JP2015065779A - Battery charge controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a battery by determining deterioration of the battery accurately, and performing activation early when the battery deteriorated.SOLUTION: Internal resistance of an on-vehicle battery 62 is detected and stored. The increment ΔR of the value Rof battery internal resistance detected latest from the initial value Rof internal resistance detected and stored after installation of the battery 62 is determined, and control for activation of the battery 62 is performed when the increment ΔR goes above a predetermined value ΔR.

Description

  The present invention relates to a charging control device for a battery mounted on a vehicle.

  A vehicle is equipped with a battery for storing electric power generated by using a part of the output of the internal combustion engine and supplying electric power to a cranking motor of the internal combustion engine and other electrical components. When the battery deteriorates over time, the battery cannot be charged sufficiently, and sufficient electric power is not supplied to the cranking motor during cranking, so that the internal combustion engine cannot be started stably and quickly. For this reason, inconveniences such as idling stop are prohibited in a vehicle that performs idling stop.

  Therefore, steps are taken to cope with the performance degradation accompanying the aging of the battery. For example, the battery voltage is sampled during cranking to determine the average or minimum value, the battery's electromotive voltage and the motor current are considered constant, the battery's internal resistance is calculated, and the internal resistance value is a predetermined determination When the threshold value is exceeded, it is determined that the battery has deteriorated over time. If it is determined that the battery has deteriorated over time, the power generation voltage during the subsequent operation is further increased to keep the battery charge rate high (see, for example, Patent Document 1).

  However, in the conventional control, since the determination threshold value to be compared with the internal resistance of the battery is a fixed value, individual differences such as the battery, motor, and circuit resistance are ignored, and the accuracy of the determination is not necessarily high.

  In addition, in order to extend the life of the battery, it is conceivable to activate the battery by increasing the amount of charge or applied voltage to the battery more than normal when the battery deteriorates.

  The activation of the battery is preferably performed before the battery is significantly degraded. However, as described above, since there are individual differences in the battery, when the determination threshold is fixed, when the battery is determined to be deteriorated, the battery is actually greatly deteriorated. there is a possibility.

  Alternatively, in order to avoid this, the determination threshold value may be set low in advance, but in this case, a battery that has not deteriorated may be erroneously determined to be deteriorated. As a result, there is a concern that in an idle stop vehicle, an opportunity to perform idle stop is taken away.

JP-A-8-214469

  An object of the present invention is to more accurately determine battery deterioration and implement activation processing in a timely manner to extend the life of the battery.

  In order to solve the above-described problems, a vehicle battery charge control device according to the present invention has a configuration as described below. That is, the vehicle battery charge control device according to the present invention detects the internal resistance of the in-vehicle battery, stores the detected battery internal resistance, and detects the value of the most recently detected battery internal resistance after the installation of the battery. The initial value of the stored internal resistance or the increase range from the past value of the internal resistance detected and stored within a predetermined period in the past is obtained, and if the increase range exceeds the predetermined value, the activation of the battery Take control.

  In such a case, the detected battery internal resistance value itself is not compared with a fixed threshold value, but by referring to the increase range of the internal resistance, the deterioration of the battery can be considered in consideration of individual differences such as the battery. The degree can be determined with higher accuracy.

  In the present invention, the “increase width” is a concept including not only the difference between the most recently detected value of the battery internal resistance and the initial value or the past value, but also an increase rate and ratio.

  According to the present invention, it is possible to more accurately determine the deterioration of the battery and implement the activation process in a timely manner to extend the battery life.

