JPH0451793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery remaining capacity detection device for a vehicle that is capable of automatically and highly accurately detecting the remaining capacity of a battery, which changes from moment to moment.

The applicant previously filed Japanese Patent Application No. 57-005449 (Japanese Unexamined Patent Publication No.
58-123479), a voltage detection means for detecting the terminal voltage of the vehicle battery, a current detection means for detecting the discharge current of the vehicle battery, and a voltage detection means for detecting the discharge current of the vehicle battery before and during cranking. a detection command means for instructing the detection of terminal voltage and discharge current; and a calculation for calculating the internal resistance of the battery from the terminal voltage and discharge current of the battery detected by the detection command from the detection command means, and converting the value into capacity. We have proposed a remaining capacity detection device for a vehicle battery, which is equipped with a circuit.

According to this remaining capacity detection device, the value of the internal resistance of the battery is uniquely determined only by the remaining capacity of the battery, regardless of the value of the load at the time. Unlike the conventional example in which the remaining capacity is detected based on the integrated value after a certain period of time, the remaining capacity detection value does not change due to fluctuations in the load current, and the remaining capacity in this type of device Detection accuracy can be significantly improved.

However, in the case of the remaining capacity detection device for which the application has been filed, the terminal voltage and discharge current data necessary for internal resistance calculation are sampled before and during cranking, so the device continues to run for a long time. Even if the remaining capacity of the battery drops below a predetermined lower limit while the vehicle is running, this cannot be detected while the vehicle is running, so the engine cannot be started using the starter after the vehicle is parked or stalled. There was a risk that something could happen.

This invention was made in view of the above problems.
The purpose of this is to enable the remaining capacity of the battery to be detected automatically and with high precision at all times, regardless of whether the vehicle is running or parked.
To provide a battery remaining capacity detection device for a vehicle capable of responsively detecting the remaining capacity of the battery when the battery capacity is insufficient, and reducing current consumption when the remaining capacity of the battery is sufficient. There is a particular thing.

In order to achieve the above object, the present invention includes: current detection means for detecting the discharge current of the vehicle battery; voltage detection means for detecting the terminal voltage of the vehicle battery; and outputting a sampling signal at every predetermined sampling time. and sampling load intermittent means for continuing a predetermined sampling load to the battery for a predetermined time if a certain condition is satisfied when the sampling signal is output. , sampling means for sampling the discharge current and the terminal voltage at least twice with a transient period of load fluctuation due to the load intermittent operation in between; internal resistance value calculating means for calculating a value; detecting whether or not the calculated internal resistance value is greater than or equal to a predetermined value; and if the state of the calculated internal resistance value continues to be greater than or equal to the predetermined value for a predetermined time, the predetermined sampling time is determined; A sample time changing means for changing to a shorter value, and the remaining battery capacity is obtained from the internal resistance value.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the hardware configuration of an embodiment of the device of the present invention, and FIG. 2 is a flowchart showing only the remaining capacity detection program extracted from the system program of the microcomputer shown in FIG. It is.

As shown in Fig. 1, the power from the battery 1 passes through a shunt resistor 2 for detecting load current, and then passes through a rear defogger 3 that functions as a sampling load and other electrical components (lamps, car radios, etc.) 4.
As is well known, the battery 1 is configured to be able to be charged floatingly by an alternator (generator) 5.

In the power supply path from the shunt resistor 2 to the rear defogger 3, a switch 6 for manually turning on and off the rear defogger 3 and a b contact R2-b of the relay R2 are inserted in series. A contact R1-a of a relay R1 is connected in parallel to the switch 6, and these relays R1 and R2 are connected to a microcomputer (hereinafter referred to as a microcomputer) via an I/O interface circuit 7. 8.

In addition to controlling the relays R1 and R2, the microcomputer 8 controls the voltages VA and VB across the shunt resistor 2.
is taken in as the data for detecting the load current and terminal voltage, and the voltage VC at the midpoint between the switch 6 and the b contact R2-b of the relay R2 is taken in as the data for determining the operating state of the rear defogger 3, and the I/O The data is taken in via the interface 7, and the remaining capacity of the battery and other remaining capacity reduction data are displayed on the display device 10 via the I/O interface 7.

