JPH0742602A - Memory backup power supply monitor in on-vehicle electric apparatus - Google Patents

Abstract

PURPOSE:To accurately and surely detect abnormality of a backup electric power line for connecting an on-vehicle mounted battery to a volatile memory. CONSTITUTION:A monitor is provided with a backup RAM 55, an on-vehicle battery 26, a main electric power line 66, a backup electric power line 71, a voltage measuring circuit 29, a CPU 52, etc. The on-vehicle battery 26 and an electronic controll unit(ECU) 51 are connected to each other by a main electric line 66 via an ignition switch 25. The on-vehicle battery 26 and the backup RAM 55 are mutually connected by bypassing the ignition switch 25 by the backup electric line 71. Voltage (backup voltage) of the backup electric power line 71 is detected by the voltage measuring circuit 29. Abnormality of the backup electric power 71 is judged by the CPU 52 when data stored in the backup RAM 55 are abnormal, and the backup voltage is lower than a specified reference voltage preliminarily set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory backup power supply monitoring device for an on-vehicle electronic device, and more particularly to a memory backup power supply monitoring device for monitoring an abnormality of a backup power line connecting a vehicle battery and a memory.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection control device for an internal combustion engine for a vehicle, in order to obtain a mixed gas having an appropriate air-fuel ratio,
The state of the vehicle is detected by various sensors and the detection signal is sent to the microcomputer. These detection signals are
The memory included in the microcomputer is used for arithmetic processing, and the arithmetic result becomes a command for operating an actuator such as a fuel injection valve. This memory is a read-only read-only memory (ROM)
In addition to the random access memory (RAM) that enables reading and writing, the backup RAM is used. The backup RAM is a memory for holding necessary data such as an abnormality diagnosis result and a learning value used for air-fuel ratio control even when the ignition switch of the vehicle is turned off. An in-vehicle battery is generally used as a power supply (backup power supply) for operating the backup RAM.

In the backup RAM, the actual voltage applied to the backup RAM (backup voltage) may be lower than the voltage required to operate the backup RAM. This phenomenon occurs when the voltage of the vehicle-mounted battery drops, the backup power line connecting the vehicle-mounted battery and the backup RAM is disconnected, or the vehicle-mounted battery is disconnected from the backup power line. Then, the data stored in the backup RAM is destroyed, and if the data is used as it is, the actuator will be actuated by incorrect data.

Therefore, for example, in Japanese Utility Model Laid-Open No. 4-72727, the voltage of the backup power line (backup voltage) is constantly monitored, and when the backup voltage becomes lower than the reference voltage, the backup power line is abnormal. It is determined (prior art 1).

Further, for example, in JP-A-58-153299 and JP-A-60-112127, it is determined that the backup power line is abnormal when the data stored in the backup RAM is destroyed. (Prior art 2).

[0006]

However, in the prior art 1, the backup voltage is constantly monitored for comparison between the backup voltage and the reference voltage. Therefore, when the voltage of the on-vehicle battery drops with the start of the internal combustion engine for the vehicle, or the wire harness is momentarily disconnected during rough road running of the vehicle, the backup voltage temporarily becomes lower than the reference voltage. However, the backup power line may be erroneously determined to be abnormal.

The data stored in the backup RAM may be destroyed by a user or a service person who intentionally removes the on-vehicle battery from the vehicle, other than when the backup power line becomes abnormal. There is also a possibility. This can be replaced by a new on-board battery or backup RAM
The purpose is to initialize the data stored in (for example, a failure code used for failure diagnosis or a learning value of air-fuel ratio control). For this reason, in the related art 2, it is impossible to distinguish whether the data destruction is due to the temporary removal of the vehicle-mounted battery or the abnormality in the backup power line.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a memory backup power supply monitoring device in an on-vehicle electronic device which can detect only a true abnormality of a backup power line.

[0009]

In order to achieve the above object, the present invention is provided in an on-vehicle electronic device M1 for driving and controlling a vehicle as shown in FIG. 1, and stores data relating to the driving of the vehicle. The in-vehicle battery M3 that also serves as a backup power source for the volatile memory M2 and the memory M2 and that supplies power for operating the memory M2.
A main power line M5 that connects between the vehicle-mounted battery M3 and the vehicle-mounted electronic device M1 via the switch M4; a backup power line M6 that bypasses the switch M4 and connects between the vehicle-mounted battery M3 and the memory M2; Data abnormality detecting means M7 for detecting the presence or absence of abnormality in the data stored in M2, backup voltage detecting means M8 for detecting the voltage of the backup power line M6 as a backup voltage, and the data abnormality detecting means M7.
When the abnormality of the data in the memory M2 is detected by the backup voltage detecting means M8, the backup voltage detecting means M8 compares the backup voltage with the reference voltage. And M9.

[0010]

The electric power of the vehicle-mounted battery M3 also serving as a backup power source is supplied to the memory M2 via the backup power line M6 bypassing the switch M4. Therefore, the memory M2 continues to hold the stored data even when the switch M4 is opened.

The data in the memory M2 is destroyed when the power supply from the vehicle-mounted battery M3 is cut off. In the present invention, the cause of the interruption of the power supply is the backup power line M.
It is determined whether or not it is due to the abnormality of No. 6 as follows.

Whether or not there is an abnormality in the data stored in the memory M2 is detected by the data abnormality detecting means M7.
The voltage of the backup power line M6 is detected as the backup voltage by the backup voltage detection means M8. Then, the data abnormality detecting means M7 causes the memory M2.
When the abnormal data is detected, the monitoring means M9 compares the backup voltage detected by the backup voltage detection means M8 with the reference voltage. According to the comparison, if the backup voltage is lower than the reference voltage, the monitoring means M9 determines that the backup power line M6 is abnormal.

