JPH0210799Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a control circuit for a vacuum cleaner, and in particular, it controls the electric blower installed in the main body of the vacuum cleaner by operating a variable resistance section installed at the end of the hose of the vacuum cleaner. The present invention aims to provide a control circuit for a vacuum cleaner that can control the rotation speed.

Conventionally, a control circuit for a vacuum cleaner, as shown in FIG. 3, includes a bidirectional thyristor 22 connected in series with an electric blower 21, a capacitor connected to the gate of this bidirectional thyristor via a trigger diode 23, and This charging circuit includes a rectifier circuit 25 having one input terminal connected to the capacitor, and an anode and a cathode connected to the output terminal of the rectifier circuit via a resistor 26. A device including a thyristor 27 and a variable resistor 28 connecting the gate of the thyristor 27 and one output terminal of the rectifier circuit 25 has been proposed. However, since a large current flows through the variable resistor 28 that controls the rotational speed of the electric blower 21, if you try to install the variable resistor 28 at the end of the vacuum cleaner's hose, you should be very careful as there is a risk of electric shock. Therefore, the variable resistor 28 is generally provided in the vacuum cleaner body. For this reason, the user must use the electric blower 2.
Each time the variable resistor 28 is operated in order to change the rotation speed of the vacuum cleaner, the user has to reach the vacuum cleaner itself, which is extremely troublesome.

The present invention solves the above-mentioned conventional drawbacks, and embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, 1 is an AC power source, and one end of this AC power source 1 is connected to a vacuum cleaner body (not shown).
A first electrode of a bidirectional thyristor 3 is connected to the other end of the AC power source 1 via an electric blower 2 built in the AC power source 1, and a second electrode of the bidirectional thyristor 3 is connected to the other end of the AC power source 1. This bidirectional thyristor 3 is connected in parallel with a series connection body of a resistor 4 and a capacitor 5 for surge protection. 6 is a trigger diode that triggers the bidirectional thyristor 3;
One end is connected to the gate electrode of the bidirectional thyristor 3, and the other end is connected to the second electrode of the bidirectional thyristor 3 via the capacitor 7. 8 is a rectifier circuit, which is constructed by connecting diodes 9, 10, 11, and 12 in a bridge type, and one input side terminal of this rectifier circuit 8 is connected to the first electrode of the bidirectional thyristor 3. However, the other input side terminal is connected to the connection point between the trigger diode 6 and the capacitor 7. 13 is a transistor, the collector of the transistor 13 is connected to one output side terminal of the rectifier circuit through a resistor 14, and the base of the transistor 13 is connected to one output side terminal of the rectifier circuit through resistors 15 and 17 for electric shock protection and a variable resistor 16. The emitter of the transistor 13 is connected to the other output terminal of the rectifier circuit 8. Then, the rectifier circuit 8, the resistors 14, 15, 17, and the transistor 1
3 and the variable resistor 16 constitute a charging circuit for the capacitor 7.

The operation of the above circuit configuration will be explained below.

The capacitor 7 is charged by the charging circuit, and the charging voltage of the capacitor 7 is applied to the trigger diode 6.
When the breakover voltage reaches the breakover voltage, the trigger diode 6 becomes conductive, a gate current flows through the bidirectional thyristor 3, the bidirectional thyristor 3 becomes conductive, and the conductive blower 2 rotates. When the variable resistor 16 of the charging circuit for the capacitor 7 is changed, the base current of the transistor 13 changes, and the amplified collector current changes accordingly, making it possible to change the charging speed of the capacitor 7. can.

The amplification rate of transistor 13 is several 10 times to several 100 times
Since the current is twice as large, the current flowing through the base circuit can be minute, and therefore the resistors 15 and 17 for electric shock protection can be set to large values, eliminating the risk of electric shock even if the human body touches it. In this way, the variable resistor 16
By changing , the conduction angle of the trigger diode 6 changes. That is, the conduction angle of the bidirectional thyristor 3 changes, the current flowing to the electric blower 2 changes, and the rotational speed of the electric blower 2 is eventually controlled. Since only a small current flows through the variable resistor 16 that controls the charging speed of the capacitor 7, it is possible to install the variable resistor 16 at the end of the vacuum cleaner hose by simply using a simple insulation structure. As a result, when the user changes the rotational speed of the electric blower 2, he/she only has to operate the variable resistor 16 at hand while cleaning, thereby eliminating the troublesome work required in the past.

