JPH071986B2 - Vacuum cleaner - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric vacuum cleaner having a built-in secondary battery.

[Prior Art] Conventionally, as shown in FIG. 11, there is an electric vacuum cleaner having a built-in secondary battery 81 for driving an electric blower 80.
In the charging circuit 82 for charging 81, AC adapter
The charging current from 83 flows from the transistor element 84 to the diode 85 and the switch 86, and the secondary battery 81 is charged.
When the secondary battery 81 is charged to a specified voltage value, the overcharge prevention circuit 87 detects this voltage value and controls the charging current.

At this time, while the secondary battery 81 is being charged, a part of the charging current flows through the LED 88 and the LED 88 is lit to consume a few mmW of power.

When charging is completed, the charging current flows to the overcharge prevention circuit 87,
Since it does not flow to LED88, LED88 goes out.

[Problems to be Solved by the Invention] As described above, while the secondary battery 81 is being charged, the LED 88 is used as a display element indicating that the LED 8 is being charged.
While 8 was lit, several mmW of power was consumed here, and this amount of power wasted wastefully, and special wiring was required to incorporate the LED 88 in the circuit.

In addition, heat loss due to current flowing through the power switching element used in the overcharge prevention circuit 87 has been a problem.

[Means for Solving Problems] The present invention provides a charging circuit in which a charging current is supplied to a secondary battery via a power switching element, and the power switching element is installed close to the inner rear surface of the main body. A temperature sensor that detects the temperature rise of the power switching element is arranged on the outer surface of the main body opposite to the switching element, and an opening is provided on the outer wall of the main body that is interposed between this temperature sensor and the power switching element. The temperature sensor senses the temperature rise when a charging current flows through the element, and uses the heat loss of the power switching element to display information such as charging, completion of charging and the like.

[Operation] When the charging current of the secondary battery flows through the power switching element, the power switching element generates heat and warms the surrounding air. The warmed air passes through an opening provided in the main body, is sensed by a temperature sensor provided at a position facing the power switching element, and indicates that the temperature sensor is being charged.

When the secondary battery is charged to the specified voltage, this voltage is detected by the overcharge prevention circuit, the power switching element is turned off, and the charging current flows to the overcharge prevention circuit, so the temperature of the power switching element drops, The temperature sensor that senses this temperature indicates that charging is complete.

[Embodiment] An embodiment of the present invention will be described in detail with reference to FIGS.

1 to 3, reference numeral 1 denotes a main body of an electric vacuum cleaner having a built-in secondary battery 2, in which an electric blower 3 is disposed, and a heat radiating plate 4 is provided near an inner back surface of a side wall. Installed.

The heat radiating plate 4 is made of a material containing aluminum having a high thermal conductivity, and a temperature that does not vary depending on the position is used. As shown in FIG. 4, a power switching element 5 for charging and a power transistor 6 for discharging are connected to both ends of the heat radiating plate 4, and the power switching element is formed by flowing a charging current or a discharging current, respectively. 5. The heat generated by the power transistor 6 is radiated.

A temperature sensor 7 is arranged on the outer surface of the main body 1 facing the power switching element 5, and an opening 8 is formed on the outer wall of the main body 1 interposed between the temperature sensor 7 and the power switching element 5. The temperature sensor 7 is provided so that the temperature rise of the power switching element 5 can be accurately detected.
It is configured to be sensed by.

As the temperature sensor 7, a liquid crystal temperature sensor is used. As shown in FIG. 5, this is a digital thermotape that displays the temperature sensed from 38 ° C to 58 ° C at intervals of 2 ° C by numbers. It is used.

This temperature sensor 7 (digital thermo tape) is the sixth
As shown in the figure, it is divided into a display section 17 for displaying the completion of charging and a display section 18 for displaying the state of charging, and is attached to the main body 1 at a position facing the power switching element 5. The display section 18 during charging has a number indicating 0, 20, 40, 60, 80% to indicate the state of charge, and the display section 17 indicating completion of charging has a number of 100%. The heat generated by the power switching element 5 in each state is sensed and displayed.

In addition, FIG. 7 shows a display unit 18a that uses a digital thermotape as the temperature sensor 7 and displays from charging to completion of charging. It is divided and displayed.

