JP2007051943A - Apparatus for detecting abnormality of current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor abnormality detecting apparatus capable of detecting abnormalities of current sensors by using a simple apparatus and abnormality determination algorithm. <P>SOLUTION: The current sensor abnormality detection apparatus is an abnormality detection apparatus (1) for detecting the abnormalities of a current sensor (12) for detecting a charging current or a discharge current of a battery (8) charged by a dynamo-electric generator (6) mounted to a vehicle and comprises an operating state detection means (14) for detecting whether the vehicle is in a state of deceleration; a dynamo-electric generator control means (16) for controlling the output voltage of the dynamo-electric generator into a first voltage so as to charge the battery, when a state of deceleration is detected and controlling the output voltage of the dynamo-electric generator into a second voltage lower than the first voltage, when a state of nondeceleration is detected; and an abnormality determination means (18) for determining the abnormalities of the current sensor, on the basis of the changes in the current value measured by the current sensor, when the output voltage of the dynamo-electric generator is switched. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abnormality detection device for a current sensor, and more particularly to an abnormality detection device for a current sensor that detects an abnormality of a current sensor that detects a charge / discharge current of a battery charged by a generator mounted on a vehicle.

  Japanese Patent Laying-Open No. 2000-206221 (Patent Document 1) describes an abnormality detection device for a current sensor. In this current sensor abnormality detection device, while a current value of approximately zero is detected by the current sensor, the voltage detected by the voltage sensor exceeds a predetermined number of times with a variation rate of a predetermined value or more within a predetermined time. It is determined that the current sensor is abnormal when it rises and falls.

JP 2000-206221 A

  However, in the current sensor abnormality detection device described in Japanese Patent Laid-Open No. 2000-206221, it is necessary to refer to the detection voltage by the voltage sensor in order to determine the abnormality of the current sensor. Furthermore, in this abnormality detection device, it is necessary to detect the magnitude of the fluctuation rate of the voltage within a predetermined time, and to detect how many times the fluctuation of the fluctuation rate exceeds a predetermined value. For this reason, there exists a problem that the apparatus and abnormality determination algorithm for determining abnormality of a current sensor become complicated.

  Accordingly, an object of the present invention is to provide an abnormality detection device for a current sensor that can detect an abnormality of the current sensor with a simple device and an abnormality determination algorithm.

  In order to solve the above-described problems, the present invention provides an abnormality detection device that detects an abnormality of a current sensor that detects a charging current or a discharging current of a battery charged by a generator mounted on a vehicle. The operating state detecting means for detecting whether or not the vehicle is in a decelerating state, and when the decelerating state is detected by the operating state detecting means, the output voltage of the generator is set to the first so that the battery is charged. In the non-decelerated state, the generator control means for controlling the output voltage of the generator to be a second voltage lower than the first voltage, and the generator control means An abnormality detection device for a current sensor, comprising: abnormality determination means for determining abnormality of the current sensor based on a change in a current value measured by the current sensor when the output voltage is switched.

  In the present invention configured as described above, the driving state detecting means detects whether or not the vehicle is in a decelerating state. When the vehicle is in a decelerating state, the generator control means controls the generator so that the output voltage of the generator becomes the first voltage, and charges the battery. The generator control means controls the generator so that the output voltage of the generator becomes a second voltage lower than the first voltage when the vehicle is not in a decelerating state, so that the battery is not charged. Otherwise, a smaller amount of charging is performed than when the output voltage is the first voltage. The abnormality determination unit determines abnormality of the current sensor based on a change in a current value measured by the current sensor when the output voltage of the generator is switched by the generator control unit.

  According to the present invention configured as described above, since the battery is charged mainly when the vehicle is in a decelerating state, the surplus kinetic energy of the vehicle is not wasted by the brake or the like, and the electric energy is consumed. As recovered. Further, since the abnormality of the current sensor is detected based on the change of the charging current flowing at that time, it is possible to easily detect the abnormality such as the stack failure of the current sensor without sacrificing the fuel consumption.

  In the present invention, preferably, the abnormality determination means determines abnormality of the current sensor based on a change in a current value measured by the current sensor when the output voltage of the generator is switched from the second voltage to the first voltage. To do.

In the present invention configured as described above, an abnormality is detected based on a change in the current value when the output voltage of the generator is switched from the second voltage to the first voltage higher than the second voltage.
According to the present invention configured as described above, even when the battery is deteriorated, a sufficient change in the current value occurs, so that the abnormality of the current sensor can be detected more reliably.

