JPH035140B2 - - Google Patents

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to battery-powered electrical equipment.

[Background technology]

In general, in this type of battery-powered electrical equipment that uses batteries (including storage batteries) as a power source to drive loads, the amount of electricity that can be used each time the battery is replaced or charged is limited, and the remaining capacity is limited. If the battery gets low, the battery must be replaced or recharged. Therefore, users would like to be able to display the remaining capacity or whether the amount of electricity is being consumed appropriately (whether there is an overload condition due to incorrect usage). I'm here. Conventionally, there has been a remaining capacity display means for displaying the remaining capacity of a battery as shown in FIG. In other words, the voltage comparator 5 determines whether the voltage V' _{2 obtained by dividing the terminal voltage V 2 of} the battery 2 decreases below the reference voltage Vs due to the current flowing through the load 1.
When the remaining capacity is low, the display 7 is activated to indicate that the remaining capacity is low. In the figure, 3 is a voltage divider, 4 is a reference voltage generation circuit, 6 is an amplification circuit, 8 is a constant voltage power supply, and 10 is a power switch. Note that the load 1, such as a motor for driving a circular saw, whose load current changes depending on the usage condition.
In this case, the terminal voltage _V2 of battery 2 will also fluctuate, making it impossible to accurately determine whether there is a remaining capacity.In such a case, as shown in Figure 2, A constant load 1a made of a resistor having a predetermined resistance value is provided in parallel with the load 1, and a power switch 10' also serves as a switch for checking remaining capacity.
before switching to the load side (b side).
side) to determine the remaining capacity.

On the other hand, as an overload display means for displaying whether or not the amount of electricity is being consumed properly, there is a device shown in FIG. 3. That is, the current flowing through the load 1 is detected by the voltage Vi across the shunt 11 connected in series with the load 1, and the voltage across the shunt 11 is detected.
In some cases, a voltage comparator 5 determines whether Vi is larger than the reference voltage Vs', and when it becomes larger, a display 7 displays the information.

By the way, in order to satisfy the above-mentioned user's request, it would be sufficient to incorporate the above-mentioned remaining capacity display means and overload display means into a battery-powered electric device.
In these conventional examples, the remaining capacity is detected based on the terminal voltage V ₂ of the battery 2 at a constant load, and overload is detected based on the voltage Vi across the shunt 11 at an actual load.
Since different detection means are used, the configuration becomes complicated (for example, detection means and voltage comparison means are each required), which increases costs. There was a problem in that energy loss always occurred due to the flow divider 11.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a battery-type device that can express remaining capacity display means and overload display means with a simple configuration, and that has less energy loss. Our goal is to provide electrical equipment.

[Disclosure of the invention]

Embodiment 1 FIG. 4 shows an embodiment of the present invention, and in the figure,
4 ₁ is a reference voltage generation circuit that generates a reference voltage Vs ₁ of the remaining capacity display means A that determines the remaining capacity based on the terminal voltage V ₂ of the battery 2 and displays it on the display 7 ₁ ; 4 ₂ is a reference voltage generation circuit of the battery 2; An overload condition based on the terminal voltage V ₂ (that is, a condition in which an overcurrent flows and the terminal voltage V ₂ falls below a predetermined level due to a voltage drop in the battery's internal resistance)
10a to _10d are changeover switches forming display switching means C for switching between _both display means. can be,
The changeover switches 10a to 10d can be switched in conjunction with one operator. 9 in the diagram
is a delay circuit. Note that the other configurations are the same as the conventional example shown in FIG.

The operation of the first embodiment will be explained below. Now, the changeover switch 10a which also serves as the power switch
When 10d is switched from the off side (OFF side) to the remaining capacity display means side (a side), the reference voltage Vs ₁ output from the reference voltage generation circuit 4 ₁ is applied to the reference input terminal of the voltage comparison circuit 5. With constant load 1
A divided voltage V' 2 obtained by dividing the terminal voltage V ₂ of the battery 2 to which a is connected by the voltage divider ₃ is applied to the voltage comparator circuit 5.
When the divided voltage V' ₂ becomes lower than the reference voltage Vs ₁ , a display activation signal is output from the voltage comparator 5 and sent to the display 7 via the amplification circuit 6 and the delay circuit 9. ₁ is activated to display that the remaining capacity of battery 2 is below a predetermined value.
Here, the delay circuit 9 is designed to delay the display activation signal until the changeover switches 10a to 10d are switched to the OFF side (OFF side), and the changeover switches 10a to 10d are switched to the overload display side (b side). Even if the battery is overloaded, the display ₇₁ continues to operate to indicate that the remaining capacity is low. At this time, the reference voltage generation circuit 4 ₂ does not generate the reference voltage Vs ₂ .

Next, when the terminal voltage V ₂ of the battery 2 under constant load is large and the remaining capacity is above a predetermined value, the changeover switches 10a to 10d are set to the overload display means side (b
side), the reference voltage Vs ₂ output from the reference voltage generation circuit 4 ₂ is applied to the reference input terminal of the voltage comparator 5, and the battery connected to the load 1 consisting of the circular saw driving motor is applied. 2 terminal voltage
A divided voltage _V'2 of _V2 is applied to the comparison input terminal of the voltage comparator circuit 5, and when the divided voltage _V'2 falls below the reference voltage _Vs2 , the voltage comparator circuit 5 outputs a display activation signal. An indicator ₇₂ is activated via the amplification circuit 6 to indicate that an overload condition has occurred. As described above, in the present invention, both the detection of the remaining capacity of the remaining capacity display means A and the detection of the overload state of the overload display means B are performed using the terminal voltage of the battery 2.
_V2 , the detection means and voltage comparison means can be used for both display means A and B, and the configuration can be simplified. Furthermore, since the shunt 11 is not used as an overload detection means as in the conventional example shown in FIG. 3, no energy loss occurs and the amount of electricity in the battery 2 can be used effectively. There is.