With such a display, it is possible to clearly grasp the progress of charging with eyes.

FIG. 2 shows the charging / discharging circuit 9, and the AC adapter 10
A power switching element 5, a diode 11, a switch 12 for switching between charging and discharging, and a secondary battery 2 are connected in series to form a charging circuit, and between the emitter and the base of the power switching element 5. Is connected to an overcharge prevention circuit 13 to control the charging current.

On the other hand, the + terminal of the secondary battery 2 is connected to the power transistor 6 for discharging via the switch 12 to form a discharging circuit, and the base of the power transistor 6 is not connected via the variable resistor 14. The gear shift power control circuit 15 is connected to control the discharge current.

First, the case of charging the secondary battery 2 will be described.

In FIG. 2, the switch 12 is turned on to the charging side (the diode 11 side) during charging. Therefore, the charging current from the AC adapter 10 flows from the collector of the power switching element 5 to the emitter, flows into the secondary battery 2 via the diode 11 connected to the emitter, and charges the secondary battery 2. At this time, most of the charging current flows through the power switching element 5, and the resistor 16 causes the overcharge prevention circuit 13 to pass through.
It does not flow to the side.

When the voltage across the secondary battery 2 is charged to a specified voltage, the overcharge prevention circuit 13 detects this voltage and the charging current is controlled. That is, the power switching element 5 is turned off, the charging current flows to the overcharge prevention circuit 13 via the resistor 16, and the charging current does not flow to the secondary battery 2.

When a charging current flows through the power switching element 5, the element itself generates heat, but this heat is radiated from the heat radiating plate 4 and radiated to the outside of the main body 1 through the opening 8 as shown in FIG. The temperature sensor 7 senses, and the temperature sensor 7 indicates that charging is in progress.

Here, since the main body 1 is made of synthetic resin, the thermal conductivity is generally poor, but since the opening 8 is provided,
The heat generated by the power switching element 5 during charging can be accurately detected by the temperature sensor 7 and displayed.

FIG. 8 shows a case where a transistor is used as the power switching element 5, and shows the temperature characteristic S of the power switching element 5 with respect to time t, the voltage characteristic V across the secondary battery 2, and the charging current characteristic I, respectively. However, as is clear from these characteristic curves S, V, and I, a sufficiently large charging current is maintained until the time t ′ from the start of charging to the time when the voltage across the secondary battery 2 reaches the specified voltage value. Since it flows, the heat generation amount of the power switching element 5 becomes large,
The temperature sensor 7 senses this, and a display corresponding to the amount of heat generation is displayed on the display unit 18 that displays charging.

After the time t ′, the charging current shows a peak value again, so the generated heat also shows a peak value, and thereafter, the charging current drops exponentially, and at time t ″, the charging is almost completed, The amount of heat generated by the power switching element 5 also drops sharply accordingly, and the correct charging completion time is displayed on the display unit 17.

Here, the temperature sensed by the temperature sensor 7 is 40 when the charging is completed.
If it is above ℃, it will not react at the outside temperature, and the accurate charging completion time will be displayed.

According to the experimental results of the inventor, the temperature sensed by the temperature sensor 7 is about 50 ° C. at the time t ′, and the time t ″ at the completion of charging is
Then, it was about 45 ° C.

When the charging completion time is displayed on the LED 88 as in the conventional case, the LED 88 is configured to display the charging completion time at the time t '. The temperature sensor 7 senses the amount of heat generated by the current flowing through the power switching transistor and displays the completion of charging.

FIG. 9 shows a case where a thyristor is used as the power switching element 5. In the case of thyristors,
When the thyristor is turned off at the time t ', the charging current does not flow abruptly, so the generated heat also drops sharply and the completion of charging is clearly displayed.

According to the results of experiments by the inventor, the temperature sensed by the temperature sensor 7 at the time of completion of charging (time t ″) when using a thyristor was slightly higher than the outside air temperature.

FIG. 10 shows that when the secondary battery 2 is discharging, that is, while the vacuum cleaner is operating, the discharge current characteristic i with respect to the suction power P (W) of the vacuum cleaner, the temperature characteristic s of the discharging power transistor 6, The airflow rate Q is shown, and the suction work rate P is proportional to the airflow rate Q.

