JPH0695993B2 - Vacuum cleaner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vacuum cleaner, and more particularly to an electric vacuum cleaner that prevents the rotation speed of an electric blower from frequently changing due to the amount of dust.

[Conventional technology]

The conventional vacuum cleaner is provided with a dust detection sensor that detects the presence or amount of dust in order to always obtain an appropriate suction force, and when the dust detection sensor detects dust, increases the rotation speed of the electric blower, I try to increase the suction power.

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional technique, dust is sucked, and the dust detection sensor detects the dust each time and changes the rotation speed of the electric blower, so the dust is detected before the next dust is detected. Even when the time until it is carried out is very short, there is a problem that the rotation speed of the electric blower changes in a short cycle, which causes annoying feeling.

An object of the present invention is to solve the above-mentioned problems and to provide an electric vacuum cleaner capable of suppressing frequent changes in the number of rotations of an electric blower and preventing annoying noise.

[Means for Solving the Problems]

In order to solve the above problems, the features of the present invention include an electric blower, a dust detection sensor that detects dust sucked by the electric blower and generates a signal, and the dust detection sensor detects the dust. In a vacuum cleaner having a control circuit that controls the rotation speed of the electric blower based on a signal, a delay circuit that delays the falling edge of the signal for a predetermined time when the dust detection sensor stops detecting dust. When the dust detection sensor detects dust, the rotation speed of the electric blower is controlled to be higher than a predetermined rotation speed, and the dust detection sensor stops detecting the dust. In such a case, the rotation speed of the electric blower is kept at a rotation speed higher than the predetermined rotation speed for a time corresponding to the predetermined time delayed by the delay circuit. That.

[Action]

According to the present invention, when the dust detection sensor no longer detects dust, the rotation speed of the electric blower is set to a rotation speed higher than the predetermined rotation speed for a time corresponding to the predetermined time delayed by the delay circuit. Since the electric blower is held, it is possible to suppress frequent changes in the rotation speed of the electric blower and prevent the generation of a jarring sound.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a vertical sectional view of an electric vacuum cleaner according to an embodiment of the present invention. In the figure, 1 is a vacuum cleaner body, 2 is a dust suction port, which is mechanically connected to the vacuum cleaner body 1 by a pipe 3. 4 is a suction blower, a motor 5
Drive to rotate by. 6 is a dust case for collecting dust 8 and 7 is a dust detection sensor. Moreover, the arrow shows the flow path of air.

FIG. 1 shows a block diagram according to an embodiment of the present invention.
In the figure, reference numeral 7 denotes the above-mentioned dust detection sensor. Generally, for hard dust such as sand, a piezoelectric element or the like that generates electricity is used by the so-called piezo effect in accordance with the impact pressure due to suction. .

Further, for light weight and relatively large volume dust such as paper and lint, a light emitting diode and a photodiode are used.

Further, the above piezoelectric element may be used in combination with a light emitting diode, a photodiode or any other suitable sensor depending on the nature of dust.

Reference numeral 9 denotes an amplifier circuit, which amplifies an electric signal output of, for example, about 1 volt from the dust detection sensor 7 and drives the delay circuit 10 at the next stage. Further, if necessary, a waveform shaping circuit such as a clipper for the amplitude of the pulsed electric signal or a noise limiter is provided.

Reference numeral 10 denotes a delay circuit, which is a so-called CR delay circuit composed of a resistor R and a capacitor C (not shown), to which a simple logical operation element for controlling the delay time is added.

Reference numeral 11 denotes a control circuit for controlling the rotation of the motor, which is usually a bidirectional 3-terminal semiconductor element for turning on / off a voltage or current of a power source applied to the motor 5, and the bidirectional 3-terminal semiconductor. It is composed of a gate trigger circuit for controlling turn-on / off of elements.

Next, the operation of FIG. 1 will be described with reference to the motor control explanatory diagram of FIG.