In the present invention, preferably, when the abnormality determination means determines that the current sensor is abnormal, it further includes an abnormality notification means for notifying the vehicle occupant of the abnormality of the current sensor.
According to the present invention configured as described above, since the abnormality of the current sensor is promptly notified to the vehicle occupant, overcharging or over-discharging of the battery due to leaving the abnormality of the current sensor is prevented. be able to.

  In the present invention, preferably, the generator control means determines that the output voltage of the generator is higher than the second voltage and is always charged when the abnormality determination means determines that the current sensor is abnormal. The generator is controlled so that

In the present invention configured as described above, when it is determined that the current sensor is abnormal, the output voltage of the generator is always set to a voltage higher than the second voltage. Can be secured.
According to the present invention configured as above, since the battery is sufficiently charged even when the current sensor is abnormal, it is possible to prevent the vehicle from being unable to run due to an excessive decrease in the remaining battery capacity. can do.

  According to the abnormality detection device for a current sensor of the present invention, an abnormality of the current sensor can be detected by a simple device and an abnormality determination algorithm.

  Next, a current sensor abnormality detection device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of an electric system mounted on a vehicle including a current sensor abnormality detection device according to an embodiment of the present invention. FIG. 2 is a flowchart showing the operation of the current sensor abnormality detection device according to the embodiment of the present invention. FIG. 3 is a time chart showing the target output voltage of the generator, the battery voltage, and the charge / discharge current of the battery.

  As shown in FIG. 1, an ECU (engine control unit) 2, a warning lamp 4 that is an abnormality notification unit that notifies an abnormality of a current sensor, and an output voltage are controlled by the ECU 2. And a battery 8 charged by the generator 6 are included. Furthermore, electrical equipment such as a car stereo, an air conditioner, and a car navigation system mounted on the vehicle is connected to the generator 6 and the battery 8 as a load 10. In addition, a current sensor 12 that measures a current when the battery 6 is charged from the generator 6 and a current discharged from the battery 8 to the load 10 is disposed near the positive output terminal of the battery 8. The abnormality detection device for a current sensor according to the present embodiment detects an abnormality such as a stack failure of the current sensor 12.

  Specifically, the ECU 2 includes a CPU (Central Processing Unit), a memory, a program stored therein, various interfaces, and the like (not shown). The ECU 2 realizes various functions such as fuel injection amount control and ignition timing control of an engine (not shown) based on detection results from various sensors mounted on the vehicle. The abnormality detection device 1 for the current sensor according to the present embodiment is realized as one function of the ECU 2, and is connected to the operating state detection means 14, the generator control means 16, the abnormality determination means 18, and the ECU 2 incorporated in the ECU 2. A warning lamp 4 is used.

  The generator 6 is connected to an engine crankshaft (not shown) via a belt (not shown) and a pulley (not shown), and is configured to convert a part of the engine output into electric energy. Yes. Further, the generator 6 includes a field coil (not shown) and an armature (not shown), and these are rotated relative to each other by the engine output to generate an electromotive force on the armature (not shown). Will occur. Further, the magnitude of the electromotive force generated by the generator 6 is controlled by changing the current flowing through the field coil (not shown).

  The battery 8 has its positive terminal connected to the positive output terminal of the generator 6 and its negative terminal connected to the negative output terminal of the generator 6 so that the electric power generated by the generator 6 is charged. It is configured. Various batteries such as a nickel hydride battery and a nickel cadmium battery can be used as the battery 8.

  The load 10 is a generic term for electric devices that are mounted on a vehicle and consume the electric power generated by the generator 6, and specifically includes a car stereo, an air conditioner, a car navigation system, and the like. The generator 6 and the battery 8 are connected in parallel to the load 10. When no power is generated by the generator 6, power is supplied from the battery 8 to the load 10. Further, when electric power is generated by the generator 6, the generated electric power is configured to be charged to the battery 8 and supplied to the load 10.

  The current sensor 12 is disposed adjacent to the positive terminal of the battery 8 and is configured to detect a charge / discharge current of the battery 8. When the battery 8 is charged with the electric power generated by the generator 6, a current in the direction from the generator 6 toward the battery 8 is detected by the current sensor 12. Further, when electric power is supplied from the battery 8 to the load 10, the current in the direction from the battery 8 toward the load 10 is detected by the current sensor 12.

  The driving state detection means 14 is built in the ECU 2 and configured to detect the driving state of the vehicle. Specifically, the driving state detection unit 14 receives signals of the vehicle speed S and the accelerator opening θ from the vehicle speed sensor and the accelerator opening sensor mounted on the vehicle, and determines whether or not the vehicle is in a predetermined deceleration state. Is detected.

