that the thermostat abnormality determination processing is erroneously performed.

According to the present invention, the status data is composed of a plurality of bits in one byte, and if the status data is invalid data for which no status data is defined, the detection means detects a data abnormality. I do.

When the status data is composed of a plurality of bits in one byte, only a few data are defined in advance among all the data in one byte, and the other data is undefined and undefined data. In this case, unlike the conventional device in which the inversion of the status flag could not be detected, the data abnormality can be detected by determining whether or not the data is invalid data that is not defined.

In the invention according to claim 6, the storage means stores a plurality of bits of data indicating that the operation is being performed, in addition to the two states before and after the execution of the arithmetic processing.
According to this configuration, three states before, during, and after the execution of the arithmetic processing can be suitably recognized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a control device for a vehicle engine will be described below with reference to the drawings.

First, a schematic configuration of the entire cooling system of the vehicle engine will be described with reference to FIG. Engine 11
A water jacket 12 is provided inside the cylinder block and the cylinder head, and cooling water is injected into the water jacket 12. A thermostat 13 is provided at an outlet of the water jacket 12, and high-temperature cooling water passing through the thermostat 13 is sent to a radiator 15 via a cooling water circulation path 14. The cooling water that has been radiated by the radiator 15 and has dropped in temperature is returned into the water jacket 12 through the cooling water circulation path 16. Therefore, when the thermostat 13 is opened, the cooling water circulates along the route of the water jacket 12, the thermostat 13, the cooling water circulation passage 14, the radiator 15, the cooling water circulation passage 16, and the water jacket 12.
Cool 1 to a suitable temperature.

Here, the operation of the thermostat 13 and the reason for disposing it will be briefly described. The thermostat 13 closes during the warm-up operation of the engine 11 to stop the circulation of the cooling water. As a result, the cooling water (particularly, the cooling water temperature is low during the warm-up operation) is not supplied to the engine 11, so that the engine 11 is quickly warmed up, and the fuel efficiency can be improved and the emission can be reduced. When the temperature of the cooling water on the engine 11 side reaches a predetermined thermostat valve opening temperature (for example, about 80 ° C.) and the thermostat 13 opens, the cooled cooling water on the radiator 15 side is circulated to the engine 11 side,
The engine temperature can be cooled to an appropriate temperature range.

A water pump 17 is provided at the inlet of the water jacket 12. The water pump 17 is connected to a cooling fan 18 installed behind the radiator 15, and the water pump 17 and the cooling fan 18 are integrally driven to rotate by engine power transmitted via a belt 19. The rotation of the water pump 17 promotes the circulation of the cooling water in the cooling water circulation path. Further, the heat radiation effect of the radiator 15 is enhanced by the rotation of the cooling fan 18, and the cooling of the cooling water in the radiator 15 is promoted.

A water temperature sensor 20 for detecting the temperature of the cooling water in the water jacket 12 is provided in a cylinder block of the engine 11. The mounting position of the water temperature sensor 20 may be a cooling water circulation path closer to the engine 11 than the thermostat 13, and may be, for example, a portion of the water jacket 12 on the cylinder head side.

The output signal of the water temperature sensor 20 is taken into an electronic control unit 30 (hereinafter abbreviated as "ECU"). The ECU 30 is mainly composed of a microcomputer and has functions such as engine control and abnormality diagnosis of the thermostat 13, which will be described later in detail.

The ECU 30 has a water temperature sensor 2 as information for performing engine control and thermostat abnormality diagnosis.
In addition to the coolant temperature signal from 0, the engine speed sensor 21
, An intake air amount signal from the intake air amount sensor 22, an intake air temperature signal from the intake air temperature sensor 23, and a vehicle speed signal from the vehicle speed sensor 24, and further indicate the operating state of the blower motor of the air conditioner 25. The signal is also read. The ECU 30 outputs a signal to a warning lamp 26 that warns the thermostat 13 and other abnormalities when it is determined.

