JP2009113702A - Deterioration determination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deterioration determination device which accurately carries out deterioration determination by the voltage measurement of a lead battery. <P>SOLUTION: In the deterioration determination device, an AI unit 1 measures the voltage of the lead battery through a voltage measurement part, and a calculation part calculates the minimum voltage value Vst of voltage values measured when an engine is started (S104), and then calculates a voltage difference ΔVst between the minimum voltage value Vst0 of the lead battery in a non-deteriorating state which is stored in an EEPROM when the engine is started and the most recently measured minimum voltage value Vst of the lead battery (S114). It is temporarily determined that the lead battery is deteriorated when the voltage difference ΔVst is above a determination threshold Vth (S116), it is determined whether or not temporary determination is successively carried out five times (S120), and it is informed to a driver that the lead battery is determined to be deteriorated during temporal judgement (S124). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a deterioration determination apparatus, and more particularly, to a deterioration determination apparatus that determines deterioration of a lead battery mounted in an automobile.

  In general, an automobile is equipped with a lead (storage) battery that starts an internal combustion engine and supplies electric power to various electrical components. Such a lead battery is called a lead battery for an automobile. The automobile 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.

  By the way, in recent years, the load on lead batteries due to electrical components such as car navigation systems has increased, and in consideration of environmental problems, hybrid electric vehicles that combine an electric motor and engine, and when the signal is stopped, the engine is stopped and restarted when starting. ISS system (automatic) vehicles have been developed. Under such a usage environment, it is necessary to constantly check the current battery state so that there is no trouble in driving, so lead battery state detection technology has been actively researched and developed. .

  As a state detection technology for a lead battery for automobiles, an instantaneous drop (minimum voltage value Vst) of the lead battery voltage when the starter motor functions and the engine is started, that is, when the engine starts to rotate is detected ( 4), a deterioration determination device (see, for example, Patent Document 1) that monitors whether the drop does not exceed a threshold value, or the degree of pulsation of the engine start-up voltage (see FIG. 4) is detected to be constant. A degradation determination device (see, for example, Patent Document 2) that monitors whether or not the degree is exceeded is known. The technology for judging deterioration by monitoring the voltage of the lead battery at the time of starting the engine is reasonable, and the judgment of deterioration of the lead battery can be grasped almost accurately.

JP 2001-163129 A JP 2007-015477 A

  However, the information at the time of starting the engine includes not only the deterioration state of the lead battery, but also the open circuit voltage (OCV) of the lead battery at the time of measurement, the temperature, the charging state, the (temporary) change in the usage pattern, the engine Noise is mixed depending on the starting interval and the like, and a slight difference in value occurs every time the engine is started. Depending on the type of vehicle, there are differences in error. Naturally, correction for these parameters should be performed, but it is still not perfect, and there is a problem that erroneous determination occurs regarding the deterioration of the lead battery.

  An object of the present invention is to provide a deterioration determination device capable of accurately determining deterioration by measuring the voltage of a lead battery in view of the above-described case.

  In order to solve the above-described problems, the present invention provides a deterioration determination apparatus for determining deterioration of a lead battery mounted on an automobile, a voltage measurement unit that measures the voltage of the lead battery, and a voltage measured by the measurement unit. Among the calculation means for calculating the minimum voltage value of the lead battery when the engine is started, the latest minimum voltage value Vst calculated by the calculation means, and the preset deterioration determination threshold value Vth. A first deterioration determining means for determining the deterioration of the lead battery; and determining whether or not the deterioration determination of the lead battery by the first deterioration determining means has been continuously performed a plurality of times. And second deterioration determining means for determining that has deteriorated.

  In the present invention, the voltage of the lead battery is measured by the voltage measuring means, and the minimum voltage value at the time of starting the engine of the lead battery is calculated among the voltages measured by the voltage measuring means by the calculating means, and calculated by the first deterioration determining means. The deterioration of the lead battery is determined based on the latest lowest voltage value Vst calculated by the means and a preset deterioration determination threshold value Vth. Then, the second deterioration determination means determines whether or not the deterioration determination of the lead battery by the first deterioration determination means has been continuously performed a plurality of times, and it is determined that the lead battery has deteriorated when an affirmative determination is made.