Next, FIG. 2 is a flowchart showing only the remaining capacity detection process in the system program that defines the operation of the device of this embodiment. will be explained systematically.

As is well known, this type of vehicle microcomputer sequentially executes multiple system programs corresponding to various types of control in a time-sharing manner. When the program starts, a predetermined initial process is executed in step (101).

In this initial processing (101), a counter for determining the timer period TS, which will be described later, a count-up flag FTS indicating its count-up,
2 performed every time each sampling timing arrives
A counter for determining the time interval T2 for sampling of 3 times and various data registers provided in other working areas are reset, etc.

Next, when steps (1011) to (1013) are executed, numerical data indicating the number of reference clocks corresponding to the period TS is set in the TS counter for sampling notification determination.

That is, in step (1011), the state of the capacity reduction approaching flag FTO, which was set or reset by the previous program execution, is determined.

Here, if it is determined that FTO="0", that is, if it is determined that there is still sufficient margin for capacity reduction, step (1012) is executed and the sampling period TSO is set to be long enough. Ru.

On the other hand, if it is determined in step (1011) that the capacity is approaching a decrease, step (1013) is executed and the sampling period is
The value of TS1 is set sufficiently short.

As a result, if the remaining capacity of the battery still has enough room for the predetermined lower limit,
Whereas data sampling instructions are given every sufficiently long sampling period (e.g. 30 seconds),
When the remaining capacity of the battery approaches a predetermined lower limit, a short sampling period (e.g. 5 seconds, 10
15 seconds, etc.).

On the other hand, as shown in FIG. 3, the contents of the TS counter are decremented by one in step (1001) each time an external reference clock arrives due to the system interrupt function provided in this type of microcomputer.

Then, by executing step (1002) each time, a count up is determined depending on whether the content of the TS counter is "0" or not, and the TS
Only when the counter counts up, the count up flag FTS is set to "1".

On the other hand, in the main flow shown in Figure 2,
Following each timer TS setting process (1012) and (1013),
In step (103), the count up of the TS counter is determined based on the contents of the flag FTS, and if the determination result is NO, the waiting time is used to determine whether the vehicle is up or down in step (104). Processes necessary for other controls are performed, and at the same time as they are completed, the repeat step (103) is executed.

Next, after setting the timer TS, the set period TS
elapses, the execution result of step (103) is
YES, and then step (105) is executed to perform data import processing.

In this data acquisition process, as shown in Figure 1, the voltages VA and VB across the shunt resistor 2 are
is taken into the microcomputer 8 via the A/D converter 9, and the voltage VC at the connection point between the switch 6 and the relay R2 is similarly taken into the microcomputer 8 via the I/O interface 7. , These imported data are stored in the VA1 register in the working area.
Stored in the VB1 register and VC register, respectively.

Next, when step (1051) is executed, based on the captured data VA1, VB1,
A determination is made as to whether the value of the load current I1 at that time is greater than or equal to a preset current value IS1.

Here, the set current value IS1 is used to detect whether or not a load with relatively large power consumption is being driven at that time, and for this reason, it is set appropriately according to the electrical load installed on the vehicle. ing.

Next, by executing step (1051), if it is determined that the value of the load current I1 at that time is smaller than the set current IS1, the value of a predetermined counter CONTA provided in the working area is reset to "0". Thereafter, the processes following step (1114), which will be described in detail later, are performed.

On the other hand, by executing step (1051), the value of the load current I1 at that time is changed to the set current IS1.
If it is determined that the value is above, step (1053) is executed and the value of the counter CONTA is +
It is incremented by 1, and each time it is repeatedly determined whether the count value has reached the set value AS.

Here, the value of the set value AS is determined by the fact that a load that consumes relatively little power and is driven intermittently, such as a turn signal lamp, is in operation.
It is set to detect that the value of the load current I1 intermittently (for example, every second) exceeds the set current IS1,
Therefore, during such intermittent driving, step (1054)
By repeatedly executing the closed loop of → (105) → (1051) → (1053) → (1054),
The value of the counter CONT A is set slightly larger than the maximum count value that can be reached.

