JPH1190087A - Drum type washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further reduce time for washing by driving a motor to rotate a drum clockwise and counterclockwise by an invertor device and applying braking force to the rotation of the motor by reducing the output frequency of the invertor device during rotation of the motor. SOLUTION: An invertor device is composed by connecting transistors 92U-92Z in a three-phase all wave bridge connection as switching elements, a DC voltage is applied thereon as input from a power source circuit 91, and the transistors 92U-92Z are ON/OFF controlled in a suitable ignition order to generate three-phase AD current as the output to be applied on a motor 9 to drive a drum clockwise and counterclockwise. The ignition interval to switch ON/OFF the transistors 92U-92Z is gradually shortened to switch ON/ OFF at prescribed ignition intervals for a prescribed time. Next, the ignition intervals are prolonged as the ignition pattern is kept the same to make the motor 9 act as a generator to apply braking force on the rotation of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum type washing machine for performing washing and drying in a drum by rotating the drum forward and backward, and in particular, a motor for rotating the drum using an inverter device. It relates to what is driven.

[0002]

2. Description of the Related Art A drum-type washing machine has a structure in which a drum rotates around a horizontal axis in a water tub. By rotating the drum, a process from washing to drying is performed in the drum. -It is a typical washing machine that has a series of washing functions of rinsing, dehydrating, and drying.

Generally, in a drum type washing machine, in order to improve washing performance, forward rotation → reverse rotation → forward rotation → reverse rotation →
..., the rotation of the drum is reversed at a predetermined cycle. This uses a motor capable of rotating the drum forward and reverse, and energizes the motor for a predetermined time so that the motor rotates forward, and after the motor stops rotating forward, the motor rotates reversely. This is performed by repeating a cycle in which the motor is energized for a predetermined time, the reverse rotation of the motor is stopped, and then the motor is energized for a predetermined time so that the motor rotates forward. Then, the shorter the time until the rotation of the electric motor is stopped, the shorter the time required for the drum to be inverted, and the more the washing ability is improved, so that the washing time is shortened.

The reason for stopping the motor when reversing the rotation of the motor is that if a torque is generated in a direction opposite to the direction of rotation while the motor is rotating, an excessive load may be applied to the motor. Alternatively, an impact force is exerted on the electric motor or the driving mechanism, thereby shortening the life of these components and generating noise.

[0005] Normally, as shown in Fig. 8, the rotation of the motor is stopped by providing a power cut-off period, that is, the motor is coast-stopped. In this case, the rotation of the motor stops. Since the time until the rotation is long and the stop of the rotation of the motor is in a so-called uncontrolled state, the power supply to rotate in one direction is started after the power supply to rotate in one direction is started. The time required for the rotation to stop due to inertia stop must be set longer than the time that is expected to be sufficient, so that the drum can be reversed in a short time. Absent. Therefore, the following drum-type washing machine has been proposed in order to solve this problem, perform the reversal of the drum in a shorter time, and improve the washing ability to shorten the washing time.

[0006] For example, a motor is designed to brake the rotation of a motor by passing a DC current through an armature winding of an electric motor for rotating a drum (hereinafter referred to as "DC braking") (Japanese Patent Application Laid-open No. Sho. 63-24987), and
As shown in FIG. 9, motors for rotating the drum are separately provided for washing and dehydrating, and the washing motor 100 provided for washing is provided with a reduction ratio (the electric motor of the motor) higher than the dehydrating motor 200 provided for dehydrating. The number of revolutions / number of revolutions of the drum is set to be large, and a greater braking force is obtained by performing DC braking using the washing motor 100 having a large reduction ratio (Japanese Patent Laid-Open No. 252493/1990). reference)
Is mentioned.

[0007]

Here, a static magnetic field is generated by flowing a DC current through the armature winding of the motor,
When the rotor cuts off the magnetic flux, an overcurrent is generated in the rotor. That is, in DC braking, the inertial energy due to the rotation of the electric motor is consumed as heat, and the temperature rise increases as the braking force increases.

[0008] Therefore, in the above-mentioned conventional drum-type washing machine that performs DC braking, the braking force cannot be set so large, and the time until the rotation of the electric motor stops is not shortened so much. As a result, the cleaning ability was not significantly improved, and the reduction of the cleaning time could not be made effective. In addition, there is a fear that the insulation of the windings is deteriorated due to the temperature rise, and the life of the motor is shortened. In addition, there is another problem that a large amount of power is consumed because a direct current flows through the armature winding.

Accordingly, an object of the present invention is to provide a drum type washing machine in which the washing time is further reduced.

[0010]

In order to achieve the above object, a drum type washing machine according to the first aspect of the present invention has a drum for performing washing and drying inside by rotating the machine forward and reverse. Then, in a drum type washing machine in which an electric motor for rotating the drum forward and reverse is driven by an inverter device, a braking force is applied to the rotation of the electric motor by reducing the output frequency of the inverter device while the electric motor is rotating.