1 is a schematic configuration diagram of an internal combustion engine in an embodiment of the present invention. The schematic circuit diagram of the electrical equipment system in the embodiment. The principle figure of the current sensor in the embodiment. The flowchart which shows the flow of the process which the control apparatus in the embodiment performs.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  As schematically shown in FIG. 2, a cranking motor 61 and a plurality of electric loads 64 and 69 for starting the internal combustion engine are mounted on the vehicle. Specific examples of the electric loads 64 and 69 include a magnet clutch interposed between the crankshaft of the internal combustion engine and the compressor for compressing the refrigerant of the air conditioner, an air blower for the air conditioner, and a defogger for removing fog from the rear glass. Examples include audio equipment, car navigation systems, illumination lamps (head lamps, tail lamps, fog lamps, blinkers (turn signal lamps), etc.), radiator fans that cool cooling water, and electric power steering devices.

  An alternator 63, which is a source of power supply to the electric loads 64 and 69, is a type of generator that is driven to rotate by receiving a driving force transmitted from a crankshaft of an internal combustion engine and generates electric power. The alternator 63 is connected to the crankshaft via a winding transmission mechanism having a belt and a pulley as elements. The magnitude of the voltage generated and output by the alternator 63 can be controlled via the regulator 65. The regulator 65 is a known IC type attached to the alternator 63 and performs a switching operation for switching ON / OFF the energization of the field coil of the alternator 63.

  The output voltage of the alternator 63, that is, the voltage induced in the stator coil of the alternator 63 increases in proportion to fDUTY which is the DUTY ratio of the field current flowing through the field coil. The regulator 65 receives a signal r for instructing an output voltage of an alternator from an ECU (Electronic Control Unit) 0, and performs PWM control for adjusting fDUTY so as to realize the instructed output voltage. With this PWM control, the power generated by the alternator 63 can be increased or decreased. The amount of power generated by the alternator 63, in other words, the amount of charge to the battery 62 and / or the amount of power supplied to the electrical load increases as fDUTY increases and decreases as fDUTY decreases.

  In the regulator 65 of the vehicular alternator 63 that is widely used, the output voltage of the alternator 63 can be switched to two stages, for example, 14.5V or 12.8V. In this case, the engine control ECU 0 inputs to the regulator 65 a signal r that instructs whether the output voltage of the alternator 63 is HI potential = 14.5V or LO potential = 12.8V.

  As the regulator 65, a linear regulator capable of continuously changing the output voltage of the alternator 63 within a predetermined range, for example, between 12V and 15.5V may be employed. In this case, the engine control ECU 0 inputs a signal r that instructs the regulator 65 to set the output voltage of the alternator 63 to any value within the range.

  The LO potential or minimum output voltage of the alternator 63 is preferably set to a voltage lower than the voltage of the battery 62 or a low voltage close to the voltage of the battery 62. Although the battery voltage varies depending on the state of charge of the battery 62 and the like, it is usually a predetermined voltage, for example, 12 V or more.

  The alternator 63 becomes a mechanical load when viewed from the internal combustion engine. When the output voltage of the alternator 63 exceeds the voltage of the battery 62, the battery 62 is charged and power is supplied from the alternator 63 to the electric load. That is, the alternator 63 performs the work of generating electric energy by consuming energy of rotation of the crankshaft. The amount of charge to the battery 62 and the amount of power supplied to the electrical load depend on the potential difference between the output voltage of the alternator 63 and the battery voltage.

  Conversely, when the output voltage of the alternator 63 is less than or close to the battery voltage, the battery 62 is not charged, and no power is supplied from the alternator 63 to the electric load (power supply from the battery 62 to the electric load). Sometimes). That is, the alternator 63 does not perform work that consumes the energy of rotation of the crankshaft, or the work is reduced.

  In short, when a high output voltage is commanded from the engine control ECU 0 to the regulator 65, the mechanical load of the alternator 63 with respect to engine rotation increases, and when a low output voltage is commanded, the mechanical load of the alternator 63 with respect to engine rotation decreases.

  As described above, the battery 62 is charged by receiving supply of electric power generated by the alternator 63. On the other hand, the battery 62 supplies electric power to a cranking motor 61 and various electric loads 64 and 69 for starting the internal combustion engine.