As a result, even when the turn signal lamp etc. is on for a short time, the step (108)
Therefore, the rear defogger 3 is not energized for sampling, thereby avoiding wasteful power consumption due to sampling.

On the other hand, if a load with relatively large power consumption is actually being driven, the execution result of step (1054) is YES, and then the counter CONT A is reset in step (1055).

Then, when step (106) is executed, the VC
Depending on whether or not the voltage VC stored in the register is 0 volts, the operating state of the rear defogger 3 at that point in time is determined.

That is, when the manual switch 6 is closed and the rear defogger 3 is in operation, the value of the voltage VC is a predetermined positive voltage, whereas if the switch 6 is open and the rear defogger 3 is in the non-operating state, Voltage
The value of VC is 0 volts, and the operating state of the rear differential camera 3 is determined based on this value.

Next, by executing step (106), if it is determined that the rear differential camera 3 is in a non-operating state at that point, then step (108) is executed, and the I/O interface 7 is activated by a command from the microcomputer 8. The relay R1 is driven via the relay R1, and its a contact R1-a closes, thereby starting energizing the rear defogger 3.

On the other hand, if it is determined that the rear differential camera 3 is in operation by executing step (106), step (107) is executed, and the relay is sent via the I/O interface 7 according to the command from the microcomputer 8. When R2 is driven and its b contact R2-b opens, power to the rear defogger 3 is cut off.

In this way, when the power supply to the rear defogger 3 is cut off and then started again, the value of the load current flowing through the shunt resistor 2 starts decreasing or increasing from that moment while drawing a predetermined transient characteristic curve. .

On the other hand, at the same time as energization of relay R1 or R2 is started, step (109) is executed.
A so-called soft timer process determines whether or not a minute time T2 has elapsed, and as the time T2 elapses, step (110) is subsequently executed to perform the second data acquisition process.

In this data acquisition process, the voltages VA and VB across the shunt resistor 2 are read into the microcomputer 8 via the A/D converter 9, and stored in the VA2 register and VB2 register provided in the working area, respectively. .

Note that the time T2 between the first data import process performed in step (105) and the second data import process performed in step (110)
The value of is determined in consideration of the value of the sampling load (in this example, the rear defogger 3) and the battery remaining capacity detection accuracy, and is determined to be approximately 0.1 to 0.5 seconds in this embodiment.

Then, when step (113) is executed, relay R2 or R1 driven by step (107) or (108) is deenergized, respectively.
As a result, the rear defogger 3 is returned to its original operating state.

Next, when step (1131) is executed, it is determined based on the data VA2 and VB2 taken in after the load change whether the value of the load current I2 at the time of the data acquisition is greater than or equal to a preset value IS2. A determination is made.

Here, the value of the set current IS2 is used to determine whether the value of the load current I2 at that point is in the linear region of the I-VB curve in FIG. is set to be slightly larger than the current value predicted at the time when time T2 has elapsed after the rear defogger 3 is turned on from off when the load current I1 is initially in the non-linear region.

As a result, when the sampling timing arrives after the period TS has elapsed, if the value of the load current I1' is in the non-linear region of the I-VB curve as shown in FIG. Step (1114) and the following processes will be executed.

In contrast, the execution result of step (1131) is
If YES, each captured data VA1,
VA2, VB1, and VB2 are each used as a basis for calculation, and the internal resistance value R is accurately determined.

That is, when step (111) is executed,
Each of the imported data VA1, VA2, VB1,
Based on VB2 and the resistance value R0 of the shunt resistor 2 stored in advance, the load current I before driving the relay R1 or R2 is determined by equations (1) to (3).
1. Load current I at the time when time T2 has elapsed
2 and the internal resistance R of battery 1 are determined.

I1=(VB1−VA1)/R0……(1) I2=(VB2−VA2)/R0……(2) R=｜(VB1−VB2)/(I1−I2)｜……(3) Here , as shown in Figure 4, the remaining capacity of battery 1 is Q, its internal resistance is R, and its terminal voltage is VB.
Assuming that the load current is I, the slope of the I-VB curve (that is, the value of internal resistance R) is as shown in FIG.
It is known that the I-VB curve increases as the discharge current I decreases from Q3 to Q4.
It is known that in a region where the value exceeds a certain value, relatively linear characteristics are exhibited.