Embodiment 2 FIG. 6 shows another embodiment in which the load current I _L
a switch control circuit 13 that detects the alternating current component using a current transformer 12, and automatically switches the changeover switches 10b' and 10c' to the overload indicating means side (b side) when this alternating current component is equal to or higher than a predetermined value. It has been established. Note that when load 1 is idling (during light load operation) like a circular saw drive motor, the load current I _L is small and the alternating current component is small, while when cutting (during heavy load operation) the load current I L is small. Not only is _L large, but the AC component is also large.

The operation of the embodiment will be described below. now,
When the remaining capacity of the battery 2 is large and it is being used properly, the load current I _L flowing through the load 1 and the terminal voltage V ₂ of the battery 2 change as shown in Fig. 8a during idling and disconnection. . Here, the AC component of the load current I _L during idling (current transformer 1
Since the output of switch control circuit 1) is much smaller than the AC component of the load current I _L at the time of disconnection,
By setting the operation level of 3 to an appropriate value (for example, an intermediate value of AC components during idling and cutting),
Changeover switch 10b', 10 only when disconnecting
c' can be switched to the overload indicating means side (b side). Therefore, when the power switch 10 is idling immediately after being turned on, the changeover switches 10b' and 10c' are switched to the remaining capacity display means side (a).
side), and assuming that the load 1 in the idling state is a constant load, the divided voltage of the terminal voltage V ₂ of the battery 2 is
V' ₂ is compared with a reference voltage, and it is determined whether the remaining capacity is below a predetermined value, and the result is displayed on the display ₇₁ . Next, when cutting, selector switch 10
b' and 10c' are switched to the overload indicating means side (b side) by the switch control circuit 13, and the divided voltage V' ₂ of the terminal voltage V ₂ of the battery 2 is compared with the reference voltage Vs ₂ to detect the overload. It determines whether it is under load or not and displays it on the display ₇₂ . FIG. 8b is a diagram showing the load current I _L and the terminal voltage _{V 2} of the battery 2 when the remaining capacity of the battery 2 becomes less than a predetermined value. When there is sufficient capacity (Figure 8a)
It has decreased (11.3V→10.9V) compared to . Therefore, by setting the reference voltage Vs ₁ to a value corresponding to the terminal voltage V ₂ =11V, it is possible to indicate on the display 7 ₁ that the remaining capacity has become less than a predetermined value. On the other hand, FIG. 8c is a diagram showing the load current I _L and the terminal voltage V ₂ of the battery 2 when the battery 2 is overloaded due to improper use, and the terminal voltage V of the battery 2 when disconnected. ₂ drops significantly (10.5V→
9.0V) Therefore, by setting the reference voltage Vs ₂ to a value corresponding to the terminal voltage V ₂ =9.3V, it is possible to indicate on the display 7 ₂ that an overload condition has occurred.

〔Effect of the invention〕

The present invention is configured as described above, and includes a remaining capacity display means that determines and displays that the remaining capacity has become less than a predetermined amount based on the terminal voltage of the battery to which the load is connected; The circuit is constructed by changing the reference voltage of the same voltage comparator, and an overload display means for determining and displaying an overload state in which the load is not being used properly based on the terminal voltage of the battery. Because it is standardized, remaining capacity display and overload display can be realized with a simple circuit.
This has the effect of reducing costs. In addition, since a display switching means is provided to switch between both display means according to the load condition connected to the battery, for example,
When a constant load (including a motor that is idling) is connected to the battery, a remaining capacity display is displayed, while when a fluctuating load is connected to a battery, an overload display is displayed. This has the effect of making it possible to display an appropriate usage display according to the load condition. Moreover, unlike the conventional example shown in FIG. 3, a flow divider is not used, so there is an advantage that energy loss can be reduced.

[Brief explanation of the drawing]

1 to 3 are circuit diagrams of a conventional example, FIG. 4 is a circuit diagram of an embodiment of the present invention, FIG. 5 is a flowchart of the same, FIG. 6 is a circuit diagram of another embodiment, and FIG. The figure is a flowchart of the same as above, and FIGS. 8a, b, and c are explanatory diagrams of the same operation. 1 is the load, 2 is the battery, A is the remaining capacity display means, B
C is an overload display means, and C is a display switching means.

Claims (1)

[Claims] 1. By comparing the terminal voltage of the battery to which the load is connected with a first reference voltage using a voltage comparator, it is determined and displayed that the remaining capacity has become less than a predetermined amount. The residual capacity display means compares the terminal voltage of the battery to which the load is connected with the second reference voltage using the voltage comparator, thereby determining and displaying an overload condition in which the load is not being used properly. A battery-powered electric device comprising an overload display means and a display switching means for switching between the two display means according to the state of a load connected to the battery. 2. The battery-powered electric device according to claim 1, wherein the display switching means is formed by a changeover switch that switches between the reference voltage and the display means in conjunction with a single operator. 3. Claim 1, comprising a display switching means that detects the load current with a current transformer and automatically switches to the overload display means when the AC component of the load current exceeds a predetermined value. Battery-operated electrical equipment as described in Section 1.