As described above, the backup voltage and the reference voltage are compared only when the abnormality of the data in the memory M2 is detected. Therefore, even if the voltage of the on-vehicle battery M3 drops with the start of the internal combustion engine for a vehicle, or the wire harness is momentarily cut off during rough road traveling of the vehicle, the backup voltage temporarily becomes lower than the reference voltage. , The two voltages are not compared, and the backup power line M6 is not determined to be abnormal.

In addition to the abnormality such as the disconnection of the backup power line M6, the cause of the data abnormality of the memory M2 may be that the user or a service person intentionally removes the vehicle-mounted battery M3 from the vehicle. On the other hand, when the backup power line M6 becomes abnormal due to a disconnection or the like, only the backup voltage drops. Therefore, by comparing the two voltages, it is possible to distinguish whether the data abnormality is due to the abnormality of the backup power line M6 or the removal of the vehicle-mounted battery M3.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. FIG. 2 is a schematic configuration diagram showing a gasoline engine having a memory backup power supply monitoring device of the present embodiment and its peripheral devices. The vehicle is equipped with a V-type engine as an internal combustion engine. In the engine main body 1 that constitutes the majority of the V-type engine, each cylinder is divided into a left bank 2 and a right bank 3. Intake manifolds 4L and 4R and exhaust manifolds 5L and 5R are connected to the left and right banks 2 and 3, respectively.

The intake manifolds 4L and 4R are communicated with a common surge tank 6 and intake pipe 7, respectively.
An air cleaner 8 is provided on the inlet side of. Each of the intake manifolds 4L and 4R, the surge tank 6, the intake pipe 7 and the like constitute an intake passage. The air taken in from the air cleaner 8 is guided to the intake manifolds 4L and 4R through the intake pipe 7 and the surge tank 6. Further, the air guided to the intake manifolds 4L, 4R is supplied to the combustion chambers 2a, 3 at the timing when the intake valves 9L, 9R are opened in the left and right banks 2, 3, respectively.
It is introduced into a.

In the middle of the intake pipe 7, each combustion chamber 2a, 3a
A throttle valve 10 for adjusting the intake air amount Q introduced into the engine is provided. The throttle valve 10 is opened and closed in conjunction with the operation of an accelerator pedal (not shown).
The intake manifolds 4L, 4R are respectively provided with injectors 11L, 11R for fuel injection corresponding to the respective cylinders. Further, spark plugs 12L and 12R are provided in the left and right banks 2 and 3, respectively, corresponding to the cylinders. Each of the injectors 11L and 11R is opened by energization, and by the opening of the injector, fuel pressure-fed from a fuel tank (not shown) is injected into each of the intake manifolds 4L and 4R. The injected fuel becomes a mixture with air and is introduced into each combustion chamber 2a, 3a. Furthermore, in each combustion chamber 2a, 3a, the introduced air-fuel mixture is exploded / combusted by the operation of the spark plugs 12L, 12R.

On the other hand, each exhaust manifold 5L, 5R constitutes a part of the exhaust passage. Each exhaust manifold 5L, 5
Exhaust gas after combustion is led to each R from the combustion chambers 2a and 3a at the timing when the exhaust valves 13L and 13R are opened. Then, three-way catalytic converters 14L and 14R are connected to the exhaust manifolds 5L and 5R, respectively, in order to purify the discharged exhaust gas and discharge it into the atmosphere. In addition, each three-way catalytic converter 14L, 14
Exhaust pipes 15L and 15R are connected to R, respectively. Further, the downstream side of each exhaust pipe 15L, 15R is connected to one common exhaust pipe 16. Each of the three-way catalytic converters 14L and 14R includes a hydrocarbon (H
C) and carbon monoxide (CO) are oxidized and nitrogen oxide (NOx) is reduced to purify the exhaust gas.

Each spark plug 12 in each of the left and right banks 2 and 3
L and 12R have separate distributors 17L and 1
The ignition signal distributed at 7R is applied. Each distributor 17L, 17R is a separate igniter 18
The high voltage output from L, 18R is applied to the crankshaft 1
Each spark plug 12 in synchronization with the rotation of 9 (crank angle)
Distribute to L and 12R. And each spark plug 12L,
The ignition timing of 12R is the same for each igniter 18L, 18L.
It is determined by the high voltage output timing from R.

The engine body 1 is provided with a rotation speed sensor 31 for detecting the rotation speed of the crankshaft 19 as the engine rotation speed NE. Further, the left and right banks 2 and 3 of the engine body 1 are provided with crank angle reference positions G1 and G2, such as cylinder discrimination and top dead center position, based on the rotation of the camshafts 20L and 20R that interlock with the crankshaft 19. A first cylinder discrimination sensor 32 and a second cylinder discrimination sensor 33 for detecting are provided.

An air flow meter 34 is attached downstream of the air cleaner 8. This air flow meter 3
4, the amount Q of intake air taken into each combustion chamber 2a, 3a of the engine body 1 through the intake pipe 7 and the like is detected. An intake air temperature sensor 35 is attached near the air flow meter 34. With this intake air temperature sensor 35, the intake pipe 7
The temperature of the air taken in, that is, the intake air temperature THA is detected. A throttle sensor 36 is provided near the throttle valve 10. The throttle sensor 36 detects the opening of the throttle valve 10, that is, the throttle opening TA. A water temperature sensor 37 is attached to the engine body 1. This water temperature sensor 37
Thus, the temperature of the cooling water in the engine body 1, that is, the cooling water temperature THW is detected.