Therefore, if sampling is performed so that the values of the detected load currents I1 and I2 are both in the linear region of the IVB curve, the battery voltage at that point is determined based on the value of the internal resistance R obtained by the calculation. 1's remaining capacity Q can be accurately known.

Next, when step (1111) is executed, it is determined whether the internal resistance value R obtained by the above calculation is greater than or equal to a predetermined set value RS0.

Here, the value of the set value RS0 is determined in accordance with the remaining capacity of the battery at the lower limit value for driving the starter motor.

Then, in step (1111), R≧RS0
When the following conditions are met, a predetermined capacity reduction flag FR set in the working area is set to “1”.
On the other hand, if the condition R≧RS0 is not satisfied in step (1111), the flag FR is set to "0" in step (1114).
will be reset to

Next, when step (1115) is executed, a predetermined shift register provided in the working area is shifted to the right, and at the same time, the state of the flag FR at that time is set in its MSB.

Subsequently, when step (1116) is executed, it is determined whether all N bits following the MSB in the shift register are "1".

Here, the value of the numerical value N is set so that when a capacity decrease is continuously detected for a period determined by the period TS×N, this can be reliably determined as a capacity decrease.

In other words, the capacity of the battery naturally varies slightly microscopically due to non-uniformity of the electrolyte and vibrations when the vehicle is running. This is to prevent a situation in which there is a relatively large amount of noise and a malfunction caused by these noises and is determined to be a temporary decrease in capacity to be mistaken as an actual decrease in capacity.

Therefore, only if capacity reduction is continuously determined in step (1111) for a period of time determined by TS×N or more, the determination result in step (1116) is
YES, and then step (1117) is executed, and the microcomputer 8 issues an output signal indicating a decrease in capacity for the first time.

On the other hand, the execution result of step (1116) becomes NO until all N bits to the right of the MSB in the shift register are determined to be "1" due to execution of step (1116), and then step (1118) is executed. ) is executed.

In step (1118), the shift register is
It is determined whether all M bits starting from MSB are "1".

Here, the value of the numerical value M is set so that M<N. In other words, the execution result of step (1118) is YES, which means that the capacity reduction was determined in step (1111). It is not long yet, which means that the capacity is about to decrease.

Then, the execution result of step (1118) is YES
Then step (1120) is executed,
A predetermined capacity reduction approaching flag FT0 is set to "1", and the remaining capacity detection program ends.

Next, after executing other processes, when the remaining capacity detection program starts running again, following the initial process in step (101), in step (1011), the remaining capacity detection program detects the approaching capacity reduction that was set or reset by the previous program execution. flag
The state of FT0 is determined.

Here, if it is determined that FT0="0", that is, if it is determined that there is still sufficient margin for capacity reduction, step (1012) is executed and the sampling period TS0 is set to be long enough. Ru.

On the other hand, if it is determined in step (1011) that the capacity is approaching a decrease, step (1013) is executed and the sampling period is
The value of TS1 is set sufficiently short.

As a result, if the remaining capacity of the battery still has enough room for the predetermined lower limit,
Whereas data sampling instructions are given every sufficiently long sampling period (e.g. 30 seconds),
When the remaining capacity of the battery approaches a predetermined lower limit, a short sampling period (e.g. 5 seconds, 10
15 seconds, etc.), and as a result, the responsiveness of battery capacity detection becomes faster, making it easier to drive the starter motor etc. when the battery capacity approaches a predetermined lower limit. Therefore, if the remaining capacity of the battery suddenly decreases, this can be quickly displayed.

In other words, if the battery capacity is insufficient,
In addition to shortening the sampling period to improve the accuracy of internal resistance judgment (capacity judgment), if the battery capacity is not insufficient, the sampling period is lengthened and used for measurement by driving a relay to calculate internal resistance. The frequency of excessive current action can be reduced.

Although a routine for displaying the remaining capacity of the battery is not shown in this embodiment, this may be performed by a separate display-only processing program, or, for example, at step (111).
Of course, it is sufficient to display the determined internal resistance value R immediately following the calculation process.