  In order to prevent a shortage of the amount of power stored in the battery 62 and to avoid overcharging the battery 62, the charging current flowing into the battery 62 and the discharging current flowing out from the battery 62 are constantly monitored, and the balance between charging and discharging. Need to figure out. Therefore, in this embodiment, the battery current sensor 66 for measuring the current flowing into and out of the battery 62 is provided.

The battery current sensor 66 has a function of measuring the internal resistance of the battery 62 in addition to the function of measuring the battery current. Internal resistance measurement function battery current sensor 66 is provided is a principle diagram as shown in FIG. 3, a constant current source circuit 66a supplies a constant current I _s of the constant amplitude of the alternating voltage drop due to the internal impedance of the battery 62 using a voltmeter 66b for detecting a V _2, and requests the internal impedance of the battery 62 by an alternating current four-terminal method.

  The constant current source circuit 66a and the voltmeter 66b are connected to both electrodes of the battery 62 via a positive / negative source terminal 66c and a positive / negative sense terminal 66d, respectively. A DC cut capacitor 66e is disposed between the constant current source circuit 66a and one source terminal 66c and between the voltmeter 66b and each sense terminal 66d.

When the voltage drop V ₂ the voltage meter 66b has been detected is divided by a constant current I _s can be calculated internal impedance of the battery 62. However, the internal impedance of the battery 62 includes not only actual resistance but also reactance.

The battery current sensor 66 also includes a circuit for performing synchronous detection to extract a component derived from the actual resistance by dividing the voltage drop V ₂ due to the impedance of the battery 62 into a component derived from the actual resistance and a component derived from the reactance. Built in.

Here, V ₁ a reference signal voltage (voltage of the reference signal) derived from the constant current I _s is supplied from the constant current source circuit 66a, when the signal voltage is V ₂ to perform the synchronous detection, V ₁ and V ₂ These can be represented by the following formulas (1) and (2), respectively.
V ₁ = Asinωt (1)
V ₂ = Bsin (ωt + θ) (2)
Θ of V ₂ is a phase difference with respect to V ₁ generated by reactance inside the battery 62.

When synchronous detection is performed for V ₁ and V ₂ , the following equation (3) is obtained.
V ₁ × V ₂ = {ABcos θ−ABcos (2ωt + θ)} / 2 (3)
The first term of equation (3) represents the voltage drop due to the actual resistance. On the other hand, the second term of Equation (3) is a voltage drop due to reactance, and is attenuated by a low-pass filter included in a circuit for performing synchronous detection. Therefore, the actual resistance of the battery 62 can be known based on the first term of the equation (3).

  The battery current sensor 66 also includes a circuit for outputting a signal h indicating the value of the actual resistance of the battery 62 obtained as described above as the internal resistance of the battery 62.

  The engine control ECU 0 that is the battery charge control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. A sensor for knowing an accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (engine output required by the driver, that is, a required load), and a shift lever range ( Shift range signal d output from the shift position switch), intake air temperature / intake pressure signal e output from the temperature / pressure sensor for detecting the intake air temperature and intake pressure in the intake passage 3 (especially the surge tank 33), internal combustion Cooling water temperature signal f output from a water temperature sensor that detects the cooling water temperature indicating the temperature of the engine, intake camshaft A cam angle signal output from cam angle sensor at a plurality of cam angle of shift or the exhaust camshaft g, battery status signal h for indicating the status of the battery 62 output from the battery current sensor 66 are inputted.

  From the output interface, a voltage regulator that controls the ignition signal i for the igniter of the spark plug 12, the fuel injection signal j for the injector 11, the opening operation signal k for the throttle valve 32, and the voltage generated by the alternator 63. A voltage instruction signal r or the like is output to 65.

