JP4626558B2 - Battery status determination device - Google Patents

Description

  The present invention relates to a battery state determination device, and more particularly to a battery state determination device that determines a deterioration state of a lead battery mounted in a vehicle.

  Lead batteries (lead batteries for automobiles) mounted on vehicles supply power not only to vehicles but also to various electric devices mounted on vehicles. Further, the vehicle is equipped with a generator (alternator) driven by an engine, and the lead battery is charged by the operation control of the alternator to maintain the capacity. In recent years, for example, electric loads on vehicles such as car navigation systems have increased, and in consideration of environmental problems, hybrid electric vehicles that combine an electric motor and engine, or when the signal is stopped, the engine is stopped and restarted at the start (with an ISS system E) Automobiles have been developed.

  In such a lead battery usage environment, the deterioration state of the lead battery is accurately detected and the current state of charge is grasped, so that there is no hindrance to vehicle travel (for example, various electric devices while the engine is stopped). If the remaining capacity of the lead battery is reduced due to the load of the battery, sufficient output to start the engine cannot be obtained, and it may not be possible to restart the engine after the engine stops)), accurately detecting the deterioration state of the lead battery Technology becomes important.

  As a lead battery state detection technology, when the starter motor functions and the engine is started, that is, when the engine starts to rotate, the instantaneous drop of the lead battery voltage, that is, the minimum voltage value (Vst) is detected. (See FIG. 3), a technique for monitoring whether or not the drop exceeds a threshold is known (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 7-631141

  When considering commercialization of a battery state determination device for a lead battery, it is difficult to constantly detect the minimum voltage value (Vst). It can easily be imagined that it is necessary to use it under the circumstances. In addition, if the lowest voltage detection device is always used in an on-vehicle situation, the space in the engine room is limited, so it is difficult to mount a large-scale device and it is considered necessary to mount a compact device.

  On the other hand, when the minimum voltage value (Vst) is acquired a plurality of times, for example, when the average value is a true minimum voltage value, when the minimum voltage value is measured in the engine room of the vehicle, Although the frequency is low, erroneous measurement may be performed. In order to increase the accuracy of the minimum voltage value, the voltage measurement of the lead battery at the time of starting the engine is generally performed at a high speed of 100 Hz or more (A / D converter having a sampling speed of 100 Hz or more is used). If voltage measurement is performed at a high speed, erroneous measurement is more likely to occur. This erroneous measurement is detected irregularly at one point, which is very troublesome in the battery state determination device that detects the state of the lead battery from the voltage of the lead battery.

  An object of the present invention is to provide a battery state determination device that can accurately determine the deterioration state of a lead battery mounted on a vehicle.

  In order to solve the above problems, the present invention provides a battery state determination device for determining a deterioration state of a lead battery mounted on a vehicle, wherein the analog voltage at the start of the lead battery engine at a speed of 100 Hz or higher is a digital voltage value. Conversion means for converting to a minimum voltage value extraction means for extracting a minimum voltage value (Vst) at the time of engine start of the lead battery from the digital voltage value converted by the conversion means, and the minimum voltage value extraction means Among the plurality of the minimum voltage values (Vst) extracted each time the engine is started, the minimum voltage value equal to or higher than the preset upper limit voltage value and the minimum voltage value equal to or lower than the preset lower limit voltage value are deleted. Determination means for determining whether one of the median value, the mode value, and the average value of the remaining minimum voltage values is equal to or less than a predetermined determination reference voltage value.

  In the present invention, the analog voltage at the time of starting the engine of the lead battery is converted into a digital voltage value by the converting means at a speed of 100 Hz or more, and the lead voltage of the lead battery is selected from the digital voltage values converted by the converting means by the minimum voltage value extracting means. A minimum voltage value (Vst) at the time of engine start is extracted, and a predetermined upper limit voltage value among a plurality of minimum voltage values (Vst) extracted by the determination unit every time the engine is started by the minimum voltage value extraction unit. The minimum voltage value above and the minimum voltage value below the preset lower limit voltage value are deleted, and the median, mode, or average value of the remaining minimum voltage values is less than the preset reference voltage value Is determined, the deterioration state of the lead battery is determined. According to the present invention, among the plurality of minimum voltage values extracted by the minimum voltage value extraction unit by the determination unit, the minimum voltage value equal to or higher than the upper limit voltage value and the minimum voltage value equal to or lower than the lower limit voltage value, which is considered to be erroneous measurement. Is deleted, and it is determined whether any of the median, mode, and average of the remaining minimum voltage values is less than or equal to the preset determination reference voltage value. Can do.