On the other hand, a first air-fuel ratio sensor 38 and a second air-fuel ratio sensor 39 are provided on the upstream side and the downstream side of the one-way three-way catalytic converter 14L in the middle of the exhaust passage. Similarly, the third air-fuel ratio sensor 40 and the fourth air-fuel ratio sensor 4 are provided in the middle of the exhaust passage and upstream and downstream of the other three-way catalytic converter 14R.
1 are provided respectively. These air-fuel ratio sensors 3
The oxygen concentration Ox in the exhaust gas is detected from 8 to 41. Each of the air-fuel ratio sensors 38 to 41 is provided with a sensor element having a temperature characteristic, and for the purpose of adjusting their temperature,
Each of the air-fuel ratio sensors 38 to 41 is provided with a first heater 38a, a second heater 39a, a third heater 40a, and a fourth heater 41a of an electric heating type for heating the sensor element.

A vehicle speed sensor 42 is provided on the transmission 21 drivingly connected to the engine body 1. The vehicle speed sensor 42 detects the traveling speed of the vehicle, that is, the vehicle speed SPD.

In addition, the intake passage is provided with a bypass passage 22 that bypasses the throttle valve 10 and connects the upstream intake pipe 7 of the valve 10 and the downstream surge tank 6 to each other. A linear solenoid type idle speed control valve (ISCV) 23 is provided in the middle of the bypass passage 22. The opening of the ISCV 23 is controlled to stabilize the idling of the engine when the throttle valve 10 is fully closed. Therefore, by controlling the opening of the ISCV 23 during idling, the amount of air flowing through the bypass passage 22 is adjusted, and as a result, the amount Q of intake air into the combustion chambers 2a, 3a of the left and right banks 2, 3 is adjusted. It

On the other hand, a warning lamp 24 is provided on the instrument panel (not shown) in the driver's seat of the vehicle. The warning lamp 24 is turned on to inform the driver of the occurrence of an abnormality when an abnormality occurs in the backup power line 71 described later. The warning lamp 24 is connected to an in-vehicle battery 26 via an ignition switch 25 for starting and stopping the engine body 1.

Further, the vehicle of this embodiment has a self-diagnosis function for detecting an abnormality in each part, storing the abnormality, and displaying the abnormality. Therefore, an external diagnostic device 27 is provided separately from the vehicle. This external diagnostic device 2
7 is usually installed in a repair shop, and is connected to the vehicle through a connector 28 by a service person when the vehicle is inspected or repaired.

The various sensors 31 to 33, 35 to 42,
Various actuators 11L, 11R, 18L, 18R, 23, 24, 38 based on the detection signals from the air flow meter 34 and the diagnosis request signal from the external diagnosis device 27.
An electronic control unit (hereinafter referred to as “ECU”) 51 as an on-vehicle electronic device is provided to drive and control the a, 39a, 40a, 41a and the external diagnostic device 27.

FIG. 3 shows the internal structure of the ECU 51.
The ECU 51 includes a central processing unit (CPU) 52, a read-only memory (ROM) 53, and a random access memory (RAM) 5 which constitute data abnormality detection means and monitoring means.
4. Backup RAM 55 as volatile memory,
An A / D converter 56, an input / output device 57, a serial communication controller 58, and the like are provided, and these are connected to each other by a bus 59. The CPU 52 executes various arithmetic processes according to a preset control program, and the ROM 53 stores in advance control programs and initial data necessary for the CPU 52 to execute arithmetic processes. The RAM 54 temporarily stores the calculation result of the CPU 52. Backup R
The AM 55 is backed up by the in-vehicle battery 26 so as to retain various data even after the power is turned off.

The backup RAM 55 is shown in FIG.
A plurality of data areas (first data area 110, second data area 120, third data area 130) as shown in (a) and (b) are prepared. Each data area 11
Reference numerals 0, 120, and 130 denote areas 111 and 12 for storing failure codes (hereinafter referred to as failure code storage areas).
1, 131, an area for storing a frame number (priority order) (hereinafter, referred to as a frame number storage area) 112,
122, 132, areas for storing data indicating the vehicle state (hereinafter, referred to as vehicle state storage area) 113, 1
It consists of 23 and 133. Here, the frame number indicates the priority order (important failure order of failures, that is, importance),
The smaller the value is, the more important the failure is.
Further, as the data indicating the state of the vehicle, the engine speed NE, the vehicle speed SPD, the engine load (the amount of intake air per one engine revolution) Q / N, the throttle opening TA, etc. are used.

In the backup RAM 55,
When no abnormality has occurred in the fuel system or sensor of the vehicle, data indicating the vehicle state is stored in each vehicle state storage area 113, 123, 133. Then, this data is updated every predetermined time (for example, 8 ms) unless an abnormality occurs. Also, if no abnormality occurs in this way,
Failure codes are not stored in the failure code storage areas 111, 121, 131, and the frame number storage areas 112, 12
No frame number is stored in 2,132.

As shown in FIG. 3, the A / D converter 56 is used.
An air flow meter 34, an intake air temperature sensor 35, a water temperature sensor 37, and air-fuel ratio sensors 38 to 41 are connected to each. Further, an on-vehicle battery 26 is connected to the A / D converter 56 via a voltage measuring circuit 29 and an ignition switch 25. The voltage measuring circuit 29 constitutes a backup voltage detecting means.

The external diagnostic device 27 is detachably connected to the serial communication controller 58 via the connector 28. Then, serial communication is performed between the external diagnostic device 27 and the serial communication controller 58 to exchange data.