  In the present invention, the first deterioration determination means may determine that the lead battery has deteriorated when the minimum voltage value Vst is smaller than the deterioration determination threshold value Vth, or the lead means has no deterioration state by the calculation means. Lead when the difference or ratio value between the minimum voltage value Vst0 calculated in step 4 and the latest minimum voltage value Vst calculated by the calculation means in the non-deteriorated or deteriorated state of the lead battery is larger than the deterioration determination threshold value Vth. It may be determined that the battery has deteriorated.

  According to the present invention, the second deterioration determination means determines that the lead battery has deteriorated when the deterioration determination of the lead battery by the first deterioration determination means is continuously performed a plurality of times. In addition, it is possible to repel the erroneous deterioration determination due to the measurement error and to accurately perform the deterioration determination.

  Hereinafter, an embodiment in which the present invention is applied to a deterioration determination device arranged integrally with an automotive lead battery (model: 65B24R) will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the lead battery 10 has a substantially rectangular battery case 8 serving as a battery container, and a total of six electrode plate groups are accommodated in the battery case 8. As the material of the battery case 8, it is possible to select a polymer resin such as polyethylene (PE), polypropylene (PP), and acrylic butadiene styrene (ABS) that is excellent in terms of formability, insulation, durability, and the like. it can. In each electrode plate group, a plurality of negative electrodes and positive electrodes are laminated via a separator, and the cell voltage is set to 2.0V. Therefore, the nominal voltage of the lead battery 10 is 12V. The upper part of the battery case 8 is bonded or welded to an upper lid 9 made of a polymer resin such as PE that seals the upper opening of the battery case 8.

  The upper lid 9 is provided with two (positive and negative) output terminals 7 for supplying electric power to the outside by using the lead battery 10 as an automobile power source. The upper lid 9 accommodates (incorporates) an AI unit 1 as a deterioration determination device that determines deterioration of the lead battery 10.

  The AI unit 1 is composed of an AD converter, a reference power source, etc., and measures a voltage of the lead battery 10, a temperature measuring unit, which is composed of an AD converter, a thermistor, etc., and measures the temperature of the lead battery 10, and a microprocessor , ROM, RAM, nonvolatile memory EEPROM, etc., a coil-type buzzer (not shown), a transistor for operating the buzzer, resistors, etc. A notification unit to be generated, an operation display unit configured to include an operation button 3, a light emitting diode (hereinafter referred to as an LED), a transistor, a resistor, and the like, and turn on the LED to indicate that the lead battery 10 needs to be replaced. 2 are provided. The AI unit 1 is connected to the output terminal 7 by a connecting conductor in the upper lid 9, and operating power is supplied from the lead battery 10.

  A buzzer sound emitting hole 6 is formed at a position where the buzzer of the AI unit 1 is mounted on the upper lid 9, and the upper surface of the operation display unit 2 of the AI unit 1 is substantially flush with the upper surface of the upper lid 9. .

(Degradation judgment principle)
Next, the principle of determining deterioration of the lead battery 10 by the AI unit 1 will be described.

  The microprocessor (hereinafter abbreviated as MP) captures the digital voltage value of the lead battery 10 via the voltage measurement unit and stores it in the RAM every predetermined time (for example, 2 ms). The health condition (deterioration) of the lead battery 10 is determined based on the above.

  In general, in an automobile having an internal combustion engine such as a gasoline engine vehicle or a diesel engine vehicle, electric power is supplied from a lead battery, and a cell motor is rotated to start the engine. At this time, a large current flows, and accordingly, the voltage between the terminals of the lead battery greatly drops. When the voltage drop at this time and the time change of the current are measured, a sharp peak-shaped large current flows immediately after the current starts to flow into the cell motor, and at the same time, the voltage between the terminals of the lead battery shows a sharp valley-shaped voltage drop. (See FIG. 4). The minimum voltage value Vst at which this voltage drop is maximum appears simultaneously at the maximum current value Ist at which the discharge current from the lead battery is maximum.