FIG. 2 is a block diagram showing an electrical configuration inside and around the ECU 30. As shown in FIG. A one-chip microcomputer 40 is provided in the ECU 30. The ECU 30 is also provided with an input / output interface (I / O) 31 and an external device connection interface (I / F) 32. Through these interfaces 31 and 32, various sensors and actuators and one-chip Data exchange with the microcomputer 40 and data exchange between the external device 50 and the one-chip microcomputer 40 are realized respectively.

Here, the external device 50 is a device such as a personal computer having a data communication function, and has a function of reading out and displaying abnormal code information stored and held in the one-chip microcomputer 40. ing.

The one-chip microcomputer 40 includes:
CPU41, ROM42, RAM43, EEPROM4
4 and an address data bus 45 for electrically connecting these elements to the interfaces 31 and 32 are integrated in one IC (LSI) chip. The ROM 42 stores an engine control program, a thermostat abnormality determination program, and the like in advance. The RAM 43 is configured as a volatile memory that temporarily holds data when power is supplied, and the RAM 43 is used to write calculation results for engine control and abnormality diagnosis.
The EEPROM 44 is configured as a non-volatile memory that retains stored data without losing the stored data even when the power supply is cut off. The EEPROM 44 stores abnormality code information indicating a target for which abnormality has been determined and an operation state when an abnormality occurs. Abnormal information useful for identifying an abnormality, such as indicated data, is stored.

The power supply circuit 33 is provided in the ECU 30. The power supply circuit 33 converts the battery power to a predetermined constant voltage (5V) and supplies power to various electronic components in the ECU 30. Further, a main relay 51 is provided so that power is supplied to the ECU 30 even when the ignition is detected to be off. The ECU 30 performs a predetermined process after the ignition is turned off, and then switches off the main relay 51 to shut off its own power. It outputs a control signal.

In this embodiment, the engine 11
Only after the cold start, the temperature change of the engine cooling water is monitored to determine whether the thermostat 13 is abnormal. That is, when an “open failure” occurs in which the thermostat 13 is left open, even when the engine 11 is cold started, the cooling water in the radiator 15 is circulated through the water jacket 12 from the beginning, so that the engine 1
The rise of the cooling water temperature on one side is prevented. Therefore, the presence or absence of an open failure of the thermostat 13 is determined by detecting the degree of increase (inclination) of the cooling water temperature and comparing it with the normal state, and when a failure occurs, the driver is warned to that effect. In such a case, the open failure of the thermostat 13 can be determined only during a period in which the temperature rise process of the cooling water can be monitored during the cold start of the engine 11 and cannot be determined thereafter. Is forbidden so as not to be misjudged.

Incidentally, as an abnormal mode of the thermostat 13, there is a "close fault" in which the thermostat 13 is left closed in addition to the open fault.
Even if the cooling water temperature on the engine 11 side rises, the radiator 15
There is a possibility that the cooling water on the side is not circulated to the engine 11 side and the engine 11 is overheated. Therefore, the temperature change of the engine cooling water is monitored to determine the presence or absence of a closed failure, and when a failure occurs, the driver is warned of the failure. However, the closed failure of the thermostat 13 can always be determined not only during the cold start of the engine 11, and therefore, even if the abnormality determination is performed again after the completion of the engine warm-up, no erroneous determination is made.

Next, the process of judging a thermostat open failure will be described together with the process of judging an abnormality of the water temperature sensor 20 associated therewith. FIG. 3 is a flowchart showing the abnormality determination processing of the water temperature sensor 20, and the processing is executed by the CPU 41 at predetermined time intervals (for example, 65 ms).

In steps 101 and 102, it is determined whether or not the output voltage Vthw of the water temperature sensor 20 is within a range from a predetermined lower limit value Vmin to an upper limit value Vmax. The lower limit value Vmin and the upper limit value Vmax are set based on a water temperature value that can actually exist, and the output voltage V
If thw is an appropriate voltage value corresponding to, for example, water temperature = −40 to 120 ° C., both steps 101 and 102 are determined to be affirmative.

