JPS6118463Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention relates to a battery residual quantity meter.
This makes it possible to almost ignore variations in voltage drop due to the amount of current, and also allows for segmented display.

A battery fuel gauge is essential for electric vehicles. Although it is desired that this fuel gauge has high reliability, it is desirable that it be inexpensive in terms of cost. Conventional fuel gauges include a very simple voltmeter type, an improved partial voltage expansion type, a type that compensates for the voltage drop due to current, and a current-carrying type that uses a special semiconductor element. There are various types such as flowmeters.

Each of these fuel gauges has functional advantages and disadvantages, and although the appropriate one is selected and used depending on the vehicle, many of them are used without necessarily achieving the desired function. The reality is that this is the case.

The present invention has been made in consideration of this point, and aims to provide a battery gauge that makes it possible to almost completely ignore the fluctuation in voltage drop due to the amount of current, is capable of detailed display, and has a relatively high accuracy.

An embodiment of the present invention will be described with reference to FIG. 1. Reference numeral 1 denotes a battery as a power source, which is mounted on the vehicle in the case of a fuel gauge used in a vehicle. Reference numeral 2 denotes a motor and other loads, which are connected in series to the battery 1 together with the shunt resistor 3. The input sides of the upper limit current detection circuit 4 and the lower limit current detection circuit 5 are commonly connected to the connection point between the shunt resistor 3 and the battery 1.

The output sides of the upper limit current detection circuit 4 and the lower limit current detection circuit 5 are respectively connected to two input terminals of an AND circuit 6. The output side of this AND circuit 6 is connected to the operating end of a switch circuit 7.
As a result, the switch circuit 7 is turned on when receiving the signal from the AND circuit 6.

One pole of the switch circuit 7 is connected to the positive side of the battery 1, and the other pole is connected to the input side of the voltage holding circuit 8. A display 10 is connected to the output side of the voltage holding circuit 8 via a high impedance amplifier 9.

This fuel gauge with such a configuration operates as follows. The curve in FIG. 2 is the waveform of the current flowing through the load 2. If the load 2 is a motor for driving the wheels of an electric vehicle, there will be a large change as described above.

When the current value of this current falls within the range between the upper limit current value a detected by the upper limit current detection circuit 4 and the lower limit current value b detected by the lower limit current detection circuit 5, the AND circuit 6 The switch circuit 7 is then turned on, and the voltage across the shunt resistor 3 at that time is maintained as shown by the curve.

This value is amplified by the high input impedance amplifier 9, and is displayed on the display 10 as a value such as . That is, the voltage of the voltage holding circuit 8 is
It will gradually fluctuate only when the load current is at a certain value.

Since the present invention is configured as described above, it has the following effects.

It is possible to display the voltage drop with almost no variation due to the amount of current.

Since there is little variation in the holding voltage, subdivided display is possible.

There are fewer misidentifications due to self-reset voltage.

Although it has high precision, it can be manufactured at low cost.

Some displays consume less power.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing the operation of the device shown in FIG. 1... Battery, 2... Load, 3... Shunt resistance, 4... Upper limit current detection circuit, 5... Lower limit current detection circuit, 6... AND circuit, 7... Switch circuit, 8... Voltage holding circuit , 10...Display device.

Claims (1)

[Scope of utility model registration request] A shunt resistor is connected in series in a continuous circuit between the battery and the load, an upper limit current detection circuit and a lower limit current detection circuit are commonly connected to the shunt resistor, and the output side of the current detection circuit is connected to two of the AND circuits. a switch circuit connected between the battery and a voltage holding circuit, and an indicator connected to the output side of the voltage holding circuit. Fuel gauge.