Next, the control width of the rotational speed of the electric blower in this embodiment and the conventional example will be compared and explained with reference to FIG.

The rotation speed of the electric blower is determined by the current flowing through the electric blower, ie, the speed at which the charging voltage of the capacitor reaches the breakover voltage of the trigger diode. Note that FIG. 4A shows the power supply voltage waveform.

First, when the value of the variable resistor is at its minimum, in the case of the conventional example, the thyristor 27 becomes conductive and charging current begins to flow into the capacitor 24 only when the AC power supply voltage increases to a certain extent as shown in Figure 4B. However, in the case of this embodiment, even if the AC power supply voltage 1 is small as shown in FIG. Overvoltage can be reached. In addition, when the value of the variable resistance is maximum, in the case of the conventional example, when the thyristor 27 is near the peak of the AC power supply voltage, as shown in FIG.
conducts and charges the capacitor 24, but the charging current of the capacitor 24 is large near the peak of the power supply voltage, and the charging voltage of the capacitor 24 instantly reaches the breakover voltage of the trigger diode 23. On the other hand, in the case of this embodiment, even if the base current is large to some extent near the peak of the AC power supply voltage as shown in FIG.
The time for the charging voltage to reach the breakover voltage of the trigger diode 6 can be delayed. In this way, in the case of this embodiment, the speed at which the capacitor 7 reaches the breakover voltage of the trigger diode 6 can be controlled more widely than in the conventional example.
In other words, the rotational speed of the electric blower can be controlled over a wide range.

Note that FIG. 2 shows another embodiment of the present invention, and the same parts as in FIG. 1 are given the same numbers. 18 is an on/off switch connected in series to the variable resistor 16. When the on-off switch 18 is in the open state, the capacitor 7 is not charged, and therefore the electric blower 2 does not rotate. By providing the on/off switch 18 and the variable resistor 16 at the end of the vacuum cleaner hose, the user can control the rotation speed of the electric blower by hand, and
It is also possible to control the rotation stop and start of the electric blower.

As described above, according to the present invention, a small current flows through the variable resistor that controls the rotation speed of the electric blower of the vacuum cleaner, so the variable resistor can be installed at the end of the hose without strict insulation. As a result, the user can control the rotation speed of the electric blower with the end of the hose while cleaning, and the rotation speed of the electric blower can be controlled over a wide range, which has great practical value. It is what it is.

[Brief explanation of the drawing]

Fig. 1 is a control circuit diagram of a vacuum cleaner showing one embodiment of the present invention, Fig. 2 is a control circuit diagram of a vacuum cleaner showing another embodiment of the invention, and Fig. 3 is a control circuit diagram of a vacuum cleaner showing a conventional example. FIGS. 4A to 4E, a control circuit diagram of a vacuum cleaner, are comparison diagrams of capacitor charging speeds of an embodiment of the present invention and a conventional example. 2... Electric blower, 3... Bidirectional thyristor, 6... Trigger diode, 7... Capacitor, 8... Rectifier circuit, 13... Transistor, 1
6...Variable resistor, 18...Open/close switch.

Claims (1)

[Scope of claim for utility model registration] (1) A bidirectional thyristor connected in series with an electric blower, a capacitor connected to the gate of this bidirectional thyristor via a trigger diode,
Equipped with a charging circuit that charges this capacitor,
This charging circuit consists of a rectifier circuit with one input side terminal connected to the above capacitor, a transistor whose collector and emitter are connected to the output side terminal of this rectifier circuit, and the base of this transistor and one output side terminal of the above rectifier circuit. A control circuit for a vacuum cleaner comprising a resistor for protecting against electric shock and a variable resistance section provided at the end of a hose of the vacuum cleaner. (2) The control circuit for a vacuum cleaner according to claim 1, wherein the variable resistance section includes an on-off switch and a variable resistor connected in series with the on-off switch.