WO2008099276A1

WO2008099276A1 - Vehicle control device

Info

Publication number: WO2008099276A1
Application number: PCT/IB2008/000343
Authority: WO
Inventors: Yasuhiro Oi; Koji Ide
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2007-02-15
Filing date: 2008-02-14
Publication date: 2008-08-21
Also published as: JP2008196441A

Abstract

A vehicle control device which performs learning control to correct error components present in parameters relating to control of a vehicle includes: a first storage device (28), that retains stored data even when the power is not supplied; a learned value storage device that stores learned values calculated during the learning control in the first storage device (28) (S 104); a failure detection device that detects a failure in any device relating to the learning control (S 116); and a learned value erasing device that erases the learned value stored in the first storage device (28) when a device failure is detected by the failure detection device (si 18). Thus, when any device relating to vehicle control fails, the continued use of learned values affected by the failure after the failed device is repaired is prevented.

Description

VEHICLE CONTROL DEVICE

BACKGROUND OP THE INVENTION

1 , Field of the Invention

[0001] This invention relates to a vehicle control device which performs learning control and, more particularly, to a vehicle control device having a non-volatile memory in which data may be electrically rewritten.

2, Description of the Related Art

[0002] A vehicle control device having a Static Random Access Memory (hereinafter "SRAM") for temporarily storing control data and a non-volatile memory in which data can be electrically rewritten (hereinafter "EEPROM") as described in Japanese Patent Application Publication No.10-252547, for example, is conventionally known. The SRAM is a memory which is supplied with backup power from a battery voltage and the EEPROM is a memory which retains the stored data even when the power is shut off,

[0003] In the above conventional vehicle control device, learning control in which the results of control in the past are evaluated to correct the control parameters and/or the control theory is performed to eliminate the effect of aging degradation or variations of control targets such as sensors and actuators. In the learning control, learned values stored in the SRAM are written into the EEPROM at appropriate times. Therefore, even if the learned values stored in the SRAM are lost due to, for example, a disruption in the supplied power, the previously learned values may be used when the data in the EEPROM are read out.

[0004] In a vehicle control system, malfunction diagnosis control (diagnosis) is performed on devices relating to vehicle control such as sensors and actuators. Therefore, because the user is immediately informed of a malfunction of any of the devices, and a situation in which control of the vehicle is continued based on erroneous sensor signals is avoided effectively,

[0005] When a failure (i,e. malfunction) in any of the devices is detected, it is highly possible that the learned values relating to the control of the failed device have been affected by the failure, Thus, when the device is replaced or repaired, the learned values cannot be used any more. However, because the EPPROM is a non-volatile memory, the learned values stored in the memory are not lost even if the power source voltage is shut down when replacing the defective device, Thus, when the learned values used before the device malfunctioned are used after recovery of the system, it is likely that improper learning control will be executed and may cause troubles such as engine start failure. To avoid such a situation, it may be a good idea to erase the learned values manually when the device is replaced. However, because many systems have become more complex in recent years, the number of work steps would be increased significantly.

SUMMARY OF THE INVENTION

[0006] This invention provides a vehicle control device which, when any of devices relating to vehicle control fails, prevents the continued use of learned values affected by the failure after the failed device is repaired.

[0007] According to a first embodiment of the invention, a vehicle control device that performs learning control to correct error components that reside in parameters relating to control of a vehicle, includes: a first storage device that retains stored data even when the power supply is interrupted; a learned value storage device that stores learned values calculated during the learning control in the first storage device; a failure detection device that detects a failure in any device relating to the learning control; and a learned value erasing device that erases the learned value stored in the first storage device when a device failure is detected by the failure detection device. The erasure of the learned values stored in the first storage device may be a complete erasure of all the stored learned values or an erasure of selected learned values. The erasure of selected learned values may be associated with the particular device that has failed.

[0008] According to the vehicle control device described above, the learned values calculated during the learning control are stored in the first storage device. Then, when a failure in a device relating to the learning control is detected, all or some of the learned values stored in the first storage device are erased, Thus, a situation in which learned values affected by the failure in the failed device are used after repair of failed device is effectively avoided.

[0009] According to the vehicle control device described above, a non-volatile memory in which data is electrically rewritten (EEPROM) may be used as the first storage device.

[0010] The learned value storage device may backup the learned values stored in a second storage device, that stores data when power is supplied and loses stored data when power supply is not supplied, to the first storage device if the power supply is not supplied. In addition, the vehicle control device may further include a learned value recovery device that restores the learned values transferred to the first storage device into the second storage device once the power supply to the second storage device is restored.

