JPH05333121A - Charge and discharge display circuit - Google Patents

Abstract

PURPOSE:To stabilize display to show a charge and discharge condition of a battery by stopping the display of all display units when output of an electric current sensor being influenced easily by surrounding noise is in the vicinity of zero ampere. CONSTITUTION:A battery relay 12 is operated by operation of a key switch 11, and a charging electric current is supplied to a battery 1 from a generator 13 through a battery cable 2. An electric current sensor 3 detects the electric current flowing in this cable 2, and charge (discharge) detecting comparators 5-1 (5-2) in a comparing. circuit 5 compare output voltage obtained by amplifying (4) the output signal with different reference voltage, and sends a result to a control circuit 7. The circuit 7 lights discharge (charge) display units 8-1 (8-2) according to a compared result when judged that display of discharge (charge) is necessary. When an electric current value detected (3) in this display is within range of 0+alpha or 0-beta ampere, the circuit 7 stops display output so that respective display units may not display. When the value exceeds an alphaor beta value, the circuit 7 releases the stopping, and continues lighting of the respective display units.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for charge / discharge display of a battery mounted on an automobile.

[0002]

2. Description of the Related Art A current sensor using a Hall IC is mounted on a battery cable, the output of the current sensor is amplified by an amplifier, the voltage of the amplifier output is identified by a comparison circuit, and the output of the comparison circuit is operated. There is known an optical display on a seat. This device can display the charge / discharge of the battery. In a practical device, the output voltage of the current sensor is positive or negative, that is, whether the battery is in a charged state or a discharged state, because the battery charge / discharge of an automobile does not need to be displayed so strictly. It is common to display only the polarity.

This device is a superior device that does not require disconnection of the current path through the battery cable to connect a series resistor, is structurally robust, has few failures, and will be used in the future as sensor elements. It is considered to be widely used as the cost of semiconductor devices constituting an amplifier and an amplifier decreases.

[0004]

Since this device uses the weak voltage obtained at the output of the current sensor after amplifying it by the semiconductor amplifier, it has a drawback that it is easily affected by ambient noise. The source of noise may be the ignition system of the engine of the own vehicle, a vehicle traveling in close proximity, or an industrial machine tool along the road. When affected by noise, the positive and negative two displays change rapidly around the limit of the display, or the two displays are displayed simultaneously.

For example, as described above, in a device having a structure in which the polarity of the current sensor is positive or negative or only the polarity is displayed, when the output of the current sensor is in the vicinity of zero amperes, a positive indication is given. The negative display and the negative display fluctuate due to the influence of the noise voltage, and it often happens that the two displays appear to be lit at the same time.

Although such a phenomenon can be improved by using a high-grade current sensor or a high-grade amplifier, the use of high-grade elements makes the device expensive.

The present invention has been made against such a background, and an object thereof is to provide a display stable device. An object of the present invention is to inexpensively construct a charge / discharge display circuit.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a current sensor having a battery cable inserted therein, an amplifier for amplifying an output signal of the current sensor, and an output voltage of the amplifier as an input, the output voltages being different from each other. In a charge / discharge display circuit including a plurality of comparison circuits for comparing with a voltage and a plurality of indicators for optically displaying outputs of the plurality of comparison circuits, a current value of the battery cable is 0+.
It is characterized in that the display is set so as not to be displayed on any display when it is in the range of α, 0-β amperes.

The above α is set to 1 to 5 and β is set to 1 to 5,
A low-pass filter is preferably inserted in the amplifier and / or its input circuit and / or its output circuit.

[0010]

Function: The current value detected by the current sensor is 0 + α, 0-β
When it is amperes, neither the positive display indicating charging or the negative display indicating discharging is displayed. Here, the values of α and β are determined as a design depending on the capacity (AH) of the battery and the capacity of the charging device, but about 1 to 5 is suitable for a large vehicle, and about 0.5 to 2 is suitable for a passenger car or a small freight vehicle. is there.

The absolute value of the current value detected by the current sensor is α
Alternatively, when β is exceeded, the magnitude of the mixed noise is relatively smaller than that of the signal, and the influence of noise is reduced. Further, in a state where the absolute value of the current value is extremely small, that is, α or β or less, the duration is short in a general automobile, and it is almost never that the display is not performed for a long time.

A low-pass filter may be inserted in the amplifier circuit or its input circuit or output circuit to eliminate the effect of volatile noise. By inserting a suitable low-pass filter, most of the effects of noise generated from the engine ignition system can be eliminated.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a circuit diagram showing the configuration of the embodiment of the present invention.