  Assuming that the engine starting system electrical resistance is R, Ohm's law is established as shown in the following formula (1) at the timing when the minimum voltage value Vst and the maximum current value Ist appear.

  The engine starting system electric resistance R is the resistance of the engine starting system constituted by a cell motor, a harness, etc. at the time of starting the engine. The total resistance obtained by adding the resistance of the cell motor as a stationary conductor to the resistance of the vehicle harness, electric contact, etc. It is. It should be noted that the engine starting system electric resistance R is a constant value only at the timing when the minimum voltage value Vst is taken, and at other timings, the engine starting system electric resistance R changes with time. Not satisfied.

  In other words, if the vehicle is the same, if the engine starting voltage can be acquired at the timing of the lowest voltage value Vst, the engine starting system electric resistance R itself is a constant with a constant resistance value using the formula (1). This resistor can be used to judge deterioration of lead batteries.

  On the other hand, when the open circuit voltage of the lead battery is Vo and the internal resistance of the lead battery is r at the timing when the minimum voltage value Vst and the maximum current value Ist appear, the following equation (2) is established.

  By substituting equation (1) into equation (2), the following equation (3) is obtained.

  From equation (3), it can be seen that the minimum voltage value Vst is a function of the open circuit voltage Vo, the engine starting system electrical resistance R, and the internal resistance r of the lead battery. The internal resistance r shows the minimum value in the non-degraded state of the lead battery, and increases as the health state (SOH) decreases. Therefore, from Equation (3), the minimum voltage value Vst is an indicator of the health status of the lead battery. In other words, when the health state of the lead battery is reduced (when the lead battery is deteriorated), the internal resistance r is increased, so that the minimum voltage value Vst is lowered.

  FIG. 3 shows the transition of the terminal voltage of the lead battery at the time of starting the engine for the lead battery in the non-degraded state (initial state) and the same lead battery after deterioration. In FIG. 3, the lowest voltage value at the time of starting the engine of the lead battery in the non-degraded state is represented by Vst0, and the latest lowest voltage value at the time of starting the engine after deterioration is represented by Vst. In FIG. 3, as the lead battery deteriorates, the voltage difference ΔVst (= Vst0−Vst) between the lowest voltage value Vst0 in the non-degraded state and the lowest voltage value Vst after deterioration increases.

  In accordance with the above principle, the AI unit 1 determines that the lead battery 10 has deteriorated and needs to be replaced when the voltage difference ΔVst becomes larger than a determination threshold value Vth described later. However, as described above, in order to use the above principle (Equation (1)), it is assumed that the minimum voltage values Vst0 and Vst at the time of starting the engine are accurately obtained. Therefore, the minimum voltage values Vst0 and Vst Need to be acquired at the optimal timing.

(Engine condition judgment)
The AI unit 1 also has a function of detecting the engine state based on the voltage of the lead battery 10 measured through the voltage measuring unit. That is, the MP constantly monitors (measures) the voltage of the lead battery 10, and determines the engine state of engine start, engine start, and engine stop from the change in voltage measured via the voltage measurement unit.

<Engine start>
MP is a voltage drop of Y (0.50 to 3.0) V or more within X (1 to 100) ms after the start of discharge of the lead battery 10 (for example, preferably a voltage of 1.5 V or more within 15 ms). It is determined whether or not the engine has started, and if it is affirmative, it is determined that the engine has been started. As the voltage value of a, for example, a voltage value of 109 to 121% of the OCV of the lead battery 10 can be used. On the other hand, when a negative determination is made, it is considered that an in-vehicle electrical component such as a car air conditioner or a car navigation system has been started, and the engine is not started.

<Engine is running>
After the positive determination of the engine start described above, the MP always has the voltage of the lead battery 10 equal to or higher than the predetermined value a described above (since the generator (alternator) is operating when the engine is running, the lead battery 10 It is determined whether the engine is in a charged state and the voltage is higher than OCV.) If the determination is affirmative, it is determined that the engine is being started.