If the output voltage Vthw is within the proper range and both steps 101 and 102 are YES, step 10
Then, the process proceeds to step S6, where an abnormality determination counter N for counting the number of times the water temperature sensor 20 determines abnormality is reset to 0, and the present process is temporarily terminated.

On the other hand, if the output voltage Vthw falls outside the appropriate range and the result of any of steps 101 and 102 is NO, it is determined that the water temperature sensor 20 is disconnected or short-circuited, and the routine proceeds to step 103. In step 103, the abnormality determination counter N is incremented by one, and abnormality determination is performed five times in a row. If step 104 is affirmatively determined, the process proceeds to step 105. In step 105, the code information indicating the abnormality of the water temperature sensor 20 is stored in the RAM 43, and the process ends.

It should be noted that the abnormality determination method other than the water temperature sensor 20 is different from the determination method itself, but if it is determined that an abnormality has occurred, the abnormality code information is stored in the RAM as in step 105.
The processing stored in 43 is executed.

FIG. 4 is a flowchart showing the abnormality determination processing of the thermostat 13, and this processing is executed by the CPU 41 at predetermined time intervals (for example, 65 ms). According to this process, an open failure (open-open failure) is determined among the abnormal modes of the thermostat 13. In the process of FIG. 4, the state variable e composed of a plurality of bits in one byte
Using the jdg, the state variable e is individually set depending on whether the state is before abnormality determination, during abnormality determination, or abnormality determination completed.
One of “0”, “2”, and “4” is set in jdg. In this case, out of all data (256 data) in one byte, only three ejdg values are defined in advance, and the other ejdg values are undefined illegal data.

More specifically, first, in step 201, it is determined whether or not the engine has been started. For example, if the engine speed is 400 rpm or more and a starter switch (not shown) is off, it is determined that cranking has been completed and engine start has been completed. If a negative determination is made in step 201 at the beginning of the engine startup, the routine proceeds to step 202, where the state variable ejdg is set to “0” indicating before the abnormality determination, and the ejdg value is stored in the RAM 43.

If the engine has been started, step 2
Proceeding to 03, it is determined whether or not the abnormality determination of the thermostat 13 has been completed based on the state variable ejdg. e
If jdg = 4, it is considered that the abnormality determination has already been completed, and this processing is terminated as it is.

If ejdg ≠ 4, it is determined that the abnormality determination has not been completed, and the routine proceeds to step 204, where it is determined whether or not the abnormality determination of the thermostat 13 is being performed based on the state variable ejdg. Determine. At this time, if ejdg = 0 or 2, step 204 is affirmatively determined, and the routine proceeds to step 205. In step 204, it is also determined whether or not the engine 11 is in a cold start, and only when it is determined that the engine 11 is in a cold start, the affirmative determination in step 204 is made.

In step 205, the comparison water temperature Tf is calculated from the operation state history such as the intake air amount and the vehicle speed. That is, when step 205 is first performed, the state variable ejd
g is “0”, and the detected value (actual value) of the cooling water temperature is set as the comparative water temperature Tf. When step 205 is performed for the second time or later, the state variable ejdg is “2”, and a predetermined value determined according to the intake air amount or vehicle speed at that time is added to the previous value of the comparison water temperature Tf, The value after the addition is set as a new comparison water temperature Tf. At this time, the comparative water temperature Tf is set to a larger value, for example, as the intake air amount increases or the vehicle speed increases.