  The generator control means 16 is built in the ECU 2 and is configured to control the generator 6 based on the operation state detected by the operation state detection means 14. Specifically, the generator control means 16 increases the current flowing through the field coil (not shown) of the generator 6 when the driving state detection means 14 detects the deceleration state of the vehicle, and the output voltage of the generator 6 is increased. Is controlled to be higher. On the other hand, when the vehicle is in a non-decelerated state, the generator control means 16 reduces the current flowing through the field coil (not shown) of the generator 6 and decreases the output voltage of the generator 6. In the present embodiment, the generator control means 16 controls the generator 6 so that the output voltage of the generator 6 is 14V during deceleration and 12.5V during non-deceleration.

  The abnormality determination means 18 is built in the ECU 2 and is configured to determine an abnormality of the current sensor 12 and to turn on the warning lamp 4 when there is an abnormality. Specifically, the abnormality determination unit 18 is configured to measure the current measured by the current sensor 12 when the generator control unit 16 switches the output voltage of the generator 6 from a low voltage during non-deceleration to a high voltage during deceleration. Based on the behavior, the abnormality of the current sensor 12 is determined.

Next, with reference to FIGS. 2 and 3, the operation of the abnormality detection device 1 for a current sensor according to the embodiment of the present invention will be described.
FIG. 2 is a flowchart showing the operation of the current sensor abnormality detection device, and this process is repeatedly executed during operation of the engine (not shown). First, in step S <b> 1 of FIG. 2, the vehicle speed S detected by the vehicle speed sensor mounted on the vehicle and the accelerator opening θ detected by the accelerator opening sensor are input to the driving state detection means 14. In step S <b> 1, the current I detected by the current sensor 12 is input to the abnormality determination unit 18.

  Next, in step S2, the driving state detection unit 14 determines whether or not the vehicle speed S input in step S1 is equal to or higher than a predetermined vehicle speed. If it is equal to or higher than the predetermined vehicle speed, the process proceeds to step S3, and if it is lower than the predetermined vehicle speed, the process proceeds to step S6. In step S3, the driving state detection means 14 determines whether or not the accelerator opening θ input in step S1 is 0 (fully closed). When the accelerator opening degree θ is 0, the process proceeds to step S4, and when the accelerator opening degree θ is not 0, the process proceeds to step S6. That is, the driving state detection means 14 determines whether the vehicle is in a decelerating state or a non-decelerating state depending on whether or not the accelerator opening degree θ is zero.

  If the vehicle speed S is less than the predetermined vehicle speed, the process of step S6 is performed even if the accelerator opening θ is 0 and the vehicle is in a decelerating state. However, in the “non-decelerating state” in this specification, Assume that all the states in which the process of step S6 is performed are included. The reason why the vehicle speed is considered for the case of the deceleration state in which the process of step S4 is performed and the case of the non-deceleration state in which the process of step S6 is performed will be described later.

  Next, in step S4, since it is determined that the vehicle is in a predetermined deceleration state, the driving state detection means 14 sets the deceleration flag to 1 and proceeds to step S5. In step S5, since the deceleration flag is 1, the generator control means 16 sets the target value of the output voltage of the generator 6 to 14V that is the first voltage, and the generator so that the output voltage becomes the first voltage. 6 is controlled. That is, when the output voltage of the generator 6 is lower than the first voltage, the generator control means 16 increases the current flowing through the field coil (not shown) of the generator 6 and is higher than the first voltage. In this case, the current flowing through the field coil (not shown) of the generator 6 is reduced so that the output voltage of the generator 6 is controlled to be the first voltage. When the output voltage of the generator 6 is controlled to the first voltage, the power generated by the generator 6 is charged in the battery 8. Thereby, at the time of deceleration, the surplus kinetic energy of the vehicle is converted into electric energy and recovered by the battery 8.

  On the other hand, in step S6, since it is determined that the vehicle is not in the predetermined deceleration state, the driving state detection means 14 sets the deceleration flag to 0 and proceeds to step S7. In step S7, since the deceleration flag is 0, the generator control means 16 sets the target value of the output voltage of the generator 6 to 12.5 V that is the second voltage, so that the output voltage becomes the second voltage. The generator 6 is controlled. When the output voltage of the generator 6 is controlled to a second voltage lower than the first voltage, the generator 6 hardly generates power and the battery 8 is not charged. In this case, power is supplied to the load 10 mainly from the battery 8. For this reason, when a load is applied to the engine, such as when the vehicle is accelerated, the engine output is hardly used for power generation by the generator 6, and an excessive load on the engine is prevented. The When the vehicle speed is less than the predetermined vehicle speed, the process of step S6 is performed even when the vehicle is in a deceleration state, and the battery 8 is not charged. This is because when the vehicle speed is less than a predetermined value, the kinetic energy of the vehicle is very small and there is almost no energy that can be recovered by power generation.