<Engine stop>
(1) After determining that the engine is being started, if the voltage of the lead battery 10 becomes equal to or less than a certain value b: it is determined that the engine is stopped from the engine starting state. For example, a voltage value of 103 to 108% of the OCV of the lead battery 10 can be used as the voltage value of b. Also, (2) after determining that the engine is being started, when the voltage of the lead battery 10 decreases at a speed equal to or higher than a certain value c and the voltage drop is equal to or more than a certain value d: It is determined that the vehicle has stopped. The voltage drop rate of c can be 1.0 to 4.0 V / s, and the voltage drop width of d can be 0.05 to 0.20 V. Further, (3) after determining that the engine is in operation, the voltage of the lead battery 10 decreases to a certain value e or less, and the voltage change width at that time is a certain constant value f with a certain time width. When the value is less than or equal to g: It is determined that the engine is stopped from the engine starting state. A voltage value of 102 to 109% of the OCV of the lead battery 10 can be used as the voltage value of e, 0.01 to 1.0 s can be used as the value of f, and 0.1 to 0.3 V can be used as the change width of the voltage of g. . MP determines that the engine has stopped when it falls under any of (1) to (3).

  In addition, MP acquires the voltage of the lead battery 10 measured after the polarization reaction of the lead battery 10 is eliminated after the engine is stopped (for example, after 6 hours have elapsed) as an OCV.

(Operation)
Next, with reference to a flowchart, the operation of the AI unit 1 will be described with the MP as a main component. When power is supplied from the lead battery 1 to the AI unit 1, program data including a program and a determination threshold value Vth is expanded from the ROM to the RAM in the initial setting process to determine deterioration of the lead battery 10. The deterioration determination routine is executed.

  As shown in FIG. 2, in the deterioration determination routine, first, in step 102, the process waits until the engine is started. The MP determines the engine start based on the engine state determination described above. When it is determined that the engine has been started, in the next step 104, referring to the voltage value stored in the RAM, the first lowest voltage value measured at the start of discharge of the lead battery 10 and after the start of discharge of the lead battery 10 The lowest voltage value measured within 15 ms is calculated as the lowest voltage value Vst at engine start. Note that the MP measures the temperature of the lead battery 10 via the temperature measuring unit, and corrects the temperature of the lowest voltage value Vst to, for example, a voltage value at room temperature (25 ° C.) based on the acquired temperature value.

  In the next step 106, it is determined with reference to the EEPROM whether or not the lowest voltage value Vst0 at the time of starting the engine of the lead battery 10 in the non-deteriorated state has already been acquired. That is, if the minimum voltage value Vst0 is written at a predetermined address in the EEPROM, it is determined that the minimum voltage value Vst0 has already been acquired (affirmed). If it is null, the minimum voltage value Vst0 is acquired. Judge that it is not (deny).

  If the determination in step 106 is negative, it is determined in step 108 whether or not the minimum voltage value Vst calculated in step 104 satisfies the condition of the minimum voltage value Vst0 when the engine of the lead battery 10 in the non-degraded state is started. to decide. This condition is, for example, (1) within six months from when the lead battery 10 is attached to the automobile (beginning of use), and (2) the OCV of the lead battery 10 before starting the engine (for example, The open circuit voltage when 6 hours have elapsed since the previous engine stop) can be 12.5 V or more. In the present embodiment, since the operation button 3 is arranged on the operation display unit 2, in order to determine the condition (1), for example, when the operation button 3 is pressed a predetermined number of times by a predetermined operation, the MP is Alternatively, it may be determined that the lead battery 10 is attached to the automobile and time is measured from that time. As is clear from the condition (1), the “no deterioration state” of the “minimum voltage value Vst0 at the start of the engine of the lead battery 10 in the no deterioration state” in this embodiment is a complete state in which SOH is 100%. Not only the non-degraded state but also the substantially non-degraded state in the initial state in which the lead battery 10 is healthy.