  In the present invention, for example, the upper limit voltage value may be set to 10.5 V and the lower limit voltage value may be set to 3.0 V, or the upper limit voltage value may be set to the maximum value and the lower limit voltage value among the minimum voltage values (Vst). You may set to the minimum value among the minimum voltage values (Vst). Further, the storage device further includes a nonvolatile storage unit that stores the minimum voltage value (Vst) extracted by the minimum voltage value extraction unit, and the determination unit reads out the plurality of minimum voltage values (Vst) stored in the storage unit. May be. Furthermore, in order to eliminate the inaccuracy of voltage measurement due to charge / discharge polarization by the lead battery, the engine start interval determination means for determining whether the engine start has been performed for a predetermined time or more after the engine stop is further provided. When the determination is affirmative, the lowest voltage value extracting means may extract the lowest voltage value (Vst) at the time of starting the engine of the lead battery from the digital voltage value converted by the converting means.

  According to the present invention, among the plurality of minimum voltage values extracted by the minimum voltage value extraction unit by the determination unit, the minimum voltage value equal to or higher than the upper limit voltage value and the minimum voltage value equal to or lower than the lower limit voltage value, which is considered to be erroneous measurement. Is deleted, and it is determined whether any of the median, mode, and average of the remaining minimum voltage values is less than or equal to the preset determination reference voltage value. The effect of being able to be obtained can be obtained.

  Hereinafter, the best mode of a battery state determination device according to the present invention will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, a battery state determination device 1 according to the present embodiment includes a differential amplifier circuit and the like, a voltage sensor 3 that measures a voltage between terminals of a lead battery 2, and a micro that determines a battery state of the lead battery 2. A computer (hereinafter referred to as a microcomputer) 10 is provided and is disposed in the engine room of the automobile.

  The lead battery 2 has a substantially rectangular battery case serving as a battery container. The battery case material is excellent in terms of moldability, electrical insulation, corrosion resistance and durability, for example, polymer resins such as acrylic butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc. Can be selected. A total of six sets of electrode plates are accommodated in the battery case. In each electrode plate group, a plurality of negative electrodes and positive electrodes are laminated via a separator, and the cell voltage is 2.0V. Therefore, the nominal voltage of the lead battery 2 is 12V. The upper part of the battery case is bonded or welded to an upper lid made of a polymer resin such as ABS, PP, PE or the like that seals the upper opening of the battery case. The upper lid is provided with a positive external output terminal and a negative external output terminal for supplying electric power to the outside using a lead battery as a power source.

  A positive external output terminal of the lead battery 2 is connected to a central terminal of an ignition switch (hereinafter referred to as IGN switch) 5. The IGN switch 5 has an OFF terminal, an ON / ACC terminal, and a START terminal in addition to the central terminal, and the central terminal and any of these OFF, ON / ACC, and START terminals can be switched in a rotary manner. Is possible.

  The START terminal is connected to an engine starting cell motor (starter) 9. The cell motor 9 can transmit a rotational driving force to the rotating shaft of the engine 8 via a clutch mechanism (not shown).

  Further, the ON / ACC terminal is one end of a generator 7 that generates electricity by the rotation of the engine 8 through an auxiliary device 6 such as an air conditioner, a radio, a lamp, and a regulator that allows current flow in one direction and smoothes the voltage. It is connected to the. That is, one end side (anode side) of the regulator is connected to one end of the generator 7 and the other end (cathode side) is connected to the ON / ACC terminal. The rotating shaft of the engine 8 can transmit power to the generator 7 via a clutch mechanism (not shown). For this reason, when the engine 8 is in a rotating state, the generator 7 is operated via a clutch mechanism (not shown), and the electric power from the generator 7 is supplied (charged) to the auxiliary machine 6 and the lead battery 2. Note that the OFF terminal is not connected to any of them.

  The external output terminal of the lead battery 2 is connected to the voltage sensor 3, and the output side of the voltage sensor 3 is connected to an A / D converter as conversion means built in the microcomputer 10. The A / D converter converts the analog voltage input from the voltage sensor 3 into a digital voltage value. For this reason, the microcomputer 10 can take in the voltage of the lead battery 2 as a digital value.

  The microcomputer 10 functions as a CPU that functions as a central processing unit, a ROM in which program data such as a basic control program of the battery state determination device 1 and a determination reference voltage value to be described later is stored, and a work area for the CPU and temporarily stores data. It includes a RAM and the like that are stored in the memory. Further, an EEPROM (nonvolatile memory) (not shown) as a storage means is connected to the external bus of the microcomputer 10. The other end of the generator 7, the cell motor 9 and the auxiliary machine 6, the negative external output terminal of the lead battery 2, and the microcomputer are each connected to the ground. Note that the microcomputer 10 of the present embodiment samples the voltage of the lead battery 2 at the time of engine start at 1 msec intervals and stores the sampling result in the RAM.