The input / output device 57 is connected to the rotation speed sensor 31, the cylinder discrimination sensors 32 and 33, the throttle sensor 36, and the vehicle speed sensor 42, respectively. The I / O device 57 includes an ISCV 23, each injector 11L,
11R, each igniter 18L, 18R and warning lamp 2
4 are connected to each other. Further, the heaters 38 a to 41 a are connected to the input / output device 57 via the drive circuit 60.

Then, the CPU 52 controls the sensors 31 to 31.
Various signals from 3, 35 to 42, the air flow meter 34, the vehicle-mounted battery 26, etc. are read as input values via the A / D converter 56 and the input / output device 57. Also, CPU5
Reference numeral 2 reads a diagnosis request signal (for example, a frame number indicating the importance of abnormality) output from the external diagnosis device 27 as an input value via the serial communication controller 58.

The CPU 52 performs various calculations based on these input values, and suitably drives and controls the ISCV 23, the injectors 11L and 11R, the igniters 18L and 18R, and the warning lamp 24 via the input / output device 57 based on the calculation results. . Similarly, the CPU 52 uses the input / output device 57 and the drive circuit 60 to output each heater 3 based on the calculation result.
8a-41a are suitably drive-controlled.

For example, the CPU 52 has the valve opening time (injection time) of the injectors 11L and 11R for determining the fuel injection amount.
TAU is calculated according to the following equation (1). TAU = TP × FAF × GAF × K (1) where TP is the basic injection time, the ratio of the intake air amount Q by the air flow meter 34 and the engine speed NE by the speed sensor 31, more specifically, the engine. It is a value obtained from the intake air amount per rotation (Q / N). FAF is an air-fuel ratio correction value, and the first and second air-fuel ratio sensors 38, 3
It changes around “1.0” based on the signal from 9.
GAF is an air-fuel ratio correction learning value stored in the backup RAM 55. In the present embodiment, the air-fuel ratio correction learning value GAF changes in the vicinity of "1.0" when the air-fuel ratio correction value FAF is close to "1.0", and the air-fuel ratio correction value FAF is out of the predetermined range. When changes. K is a correction coefficient, which is determined by the cooling water temperature THW detected by the water temperature sensor 37, the intake air temperature THA detected by the intake air temperature sensor 35, and the like.

Further, the CPU 52 uses various sensors 31 to 31.
3, 35-42, air flow meter 34, misfire, fuel system, three-way catalyst, etc. are diagnosed. Then, the CPU 52
When the diagnosis request signal is received from the external diagnostic device 27, the diagnostic result is output to the external diagnostic device 27 via the serial communication controller 58 and displayed on the same device 27. The diagnosis content also includes whether or not the data stored in the backup RAM 55 has been destroyed.

Next, the on-vehicle battery 26 and the backup R
The connection relationship with the AM 55, the configuration of the voltage measuring circuit 29, and the like will be described. As shown in FIG. 4, the positive terminal of the vehicle-mounted battery 26 is connected to the E terminal via the ignition switch 25.
The external input terminal 61 of the CU 51 is connected to the power source I
The internal input terminal 63 of C62 is connected. Power supply IC
The A / D converter 56 is connected to the internal output terminals 64 and 65 of 62.
And the CPU 52 are respectively connected. A line connecting the on-vehicle battery 26 and the A / D converter 56 and a line connecting the on-vehicle battery 26 and the CPU 52 are main power lines 66. The main power line 66 is provided only when the ignition switch 25 is on.
This is for supplying normal power (main power) of the on-vehicle battery 26 to the A / D converter 56 and the CPU 52.

Similarly, the positive terminal of the on-vehicle battery 26 bypasses the ignition switch 25 and bypasses the ECU 5
1 external input terminal 67 is connected to the power supply IC 62
The internal input terminal 68 of is connected. The backup RAM 55 is connected to the internal output terminal 69 of the power supply IC 62. A line that bypasses the ignition switch 25 and connects the vehicle-mounted battery 26 and the backup RAM 55 is a backup power line 71. Therefore, the in-vehicle battery 26 functions as a backup power supply, and the backup power is supplied from the in-vehicle battery 26 to the backup RAM 55 via the backup power line 71. Therefore, power is supplied to the backup RAM 55 regardless of the on / off operation of the ignition switch 25, and the backup RA
The data stored in M55 is retained.

The external input terminal 67 is grounded via resistors 75 and 76 connected in series, and the input terminal 77 of the A / D converter 56 is connected to a connection point b between the resistors 75 and 76. . Therefore, the voltage of the on-vehicle battery 26 is equal to the resistance 7
The voltage is divided by 5, 76 and applied to the A / D converter 56. In this way, the voltage is divided by the resistors 75 and 76 because the voltage of the on-vehicle battery 26 (usually 12 V) is divided by the A / D converter 5.
This is to reduce the input voltage to 6 (usually 5 V).
Reference numeral 80 in FIG. 4 denotes a capacitor for removing noise and protecting the A / D converter 56 against surges.
Reference numerals 8 and 79 are diodes for preventing current from flowing backward.

In this embodiment, the resistors 75, 76 and the capacitor 80 constitute a voltage measuring circuit 29. In other words, the voltage measuring circuit 29 monitors the resistance 75,
The voltage of the backup power line 71 divided by 76 is detected as the backup voltage. After this backup voltage is converted into a digital signal by the A / D converter 56,
It is output to the CPU 52. The CPU 52 compares a preset reference voltage with the backup voltage, and determines whether there is an abnormality in the backup power line 71 based on the comparison result.

The power source Vcc is supplied with E through a warning lamp 24.
The external output terminal 81 of the CU 51 is connected to the resistor 8
2 and a warning lamp control transistor 83 are connected in series. The emitter terminal of the transistor 83 is grounded through the resistor 84, and the base terminal is connected to the output terminal 85 of the CPU 52. And the CPU 52
Turns on / off the transistor 83 according to the presence / absence of an abnormality in the backup power line 71. The warning lamp 24 is turned on and off based on this on / off operation. In addition,
The resistors 82 and 84 are for protecting the transistor 83.