[0011] According to the vehicle control device described above, the learned values stored in a second storage device are backed up in the first storage device when the power to the second storage device is not supplied. Then, once the power supply is to the second storage device is restored, the learned values transferred to the first storage device are restored to the second storage device. Thus, even if the learned values stored in the second storage device are lost, the learned values can be recovered and used continuously,

[0012] The vehicle control device may further include a learned value retention device that retains the learned values stored in the second storage device if a failure in any of the devices is detected by the failure detection device,

[0013] According to the vehicle control device described above, a failure in any of the devices relating to the learning control is detected and the learned values stored in the first storage device are erased, the learned values stored in the second storage device are not erased but retained. Thus, because learned values which correct the effect of the failure are used before the device is repaired, learning control can be carried out such that the effect of the failure may be further compensated for.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features, advantages, and technical and industrial significance of this invention will be better understood by reading the following detailed description of example embodiments of the invention, when considered in connection with the accompanying drawings, in which:

FIG. 1 is a view illustrating the configuration of an ECU 10 according to a first embodiment of the present invention, and

FIG. 2 is a flowchart of a routine that is executed in the first embodiment of the present invention,

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] In the following description and the accompanying drawings, the present invention will be described in greater detail with reference to example embodiments,

[0016] A first embodiment is described below. FIG. I is a view illustrating the configuration of a first embodiment of the present invention. A vehicle control device of this first embodiment controls an internal combustion engine (engine) 2 mounted in a vehicle, As shown in FIG. 1, the internal combustion engine 2 has an ECU (Electronic Control Unit) 10 as a control device. The ECU 10 comprehensively controls various devices for operation of the engine 2 based on operation data of the engine detected by a plurality of sensors. A plurality of actuators (not shown) are connected to the output of the ECU 10, A plurality of sensors and devices (not shown) are connected to the input of the ECU 10. The ECU 10 performs various control functions on the engine 2, such as fuel injection control, ignition timing control, throttle control, and diagnosis, based on input signals from the sensors. The configuration of the ECU 10 is described below in detail.

[0017] The ECU 10 of this first embodiment has a CPU 12. The CPU 12 performs various operations to control the engine. The ECU 10 also has a ROM 22 in which programs to be executed by the CPU 12 are stored, and an NRAM 24 and an SRAM 26 as RAM for arithmetic operations and temporary storage of the results of control operations performed by the CPU 12 and other data. The NRAM 24 is a memory that is not supplied with backup power from a battery voltage and loses the stored data when the ignition is turned off. In contrast, the SRAM 26 is a memory that is supplied with backup power from a battery voltage and retains the stored data even when the ignition is turned off. The ECU 10 also has an EEPROM 28 as shown in FIG. 1. The EEPROM 28 is a non-volatile memory in which data may be electrically rewritten and which retains the stored data even when the ignition is turned off.

[0018] As shown in FIG. 1, the ECU 10 has an input circuit 14 and an output circuit 16. The input circuit 14 inputs signals from various sensors (not shown), such as an engine speed sensor and coolant temperature sensor, into the CPU 12, The output circuit 16 actuates various actuators (not shown), such as injector and relay, based on drive signals output from the CPU 12, The ECU 10 also has a power source circuit 18. The power source circuit 18 receives an ignition voltage supplied from a battery (not shown) via an ignition switch (not shown) and outputs an operating voltage to the CPU 12, the ROM 22, the NRAM 24, the SRAM 26, and the EEPROM 28. The power source circuit 18 also receives a battery voltage supplied directly (not via the ignition switch) from the battery and outputs a backup voltage for data retention to the SRAM 26,

[0019] The operation of this first embodiment is next described. The ECU 10 executes engine control functions such as fuel injection control, ignition timing control, throttle control, and diagnosis according to the programs stored in the ROM 22. More specifically, when the ignition switch is turned on, an operating voltage is output from the power source circuit 18 to the CPU 12, the ROM 22, the NRAM 24, the SRAM 26, and the EEPROM 28. Then, engine control functions are executed according to the programs stored in the ROM 22, and the actuators are operated via the output circuit 16 based on sensor signals input into the input circuit 14.