(Operation)
Next, with reference to a flowchart, the operation of the battery state determination device 1 of the present embodiment will be described with the CPU of the microcomputer 10 as a main component. When the microcomputer 10 is powered on, the CPU executes a battery state determination routine for determining the battery state of the lead battery 2. The program and program data stored in the ROM are expanded in the RAM by an initial setting process (not shown) after turning on the power to the microcomputer 10.

  As shown in FIG. 2, in the battery state determination routine, in step 112, it is determined whether or not the engine has been started by determining whether or not a notification that the center terminal of the IGN switch 5 is connected to the START terminal has been received. Determine whether. The notification that the center terminal is connected to the START terminal may be received directly from the IGN switch 5 or via the vehicle control system 11.

  In the next step 114, voltage data of the lead battery 2 at the time of starting the engine is taken (stored in the RAM). As described above, the sampling rate of the A / D converter built in the microcomputer 10 is 1 msec, and the voltage of the lead battery 2 at the time of starting the engine can be taken in with high accuracy, but the sampling rate is less than 100 Hz. Since the resolution is low (see FIG. 3), the minimum voltage value Vst cannot be accurately captured.

  Next, at step 116, the minimum value of the voltage data of the lead battery 2 at the time of engine start stored in the RAM is extracted and written to the EEPROM as the minimum voltage value Vst of the lead battery 2 at the time of engine start.

  In step 118, a plurality of minimum voltage values Vst written in the EEPROM are read each time the engine is started. Next, in step 120, among the read minimum voltage value Vst, a minimum voltage value Vst that is equal to or higher than a preset upper limit voltage value (eg, 10.5 V) and a preset lower limit voltage value (eg, 3.0 V). By excluding the following minimum voltage values, data regarded as erroneous measurement data is excluded, and an average value of the remaining minimum voltage values Vst is calculated.

  Next, in step 122, it is determined whether or not the lead battery 2 has deteriorated by determining whether or not the average value calculated in step 120 is less than or equal to a preset determination reference voltage value (for example, 8.00 V). To do. If the determination is affirmative, in the next step 124, the vehicle control system 11 is informed that the lead battery 2 has deteriorated, and the battery state determination routine is terminated. The vehicle control system 11 that has received the notification that the lead battery 2 has deteriorated may not be able to restart the engine (ISS) after the vehicle stops, so the driver panel displays that the lead battery 2 has deteriorated on the installation panel. Prompts replacement of the lead battery 2. On the other hand, when the determination at step 122 is negative, the battery state determination routine is terminated.

(Action / Effect)
Next, functions and effects of the battery state determination device 1 of the present embodiment will be described.

  In the battery state determination device 1 of the present embodiment, in order to capture the digital voltage value of the lead battery 2 at the time of engine start with high resolution, an A / D converter with a sampling speed of 1 msec is built in the microcomputer 10 to start the engine. Each time, the minimum voltage value Vst is accurately extracted and stored in the EEPROM (step 116). Of the minimum voltage values Vst read out from the EEPROM, the minimum voltage value Vst greater than the upper limit voltage value and the lowest voltage value less than the lower limit voltage value. By eliminating the voltage value, data regarded as erroneous measurement data is excluded, the average value of the remaining minimum voltage value Vst is calculated (step 120), and the deterioration state of the lead battery 2 is determined (step 122). ). According to the battery state determination apparatus 1 of the present embodiment, even when the high-speed A / D converter is used and the engine is easily placed in an engine room that is easily affected by electromagnetic waves or the like, the data of the lowest voltage value Vst that is regarded as erroneous measurement data. Therefore, the deterioration state of the lead battery 2 can be accurately determined.

  In the present embodiment, data regarded as erroneous measurement data is excluded and the average value of the remaining minimum voltage values Vst is calculated (step 120), and the average value is compared with the determination reference voltage value to thereby lead Although the example of determining the deterioration state of the battery 2 (step 122) has been shown, the present invention is not limited to this, and the median or mode of the lowest voltage value Vst is calculated and determined as the median or mode. You may make it compare with a reference voltage value.

  In the present embodiment, the minimum voltage value Vst read from the EEPROM is excluded from the minimum voltage value Vst that is equal to or higher than the upper limit voltage value (10.3 V) and the minimum voltage value that is equal to or lower than the lower limit voltage value (3.0 V). However, the present invention is not limited to this. For example, the maximum value of the minimum voltage value Vst and the minimum value of the minimum voltage value Vst are excluded. It may be.

