JPS63234930A - vacuum cleaner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vacuum cleaner, and more particularly to a speed control device for an electric motor serving as a drive source for the vacuum cleaner.

[Conventional technology]

An electric blower consisting of a fan and an AC commutator is used as the drive source for a vacuum cleaner. However, it involves mechanical sliding between a brush and a commutator, and with the recent trend toward smaller size and lighter weight due to higher speeds, commutation conditions have become stricter, causing sparks to be generated from the brushes and resulting in a shortened brush life.

As a countermeasure to this problem, an electric blower using a brushless DC motor has been proposed as described in Japanese Patent Laid-Open No. 60-242827. However, no consideration has been given to a speed control method for brushless DC motors suitable for vacuum cleaners.

Furthermore, it has not been clarified how to control a conventional AC commutator or an electric motor driven by an inverter when a foreign object enters the intake path and the airtight state occurs.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration the speed control method of a brushless DC motor suitable for a vacuum cleaner, and has the problem of not being able to cope with excessive rotation of the vacuum cleaner due to clogging of the filter or the like.

An object of the present invention is to maintain the rotational speed at that time even when the load condition of the vacuum cleaner falls below the minimum operating point, thereby preventing destruction of the fan, etc. due to overspeeding.

[Means for solving problems]

The above purpose is to detect the load current of the vacuum cleaner, compare the detected current value with a predetermined current value, and if the detected current value is smaller than the predetermined current value, correct the speed command of the speed control device. This is achieved by controlling the rotation speed to be constant.

[Effect]

In addition to AC commutator machines, there are inverter-driven motors such as induction motors and brushless DC motors, but in any of these motors, clogs in the intake path, clogging in the filter, etc. can be determined from the load current and current change state. Controls the speed of the electric motor. Thereby, even if the vacuum cleaner is in a sealed state, the rotation speed will not exceed the minimum operating range, and a vacuum cleaner with good operability can be obtained.

〔Example〕

Conventionally, AC commutator motors using mechanical carbon brushes have been mainly used as electric motors for vacuum cleaners. However, in response to demands for higher speeds and higher performance, electric motors that are driven by inverters and do not require the brushes have been proposed.

Examples of electric motors that are not equipped with brushes and can be driven by an inverter include brushless DC motors, induction motors, reluctance motors, and even hysteresis motors, all of which can be used as vacuum cleaner motors. be.

Although the present invention is thus applicable to any electric motor drive device, for convenience, a brushless DC motor driven by an inverter will be described as an example of the present invention.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 2 shows the overall configuration of a speed control device comprising a brushless DC motor and an inverter control device according to the present invention.

Inverter control bag @10 connects AC power supply 14 to rectifier circuit 1
5 and a smoothing capacitor 16, the illustrated DC voltage Ea is obtained and supplied to the inverter 20.

The inverter 20 is a 120-degree conducting inverter 1 composed of transistors Trt to Trs and free-wheeling diodes D1 to D8. It is assumed that the conduction period (120 electrical degrees) of a is controlled by chopper operation under pulse width modulation.

Furthermore, a low resistance R1 is connected between the common emitter terminals of the transistors TR4 to TRe and the common anode terminals of the freewheeling diodes D4 to DB.

The brushless DC motor 9 consists of a rotor 9-2 whose field is a two-pole permanent magnet and a stator into which an armature winding 9-1 is inserted, and the winding current flowing through the armature winding 9-1 is as follows. Since the voltage also flows through the low resistance R1, the load current Io of the motor 9 can be detected by the voltage drop across the low resistance R1.

The control circuit that controls the speed of the brushless DC motor 9 is
A magnetic pole position detection circuit 12 which detects the magnetic pole position of the rotor 9-2 of the microcomputer 132 by receiving the output from the Hall element 11. Current detection circuit 17 that detects the value of load current ID from the voltage drop across low resistance R1. Transistor T Rt
” A pace driver 19 that drives the TRB. It is composed of a speed command circuit 17 that transmits a reference speed to the microcomputer 13.

The magnetic pole position detection circuit 12 is a circuit that receives the output from the Hall element 11 and forms a position detection signal 12S corresponding to the rotor position. Then, using this position detection signal 12S, the rotational speed of the brushless DC motor 9 is calculated and determined by the microcomputer 13.

The current detection circuit 17 is a circuit that detects a load current ID in response to a voltage drop across the low resistance R1, and forms a current detection signal 17S using an A/D converter (not shown) or the like.

Further, the microcomputer 13 includes a CPU, R
Consists of OM, RAM, etc., and each has an address bus, a data bus, and a control bus (not shown).
It is connected by.

The ROM contains various processing programs necessary to drive the brushless DC motor 9.

For example, information related to speed calculation processing, command import processing, speed control processing, etc. is stored.

On the other hand, the above-mentioned RAM is made up of a storage section for reading and writing various data necessary for executing the above-mentioned various processing programs.