  When a negative determination is made at step 108, the process returns to step 102 in order to obtain the lowest voltage value Vst0 when the engine of the lead battery 10 in the non-degraded state is started. The minimum voltage value Vst is stored (written) in the EEPROM as the minimum voltage value Vst0 when the engine of the lead battery 10 in the non-degraded state is started, and the process proceeds to step 112.

  On the other hand, if the determination in step 106 is affirmative, in step 112, the minimum voltage value Vst0 at the time of engine start of the non-degraded lead battery 10 is read from the EEPROM, and in the next step 114, the voltage difference ΔVst (= Vst0−Vst ) Is calculated.

  Next, in step 116, it is determined whether or not the voltage difference ΔVst is larger than a predetermined determination threshold value Vth (stored in the ROM and developed in the RAM). In the case of negative determination, since the deterioration information “0” described later is written in the EEPROM, the deterioration has not progressed so much as to require replacement of the lead battery 10 (because it is not necessary to issue a warning to the driver). Return to 102.

  On the other hand, when the determination in step 116 is affirmative, that is, when it is temporarily determined that the lead battery 10 has deteriorated, “1” is written as the latest deterioration information in the EEPROM. The deterioration information is information indicating whether or not provisional determination has been made. When the provisional determination is made that the deterioration has occurred (when affirmative determination is made in step 116), for example, the deterioration information is expressed by binary “1”. When a provisional determination is made that there is no deterioration (when a negative determination is made in step 116), it can be represented by a binary "0". In this embodiment, the EEPROM has a storage area of 5 bytes for writing deterioration information, and can store the latest deterioration information and the past four deterioration information.

  In the next step 118, deterioration information of the past four times is read from the EEPROM, and in step 120, it is determined whether or not the deterioration determination has been made five times continuously with the latest deterioration information. If the determination is negative, it is determined that the lead battery 10 has not deteriorated (it is determined that an irregular measurement value or measurement error has affected it), and the process returns to step 102.

  On the other hand, when the determination in step 120 is affirmative, in step 122, the process waits until the engine stops. The MP determines the engine stop by the above-described engine state determination. When it is determined that the engine is stopped, in the next step 124, the fact that the lead battery 10 needs to be replaced is notified by an audible means using a buzzer and a visual means using an LED as described below, and the process returns to step 102. .

  In the present embodiment, since the AI unit 1 is accommodated in the upper lid 9 of the lead battery 10, the AI unit 1 is disposed at a place where the lead battery 10 is installed. Most of them are in the engine room or in a car such as a passenger compartment, and the alarm sound generated by the buzzer is difficult to hear due to vehicle noise while driving. For this reason, the generation timing of the alarm sound generated by the AI unit 1 is set as follows, and the alarm sound is generated at a timing at which the user can easily hear the alarm sound, so that the alarm sound is reliably transmitted to the user. The AI unit 1 outputs a high level signal to the gate of the transistor that turns on the LED via the DA converter immediately after determining that the engine has stopped, and turns on the LED. A high-level signal is sent to the gate of the transistor that operates the buzzer via the DA converter of this type to generate a warning sound.

  At the timing of stopping the engine from the engine starting state, it is estimated that the user often performs a series of operations of getting out of the automobile, closing the door, locking the door, and leaving the automobile. Accordingly, when a warning sound is generated, if a certain time lag is provided from the timing when it is determined that the engine has stopped, there is a high possibility that an alarm will be transmitted to the user.

  According to the AI unit 1 of the present embodiment, in most cases, the alarm sound can be reliably transmitted to the user, but it is actually determined that the alarm sound is generated on the assumption that several missed hearings occur. The value Vth may be set slightly higher with a margin.

  On the other hand, in the display of the battery state of the lead battery 10 by the LED, the LED is turned on and displayed immediately after the engine is stopped. The time is about 5 minutes in this embodiment. Further, the AI unit 1 has an operation button 3 disposed on the operation display unit 2. This is because a user who hears a warning sound from the buzzer or desires to know the battery state can check the health state of the lead battery 10. That is, when there is an input by the operation button 3, the battery state is displayed by the LED so that the user can arbitrarily grasp the battery state. In the present embodiment, the LED indicating that the lead battery 10 needs to be replaced is lit using a red LED in order to alert the user.