  Furthermore, in this embodiment, in order to suppress the power consumption of the lead battery 2, the example in which the operating power is not supplied to the battery state determination device 1 while the vehicle is parked is shown, but the present invention is not limited to this, You may make it return to step 112 after the process in step 124, and at the time of negative determination of step 122. In this case, since the operating power is always supplied to the battery state determination device 1, it is not necessary to use an EEPROM that is expensive.

  In the present embodiment, an example is shown in which the minimum voltage value Vst is measured each time the engine is started. However, the discharge polarization is accumulated while the lead battery 2 is being discharged (during vehicle operation), and the polarization is eliminated. Therefore, it is determined whether or not a predetermined time (for example, 6 hours, preferably 8 hours or more) has elapsed after the engine is stopped, and the minimum voltage value Vst is extracted when an affirmative determination is made. Also good. Such a determination is preferably made before step 116 in the battery state determination routine described above. Whether or not a predetermined time has elapsed after the engine is stopped may be determined by the microcomputer 10 using an internal clock, or may be provided with a separate timer (IC), or the vehicle control system 11. The microcomputer 10 may make a determination based on notification of the engine stop time, the engine start start time (current time), and the like. In the present embodiment, the A / D converter having a sampling speed of 1 msec (1000 Hz) is exemplified as the conversion means. However, the present invention is not limited to this, and the voltage of the lead battery 2 at the time of starting the engine is sampled at 100 Hz or more. I can do it.

(test)
The following tests were performed according to the above-described embodiment. A gasoline engine car with a displacement of 1800 cc was arbitrarily selected as a vehicle equipped with a lead battery 2. As shown in Table 1 below, engine starting voltage data was acquired 24 times in total using a voltmeter capable of measuring voltage at 1 msec intervals. It should be noted that the engine start interval was after 6 hours or more after the engine was stopped.

  Data 1, 13, and 23 are considered noise data. A simple program that derives an average value of all 24 obtained minimum voltage values Vst by calculation, and among the obtained 24 minimum voltage values Vst, a minimum voltage value Vst of 10.5 V or more and a minimum voltage of 3 V or less All the values Vst were removed, and a simple program was derived to calculate the average value of the remaining minimum voltage values Vst, and the values were compared (Table 2).

  As can be seen from Table 2, there is a difference of about 0.6 V between the two data, and this value can be regarded as a numerical value that may cause an erroneous determination.

  Since the present invention provides a battery state determination device capable of accurately determining the deterioration state of a lead battery mounted on a vehicle, the present invention contributes to the manufacture and sale of the battery state determination device. Have

1 is a block wiring diagram of a battery state determination device and a vehicle according to an embodiment to which the present invention is applicable. It is a flowchart of the battery state determination routine which CPU of the microcomputer of the battery state determination apparatus of embodiment performs. It is a graph which shows the minimum voltage at the time of engine starting of a general lead battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery state determination apparatus 2 Lead battery 3 Voltage sensor (a part of conversion means)
10 Microcomputer (part of conversion means, minimum voltage value extraction means, determination means, engine start interval determination means)

Claims (5)

In a battery state determination device for determining a deterioration state of a lead battery mounted on a vehicle,
Conversion means for converting the analog voltage at the time of engine start of the lead battery into a digital voltage value at a speed of 100 Hz or more;
Minimum voltage value extraction means for extracting the minimum voltage value (Vst) at the time of engine start of the lead battery from the digital voltage value converted by the conversion means;
Among the plurality of minimum voltage values (Vst) extracted each time the engine is started by the minimum voltage value extracting means, the minimum voltage value that is greater than or equal to a preset upper limit voltage value and the lowest that is less than or equal to a preset lower limit voltage value A determination unit that deletes the voltage value and determines whether any of the median, mode, and average of the remaining minimum voltage values is equal to or less than a predetermined determination reference voltage value;
A battery state determination device comprising:   The battery state determination device according to claim 1, wherein the upper limit voltage value is 10.5V and the lower limit voltage value is 3.0V.   The upper limit voltage value is a maximum value among the minimum voltage values (Vst), and the lower limit voltage value is a minimum value among the minimum voltage values (Vst). Battery state determination device.   Non-volatile storage means for storing the lowest voltage value (Vst) extracted by the lowest voltage value extraction means is further provided, and the determination means reads a plurality of the lowest voltage values (Vst) stored in the storage means. The battery state determination apparatus according to claim 1.   The engine further includes engine start interval determination means for determining whether engine start has been performed for a predetermined time or more after engine stop, and when the engine start interval determination means makes a positive determination, the minimum voltage value extraction means is converted by the conversion means. 5. The battery state determination device according to claim 1, wherein a minimum voltage value (Vst) at the time of engine start of the lead battery is extracted from the digital voltage value.

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