[0020] In the control functions that the ECU 10 performs on the internal combustion engine 2, learning control is carried out to correct stationary error components. More specifically, stationary error components added to parameters relating to engine control because of aging degradation and/or variations of the sensors and actuators are learned and corrected based on the history of control results. The learned values are updated every time when new values are calculated, and stored in the NRAM 24. Because the NRAM 24 loses the stored data when the ignition is turned off, the learned values stored in the NRAM 24 are periodically written into the SRAM 26. Therefore, because the learned values are retained even when the ignition is turned off, learning control may be resumed using the learned values the next time the ignition is turned on,

[0021] However, when the backup voltage is shut down because of battery power interruption or some other reason, the learned values stored in the SRAM 26 are lost. Thus, in the system of this first embodiment, the learned values stored in the SRAM 26 are periodically written into the EEPROM 28, More specifically, when the learned values stored in the SRAM 26 are updated to new values, the learned values are written into the EEPROM 28 when the ignition is turned off the next time, Therefore, even if the learned values stored in the SRAM 26 are accidentally lost, the learned values may be recovered by restoring the learned values stored in the EEPROM 28 to the SRAM 26,

[0022] One characteristic operation of this first embodiment is next described. In the ECU 10, diagnostic control for the devices connected to the ECU 10, such as the sensors and actuators, is executed. More specifically, a failure, disconnection, short-circuit and so on in any of the sensors can be detected by constantly monitoring and comparing the input signals from the various sensors, Failure diagnosis of the actuators is carried out using a current limit value and the like. When a failure is detected, the user is immediately informed.

[0023] When a failure in any of the devices is detected as a result of the diagnostic control, if the failure is a sudden failure such as disconnection, it is possible to prevent the effect of the failure from overwriting the learned values by inhibiting the learning immediately after the detection of the failure. However, if a device has gradually deteriorated over time and is eventually determined to be out of order, the effect of the aging degradation of the device has already overwritten the learned values. Thus, the learned values should not be used after repair,

[0024] If the learned values are stored only in the SRAM 26, because all the data stored in the SRAM 26 if the battery power is interrupted during repair, there is no possibility that the previously learned values will be used after the repair. However, if learned values are backed up in an EEPROM as in the system of this first embodiment, the stored learned values are retained even through the battery power is interrupted, Thus, when the system is restored, the learned values can be used and may cause improper learning control, which may lead to malfunction of the devices.

[0025] Thus, in the system of this first embodiment, when a failure is detected, the learned values stored in the EEPROM 28 are erased, Therefore, a situation in which learned values affected by the device failure are used in the engine control after the failed device is repaired may be avoided.

[0026] When the learned values in the EEPROM 28 are erased, the learned values stored in the SRAM 26 are retained. Therefore, during the period after the detection of a failure and before repair, learning control may be carried out using learned values learned to compensate for the effect of the failure and malfunction due to the failure may be prevented effectively.

[0027] Referring next to FIG, 2, the specific operations performed in the first embodiment are described, FIG. 2 is a flowchart of a routine that the ECU 10 carries out to write or read learned values relating to the control of the engine 2. First, the routine for backing up learned values from the SRAM 26 to the EEPROM 28 will be described,

[0028] In the routine shown in FIG. 2, it is first determined whether the ignition is on (step 100). More specifically, it is determined here whether the ignition switch is turned on and a battery voltage has been supplied to the ROM 22, the NRAM 24, the SRAM 26, and the EEPROM 28.

[0029] If it is determined that the ignition is turned off in step 100, the routine proceeds to step 102, in which it is determined whether the learned values were changed in the immediately preceding trip. More specifically, it is determined here whether the learned value data stored in the SRAM 26 is replaced by new data in the immediately preceding trip. If it is determined that the learned values were updated, the routine proceeds to thestep 104, in which the learned value data stored in the SRAM 26 is written into the EEPROM 28. Then, a flag indicating that the ignition was turned off during this routine is turned on (step 106), and the routine is terminated. If it is determined that the learned value data was not updated in step 102, it is determined that there is no need to update the learned value data stored in the EEPROM 28, and this routine is terminated when step 106 is completed. [0030] According to the operation described above, the learned values updated in the immediately preceding trip are written into the EEPROM 28. Therefore, the most up-to-date version of the learned value data stored in the EEPROM 28 is always the most recent version.

[0031] The routine for restoring learned values from the EEPROM 28 to the SRAM 26 is next described. If it is determined that the ignition is turned on in step 100, the routine proceeds to step 108 in which it is determined whether the current routine is the first routine after the ignition was turned on. More specifically, it is determined here whether the flag in step 106 is on. If the flag is on, it is determined that the current routine is the first routine after the ignition was turned on, and the routine proceeds to step 110, in which a mirror check is performed on the SRAM 26. More specifically, the SRAM 26 data at the end of the immediately previous trip and the current SRAM 26 data are compared to determine whether any loss of the data in the SRAM 26 has occurred.