  The processor of the engine control ECU 0 interprets and executes a program stored in advance in the memory, calculates operation parameters, and controls the operation of the internal combustion engine. The engine control ECU 0 acquires various information a, b, c, d, e, f, g, h necessary for operation control of the internal combustion engine through the input interface, knows the engine speed, and fills the cylinder 1 Estimate the amount of intake air. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. As the operation parameter determination method itself, a known method can be adopted. The engine control ECU 0 applies various control signals i, j, k, r corresponding to the operation parameters via the output interface.

  The engine control ECU 0 of the present embodiment executes an idle stop that stops the idle rotation of the internal combustion engine when the vehicle stops due to a signal waiting or the like. In the engine control ECU 0, the vehicle speed is equal to or lower than a predetermined value, the brake pedal is depressed, the cooling water temperature is sufficiently high, the amount of electric power stored in the battery 62 exceeds a predetermined value, and the brake booster negative pressure is sufficiently secured. It is determined that the idle stop condition is satisfied when all the conditions such as being present are satisfied.

  When a predetermined idle stop end condition is satisfied after the idle stop condition is satisfied, the internal combustion engine is restarted. The engine control ECU 0 determines that the driver has released his / her foot from the brake pedal, the brake pedal has been further depressed, the accelerator pedal has been depressed, or a predetermined time has elapsed in the idle stop state. It is determined that the idle stop end condition is satisfied.

Further, the engine control ECU 0 uses the battery current sensor 66 to detect the internal resistance of the battery 62 when the vehicle is shipped and when the battery 62 is replaced, and the internal resistance of the battery 62 is stored in a predetermined area of the memory of the engine control ECU 0. Store as initial value R ₀ . In addition, the engine control ECU 0 detects the internal resistance of the battery 62 while the internal combustion engine is stopped, and stores it in a predetermined area of the memory of the engine control ECU 0. The internal resistance of the battery 62 is detected when the ignition switch is OFF, that is, when the cranking motor 61 and the various electric loads 64 and 69 are not operating.

  In addition, immediately after the ignition switch is turned from ON to OFF, the engine control ECU 0 performs the following process to determine the deterioration of the battery 62. The procedure of this process will be described with reference to FIG. 4 which is a flowchart.

First, the latest value R ₁ of the internal resistance of the battery 62 is detected using the battery current sensor 66 (step S1), and a difference from the initial value R ₀ , that is, an increase width ΔR is obtained (step S2). When the increase width ΔR exceeds the predetermined value ΔR _th (step S3), it is assumed that the battery 62 has deteriorated, and control for activating the battery 62 is performed after the next start (step S4). The predetermined value ΔR _th is, for example, 0.5 times the initial value R ₀ of the internal resistance. If the increase width ΔR does not exceed the predetermined value ΔR _th (step S3), it is determined that the battery 62 has not deteriorated, and the process ends.

  A specific example of the control for activating the battery 62 will be described below.

<Example 1>
In a vehicle equipped with a regulator 65 that can switch the output voltage of the alternator 63 to two levels of HI potential or LO potential, when it is determined that the battery 62 has deteriorated, the ignition switch is turned on and the internal combustion engine is started. Immediately after the operation is performed, in order to activate the battery 62, control is performed to extend the charging time in order to increase the amount of charge immediately after the start. In other words, control is performed to extend the period during which the output voltage of the alternator 63 is set to the HI potential. The extension range of the charging time is increased as the initial value R ₀ of the internal resistance is increased and as the battery temperature is decreased.

<Example 2>
When it is determined that the battery 62 is deteriorated in a vehicle equipped with a regulator 65 that can continuously change the output voltage of the alternator 63 within a predetermined range, the ignition switch is turned on and the internal combustion engine is started. Immediately thereafter, in order to activate the battery 62, control is performed to increase the output voltage of the alternator 63 in order to increase the amount of charge immediately after starting. The output voltage of the alternator 63 increases as the initial value R ₀ of the internal resistance increases, and as the battery temperature decreases.