Thereafter, at step 206, it is determined whether or not the abnormality determination condition of the thermostat 13 is satisfied.
Here, the abnormality determination condition is to determine that monitoring of a change in cooling water temperature during a predetermined period after starting the engine has been completed, and that an abnormality determination can be made based on the monitored water temperature data. 1. 1. A predetermined time (about two or three minutes) has elapsed since the start was completed; 2. The calculated comparison water temperature Tf has risen to a predetermined temperature (for example, a thermostat valve opening temperature); It is determined that the water temperature sensor 20 has been determined to be normal (determined by the processing in FIG. 3), and the process proceeds to step 208 when all of these conditions are satisfied.

At the beginning of the abnormality determination process, the above-mentioned determination condition is not satisfied, and the result of step 206 is negative, and the process proceeds to step 207. In step 207, the state variable e
jdg is set to “2” indicating that the abnormality is being determined, and the ejdg value is stored in the RAM 43. Then, thereafter, the present process is temporarily ended.

When the abnormality determination condition is satisfied, step 20 is executed.
8 and the current cooling water temperature Thw and step 205
Thermostat 1 by comparing with the comparative water temperature Tf calculated in
The normal / abnormal judgment of 3 is performed. Specifically, the cooling water temperature Th
If the difference between w and the comparison water temperature Tf is equal to or less than a predetermined value, it is considered that the thermostat 13 is closed and the cooling water temperature is quickly increased, and it is determined that the thermostat 13 is normal.
If the difference between the cooling water temperature Thw and the comparison water temperature Tf exceeds a predetermined value, it is considered that the thermostat 13 has been opened and the water temperature rise has been delayed, and the thermostat 13 is determined to be abnormal (open failure). When it is determined that an open fault has occurred,
The code information indicating the occurrence of the abnormality is stored in the RAM 43.

When the abnormality determination is completed, the process proceeds to step 209, where the state variable ejdg is set to "4" indicating the completion of the abnormality determination, and the ejdg value is stored in the RAM 43. After that, this processing ends. When the state variable ejdg is rewritten to “4”, step 203 is repeated every time thereafter.
It becomes ES and the abnormality determination of the thermostat 13 is not performed again.

On the other hand, when both steps 203 and 204 are judged to be negative, the process proceeds to step 209 without performing the abnormality determination process after step 205. Then, in step 209, the state variable ejdg is set to “4” indicating the completion of the determination.
And the ejdg value is stored in the RAM 43. That is, the negative determination of both steps 203 and 204 means that the state variable ejdg is “0, 2, 4”, which is defined in advance.
It is thought that the data is incorrect. Therefore,
When such a data abnormality is detected, the state variable ej
dg is rewritten to “4” indicating the completion of the determination, and the erroneous determination is prevented by preventing the subsequent abnormality determination processing from being performed.

It is assumed that the state variable ej is determined during the abnormality determination.
When a dg abnormality (data corruption) is detected, the state variable e
In addition to jdg, there is a high possibility that data in the same RAM is corrupted, and in such a case, the abnormality determination is forcibly stopped. This prevents a problem that the thermostat 13 is erroneously determined to be abnormal.

Incidentally, when the ignition switch (not shown) is turned off, the abnormality code information of the water temperature sensor 20 and the thermostat 13 determined in FIGS.
In addition, learning value data related to the fully closed position of the actuator such as the ISC valve and the EGR valve and the air-fuel ratio control amount, etc.
The data is transferred from the M43 to the EEPROM 44. And E
After the data is transferred to the EPROM 44, the main relay 51 is turned off and the power supply to the ECU 30 is stopped.

In the present embodiment, step 2 in FIG.
02, 207, and 209 correspond to “storage means” of the present invention, and steps 203 and 204 correspond to “detection means”. Step 209 corresponds to “prohibiting means”.

According to the embodiment described above, the following effects can be obtained. (1) An abnormality of a state variable ejdg (= state data) composed of a plurality of bits is detected, and when an abnormality occurs, the state variable ejdg is rewritten to data indicating completion of abnormality determination, and further abnormality determination is prohibited. Therefore, even if the state variable ejdg changes unexpectedly, it is possible to prevent a problem that the abnormality determination processing of the thermostat 13 is erroneously performed. In this case, since the state variable ejdg is composed of a plurality of bits instead of 1-bit flag information as in the conventional device, when the bit is inverted, the abnormality of the state variable can be appropriately detected.