Therefore, as the air volume Q increases, the rotational speed of the electric blower 3 also increases, and the discharge current flowing through the power transistor 6 for discharging increases, so the amount of heat generation also increases. Since this heat is detected by the temperature sensor 7 attached to the outside of the main body 1 through the opening 8, the suction force during operation can be displayed by the temperature sensor 7.

In addition, since the discharging current decreases when the capacity of the secondary battery 2 decreases as well as the indication that the secondary battery 2 is being discharged, this state is displayed by the temperature sensor 7, and the charging timing of the secondary battery 2 is also indicated by the temperature sensor 7. It is displayed in the same manner as during charging.

[Advantages of the Invention] The present invention allows a charging current to flow to a secondary battery in a charging circuit via a power switching element, and the power switching element is installed close to the inner rear surface of the main body, and is placed at a position facing the power switching element. A temperature sensor that detects the temperature rise of the power switching element is arranged on the outer surface of the main body, and an opening is provided on the outer wall of the main body that is interposed between the temperature sensor and the power switching element, so that the charging current is supplied to the power switching element. Since the temperature sensor detects the temperature rise when flowing and indicates that charging is complete, etc., it is not necessary to use LEDs as in the past, so there is no need for special wiring for that, and led
As a result, it is possible to save the power that wasted.

Moreover, the heat generated by the power switching element, which was originally wasted, can be utilized, which is efficient.

In addition, the charging / discharging display, which has been conventionally displayed only in two modes of lighting and extinguishing by the LED, uses a charging completion display and a charging display, and this charging display is performed in several steps. Since it is displayed, you can see the progress of charging accurately with your eyes.

Further, since the display from charging to completion of charging is divided into several stages according to the temperature by using a temperature sensor capable of sensing the temperature of a plurality of stages, the progress of charging can be visually observed.

[Brief description of drawings]

1 to 9 show an embodiment of the present invention.
The figure is a cross-sectional view of the main body 1 of the vacuum cleaner, and FIG. 2 is the secondary battery 2
FIG. 3 is a sectional view of a main part of the main body, FIG. 4 is a plan view of the heat sink 4, and FIG. 5 is a plan view of the temperature sensor 7.
FIGS. 6 and 7 are plan views of the temperature sensor 7, and FIGS. 8 and 9 show temperature characteristics, voltage characteristics, and charging current characteristics with respect to time when a transistor and a thyristor are used as the power switching element 5, respectively. Figures and 10 show discharge current characteristics, temperature characteristics, and suction power during discharge.
FIG. 11 is a diagram showing an air volume characteristic, and FIG. 11 is a charge / discharge circuit diagram showing a conventional example. 1 ... Main body of vacuum cleaner 2 ... Secondary battery 3 ... Electric blower 5 ... Power switching element 7 ... Temperature sensor 8 ... Opening 9 ... Secondary battery charge / discharge circuit 13 ... Over discharge Prevention circuit

Claims (3)

[Claims] 1. An electric vacuum cleaner comprising: an electric blower built in a main body; a secondary battery for driving the electric blower; and a charging circuit having an overcharge prevention circuit for controlling a charging current of the secondary battery. In the charging circuit, a charging current is supplied to the secondary battery via a power switching element, the power switching element is installed close to the inner back surface of the main body, and the power switching element is positioned opposite to the power switching element. A temperature sensor for detecting a temperature rise of the power switching element is arranged on the outer surface of the main body, and an opening is provided in the outer wall of the main body interposed between the temperature sensor and the power switching element. The temperature sensor detects an increase in temperature when a charging current flows, and displays a message indicating that charging is in progress, charging is completed, etc. Vacuum cleaner. 2. The temperature sensor display according to claim 1, wherein the temperature sensor senses the temperature of the power switching element during charging and the temperature sensor senses the temperature of the power switching element when charging is completed. The electric vacuum cleaner is characterized in that the two temperature sensors are respectively labeled with a charge-in-progress indication and a charge-completed indication, and the charge-indication is indicated in several stages. 3. The display device according to claim 1, wherein a temperature sensor capable of sensing temperatures in a plurality of stages is used to divide the display from charging to completion of charging into a plurality of stages according to the temperature. Vacuum cleaner.