JPS63108284A - Diagnosing device for battery for automobile - Google Patents

Abstract

PURPOSE:To eliminate the need for a current sensor and to reduce the cost by finding the internal resistance of a battery from variation in battery voltage due to the operation of a fuel injector and variation in battery current which is found previously by an experiment and deciding and diagnosing whether the battery is normal. CONSTITUTION:When an engine is in operation, various electric loads of a vehicle vary according to the power generation state of an alternator. For the purpose, the voltage variation and current variation of the battery 3 are detected to find the internal resistance of the battery 3. Namely, the internal resistance of the battery 3 is found from variation in the three-terminal voltage of the battery due to the operation of the fuel injector 2 and the current variation of the battery 3 due to the operation of the fuel injector 2 which is found previously by the experiment and whether the battery is normal or not is decided and judged on the basis of the internal resistance. Therefore, a current sensor is not necessary and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automobile battery diagnostic device for determining the quality of an automobile battery.

[Conventional technology] As a conventional automobile battery diagnostic device.

For example, there is one described in Japanese Patent Application No. 104169/1983.

This device includes a current sensor that senses the current flowing into the starter motor, a holding circuit that holds the peak value of the output change of the sensor of the starter motor, a voltage sensor that senses the terminal voltage of the battery, and a voltage sensor that senses the terminal voltage of the battery. It consists of a holding circuit that holds the peak value of the output change of the voltage sensor, and an arithmetic circuit that calculates the internal resistance of the battery from the power ratio of both holding circuits, and determines the quality of the battery from the internal resistance of the battery. , to diagnose.

[Problem that this invention attempts to solve] However,
These conventional battery diagnostic devices use current sensors to detect battery current, which not only increases cost but also lacks sufficient reliability. Ta. In addition, since the internal resistance was determined using the starter motor as a load, internal resistance could not be detected except during cranking, and the battery could not be diagnosed while the engine was running or just before the engine stopped. There were also points.

[Means for Solving the Problems] The present invention has been made for the purpose of solving these problems, and the basic conceptual diagram thereof is shown in FIG. 1. That is, the present invention includes a battery that supplies power to each load section of a vehicle, a detection means that detects a change in the terminal voltage of the battery due to the operation of an electronically controlled fuel injector, and a detection means that detects a change in the terminal voltage of the battery that is experimentally determined in advance. a storage means for storing changes in battery current due to the operation of the battery; a calculation means for calculating the internal resistance of the battery from the voltage change detected by the detection means and the current change stored by the storage means; and comparing means for comparing the determined internal resistance with a predetermined value.

[Effect] In this invention having such a configuration.

The internal resistance of the battery is determined from the change in battery terminal voltage caused by the operation of the fuel injector and the change in battery current caused by the operation of the fuel injector, which has been experimentally determined in advance, and the quality of the battery is determined and diagnosed based on this internal resistance. do.

Therefore, since a current sensor or the like is not required, costs can be reduced and reliability can also be improved. Additionally, internal resistance can be accurately determined while the engine is running.

The quality of the battery can be diagnosed even when cranking.

[Example code] Embodiments of the present invention will be described below based on the drawings.

FIGS. 2 to 5 are diagrams showing an embodiment of the present invention.

First, to explain the configuration, in FIG. 2, l is an electronic fuel control device, and this electronic fuel control device 211 outputs a control signal Sl to the fuel injector 2.

The fuel injector 2 is a solenoid valve type having a solenoid coil, and receives a control signal S1 from the control device ml.
When the fuel injector 2 injects fuel, electric power is supplied from the battery 3, and the fuel injector 2 is operated by the battery 3.
becomes an electrical load. 4 is a microcomputer connected to batch 9, and the microcomputer 4 has a microprocessor 5, a memory 6, and an interface 7.
It has the functions of a detection means, a storage means, a calculation means, and a comparison means.

The interface 7 has the terminal voltage vb of the battery 3,
A control signal S1 for the fuel injector 3 is inputted via a waveform shaping circuit, an A/D converter, and the like. The electrical characteristics of the fuel injector 2 are stored in advance as a data table in the memory 6 consisting of a ROM, and the current value I of the fuel injector 2 determined from the driving voltage and driving time of the fuel injector 2 can be used to warm up the fuel injector 2. It has become. The microprocessor 5 calculates the internal resistance r of the battery 3 based on the battery terminal voltage vb and the fuel injector 7 bottle flow value I, determines the quality of the battery 3, and outputs a determination signal S2.
is output to the display 8 via the interface 7. The display 8 displays the quality of the battery 3 based on the determination signal S2.

Next, the effect will be explained.

First, the basic principle of this invention will be explained.