Next, the operation and effect of this embodiment configured as described above will be described. The flowchart of FIG. 6 shows a routine for detecting an abnormality occurrence in the backup power line 71 among the respective processes executed by the CPU 52, and is performed as a part of the initial (initialization) process. That is, the vehicle-mounted battery 26 generally functions effectively as a backup power source only when the ignition switch 25 is off. Therefore, in the present embodiment, the abnormality detection routine is executed by the CPU 52 when the ignition switch 25 is turned on. I try to do it only immediately after it is started.

When this abnormality detection routine is started, C
In step 201, the PU 52 first determines whether the data in the backup RAM 55 has been destroyed. Examples of this determination method include commonly used mirror check and keyword check. For example, when the power supply to the backup RAM 55 is cut off, the stored data becomes a random value, so this data is compared with, for example, the fixed data in the ROM 53, and data destruction is determined based on the comparison result.

In step 202, the CPU 52 determines whether the backup voltage input via the A / D converter 56 is lower than the preset reference voltage.

When either one of the judgment conditions of step 201 and step 202 is not satisfied, that is, when the data in the backup RAM 55 is normal, or when the data is destroyed, the backup voltage is the reference voltage. In the above case, the CPU 52 determines that the backup power line 71 has not been disconnected and is normal, and proceeds to step 203. Step 20
In 3, the CPU 52 determines whether or not the normal state has continued for the past “3” trips. Here, the on / off operation of the ignition switch 25 is set to "1" trip.

When the determination condition of step 203 is satisfied, the CPU 52 outputs a signal for turning off the transistor 83 in order to turn off the warning lamp 24 in step 204. Further, the CPU 52 executes step 20.
If the determination condition of 3 is not satisfied, the process of step 204 is not performed and the abnormality detection routine is ended as it is.

On the other hand, if both the determination conditions of steps 201 and 202 are satisfied, the CPU 52 causes the backup RAM 5 to be disconnected due to the disconnection of the backup power line 71.
It is judged that the data in 5 has been destroyed, and step 20
Go to 5. In step 205, the CPU 52 outputs a signal for turning on the transistor 83 to turn on the warning lamp 24. Subsequently, the CPU 52 sets a failure code corresponding to the disconnection of the backup power line 71, and ends this abnormality detection routine.

As described above, in this embodiment, it is determined whether or not the data stored in the backup RAM 55 is destroyed. The voltage of the backup power line 71 is detected as the backup voltage. And backup RAM5
When data destruction within 5 is detected, the backup voltage is compared with a predetermined reference voltage, and if the backup voltage is lower than the reference voltage, the backup power line 71 is determined to be abnormal.

In this way, the backup voltage and the reference voltage are compared only when the data destruction in the backup RAM 55 is detected. Therefore, even if the voltage of the on-vehicle battery 26 drops with the start of the engine body 1 or the wire harness is momentarily cut off during rough road traveling of the vehicle, and the backup voltage becomes temporarily lower than the reference voltage, The two voltages are not compared. Therefore, the backup power line 71 is not determined to be abnormal, and erroneous determination can be prevented.

Further, as the cause of the data destruction of the backup RAM 55, in addition to the abnormality such as the disconnection of the backup power line 71, the user or the service person may perform the initialization of the data or the replacement with the new on-vehicle battery 26 by the vehicle. Therefore, it is conceivable that the vehicle-mounted battery 26 is intentionally removed. On the other hand, when the backup power line 71 becomes abnormal due to a disconnection or the like,
Only the backup voltage drops. Therefore, by comparing the two voltages, it is possible to distinguish whether the data destruction is due to the abnormality of the backup power line 71 or the removal of the on-vehicle battery 26.

Therefore, according to the present embodiment, unlike the prior arts 1 and 2 described above, the abnormality of the backup power line 71 can be monitored accurately and surely. Next, the failure diagnosis executed by the CPU 52 will be described.

In the flowchart of FIG. 7, among the respective processes executed by the CPU 52, the update of the data in the respective vehicle state storage areas 113, 123, 133 in the first to third data areas 110, 120, 130 of the backup RAM 55. Shows a routine for doing. This data update routine, as shown in FIG.
It is executed at each timer interrupt.

The flowchart of FIG. 8 shows a routine for detecting a high-priority failure (in this case, an abnormality in the fuel system). As shown in FIG. 10B, this fuel system abnormality detection routine is executed every time the main routine for controlling the fuel injection amount or the like is rotated (every few ms).

The flowchart of FIG. 9 shows a routine for detecting a fault with a low priority (in this case, an abnormality of the water temperature sensor 37). This water temperature sensor abnormality detection routine, as shown in FIG.
This detection signal is executed every time the A / D converter 56 converts the detection signal into a digital signal (every 4 ms). Note that, here, the abnormality detection of the water temperature sensor 37 will be described as an example, but for other various sensors, a similar abnormality detection program is prepared for each sensor.

When the processing of the fuel system abnormality detection routine of FIG. 8 is started, the CPU 52 first, at step 401, the air-fuel ratio correction value FA used in the main routine.
The product of F and the air-fuel ratio correction learning value GAF is calculated. CPU
52 determines whether or not the calculation result is between a preset lower limit value and upper limit value. The lower limit here is
It is the minimum value that can be taken when the fuel system is operating normally, and is "0.8", for example. Similarly, the upper limit is the maximum value that can be taken when the fuel system is operating normally,
For example, “1.2”. If this determination condition is satisfied, the CPU 52 determines that the fuel system is operating normally, and immediately ends the fuel system abnormality detection routine.

