JPH01136622A - Suction port body with electromotive brush for electric cleaner - Google Patents

Abstract

PURPOSE: To prevent the generation of an excessive torque during the lowering or the stoppage of rotation by a method wherein a current detection means detects a load current of a DC motor and a switching element is turned off by a control means when the load current exceeds a set current value for more than a specified time length. CONSTITUTION: When a brush 13 is entangled by dirts or the like, for in stance, to lower or stop the rotation of the brush 13 and the rotation of a DC motor 14 is lowered or stopped, no reverse electromotive force is generated in the DC motor 14, which causes a load current increase. As a result, a Zener diode 40 exceeds a Zener voltage to be turned conductive from a reverse blocking state and a base current is applied to a transistor 37 to turn on the transistor 37. With the transistor 37 on, the current is bypassed and the base current flowing through a transistor 22 decreases and the load current presents a truncated current waveform below a set current value. The transistor 37 is turned on to charge a capacitor 46.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a suction port body with an electric brush for a vacuum cleaner that eliminates deterioration and damage of a DC motor.

(Prior Art) A circuit configuration shown in FIG. 7 has been adopted as a suction port body with an electric brush for a vacuum cleaner that prevents damage and deterioration of this type of conventional DC motor.

This circuit is connected to an AC power source (not shown) via a circuit of the vacuum cleaner body (not shown).

And, at both ends connected to the circuit of the vacuum cleaner body,
On/off switch 1, fuse 2 connected in series,
The AC input end of the bridge circuit 5 for full-wave rectification is connected via the protective resistor 3 and the positive characteristic thermistor 4, and the connection point between the fuse 2 and the protective resistor 3 on one end side, which is connected to the circuit of the vacuum cleaner body. , and the other end connected to the circuit of the vacuum cleaner body, a capacitor 6 is connected between the two ends.

In addition, at the DC output end of the bridge circuit 5 for full-wave rectification,
A DC motor 7 is connected to the rotating brush via a transmission mechanism such as a belt, and this DC motor 7 has M sound prevention capacitors 8 and 9.

Next, a circuit of the above-mentioned conventional suction port body with electric brush for a vacuum cleaner will be explained.

When the on/off switch 1 is closed, the bridge circuit 5 rectifies the alternating current and rotates the direct current electric motor I17.

For example, if the rotation speed of the rotating brush decreases or stops due to an abnormal external force, the rotation speed of the DC motor 7 also decreases or stops, and the back electromotive force decreases, causing an excessive force on the circuit. A current flows. This excessive current causes the PTC thermistor 4 to self-heat, and as shown in FIG. protect.

Then, the on/off switch 1 is turned off, the current flowing through the PTC thermistor 4 is stopped, the temperature is lowered, and the resistance value returns to the normal value.

Thereafter, when the on/off switch is turned on, the DC motor 7 is driven to rotate.

(Problem to be Solved by the Invention) However, in the conventional circuit described above, it takes several tens of seconds for the positive temperature coefficient thermistor 4 to heat up and the resistance value Rth to increase. An excessive current I flows for several tens of seconds, causing abnormal heat generation in the DC motor 7 and other circuit components, causing deterioration and damage, and accelerating wear on transmission mechanisms such as belts.

Further, while an excessive current is flowing through the DC motor 7, an excessive torque is generated in the DC motor 7 and is transmitted to the rotating brushes, which is dangerous.

The present invention has been made in view of the above problems, and even if the load current increases due to a decrease or stoppage of the rotation of the DC motor due to an abnormal force being applied to the rotating brush, etc., the components of the circuit of the DC motor etc. will deteriorate and be damaged. To provide a suction port body with an electric brush for a vacuum cleaner that is safe and can prevent excessive torque from being generated while the rotation of a DC motor decreases or stops.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a suction port body with an electric brush for a vacuum cleaner that incorporates a rotating brush and a DC motor that drives the rotating brush. a switching element connected in series with the electric motor; a current detection means for detecting a load current of the DC motor; and a current detection means for turning off the switching element when the load current of the DC motor exceeds a set current value for a predetermined time or more. and control means for maintaining the switching element in the off state until the on/off switch for turning on and off the DC motor is turned off.