Transistors TR1 to TRI receive an ignition signal 138 from the microcomputer 13 and are driven by a pace driver 19. Note that the voltage command circuit 21 forms a chopper signal as described later.

In other words, in a brushless DC motor, the winding current flowing through the armature winding corresponds to the output torque of the motor, and by controlling the winding current for each rotor position, continuous control of the output torque is possible. It is something.

Figure 3 shows the performance curve of a vacuum cleaner that uses a brushless DC motor as the drive source.The horizontal axis represents the air volume Q passing through the vacuum cleaner, and the vertical axis represents the suction performance of the vacuum cleaner. Representing the suction power P. ut represents the rotational speed N of the motor and the load current In, and the range from the maximum operating point to the minimum operating point is the operating range of the vacuum cleaner. By the way, the operating point for filter clogging shifts from the maximum operating point to the minimum operating point because the air volume Q decreases according to the amount of clogging. From this, as the amount of clogging increases, the suction power Pout decreases beyond Pmax, and the performance as a vacuum cleaner becomes insufficient. Furthermore, if the degree of sealing in the intake passage increases due to clogging or foreign matter in the intake passage, the rotational speed will become higher than necessary, which will cause problems in terms of the mechanical strength of the FFI motor and the life of the bearings. Therefore, the present invention detects the load current of a brushless motor, determines the operating state from the magnitude of the current, and controls the rotational speed to a constant level when the load current drops below a certain value to prevent overspeeding. There is a particular thing.

Figure 4 shows the change in load current with respect to operating conditions. In the case of A where the air volume Q is large as shown in Figure 3, there is no clogging, and the difference with the minimum current setting value Ins shown by the chain line is shown in Figure 4. There's a big difference. On the other hand, when the air volume Q is small (B), it indicates a state where the degree of sealing has increased due to clogging or foreign matter being sucked into the intake path, and the minimum current setting value Ins shown by the chain line is
Since the minimum value Ioz of current change becomes smaller, clogging in the suction path or filter can be accurately determined based on this value even without a sensor.

FIG. 1 is a schematic block diagram showing a control circuit for driving a brushless DC motor according to the present invention. Note that the speed control system is shown as an open loop voltage control system as an example. In the figure, when a command is input to the microcomputer 13 from the speed command circuit 18, the microcomputer 13
performs command import processing and outputs the speed command N, first selects 1 for the gain K (Kx>Kg), and inputs the voltage output data V* to the D/A converter of the voltage command circuit 21. Then, this output is compared with the output of the triangular wave generation circuit by a comparator, and the output is input to the pace driver 19, the voltage to be applied to the brushless DC motor 9 is determined, and the motor is driven at the reference voltage. .

Next, the microcomputer 13
A current comparison process is performed upon receiving a signal 12S from the switch, and a switching determination processing section determines whether the load current ID is smaller or larger than the minimum current setting value Ios.

If the load current In is smaller than the minimum current setting value Ios, it is determined that a foreign object (handkerchief, nylon sheet, etc.) that is sealing the intake path has entered the air intake path, and a clogging condition is detected, and the gain is set to 2.
Since the voltage command of the brushless DC motor is corrected by subtracting the voltage correction amount ΔV (in other words, the speed command is corrected), the motor rotation speed is not increased more than necessary and over-speed is prevented. It has the effect of

〔Effect of the invention〕

According to the present invention, it is possible to determine the sealing state or the clogged state of the filter due to inhalation of foreign matter in the air intake path of a vacuum cleaner without using a detection sensor, and to perform constant rotation speed control based on this result. This has the effect of prolonging the life of the electric motor, and providing a vacuum cleaner that is safer and quieter without fear of fan destruction.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing a control circuit for driving a brushless DC motor according to the present invention, and FIG. 2 is an overall configuration diagram of a speed control device comprising a brushless DC motor and an inverter control device according to the present invention. FIG. 3 is a performance curve diagram of the vacuum cleaner, and FIG. 4 shows changes in current in response to foreign matter being sucked into the intake path and filter clogging.

Claims (1)

[Scope of Claims] 1. In a vacuum cleaner that uses an electric motor as a drive source and a speed control device that makes the speed variable, the control circuit of the speed control device is composed of a microcomputer, a current detection circuit, and a speed command circuit. The microcomputer controls the speed of the electric motor, detects the load current of the electric motor in the cleaning state, compares the detected current value with a preset minimum current value, and calculates the detected current. This vacuum cleaner is characterized in that the speed command is corrected when . 2. The vacuum cleaner according to claim 1, characterized in that the speed command is corrected so as to maintain the rotational speed at the time when the load current becomes less than or equal to the minimum set current. 3. The vacuum cleaner according to claim 1, wherein the electric motor is a brushless DC motor and the speed control device is an inverter control device.