If the determination condition in step 401 is not satisfied, the CPU 52 determines that an abnormality has occurred in the fuel system, and in step 402, sets a failure code corresponding to the abnormality in the fuel system, The abnormality detection routine is once ended.

When the process of the water temperature sensor abnormality detection routine of FIG. 9 is started, the CPU 52 firstly executes step 50.
At 1, the cooling water temperature THW by the water temperature sensor 37 is read.
Next, the CPU 52 determines the cooling water temperature TH in step 502.
It is determined whether W is between a preset lower limit value and upper limit value. The lower limit value here is a minimum value that can be taken when the water temperature sensor 37 is operating normally, and is, for example, “−50 ° C.”. Similarly, the upper limit is the water temperature sensor 3
7 is the maximum value that can be taken when operating normally,
For example, it is “140 ° C.”. If this determination condition is satisfied, the CPU 52 determines that the water temperature sensor 37 is operating normally, and once ends the water temperature sensor abnormality detection routine.

If the determination condition of step 502 is not satisfied, the CPU 52 determines that an abnormality has occurred in the water temperature sensor 37, and in step 503, the water temperature sensor 3 is detected.
The failure code corresponding to the abnormality of No. 7 is set, and this water temperature sensor abnormality detection routine is once ended.

As described above, in the fuel system abnormality detection routine of FIG. 8, a fuel system abnormality having a high priority (importance) is detected and a failure code corresponding to the abnormality is set.
Further, in the water temperature sensor abnormality detection routine of FIG. 9, an abnormality of the sensor system with a low priority (in this case, the water temperature sensor 37) is detected, and a failure code corresponding to the abnormality is set.

Next, a case will be described in which the vehicle has not been previously abnormal and the data update routine of FIG. 7 is started at timing t1 of FIG. At the start of this data update routine, FIG.
As shown in (a), no fault code is stored in any of the fault code storage areas 111, 121, 131 of the backup RAM 55. Further, no frame number is stored in any of the frame number storage areas 112, 122, 132. Then, all vehicle state storage areas 11
3,123,133, during the previous processing (timing t0)
Showing the vehicle condition (engine speed NE, vehicle speed S
(PD, etc.) is stored.

First, in step 301, the CPU 52 determines whether or not an abnormality is detected in the abnormality detection processing of the fuel system or the sensor system between the previous processing and the start of this processing. In this case, it is determined whether the failure code has been set in the fuel system abnormality detection routine of FIG. 8 or whether the failure code has been set in the water temperature sensor abnormality detection routine of FIG.

Since the vehicle condition is still normal and the failure code is not set, the CPU 52 determines that the determination condition of step 301 is not satisfied, and proceeds to step 302. In step 302, the CPU
Reference numeral 52 updates the data in the vehicle state storage area in the data area where the failure code is not stored in the backup RAM 55. In this case, as shown in FIG. 5B, the data in all the vehicle state storage areas 113, 123, 133 of the first to third data areas 110, 120, 130 are changed to the vehicle state at the timing t1. Update to the data shown. After updating the data, the CPU 52 once ends the data updating routine.

Next, a case will be described in which an abnormality occurs in the fuel system for the first time at the timing t2 in FIG. 10 and the data update routine is started at the subsequent timing t3. In this case, since the failure code is set in the fuel system abnormality detection routine, the CPU 52 determines that the determination condition of step 301 in FIG. 7 is satisfied, and proceeds to step 303. In step 303, the CPU 52 determines that the failure code in step 301 is the failure code storage area 1
It is determined whether or not the fault code is already stored in any one of 11, 121 and 131. Here, since the failure code has been set for the first time, the CPU 52 determines that the determination condition of step 303 is not satisfied,
In step 304, it is determined whether or not the failure code has a high priority.

Since the failure code in step 301 is a fuel system failure code with a high priority, the CPU 5
In step 2, it is determined that the determination condition of step 304 is satisfied, and the process proceeds to step 305. In step 305, the CPU 52 determines the three frame number storage areas 11
The storage status of the frame numbers 2, 122 and 132 is checked. Then, the frame number "1" is set in the top area (the area having the smallest number) in the frame number storage area in which the frame number is not stored. In this case, which frame number storage area 112, 122, 13
Since no frame number is stored in 2 as well, FIG.
As shown in (a), "1" is set in the frame number storage area 112 which is the top area. Also, step 305
In the above, the CPU 52 causes the failure code storage area of the same data area as the frame number storage area 112 in which the frame number is set (in this case, the failure code storage area 11
The fuel system failure code is stored in 1).

Subsequently, in step 306, the CPU 52 changes the frame number already set before the timing t3. Specifically, if the already set frame number is "1", change it to "2",
If "2", change to "3". In this case, since the frame number is not yet stored in the frame number storage areas 122 and 132, the CPU 52 does nothing in step 306.

Then, in step 302, the CPU 52 updates the data in the vehicle state storage area in the data area in which the failure code is not stored. In this case, FIG.
As shown in (a), the second and third data areas 120, 1
The data in the vehicle state storage areas 123 and 133 of 30 are updated to the data indicating the vehicle state at the timing t3. Vehicle state storage area 113 of the first data area 110
With respect to, the update of the data is interrupted, and the data stored in the previous processing (timing t1) is held. Step 3
After the processing of 02, the CPU 52 once ends the data update routine.