  Next, in step S8, the abnormality determination means 18 determines whether or not the deceleration flag has changed from 0 to 1 in the current process of the flowchart shown in FIG. That is, when the flowchart of FIG. 2 was executed last time, the deceleration flag is set to 0 in step S6, and when the deceleration flag is set to 1 in this processing, the deceleration flag changes from 0 to 1. It is judged that If the deceleration flag changes from 0 to 1, the process proceeds to step S9. Otherwise, the one-time process of the flowchart shown in FIG.

  FIG. 3 is a time chart showing a change in the target output voltage of the generator 6 on the upper solid line, a change in the battery voltage on the upper broken line, and a change in the charge / discharge current of the battery on the lower solid line. As described above, when the deceleration flag is 0, the target output voltage of the generator 6 is set to the second voltage, and when the deceleration flag is 1, the target output voltage is set to the first voltage. Accordingly, the change of the deceleration flag from 0 to 1 corresponds to the change of the target output voltage of the generator 6 from the second voltage to the first voltage in the time chart of FIG.

  When the target output voltage of the generator 6 changes from the second voltage to the first voltage, the battery voltage also changes to the first voltage following this. At this time, charging of the battery 8 is started, and a current in a predetermined direction in which the charging of the battery 8 is performed starts flowing as shown by the solid line in the lower part of FIG. Such charge / discharge current to the battery 8 is detected by the current sensor 12, and the detection result is input to the abnormality determination means 18.

  When the target output voltage of the generator 6 changes from the first voltage to the second voltage, the battery voltage follows the second voltage with a slight delay as shown by the broken line in the upper part of FIG. To change. At this time, the charging / discharging current to the battery 8 changes from the charging direction to the discharging direction as shown by the solid line in the lower part of FIG. 3 and is stable in a state where the discharging current flows slightly after the discharging current flows for a predetermined period. To do.

  Next, in step S9, the amount of change in the charge / discharge current I to the battery 8 when the target output voltage of the generator 6 changes from the second voltage to the first voltage is determined. When the change amount of the charge / discharge current I is equal to or less than the predetermined amount, the process proceeds to step S10, and when the change amount is larger than the predetermined amount, the one-time process of the flowchart shown in FIG. In step S10, the abnormality determination means 18 determines that the current sensor 12 is abnormal.

  As described above, when the target output voltage of the generator 6 changes from the second voltage to the first voltage, the charging current to the battery 8 starts to flow, so the current value I measured by the current sensor 12 is The battery 8 should change by a predetermined amount (δ in FIG. 3) in the direction of charging. However, when a stack failure occurs in the current sensor 12, the current value detected by the current sensor 12 is fixed to a substantially constant value, so that the amount of change in the current value I becomes very small. The abnormality determination means 18 determines abnormality of the current sensor 12 using this behavior of the current value I measured by the current sensor 12. The threshold value of the current change amount for determining whether there is an abnormality in the current sensor 12 is preferably set to about several A.

In step S11, the abnormality determination means 18 turns on the warning lamp 4 and notifies the vehicle occupant that an abnormality has occurred in the current sensor 12. Next, in step S12, the abnormality determination means 18 sends a signal to the generator control means 16 and prohibits the target output voltage of the generator 6 from being set to the second voltage. That is, the target output voltage of the generator 6 is fixed to the first voltage. As a result, the target output voltage of the generator 6 is set to the second voltage based on the erroneous current value measured by the abnormal current sensor 12, and the vehicle cannot run due to excessive decrease in the remaining capacity of the battery 8. That is, the so-called “battery goes up” is avoided.
The current sensor abnormality detection device 1 according to the present embodiment detects an abnormality of the current sensor by repeating the above processing.

  According to the current sensor abnormality detection device of the embodiment of the present invention, a current sensor abnormality can be detected by a simple device and abnormality determination algorithm. That is, according to the current sensor abnormality detection device of the present embodiment, since the battery is charged when the vehicle is in a decelerating state, the excess kinetic energy of the vehicle is not wasted by the brake or the like. It is recovered as energy. Further, since the abnormality of the current sensor is detected based on the change of the charging current flowing at that time, it is possible to easily detect the abnormality such as the stack failure of the current sensor without sacrificing the fuel consumption.