In FIG. 2, the dust 8 sucked from the dust suction port 2
Is detected by a dust detection sensor 7 provided on the suction path.

As described above, when a piezoelectric element is used as the dust detection sensor, a value of a pulse width of 0.5 ms and a maximum peak voltage of about 1 volt is used as an example due to the piezo effect due to the collision of dust such as sand. The pulse group with a large variation, which is the center, is shown in (a) of the sensor output characteristic diagram of FIG.
As shown in (b), (c), and (d), it is generated extremely irregularly depending on the presence and amount of dust.

Also, when a light emitting diode and a phototransistor are used to detect a thread, waste paper, etc., the amount of passing dust is detected as the amount of light received by the phototransistor, and a pulsed output signal is similarly generated.

FIG. 3 (b) shows a conventional motor rotation characteristic diagram corresponding to FIG. 3 (a).

In the figure, H indicates a high speed load operation of the motor 5, and L indicates a low speed light load operation. As shown in the figure, the motor 5 does not completely follow the pulsed electric signal output shown in FIG. 3 (a) due to the inertia caused by its rotation, but nevertheless there is no very short pulse group. It is controlled by responding to the period each time. In the figure, (e), (e),
As shown in (g), the pulsating state occurs.

FIG. 3 (c) shows a motor rotation characteristic diagram according to the present invention. In this case, by providing the delay circuit 10 described above, the trailing edge of each pulse shown in FIG. 3 (a) is delayed by several seconds, and as a result, the pulse group (a) of FIG. 3 (a) is obtained. ，
(B) and (c) form a series of rectangular waves (h) to drive the motor 5 via the control circuit 11. Motor 5
As shown in FIG. 3 (c) (chi), a comparison of high speed rotation and dust-free comparison as shown in (chi) through the periods of pulse groups (b), (c), (d) For a relatively long period, low speed rotation can be performed safely.

The preferred embodiment of the present invention has been described above with reference to the drawings. However, the constituent circuits, constituent elements, their characteristics, relative arrangements, and the like described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified. It is just an example of explanation. Also,
The delay circuit may be provided between the control circuit and the motor.
Further, there are various methods for controlling the motor, such as voltage, current, and phase, but in the gist of the present invention, they are collectively referred to as power control.

〔The invention's effect〕

As described above, according to the present invention, when the dust detection sensor no longer detects dust, the rotation speed of the electric blower is set to a value equal to the predetermined time delayed by the delay circuit from the predetermined rotation speed. Since it is also kept at a high rotation speed, it suppresses frequent changes in the rotation speed of the electric blower,
It is possible to prevent the generation of annoying sound.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a vertical sectional view of an electric vacuum cleaner, FIG. 3 (a) is a sensor output characteristic diagram, and FIG. 3 (b) is a conventional motor rotational speed characteristic. Figure, Figure 3 (c)
FIG. 4 is a motor rotation characteristic diagram of the present invention. 1 ... Vacuum cleaner body, 2 ... Dust suction port, 3 ... Pipe, 5 ... Motor, 6 ... Dust case, 9 ... Amplifier circuit, 10 ... Delay circuit, 11 ... Control circuit.

Claims (1)

[Claims] 1. An electric blower, a dust detection sensor for detecting dust sucked by the electric blower and generating a signal, and the rotation speed of the electric blower based on the signal detected by the dust detection sensor. In a vacuum cleaner having a control circuit for controlling, the dust detection sensor has a delay circuit that delays the fall of the signal for a predetermined time when the dust detection sensor stops detecting dust, and the dust detection sensor When it detects that the electric blower is controlled to increase the rotation speed of the electric blower to a higher rotation speed than a predetermined rotation speed, and when the dust detection sensor does not detect dust, the delay circuit delays it. An electric vacuum cleaner, characterized in that the rotation speed of the electric blower is maintained at a rotation speed higher than a predetermined rotation speed for a time corresponding to a predetermined time.