<Example 3>
When it is determined that the battery 62 is deteriorated regardless of the type of the regulator 65, immediately after the ignition switch is turned on and the internal combustion engine is started, the battery 62 is activated immediately after the start. In order to increase the amount of charge, control is performed to lower the battery current determination threshold used for full charge determination by a predetermined width, for example, 10%. When the battery 62 is deteriorated, the charging current at the time of full charge is lowered. Therefore, the accuracy of full charge judgment can be improved by lowering the battery current judgment threshold. The amount of decrease in the battery current determination threshold increases as the initial value R ₀ of the internal resistance increases and as the battery temperature decreases.

As described above, according to the present embodiment, the latest value R ₁ of the internal resistance of the battery 62 is not compared with the fixed threshold value, but the increased value ΔR from the initial value R ₀ is referred to and the increased value is increased. Since control for activating the battery 62 is performed when ΔR exceeds a predetermined value ΔR _th , the degree of deterioration of the battery 62 can be more accurately determined by taking into account individual differences such as the battery 62.

When the increase width ΔR from the initial value R ₀ exceeds the predetermined value ΔR _th , the battery 62 is activated at an appropriate timing to extend the life of the battery 62 by performing control for activating the battery 62. This is advantageous in terms of cost. In addition, by suppressing the deterioration of the battery 62, it is possible to increase the opportunity to perform idle stop and improve fuel efficiency, and to store more power generated in regenerative braking in the battery 62. It is done.

  Since the control for activating the battery 62 is executed immediately after the start of the internal combustion engine, that is, during the warm-up of the internal combustion engine, the power generation is not interrupted by an idle stop or the like. The battery 62 can be activated reliably. Accordingly, it is prohibited to idle stop against the driver's will to activate the battery 62, and it is not necessary to operate the internal combustion engine in order to cause the alternator 63 to generate electric power, which may give an uncomfortable feeling to passengers such as the driver. Absent.

  In addition, this embodiment is not restricted to embodiment mentioned above.

For example, when the vehicle is shipped and when the battery 62 is replaced, the internal resistance of the battery 62 is detected and stored as an initial value R ₀ of the internal resistance of the battery 62 in a predetermined area of the memory of the engine control ECU ₀ . Instead of obtaining the increase width ΔR of the latest value R _{1 from} the initial value R ₀ , the latest value R of the internal resistance of the battery 62 is stored in the state where the internal resistance of the battery 62 before a predetermined period, for example, two days ago is stored as the past value. An increase from the past value of ₁ may be obtained. When the internal resistance of the battery 62 within the predetermined period is not stored as the past value, it is preferable to determine the deterioration of the battery 62 based on the degree of increase per unit period from the past value detected at the latest time before that. .

  Not only the internal resistance of the battery is detected immediately after the ignition switch is turned from ON to OFF, but also every time a predetermined time elapses while the internal combustion engine is stopped, on condition that the ignition switch is turned off. An internal resistance may be detected.

  The rate of increase or ratio of the most recently detected internal resistance of the battery relative to the initial value or past value is obtained, and if the rate of increase or ratio exceeds a predetermined value, it is assumed that the battery has deteriorated and the battery is activated after the next start. A mode of performing control for the above may be adopted.

  Of course, the present invention may be applied to a vehicle that does not perform idle stop.

  In addition, you may change variously in the range which does not impair the meaning of this invention.

0 ... Engine control ECU (battery charge control device)
62 ... Battery 63 ... Alternator 66 ... Battery current sensor

Claims (1)

Detects the internal resistance of the vehicle battery,
Memorize the detected battery internal resistance,
Finding the increment of the value of the recently detected battery internal resistance from the initial value of the internal resistance detected and stored after installation of the battery or the past value of the internal resistance detected and stored within a predetermined period in the past,
A vehicle battery charge control device that performs control for activating a battery when the increase width exceeds a predetermined value.

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