  Further, according to the abnormality detection device for the current sensor of the embodiment of the present invention, the abnormality of the current sensor is promptly notified to the vehicle occupant by the warning lamp. Overcharge or overdischarge can be prevented.

  Further, according to the current sensor abnormality detection device of the embodiment of the present invention, when the current sensor is abnormal, the output voltage of the generator is fixed to the first voltage, so that the battery is always sufficiently charged. In other words, it is possible to prevent the vehicle from being disabled due to excessive reduction of the remaining battery capacity.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the above-described embodiment, the abnormality detection device for the current sensor is built in the ECU. However, the abnormality detection device for the current sensor is configured separately from the ECU, or in another device. It can also be configured to be built in. Further, in the above-described embodiment, the current sensor is arranged to measure the current flowing through the positive terminal of the battery, but the current sensor is arranged to measure the current flowing through the negative terminal of the battery. May be. Furthermore, in the above-described embodiment, the deceleration state and the non-deceleration state are divided into cases in consideration of the vehicle speed and the accelerator opening, but the deceleration state and the non-deceleration state may be divided into cases without considering the vehicle speed. .

  In the above-described embodiment, when abnormality of the current sensor is detected, the target output voltage of the generator is fixed to the first voltage. However, the target output voltage of the generator is set lower than the first voltage. It can also be configured to be fixed at a predetermined voltage that is higher than the second voltage and is always charged.

  Furthermore, in the embodiment described above, the abnormality detection device for the current sensor detects an abnormality in the current sensor based on a change in the current value when the target output voltage of the generator is switched from the second voltage to the first voltage. However, it is also possible to detect an abnormality based on a change in the current value when the first voltage is switched to the second voltage. Alternatively, the abnormality may be detected both when the target output voltage is switched from the second voltage to the first voltage and when the target voltage is switched from the first voltage to the second voltage. However, when the battery is deteriorated due to aging or the like, the charging / discharging current of the battery changes as indicated by the dotted line in the lower part of FIG. 3, so that the change in the current value when the second voltage is switched to the first voltage. It is more advantageous to use

  That is, as shown in the lower part of FIG. 3, the change amount δ of the current value when the second voltage is switched to the first voltage does not change much even when the battery is deteriorated, but from the first voltage to the second voltage. The amount of change when switching to is reduced due to deterioration of the battery. For this reason, the abnormality detection of the current sensor becomes difficult due to the deterioration of the battery. Therefore, it is possible to detect the abnormality of the current sensor more reliably by using the change in the current value when the second voltage is switched to the first voltage.

1 is a system configuration diagram of an electric system mounted on a vehicle including an abnormality detection device for a current sensor according to an embodiment of the present invention. It is a flowchart which shows the effect | action of the abnormality detection apparatus of the current sensor by embodiment of this invention. It is a time chart which shows the target output voltage of a generator, the battery voltage, and the charging / discharging electric current of a battery.

Explanation of symbols

1 Current sensor abnormality detection device 2 ECU
4 warning lamp 6 generator 8 battery 10 load 12 current sensor 14 operating state detection means 16 generator control means 18 abnormality determination means

Claims (4)

An abnormality detection device for detecting an abnormality of a current sensor for detecting a charging current or a discharging current of a battery charged by a generator mounted on a vehicle,
Driving state detection means for detecting whether or not the vehicle is in a deceleration state;
When the deceleration state is detected by the operating state detection means, the output voltage of the generator is controlled to the first voltage so that the battery is charged. Generator control means for controlling the output voltage of the generator to be a second voltage lower than the first voltage;
An abnormality determining means for determining an abnormality of the current sensor based on a change in a current value measured by the current sensor when the output voltage of the generator is switched by the generator control means;
An abnormality detection device for a current sensor, comprising:   The abnormality determination means determines an abnormality of the current sensor based on a change in a current value measured by the current sensor when the output voltage of the generator is switched from the second voltage to the first voltage. Item 10. An abnormality detection apparatus according to item 1.   The abnormality detection device according to claim 1, further comprising abnormality notifying means for notifying an occupant of the vehicle of the abnormality of the current sensor when the abnormality determining means determines that the current sensor is abnormal.   When the abnormality determining means determines that the current sensor is abnormal, the generator control means causes the output voltage of the generator to be higher than the second voltage and to be a predetermined voltage that is always charged. The abnormality detection device according to any one of claims 1 to 3, wherein the generator is controlled at a time.

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