Next, at the timing t4 in FIG. 10, the water temperature sensor 37 continues to become abnormal, and the subsequent timing t5.
A case where the data update routine is started will be described. In this case, the CPU 52 determines that the determination condition of step 301 is satisfied and the determination condition of step 303 is not satisfied. Since the failure code in step 301 is a sensor system failure code with a low priority, the CPU
52 determines that the determination condition of step 304 is not satisfied, and proceeds to step 307.

In step 307, the CPU 52 checks the number of frame numbers stored in the backup RAM 55. If the number is “0”, the frame number “1” is stored in the frame number storage area 112.
Frame number storage area 1 in the case of “1”
The frame number “2” is stored in 22 and the frame number “3” is stored in the frame number storage area 132 when the number is “2”. Further, the CPU 52 stores the failure code corresponding to the abnormality of the water temperature sensor 37 in the failure code storage area of the same data area as the frame number storage area in which the frame number is stored.

Specifically, in this case, the fuel system failure code and the frame number "1" are already stored in the first data area 110. That is, backup RA
The number of frame numbers stored in M55 is "1". Therefore, as shown in FIG. 11B, the CPU 52 stores the frame number “2” in the frame number storage area 122.
Is stored in the failure code storage area 121.
The failure code of is stored. CPU52 is step 302
In the vehicle state storage area in the data area in which the failure code is not stored, in this case, the vehicle state storage area 13
The data in 3 is updated to the data indicating the vehicle state at the timing t5. Regarding the vehicle state storage area 113,
Continue updating the data. Further, regarding the vehicle state storage area 123, the update of the data is interrupted, and the data stored in the previous processing (timing t3) is held.
After the processing of step 302, the CPU 52 once ends the data update routine.

If the fault code in step 301 is a fault code already stored, the CPU 52 determines that the determination condition of step 303 is satisfied, and the steps of steps 304 to 307 are skipped. Move to 302. Then, in step 302, the CPU 5
2 updates the data in the vehicle state storage area in the data area where the failure code is not stored.

In addition to the above-described order of occurrence of abnormalities, as shown in FIG. 12, from a normal state, an abnormality of the sensor system may occur first, followed by an abnormality of the fuel system. . Next, the flow of each process in the data update routine in this case will be described.

First, from the normal state at the timing t1 described above, at the timing t12 in FIG.
Became abnormal for the first time, and the subsequent timing t13
A case where the data update routine of FIG. 7 is started will be described. The CPU 52 determines that the determination condition of step 301 is satisfied and the determination condition of step 303 is not satisfied. Since the failure code in step 301 is a sensor system failure code with a low priority, the CPU 52
Determines that the determination condition of step 304 is not satisfied, and proceeds to step 307.

At step 307, the CPU 52 checks the number of frame numbers stored in the backup RAM 55. In this case, since the frame number is not stored in any of the frame number storage areas 112, 122, 132, the frame number “1” is stored in the frame number storage area 112, as shown in FIG. Further, the CPU 52 stores the failure code corresponding to the abnormality of the water temperature sensor 37 in the failure code storage area 111 in the same data area.

In step 302, the CPU 52 updates the data in the vehicle state storage area in which the failure code is not stored, in this case, the vehicle state storage areas 123 and 133 to the data indicating the vehicle state at the timing t13.
With respect to the vehicle state storage area 113, the update of data is interrupted and the data stored at the previous processing (timing t1) is held. After the processing of step 302, the CPU 52 once ends the data update routine.

Next, a case will be described in which an abnormality occurs in the fuel system at the timing t14 after the abnormality of the water temperature sensor 37, and the data update routine is started at the subsequent timing t15. In this case, the CPU 52 proceeds to step 3
It is determined that the determination condition of 01 is satisfied and the determination condition of step 303 is not satisfied. Since the failure code in step 301 is a fuel system failure code with a high priority, the CPU 52 determines that the determination condition of step 304 is satisfied, and proceeds to step 305.

At step 305, the CPU 52
The storage status of the frame numbers in the three frame number storage areas 112, 122, 132 is checked. Then, as shown in FIG. 13B, a frame number storage area in which a frame number is not stored (in this case, 122,
132), the frame number "1" is set in the frame number storage area 122 which is the first area. Then, the fuel system failure code is stored in the failure code storage area 121 corresponding to the frame number storage area 122.

Subsequently, in step 306, the CPU 52 changes the already set frame number. In this case, since the frame number "1" due to the abnormality of the water temperature sensor 37 is already stored in the frame number storage area 112, this frame number is changed to "2".

Then, in step 302, the CPU 52 updates the data in the vehicle state storage area in the data area where the failure code is not stored. In this case, the data in the vehicle state storage area 133 of the third data area 130 is updated to the data indicating the vehicle state at the timing t15. Vehicle state storage area 11 of the first data area 110
With respect to item 3, the data update is suspended. Also,
With respect to the vehicle state storage area 123 of the second data area 120, the update of the data is interrupted and the data stored in the previous processing (timing t13) is held. Step 30
After the processing of 2, the CPU 52 once ends the data update routine.

As described above, in this embodiment, the data regarding the vehicle state is constantly updated when the fuel system and various sensors are operating normally, and the update of the data is interrupted when a failure occurs. Then, in order to specify what kind of anomaly the updated data has been interrupted, a failure code is stored and the data is associated with the failure code. Therefore, even if the ignition switch 25 is turned off immediately after the failure is detected, the data indicating the vehicle status immediately before the failure can be reliably stored and held in the vehicle status storage area. As a result, it is possible to display the failure code indicating the location of the abnormality and the vehicle state data at the time of the abnormality on the external diagnostic device 27.