(Operation) In the present invention, a rotating brush is rotationally driven by a DC motor. At this time, the current detection means detects the load current of the DC motor, and when the load current exceeds a set current value for a predetermined period of time or more, the control means turns off the switching element. and,
The switching element remains in the off state until the on/off switch is turned off.

(Example) Hereinafter, one example of the suction port body with electric brush for a vacuum cleaner of the present invention will be described with reference to the drawings.

In FIG. 3, reference numeral 11 denotes a suction port body, and a connection pipe 12 connected to a hose of a vacuum cleaner body (not shown) is rotatably provided on the suction port body 11.

Further, a rotary brush 13 rotatably provided and a DC motor 14 for driving the rotary brush 13 are housed inside the suction port main body 11. and DC motor 1
A belt 16 is hung between a pulley 15 provided on the rotating shaft of the motor 4 and the rotating brush 13, so that the brush 13 rotates as the DC type IJ machine 14 rotates.

Further, a white light emitting diode 17, for example, for a safety display that illuminates the front is provided at the front part of the suction port main body 11, and a light emitting diode 17, for example, a white color, is provided at the rear part for a danger display that lights up toward the user. A light emitting diode 18 of a different color, for example red, is provided.

Further, the circuit for driving the DC electric motor $1A14 has a configuration as shown in FIG. The input end is connected to a commercial AC N source via a circuit of the vacuum cleaner body (not shown). An on/off switch 21 for turning on and off the DC motor 14 and a rotating brush 1 are connected from one input end to the other end.
A DC motor 14 that drives the DC motor 3, a switching element 22, and a current detection means 23 that detects a load current flowing through the DC motor 14 are connected in series. Further, 24 is a control means, and when the current detection means 23 determines that the load current of the DC motor 14 is larger than the set value for a predetermined period of time or more, the control means 24 turns off the switching element 22 and switches the switching element 22 in series. The display on the display means 25 connected in parallel with the connected DC type IL1 machine 14, the switching element 22, and the current detection means 23 is switched.

Next, a specific circuit of the above configuration will be explained with reference to FIG. 2.

One input terminal is connected to the AC input terminal of the rectifier circuit 32 via the on/off switch 21 and the fuse 31, and the other input terminal is directly connected to the AC input terminal of the rectifier circuit 32. A capacitor 33 is connected between the AC input terminals of the rectifier circuit 32. It is connected.

The DC output end of the rectifier circuit 32 has capacitors 33 and 34 for noise prevention between both ends and the frame, and a DC motor 14 having a stator coil in series, and an N connected as a switching element via a collector-emitter.
A PN type transistor 22 and a cement resistor 35 for absorbing spark noise are connected in series, and a resistor 36 is connected in parallel with these, that is, between the DC output terminal of the rectifier circuit 32.
An NPN transistor 37 and a resistor 38h (connected in series) are connected via the collector and emitter. Also, a resistor 39 is connected between the connection point of the resistor 36 and the collector of the transistor 37 and the base of the transistor 22. A Zener diode 40 and a resistor 41 are connected in series between the connection point between the emitter of the transistor 22 and the cement resistor 35 and the base of the transistor 37.

Further, a diode 42 and a thyristor 43 are connected in series from the connection point of the resistor 36, the resistor 39, and the collector of the transistor 37 to the negative electrode of the DC horn end of the rectifier circuit 32 via an anode and a cathode. Further, the gate of the thyristor 43 is connected to a connection point between a diode 37 and a resistor 38 via a resistor 44 and a resistor 45 connected in series, and a connection point between a resistor 44 and a resistor 45 is connected to a rectifier circuit via a capacitor 46. 32 is connected to the negative electrode side of the DC output end. Further, a resistor 47 and a capacitor 48 connected in series are connected in parallel to the thyristor 43.