(2) The state variable ejdg is composed of a plurality of bits in one byte, and if the ejdg value is not defined, it is detected that an abnormality has occurred. As a result, the necessity of performing the abnormality determination process can be accurately determined.

(3) In addition to the two states of before and after the abnormality determination (before and after the execution of the arithmetic processing), a state variable ejdg indicating that the abnormality is being determined is stored. A state can be recognized suitably. Accordingly, it is possible to prevent the inappropriate abnormality determination processing from being performed after the abnormality determination is completed, and also to prevent the erroneous determination processing from being performed when the RAM value is destroyed during the abnormality determination.

The present invention can be embodied in the following forms other than the above. In the above embodiment, the thermostat 13
As the state variable ejdg indicating three states of before abnormality determination, during abnormality determination, and completion of abnormality determination,
Each value of "0, 2, 4" was set and stored in the RAM as needed, but this configuration is changed. As the state variable ejdg, two values (for example, only 0 and 4) indicating two states of before and after the abnormality determination are given, and the state variable ejdg is stored in the RAM as needed. When the abnormality determination processing of the thermostat 13 is performed, the state variable ejdg is set to “0, 4”.
If the data is other than the above, it is determined that the variable is abnormal, and the state variable ejdg is rewritten to “4” indicating the completion of the abnormality determination.

Alternatively, a total of four or more values may be set as the state variable ejdg. Specifically, two or more values are given as a state variable ejdg indicating that abnormality is being determined,
It is configured to operate a total of four or more state variables ejdg before and after the abnormality determination. In such a configuration, for example, ejdg = 0 before abnormality determination, ejdg = 2 or 4 during abnormality determination, and ejdg = 8 after abnormality determination is completed. When the abnormality determination process of the thermostat 13 is performed, if the state variable ejdg becomes data other than “0, 2, 4, 8”, it is determined that the variable is abnormal, and the state variable ejdg is determined.
To “8” indicating the completion of the abnormality determination.

In the above embodiment, when the abnormality of the state variable ejdg is detected, the state variable ejdg is rewritten to the value (ejdg = 4) indicating the completion of the abnormality judgment. The state data abnormality detection value may be rewritten. For example, in the process of FIG. 4, when both steps 203 and 204 are NO (except when the engine is not cold started), step 20 is executed.
Unlike 2,207 and 209, “ejdg = 8” is written into the RAM 43 as the state data abnormality detection value, and thereafter, the execution of the abnormality determination processing is prohibited and the ejd
Keep the g value. According to this configuration, in the abnormality diagnosis using the external device 50 of FIG. 2, by reading the ejdg value, the abnormality of the ejdg value can be easily diagnosed, and the abnormality analysis can be suitably performed.

In the above embodiment, the thermostat 13
When the abnormality occurrence (open failure) is determined, the abnormality code information is temporarily stored in the RAM 43, and after the ignition is turned off, the RAM value is transferred to the EEPROM 44, but this configuration is changed. For example, thermostat 13
When the occurrence of an abnormality (open failure) is determined, the abnormality code information is stored in the EEPROM 44 immediately thereafter. As described above, the arithmetic processing such as the abnormality determination processing for the water temperature sensor 20 that satisfies the execution conditions many times during vehicle operation is performed as described above.
Once stored in M43, the RA
The M value is transferred to the EEPROM 44. According to this configuration,
Even if data in the RAM value is corrupted (data destruction) during normal operation of the vehicle, the code information can be reliably stored and retained without the code information being lost and not being obtained thereafter. The abnormality code information of the water temperature sensor 20 is stored in the EEPROM after the ignition is turned off.
Since the data is stored in the memory 44, there is no inconvenience that writing to the EEPROM 44 frequently occurs during driving of the vehicle, which hinders calculation of vehicle control.