That is, in recent years, in order to facilitate failure diagnosis (identification of the cause of failure) at the time of failure, it has been proposed to store not only the location of the failure but also the vehicle state at the time of the failure in the backup RAM 55. ing. On this occasion,
It is conceivable to store data indicating the vehicle condition after detecting a fault. However, in this case, there is a considerable time difference from the detection of the failure to the data storage. Therefore, if the ignition switch 25 is turned off to stop the driving of the engine immediately after the failure is detected and before the vehicle state data is stored, the power supply to the ECU 51, particularly the CPU 52 is cut off. It As a result, the vehicle state data may not be correctly stored in the backup RAM 55.

On the other hand, in this embodiment, the vehicle state data is constantly updated. Therefore, even if the ignition switch 25 is turned off immediately after the occurrence of the abnormality, it is possible to ensure accurate data of the vehicle state immediately before the occurrence of the abnormality.

Further, in this embodiment, the backup RAM 5
5, a plurality of data areas 110, 120, 130 are prepared, and the failure code storage area 111,
The failure code is stored from 121 and 131. And
The failure code storage areas 111 and 12 according to the importance of the abnormality
The frame numbers for 1,131 are changed. For this reason, in order to understand important failures at repair shops,
If the frame number “1” is output from the external diagnostic device 27 side to the CPU 52 as a diagnostic request signal, the vehicle state data relating to the abnormality of the fuel system having the highest importance can be read.

At this time, the frame number storage areas 112, 1
Only the frame number is rewritten between 22 and 132, and the vehicle state data is not moved between the vehicle state storage areas 113, 123 and 133. Therefore, when data is moved, there is a possibility that accurate data movement may not be performed if the ignition switch 25 is turned off during the movement, but in the present embodiment, such a problem can be prevented.

The present invention is not limited to the configuration of the above-described embodiment, and may be arbitrarily modified within the scope not departing from the spirit of the invention as follows. (1) In the embodiment described above, the abnormality detection routine of FIG. 6 is executed only once immediately after the ignition switch 25 is turned on. However, it is executed every predetermined time (several ms) after the CPU 52 is activated. Good.

(2) In the above embodiment, the backup voltage measured by the voltage measuring circuit 29 is converted into a digital signal by the A / D converter 56, and then the CPU 52 compares the backup voltage with the reference voltage. Instead of the A / D converter 56 and the CPU 52, a comparator may be used to compare the reference voltage and the backup voltage.

[0087]

As described above in detail, according to the present invention, when the abnormality of the data in the memory is detected, the backup voltage of the backup power line is compared with the reference voltage, and the backup voltage is lower than the reference voltage. Then, the backup power line is determined to be abnormal. Therefore, even if the voltage of the on-vehicle battery is lowered with the start of the internal combustion engine for the vehicle, or the wire harness is momentarily cut off during rough road traveling of the vehicle, the backup voltage becomes temporarily lower than the reference voltage, There is no erroneous determination that the cause of the memory data abnormality is due to the abnormality of the backup power line. Further, it is possible to distinguish whether the data abnormality of the memory is caused by the temporary removal of the vehicle-mounted battery or the abnormality of the backup power line.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a schematic configuration diagram showing a gasoline engine and its peripheral devices in an embodiment embodying a memory backup power supply monitoring device of the present invention.

FIG. 3 is a block diagram showing a configuration of an ECU in one embodiment.

FIG. 4 is a block diagram showing a connection relationship between a vehicle-mounted battery and a backup RAM, a configuration of a voltage measurement circuit, and the like in one embodiment.

5A and 5B are explanatory diagrams showing a state of a data area in a backup RAM in one embodiment.

FIG. 6 is a flowchart illustrating an abnormality detection routine executed by a CPU in an embodiment.

FIG. 7 is a flowchart illustrating a data update routine executed by a CPU in an embodiment.

FIG. 8 is a flowchart illustrating a fuel system abnormality detection routine executed by a CPU in one embodiment.

FIG. 9 is a flowchart illustrating a water temperature sensor abnormality detection routine executed by a CPU in an embodiment.

FIG. 10 is a timing chart showing timings at which a data update routine, a fuel system abnormality detection routine, and a water temperature sensor abnormality detection routine are activated in one embodiment.

11A and 11B are explanatory views showing the state of the data area in the backup RAM in one embodiment.

FIG. 12 is a timing chart showing timings at which a data update routine, a fuel system abnormality detection routine, and a water temperature sensor abnormality detection routine are activated in one embodiment.

13A and 13B are explanatory diagrams showing the state of the data area in the backup RAM in one embodiment.

[Explanation of symbols]

25 ... Ignition switch, 26 ... In-vehicle battery, 2
9 ... Voltage measuring circuit as backup voltage detecting means,
51 ... Electronic control unit (ECU) as in-vehicle electronic device,
52 ... CP constituting data abnormality detecting means and monitoring means
U, 55 ... Backup RAM as memory, 66 ...
Main power line, 71 ... Backup power line

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G06F 12/16 340 K 9293-5B

Claims (1)

[Claims] 1. A volatile memory that is provided in an on-vehicle electronic device for controlling the driving of a vehicle and stores data relating to the driving of the vehicle, and also serves as a backup power source for the memory, and for operating the memory. An on-vehicle battery that supplies electric power, a main power line that connects the on-vehicle battery and the on-vehicle electronic device via a switch, a backup power line that bypasses the switch and connects the on-vehicle battery and the memory, and stored in the memory Data abnormality detection means for detecting the presence or absence of data abnormality, backup voltage detection means for detecting the voltage of the backup power line as a backup voltage, and the data abnormality determination means has detected abnormality in the data in the memory. When the backup voltage and the reference voltage are detected by the backup voltage detection means, And a monitoring unit that determines that the backup power line is abnormal when the backup voltage is lower than the reference voltage.