Further, a light emitting diode 17 and a collector are connected in series from the positive electrode to the negative electrode of the rectifier circuit 32 via a resistor 51.
An NPN transistor 52 and a resistor 53 connected through an emitter, a light emitting diode 18 and a resistor 55 connected in series are connected in parallel. The base of the transistor 52 is connected to the thyristor 43 via a resistor 56.
A transistor 58 is connected in parallel to the diode 18, and a transistor 58 is connected in parallel to the diode 18.
The collector and emitter of this transistor 5 are connected.
The base of the transistor 8 is connected to the connection point between the emitter of the transistor 52 and the resistor 53 via a resistor 57.

Next, the operation of the above embodiment will be explained.

First, when the on/off switch 21 is turned on, a current flows through the fuse 31, is full-wave rectified by the rectifier circuit 32, and a bias current flows to the base of the transistor 22, which turns on the transistor 22 and causes the DC motor 14 to flow. Voltage is applied and it rotates. DC'l1il after power on
When starting the motor 14, the load current of the DC motor 14 exceeds the set current value due to a transient phenomenon as shown by the broken line in FIG. A base current flows through transistor 37, turning on transistor 37. As a result, the current is bypassed to the transistor 31, the base current of the transistor 22 decreases, and the DC motor 14
The load current flowing through the load current has a truncated current waveform below the set current value, as shown by the solid line in FIG. In addition, DC electric 11
Even if the transistor 31 is turned on and the capacitor 46 is charged for a predetermined time after the thyristor 114 is activated, the charging voltage Vc of the capacitor 46 is lower than that of the thyristor 43 as shown in FIG.
The thyristor 43 is not turned on because the on-voltage of 1 is not reached. That is, after the DC motor 14 is started, the thyristor 43 of the control means 25 is not turned on unless it is longer than a predetermined time until the load current becomes smaller than the set current value.

Then, when the load current of the DC motor 14 reaches a steady state below the set current value, the Zener diode 40 maintains the reverse blocking state and does not turn on, so the base current of the transistor 37 stops and the transistor 37 turns off. This results in
The DC motor 14 is driven with a large current. Then,
A rotary brush 13 is rotated via a belt 16 to scrape out dust and the like from inside the carpet.

Further, since the thyristor 43 is in an off state, a base current flows through the transistor 52, so the transistor 52 is turned on and the light emitting diode 17 is lit.

Note that at this time, the base current flows through the transistor 58 and the transistor 58 is turned on, so that the light emitting diode 18
The current is bypassed and the light emitting diode 18 does not light up.

When the rotation of the brush 13 decreases or stops due to dust or the like getting entangled in the brush 13, the rotation of the DC motor 14 decreases or stops.
4, the reverse starting force is no longer generated, so the load current increases as shown by the broken line in FIG.

As a result, the Zener diode 40 exceeds the Zener voltage and changes from a reverse blocking state to a conductive state, giving a base current to the transistor 37 and turning the transistor 37 on. When this transistor 37 is turned on, the current is bypassed and the base current flowing through the transistor 22 is reduced, so that the load current has a truncated current waveform below the set current value as shown in FIG.

Further, when the transistor 37 is turned on, the capacitor 46 is charged. Then, for a predetermined period of time, that is, the time required for the starting current to become smaller than the set current value when starting the DC motor 14, the charging voltage of the capacitor 46 exceeds the turn-on voltage of the thyristor 43, turns on the thyristor 43, and capacitor 46 is discharged. By turning on the thyristor 43 in this manner, the base current of the transistor 22 is bypassed to the thyristor 43, the transistor 22 is turned off, and thereby the transistor 37 is also turned off. Note that in the actual circuit, a current corresponding to the voltage drop across the diode 42 and the thyristor 43 flows through the base of the transistor 22;
Since the load current flowing to the I machine 14 is minute, it is harmful to the DC motor 14! #There is almost no sound.