(Action etc.)
Next, the operation and the like of the AI unit 1 of the present embodiment will be described.

  The AI unit 1 measures the voltage of the lead battery 10 via the voltage measuring unit, and calculates the lowest voltage value Vst among the voltages measured at the time of starting the engine by the calculating unit (step 104), and then stored in the EEPROM. A voltage difference ΔVst between the lowest voltage value Vst0 at the start of the engine of the lead battery 10 in the non-degraded state and the lowest voltage value Vst of the lead battery 10 measured most recently is calculated (step 114). Next, when the voltage difference ΔVst is larger than the determination threshold value Vth, provisional determination is made that the lead battery 10 has deteriorated (step 116), and provisional determination that the lead battery 10 has deteriorated is continuously performed five times. (Step 120), it is determined that the lead battery 10 has deteriorated when an affirmative determination is made, and the driver is notified (step 124).

  According to the AI unit 1 of the present embodiment, it is determined that the lead battery 10 has deteriorated when the provisional determination is made five times in succession, so that erroneous determination of deterioration due to irregular measurement values or measurement errors is rejected. It is possible to accurately determine the deterioration. For this reason, the lead battery 10 can be used until the (design) end of life. Moreover, in order to determine the deterioration of the lead battery 10 from the minimum voltage value Vst0 and the minimum voltage value Vst calculated in the non-deteriorating state of the lead battery 10, it is possible to determine the deterioration of the lead battery 10 without using a current sensor. it can.

  Furthermore, the AI unit 1 of the present embodiment includes a nonvolatile EEPROM, and the lowest voltage value Vst0 that can be obtained only when the lead battery 10 is not deteriorated is written in the EEPROM (step 110) and used for deterioration determination. Along with (Step 112), the deterioration information of the lead battery 10 at the time of starting the engine (determination result by binary in Step 116) is written. Therefore, for example, the AI unit 1 can be re-supplied even after the automobile on which the lead battery 10 is mounted is not moved for a long time (the lead battery 10 is not charged) and the power supply to the AI unit 1 is interrupted. The deterioration of the lead battery 10 can be accurately determined without losing the minimum voltage value Vst0 or the deterioration information.

  In this embodiment, in order to simplify the explanation, an example in which the deterioration of the lead battery 10 is determined at two levels of good and necessary replacement using a determination threshold is shown. However, the determination is not limited to this, and for example, the determination may be performed by subdividing into three levels of good, caution, and exchange, or more. At that time, out of the five consecutive deterioration information, for example, when 2 is “1” or the majority is “1”, it is determined that the deterioration of the lead battery 10 is a caution. Also good. Further, in the present embodiment, an example in which the replacement of the lead battery 10 is displayed by turning on the red LED is shown, but it may be blinked.

  Furthermore, in the present embodiment, an example in which the deterioration determination (provisional determination) of the lead battery 10 is performed by comparing the voltage difference Vst between the minimum voltage value Vst0 and the minimum voltage value Vst with the determination threshold value Vth. The invention is not limited to this. For example, the ratio of the minimum voltage value Vst0 and the minimum voltage value Vst may be compared with the determination threshold value Vth. Further, the minimum voltage value Vst0 is not used, the minimum voltage value Vst is compared with the determination threshold value Vth, and it is determined that the lead battery 10 has deteriorated when the minimum voltage value Vst is smaller than the determination threshold value Vth (provisional determination). ).

  Further, in this embodiment, for the sake of simplicity, an example in which one minimum voltage value Vst0 is acquired and stored in the EEPROM has been described. However, a plurality of minimum voltage values Vst0 are stored in the non-degraded state of the lead battery 10. For example, an average value or mode value of the plurality of acquired minimum voltage values Vst0 may be calculated and stored in the EEPROM. In this way, the accuracy of deterioration determination by the AI unit 1 can be further increased.