In the embodiment of the present invention, a current sensor 3 for detecting a current flowing from the battery 1 to the battery cable 2, an amplifier 4 for amplifying an output signal of the current sensor 3, and an output voltage of the amplifier 4 are used as inputs. A comparison circuit 5 including a charge detection comparator 5-1 and a discharge detection comparator 5-2 that compare the output voltage with different reference voltages, and the output of the comparison circuit 5 is used as an input for display control and a power supply circuit. 6, a discharge circuit 8-1 and a charge display 8-2 that perform optical display by inputting the output from the comparison circuit 5 through the control circuit 7. Further, as a feature of the present invention, the control circuit 7 includes a current sensor 3
The current value of the battery cable 2 detected by
and a means for preventing display on either of the discharge indicator 8-1 and the charge indicator 8-2 when in the range of α, 0-β (α, β: 1-5 amps). A low-pass filter (not shown) for noise elimination is inserted in the amplifier 4 and / or its input circuit and / or its output circuit.

Next, the operation of the embodiment of the present invention thus constructed will be described.

When the key switch 11 is operated to enter the traveling state (closed state), the battery relay 12 operates, and the charging current is supplied from the generator 13 to the battery 1 via the battery cable 2. The current sensor 3 detects the current flowing through the battery cable 2 and sends the detection signal to the amplifier 4.

The amplifier 4 receives and amplifies the output signal from the current sensor 3, and outputs the output voltage to the charge detection comparator 5-1 and the discharge detection comparator 5-2 of the comparison circuit 5, respectively. Charge detection comparator 5-1 and discharge detection comparator 5-
2 compares each with a different reference voltage, and sends the comparison result to the control circuit 7.

The control circuit 7 determines, based on the input comparison result, whether it is in the state of performing the charge display or the discharge display, and when it is determined that the discharge display is required, the discharge indicator 8-1. Is turned on, and when it is determined that the charging display is required, the charging indicator 8-2 is turned on.

During the charging / discharging display operation, the current value detected by the current sensor 3 is 0 + α, 0-, as shown in FIG.
When the value is in the range of β amps (practically, the values of α and β are 1 to 5 amps for a large vehicle, and 0.5 to 2 amps for a passenger car or a small freight vehicle), the control circuit 7 causes the discharge indicator 8-. The display output is stopped so that the display is not displayed on either 1 or the charge indicator 8-2.

In this way, even if the charge / discharge display is stopped when the current value most susceptible to the ambient noise is displayed, the duration is generally short and the display is not performed for a long time. There is almost no and there is no problem in practical use. Rather, the positive display and the negative display fluctuate due to the influence of the noise voltage, and the state in which the two displays appear to be lit at the same time gives more psychological anxiety.

When the absolute value of the current value exceeds α or β value due to continuous charging or discharging, the magnitude of the noise mixed in becomes relatively small compared to the signal,
Since the influence of noise is reduced, the control circuit 7 releases the stop of the display and continues the lighting of the discharge indicator 8-1 or the charge indicator 8-2.

If a low-pass filter is inserted in the amplifier 4 or its input circuit or output circuit, it is possible to further eliminate the effect of noise that changes drastically.

[0023]

As described above, according to the present invention, when the output of the current sensor susceptible to ambient noise is in the vicinity of zero ampere, no display is made on any display. As a result, it is possible to stabilize the display indicating the charging / discharging state of the battery, and it is possible to construct the circuit at a low cost.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a charge display and a discharge display and a display stop range in the embodiment of the present invention.

[Explanation of symbols]

 1 Battery 2 Battery Cable 3 Current Sensor 4 Amplifier 5 Comparison Circuit 5-1 Discharge Detection Comparator 5-2 Charge Detection Comparator 6 Power Supply Circuit 7 Control Circuit 8-1 Discharge Indicator 8-2 Charge Indicator 11 Key Switch 12 Battery Relay 13 generator

Claims (2)

[Claims] 1. A current sensor having a battery cable inserted therethrough, and an amplifier for amplifying an output signal of the current sensor,
Charge / discharge display including a plurality of comparison circuits for receiving the output voltage of the amplifier and comparing the output voltages with different reference voltages, respectively, and a plurality of indicators for optically displaying the outputs of the plurality of comparison circuits A charging / discharging display circuit, characterized in that, when the current value of the battery cable is in the range of 0 + α and 0-β amperes, the display is set not to display on any of the indicators. 2. The charge / discharge display circuit according to claim 1, wherein α is set to 1 to 5 and β is set to 1 to 5.