When the engine is in operation, the voltage V and main current of the battery change depending on the power generation status of the alternator and the various electrical loads of the vehicle, as shown in FIG. Therefore, if we detect the battery voltage change △V and current change ■△,
The internal resistance r of the battery can be determined. As a result, it becomes possible to determine whether the battery is good or bad based on the internal resistance.

By the way, the voltage and current characteristics during operation of the electromagnetic fuel injector are shown in Figures 4 (A) and (B), so the fuel injector current I can be calculated from the fuel injector voltage and time. I can do what I want. In addition, as shown in FIG. 3, the battery voltage change when the fuel injector is activated is hardly affected by other influences, and therefore, based on the battery voltage change △V and current change △I when the injector is activated, The internal resistance r of the battery can be determined, and as a result, the quality of the battery can be determined.

Next, the operation of the present invention will be specifically explained based on a flowchart showing a control program shown in the ff5S diagram.

In FIG. 5, 5L-S14 indicates each step, and this program is repeated and executed at, for example, every predetermined time.

First, in Sl, the maximum value Vmax and minimum (d*Vmin) of the battery voltage are set as initial values.The maximum value is set as Vmax, for example, 20V, and the minimum value Vmi
For example, let n be Ov. Next, in S2, wait for the fuel injector 2 to turn on, and when it turns on, proceed to S3. Note that the time when the fuel injector 2 turns on or off depends on the fuel 1') from the control signal Sl for the injector 2.

Next, turn on fuel injector 2 at 33 and 38.
The maximum value Vmax and minimum value Vmin of the terminal voltage vb of the battery at the time of the battery are determined. That is, in S3, input the terminal voltage vb of the battery 3, and in S4 input the terminal voltage vb of the battery 3 to Vm.
a x, and when Vmax<Vb, V m in S5
Vmax is determined by setting ax = Vb. S
In step 6, vb is compared with Vmin, and when Vmin>Vb, in step S7, V min is determined by setting Vmin=Vb.

Next, in S8, it is determined again whether the fuel injector 2 is ON or OFF, and when it is ON, S3
If it is OFF, the process proceeds to S9. In S9, the voltage change ΔV of the battery 3 is calculated according to the following equation (2).

ΔV=Vmax-Vmin...0th order, SI
At step O, the drive voltage of the fuel injector 2 and the injector current change 11- from the WIA operating time are looked up in a table, and at Sll, the internal resistance r of the battery 3 is calculated according to the following equation (2), and the process proceeds to S12.

In S12, the internal resistance r is compared with a predetermined value rth, and r<
rth, it is determined that battery 3 is good and S
13, the display circuit 8 displays that the battery is good. S17
When r>rth, it is determined that the battery 3 is defective, and in step 514, the display circuit 8 displays that the battery is defective.

Therefore, in this embodiment, the internal resistance r can be determined at any time while the engine is in operation, and the quality of the battery 3 can be accurately determined and diagnosed without being affected by charging and discharging. Also, since there is no need for a current sensor,
By reducing costs, reliability can also be improved.

[Effects of the Invention] As explained above, according to the present invention, the internal resistance of the Yatsuteri is determined based on the change in battery voltage caused by the operation of the fuel injector and the change in battery current determined in advance through experiments. Since the quality of the battery can be determined and diagnosed, the current sensor can be omitted, reducing costs and improving reliability. Furthermore, the quality of the battery can be accurately diagnosed at any time during engine operation without being affected by charging and discharging.

[Brief explanation of the drawing]

Figure 1 shows the basics of this invention! Signs, FIGS. 2 to 5 are diagrams showing an embodiment of the present invention,
Fig. 2 is a diagram of its overall configuration, Fig. 3 is a graph showing battery terminal voltage and battery charging current, Fig. 4 (A) is a graph showing injector voltage characteristics with respect to time, Fig. 4 (
B) is a graph showing the injector current characteristics with respect to time, and FIG. 5 is a flowchart showing the control program. (2)...Fuel injector, (3)...
-Battery, (4)...Microcomputer (detection means, recording means, calculation means, comparison means). 1st ull Figure 2 = Va Woman (A) +, Zu! 0 (B) Dani\1,) 'P 0 蓼 4 Figure time

Claims (1)

[Claims] a battery that supplies power to each load section of the vehicle; a detection means that detects a change in the terminal voltage of the battery due to the operation of an electronically controlled fuel injector; and an operation of the fuel injector that is determined experimentally in advance. storage means for storing the change in battery current due to the change in battery current; calculation means for calculating the internal resistance of the battery from the voltage change detected by the detection means and the current change stored in the storage means; and the internal resistance calculated by the calculation means. A diagnostic device for a battery for an automobile, comprising a comparison means for comparing resistance with a predetermined value.