In the above embodiment, based on the detection result of the water temperature sensor 20 disposed on the engine 11 side, the open failure of the thermostat 13 (opening abnormality) based on the amount of water temperature change during a predetermined period at the time of cold start of the engine. However, such an abnormality determination method may be appropriately changed. For example, another water temperature sensor is provided closer to the radiator 15 than the thermostat 13, and an open failure of the thermostat 13 is determined using the detection result of the water temperature sensor. In this case, it is preferable to compare the water temperature data on the engine 11 side with respect to the thermostat 13 and the water temperature data on the radiator side with respect to the thermostat 13 and determine the presence or absence of an abnormality according to the temperature difference. 176534, "Thermostat fault detecting device").

The nonvolatile memory for storing and holding the abnormal code information and the like is not limited to the above-described EEPROM 44, but may be another rewritable ROM (EPROM or flash ROM).
Etc.) can be adopted.

In the above-described embodiment, the processing for judging the abnormality of the thermostat 13 at the time of the cold start of the engine 11 has been described as an example of the arithmetic processing in which the execution condition is satisfied only during a specific period during the operation of the vehicle. It is also possible to apply. Immediately after the execution of the other calculation processes, such as a calculation process in which the execution condition is satisfied only once during vehicle operation and a calculation process in which the execution condition is satisfied every several hours, the calculation results are stored in an EEPROM (non-volatile memory). ) Can prevent the loss of the operation result, and as described above, provide an excellent effect that the operation result can be securely stored and held.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically illustrating an entire engine cooling system according to an embodiment of the invention.

FIG. 2 is a block diagram showing an electrical configuration inside and around an ECU.

FIG. 3 is a flowchart showing an abnormality determination process of a water temperature sensor.

FIG. 4 is a flowchart showing a thermostat abnormality determination process.

[Explanation of symbols]

11 ... engine, 13 ... thermostat, 14, 16 ...
Cooling water circulation path, 15: radiator, 30: ECU, 41
... CPU constituting storage means, detection means and prohibition means.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F01P 11/16 F01P 11/16 E

Claims (6)

[Claims] An electronic control unit for a vehicle, which performs a predetermined arithmetic processing only during a specific period during vehicle operation based on a plurality of state data, wherein at least two of the arithmetic processing during the specific period are performed before and after the execution. Storage means for defining one state data by a plurality of bits and storing the state data of the plurality of bits; detection means for detecting an abnormality of the stored state data; An electronic control unit for a vehicle, comprising: prohibition means for prohibiting execution of processing. 2. The electronic control unit for a vehicle according to claim 1, wherein said prohibiting means sets the status data as data indicating a state after the execution of the arithmetic processing when the status data is detected to be abnormal. 3. A thermostat is provided between the engine and the radiator in the middle of a circulation path of the engine cooling water, and based on a plurality of state data, a thermostat abnormality is detected from a change in the cooling water temperature only when the engine is cold started. An electronic control unit for a vehicle, wherein at least two state data before and after execution of a thermostat abnormality determination are defined by a plurality of bits, and storage means for storing the plurality of bits of state data; An electronic control device for a vehicle, comprising: detection means for detecting an abnormality in data; and prohibition means for prohibiting the execution of thermostat abnormality determination when a state data abnormality is detected. 4. The electronic control unit for a vehicle according to claim 3, wherein said prohibition means sets the status data as data indicating a state after the execution of the thermostat abnormality determination when the status data abnormality is detected. 5. The status data is composed of a plurality of bits in one byte, and the detection means detects a data abnormality if the status data is invalid data that is not defined.
The electronic control unit for a vehicle according to any one of the above. 6. The vehicle according to claim 1, wherein said storage means stores a plurality of bits of data indicating that the arithmetic processing is being performed, in addition to two states before and after the arithmetic processing. For electronic control device.