Further, when the thyristor 43 is turned on, the base current of the transistor 52 is bypassed to the thyristor 43, so the transistor 52 is turned off and the light emitting diode 17 is turned off. Further, when the transistor 52 is turned off, the base current of the transistor 58 also disappears, so the transistor 58 is turned off, and the current flowing through the transistor 58 flows to the light emitting diode 18, so the light emitting diode 18 lights up.

After the thyristor 43 is turned on, the thyristor 43 is maintained in the on state because the voltage does not drop below the holding voltage due to charging and discharging of the capacitor 48. That is, the transistor 22 remains off, and almost no current flows through the DC motor 14. Then, when the thyristor 43 becomes lower than the holding voltage by, for example, turning off the on/off switch 21, the thyristor 43 is turned off.

Note that while the thyristor 43 is on, the DC motor 1
Since almost no current flows through DC motor 4, almost no torque is generated in DC motor 14.

This prevents the belt 16 from slipping or the like.
It is possible to prevent deterioration of power transmission mechanisms such as

According to the above embodiment, the display means 25 is provided so that the light emitting diodes 17 and 18 have different colors, and the light emitting diode 18 for indicating danger is lit toward the user.
Abnormalities in the rotating brush 13 can be easily confirmed.

In addition, as the DC motor 14 approaches the end of its life, sparks between the commutators become intense, causing the fuse 31 to break, making it difficult to select the fuse 31 and the resistance value of the protective resistor. Since spark noise is absorbed by using the resistor 35, the resistance values of the fuse and protection resistor can be easily selected.

In addition, the predetermined time of the control means 24, that is, the capacitor 4
6 is set to be longer than the time required for the starting current to become smaller than a predetermined current value when the DC motor 14 is started. It is possible to prevent the load current from stopping flowing due to malfunction.

〔Effect of the invention〕

According to the present invention, the load current is detected by the current detection means, and when the current value exceeds the set current value for a predetermined period of time or more, the switching element is turned off and the load current is stopped, so that abnormal force is applied to the rotating brush. It is possible to prevent deterioration and damage to the rotating parts of the DC motor due to an increase in the load current due to a reduction in rotation or stoppage of the DC motor due to the application of Occurrence can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the suction port body with electric brush for a vacuum cleaner according to the present invention, FIG. 2 is a circuit diagram of the same, and FIG.
The figure is a partially cutaway perspective view of the same as the above, Figure 4 is a current waveform diagram when starting the same as the above, Figure 5 is a current waveform diagram when the same as the above DC motor is stopped, and Figure 6 is the charging voltage of the capacitor and the on-voltage of the thyristor. 7 is a circuit diagram showing a conventional example, and FIG. 8 is a relational diagram showing the load current and the resistance value of the thermistor. 13... Rotating brush, 14... DC motor, 21... ON/OFF switch, 22... Transistor as a switching element, 23... Current detection means, 24... Control means, 35... Cement resistor.

Claims (3)

[Claims] (1) In a suction port body with an electric brush for a vacuum cleaner that incorporates a rotating brush and a DC motor that drives the rotating brush, a switching element is connected in series to a power source that drives the DC motor and the DC motor. and,
current detection means for detecting the load current of the DC motor;
Control means for turning off the switching element when the load current of the DC motor exceeds a set current value for a predetermined time or more and maintaining the switching element in the OFF state until an on/off switch for turning on and off the DC motor is turned off. A suction port body with an electric brush for a vacuum cleaner, characterized by comprising: (2) The predetermined time of the control means is set to be longer than the time required for the starting current to become smaller than the set current value when the DC motor is started.
A suction port body with an electric brush for a vacuum cleaner as described in . (3) The switching element consists of an NPN type transistor, the current detection means uses a cement resistor, and when the load current of the DC motor exceeds the set current value and the cement resistor exceeds the set voltage, the control means Claim 1, characterized in that the base voltage of the DC motor is lowered to stop an increase in the load current of the DC motor.
A suction port body with an electric brush for a vacuum cleaner according to Items 1 and 2.