In addition, in this embodiment, in order to detect that the power load is being driven at the time when the sampling timing arrives, it is determined that the load current continuously exceeds a certain value after the sampling timing arrives. However, instead of this, the state of the load current is constantly monitored repeatedly at minute intervals, and the fact that this continuously exceeds a predetermined value is memorized using a shift register, etc., and when the sampling timing arrives, Of course, the same function can also be achieved by checking the past state of the load current.

In addition, in this embodiment, whether or not a battery capacity reduction signal is temporarily obtained due to non-uniformity of the electrolyte, fluctuation of the electrolyte, electrical noise, etc. is detected in a predetermined shift register. However, instead of this, the ratio of "1" in each consecutive bit in the shift register is determined by multiple processing, and this determines whether the data is due to noise, etc. Of course, the structure may be configured to remove the erroneous capacitance reduction signal.

Furthermore, since the rear defogger is used as the sampling load, its short duration does not impede driving in any way, and it is possible to generate sufficient load fluctuations for data sampling.

Note that the remaining capacity detection program of this embodiment is as follows:
It is assumed that the ignition key switch of the vehicle operates when it is in the accessory or on position.

As explained above, the vehicle battery remaining capacity detection device according to the present invention has the following effects.

() Regardless of whether the vehicle is running or parked, the operating state of the sampling load is changed every time a sampling period arrives, and the internal resistance is calculated based on the load current and terminal voltage before and after the sampling period. Based on this, the remaining capacity of the battery at that point in time is displayed, so the remaining capacity of the battery, which changes from moment to moment, can be accurately displayed at all times, regardless of whether cranking operations are being performed. Even when the remaining capacity gradually approaches the lower limit value, it is possible to know this.

() Detects whether the internal resistance value of the battery is greater than or equal to a predetermined value, and if the state of the battery's internal resistance continues to be greater than or equal to a predetermined value for a predetermined time (a time shorter than the time that can be determined to be a decrease in battery capacity), shorten the sampling time. Therefore, when the battery capacity is insufficient, the sampling period can be shortened to detect the remaining capacity of the battery with good responsiveness. That is,
If the battery capacity suddenly decreases due to the operation of the starter motor, etc., and the battery capacity is approaching a state where it can be determined that the battery capacity has decreased, the battery will respond quickly to this sudden decrease in battery capacity. Remaining capacity can be detected.

() Furthermore, if the state in which the internal resistance value is greater than or equal to the predetermined value does not continue for a predetermined period of time, the sampling time becomes longer, so that the current consumption for calculating the internal resistance value can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of the embodiment device of the present invention, FIG. 2 is a flowchart showing the system program of the embodiment device shown in FIG. 1, and FIG. 3 is the system program shown in FIG. FIG. 4 is a flowchart showing the interrupt processing program of the embodiment device. FIG. 4 is a diagram showing the relationship among the load current I, internal resistance R, and voltages VA and VB across the shunt resistor. FIG. It is a graph showing the relationship between the discharge current and the terminal voltage, with the parameter being the discharge current and the terminal voltage. 1...battery, 2...shunt resistance, 3...
Rear differential gear, 4...Electrical equipment, 5...Parameter, 6...Manual switch, 7...I/O interface, 8...Microcomputer, 9...A/D converter, R1, R2...Relay .

Claims (1)

[Claims] 1. Current detection means for detecting the discharge current of the vehicle battery; Voltage detection means for detecting the terminal voltage of the vehicle battery; and sampling signal output means for outputting a sampling signal at every predetermined sampling time. and sampling load intermittent means for intermittent applying a predetermined sampling load to the battery for a predetermined time if a certain condition is satisfied when the sampling signal is output; sampling means for sampling the discharge current and the terminal voltage at least twice with a transient period of accompanying load fluctuation in between; and an internal unit for calculating an internal resistance value of the battery based on the sampled discharge current and the terminal voltage. resistance value calculation means; detecting whether or not the calculated internal resistance value is equal to or greater than a predetermined value; and if the state of the predetermined value or greater continues for a predetermined time, changing the predetermined sampling time to a shorter value; A battery remaining capacity detection device for a vehicle, comprising: sampling time changing means; and obtaining a battery remaining capacity based on the internal resistance value.