  Further, in the present embodiment, the example in which the operation button 3 is pressed a predetermined number of times by a predetermined operation is shown as a starting point for determining that the lead battery 10 is in an undegraded state, in particular, the condition (1) described above. The MP may monitor whether or not the engine has been started for the first time, and when the determination is affirmative, it may be considered that the lead battery 10 is attached to the automobile, and that time may be used as a starting point for determining the condition (1) or the like. In this aspect, the starting point setting by the operation button 3 can be eliminated.

  In the present embodiment, the AI unit 1 as the deterioration determination device is stored in the upper lid 9 of the lead battery 10. However, the AI unit 1 may be used independently from the lead battery 10.

  The experiment was performed as follows. In this embodiment, when the starter motor functions and the engine is started, that is, the evaluation is performed based on an instantaneous drop (minimum voltage value Vst) of the lead battery voltage when the engine starts to rotate. Since the Vst naturally changes if the conditions of the state of the lead storage battery at the time of engine start change, no. Vst was measured 5 times for each of 1 to 6 (experimental conditions: see Table 1, experimental results: see Table 2).

  As is apparent from Tables 1 and 2, the minimum voltage value Vst varies variously under each condition. Although there are errors as shown in Table 2 under the same measurement conditions, the time zone (temperature) at which the engine is started should be different, or the charge / discharge state should change slightly each time the engine is started. As described above, although correction is performed, it causes an error, and it can be said that there is a possibility of misreading the deterioration determination. However, when the AI unit 1 (degradation determination device) of the embodiment is used and the deterioration determination is not performed unless the deterioration diagnosis is performed five times in succession, the experiment No. 6, assuming that the determination threshold value is 6.900 V, the conventional deterioration determination device determines the deterioration at the third engine start, but if the AI unit 1 of the embodiment is used, the deterioration determination is not issued at the third engine start. First, this value is recognized as an irregular value and can be repelled. As a result, it can be said that the accuracy of the deterioration determination is improved.

  Since the present invention provides a deterioration determination device capable of accurately performing deterioration determination by measuring the voltage of a lead battery, it contributes to the manufacture and sale of the deterioration determination device, and thus has industrial applicability.

It is an external appearance perspective view of AI unit of an embodiment which can apply the present invention. It is a flowchart of the deterioration determination routine which the microprocessor of the AI unit accommodated in the lead battery of the embodiment executes. It is a graph which shows the minimum voltage value at the time of engine starting of the lead battery of an undeteriorated state, and the minimum voltage value at the time of engine start of the lead battery after deterioration. It is a graph which shows the voltage change of the lead battery at the time of engine starting.

Explanation of symbols

1 AI unit (voltage measuring means, calculating means, first deterioration determining means, second deterioration determining means, deterioration determining device)
10 Lead battery

Claims (4)

In a deterioration determination device that determines the deterioration of a lead battery mounted in an automobile,
Voltage measuring means for measuring the voltage of the lead battery;
Of the voltages measured by the measuring means, calculating means for calculating a minimum voltage value at the time of engine start of the lead battery,
First deterioration determination means for determining deterioration of the lead battery based on the latest lowest voltage value Vst calculated by the calculation means and a preset deterioration determination threshold value Vth;
Determining whether or not the deterioration determination of the lead battery by the first deterioration determination means is continuously performed a plurality of times, and determining the deterioration of the lead battery at the time of an affirmative determination;
A deterioration determination device comprising:   2. The deterioration determination device according to claim 1, wherein the first deterioration determination unit determines that the lead battery has deteriorated when the minimum voltage value Vst is smaller than the deterioration determination threshold value Vth.   The first deterioration determination means includes a minimum voltage value Vst0 calculated by the calculation means in a non-deterioration state of the lead battery, and the latest minimum value calculated by the calculation means in a non-deterioration or deterioration state of the lead battery. 2. The deterioration determination device according to claim 1, wherein the lead battery is determined to have deteriorated when a difference or ratio value with a voltage value Vst is greater than the deterioration determination threshold value Vth.   The apparatus further includes a memory for storing a determination result by the first deterioration determination unit, and the second determination unit reads a past determination result stored in the memory and performs deterioration determination of the lead battery. The deterioration determination device according to any one of claims 1 to 3.

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