[0032] If it is determined that the data in the SRAM 26 has been lost in step 110, the routine proceeds tostep 112, in which the learned value data stored in the EEPROM 28 is written into the SRAM 26. Then, a flag indicating that the ignition was turned off during this routine is turned off (step 114), and the routine is terminated. If it is determined that the data in the SRAM 26 has not been lost in step 110, it is determined that there is no need to update the data in the SRAM 26, and the routine is immediately terminated.

[0033] According to the operation described above, if the learned value data stored in the SRAM 26 is lost while the ignition is turned off, the learned value data stored in the EEPROM 28 are restored to the SRAM 26. Therefore, the learned values used before the battery power interruption may be used again,

[0034] The routine for erasing the learned values in the EEPROM 28, which is carried out when a component failure is detected, is described next. If it is determined that the ignition is turned on in step 100, the routine proceeds to step 108, in which it is determined whether the current routine is the first routine after the ignition was turned on. If the flag is off, that is, the current routine is not the first routine after the ignition was turned on, the routine proceeds to the next step, in which it is determined whether a failure in any of the devices relating to the learning control has been detected (step 116), More specifically, it is determined here whether a failure in any of the devices has been detected in the failure diagnosis control, which is separately performed in the ECU 10,

[0035] If it is determined that a failure has been detected in step 116, the routine proceeds to the next step, in which the learned values in the EEPROM 28 are erased (step 118). More specifically, all the learned value data stored in the EEPROM 28 are erased. The learned values stored in the SRAM 26 are retained. Then, this routine is terminated when step 114 is completed. If it is determined that no failure has been detected in step 116, it is determined that there is no need to erase the learned value data stored in the EEPROM 28, and this routine is terminated when step 106 is completed.

[0036] According to the operation described above, if a failure in any of the devices relating to the learning control of the internal combustion engine 2 is detected, the learned value data stored in the EEPROM 28 are erased. The data stored in the EEPROM 28 are not lost only by shutting down the battery power during repair. Thus, by erasing the learned values to which the effect of the failure has overwritten prior to repair, a situation in which the learned values are used after repair is avoided and therefore malfunction may be prevented.

[0037] While all the learned values stored in the EEPROM 28 are erased when a malfunction is detected in any of the devices relating to the learning control in the first embodiment described above, the learned values to be erased are not limited thereto. That is, it is possible to selectively erase only the learned values relating to the control of the faled device in the learned value data stored in the EEPROM 28.

[0038] In the first embodiment described above, it is considered that the EEPROM 28 is a "first storage device." Also, it is considered that a "learned value storage device" may be implemented by the ECU 10 when it carries out step 104, It is also considered that a "learned value erasing device" may be implemented by the ECU 10 when it carries out step 116.

[0039] It is considered that the SRAM 26 is a "second storage device." It is also considered that a "learned value recovery device" may be implemented by the ECU 10 when it carries out step 112.

Claims

1. A vehicle control device that performs learning control to correct error components present in parameters relating to control of a vehicle, the vehicle control device characterized by comprising: a first storage device (28) that retains stored data even when power supply is not supplied; a learned value storage device that stores learned values, calculated during the learning control, in the first storage device (28)(S 104); a failure detection device that detects a failure in any device relating to the learning control (S 116); and a learned value erasing device that erases the learned values stored in the first storage device (28) when a device failure is detected by the failure detection device (Sl 18),

2. The vehicle control device according to Claim 1, characterized in that only selected learned values stored in the first storage device (28) are erased.

3. The vehicle control device according to Claim 2, characterized in that the selected learned values are the learned values associated with the device that has developed a failure.

4. The vehicle control device according to Claim 1, characterized in that the first storage device (28) is a non-volatile memory in which data can be electrically rewritten.

5. The vehicle control device according to Claim 1, characterized by further comprising: a second storage device (26) that stores data when power is supplied and loses the stored data when power is not supplied; and a learned value recovery device that restores the learned values stored in the first storage device (28) into the second storage device (26), wherein the learned value storage device transfers the learned values stored in the second storage device to the first storage device (28) as backup data when power supply is not supplied (S 104), and the learned value recovery device restores the learned values stored in the first storage device (28) to the second storage device when the power supply to the second storage device (26) is restored (S 112).

6. The vehicle control device according to Claim 1, characterized by further comprising: a learned value retention device that retains the learned values stored in the second storage device (26) when a failure in any of the devices is detected by the failure detection device (S 118).