Here, when the motor is driven by the inverter device, a negative slip occurs in the motor by lowering the output frequency of the inverter device during rotation of the motor, that is, the original rotational speed of the motor. (Hereinafter referred to as "synchronous rotation speed").
The back electromotive voltage of the armature winding becomes higher than the terminal voltage and acts as a generator.

Therefore, according to the configuration of the present invention, the inertial energy due to the rotation of the motor is absorbed as electric energy by the power supply circuit, and the rotation of the motor is braked.
Since the inertial energy due to the rotation of the electric motor is absorbed as electric energy, the braking force can be set to be large because the temperature does not increase as in DC braking.

According to a second aspect of the present invention, there is provided a drum type washing machine according to the first aspect, further comprising means for detecting a rotation speed of the electric motor, until the rotation of the electric motor stops. During this time, the output frequency of the inverter device is controlled according to the rotation speed of the electric motor.

With the above configuration, if the output frequency of the inverter is appropriately controlled, for example, a constant braking force can be applied to the rotation of the motor until the motor stops.

According to a third aspect of the present invention, there is provided the drum type washing machine according to the first or second aspect, further comprising means for detecting the number of rotations of the electric motor. By lowering the output frequency of the inverter device accordingly, the initial braking force applied to the rotation of the motor decreases as the rotation speed of the motor increases, and increases as the rotation speed of the motor decreases.

With the above configuration, it is possible to prevent a sudden increase in the power supply voltage supplied to the inverter device, and to avoid a problem that the components of the inverter device are damaged.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a front view and a side view, respectively, showing a schematic configuration of a drum type washing machine, and the structure and function of each part will be roughly described based on the drawings. The water tub 3 has a function of storing and discharging a washing liquid and a dehydrating liquid. A drum 4 is disposed inside the water tub 3 so as to be rotatable around a horizontal axis.
It has a heavy structure.

The water tank 3 is suspended by the supporting lot 2 inside the outer box 1, so that vibrations during operation are absorbed. The drum 4 is provided with a number of small holes 41 on the entire peripheral wall thereof for supplying water during washing, draining during dehydration, and introducing warm air during drying. A drying unit 5 is provided above the water tank 3, and a blower and a heater for circulating hot air are connected to the circulation duct 6 inside the drying unit 5.

At the center of the front surface of the main body, a lid 7 for taking in and out the laundry to and from the drum 4 is provided. The electric motor 9 rotates the drum 4. The drain pump 10 discharges the washing liquid and the like in the water tub 3 to the outside of the machine. Aquarium 3
A lint filter case 11 is provided in a piping path between the pump and the drain pump 10 to remove lint such as lint contained in the liquid discharged outside the machine.

An operation unit 12 is provided on the upper part of the lid 7, and the user can make various inputs from the operation unit 12 and check the washing state based on information displayed there. Switch to select the driving course, start switch to start driving,
Display means and the like are provided.

A control unit 13 is mounted on the back side of the operation unit 12, and the control unit 13 controls controlled parts such as the electric motor 9 and the drain pump 10 based on a user input from the operation unit 12. Controls a series of steps from washing to drying.

In the above construction, in the washing process, the detergent contained in the detergent case 14 is poured from above while being melted by water supply and contained in the laundry in the drum 4, and the reversal between the normal rotation and the reverse rotation is performed. This is performed by repeatedly rotating the drum 4 at a low speed. The water level of the washing liquid is detected by a water level sensor 15.

The dewatering process is performed by rotating the drum 4 at a high speed. As a result, the laundry is pressed against the inner surface of the peripheral wall of the drum 4 by the centrifugal force, and the moisture contained in the laundry is blown out of the drum 4 from a small hole provided on the entire peripheral wall of the drum 4, and It is guided to the lower part along the inner surface, and is discharged outside the machine by the drainage pump 10.

The drying process is performed by rotating the drum 4 at a low speed while blowing the air heated by the drying unit 5 and having a high temperature into the drum 4.

For the sake of safety, when the operation is started, the fitting lock of the lid 7 is locked by the lid locking mechanism (not shown) provided in the washing machine main body, so that the lid 7 cannot be opened. It has become. However, after operation,
By operating a handle (not shown) formed integrally with the lid 7 main body, the lid 7 can be easily opened.

FIG. 3 shows a drive circuit of the electric motor 9 for rotating the drum 4. In the figure, 91 is a power supply circuit, 92 is an inverter device, and the power supply circuit 91
For example, it is composed of a rectifier circuit and a smoothing capacitor, converts an AC voltage from a commercial AC power supply into a DC voltage, and supplies the DC voltage to the inverter device 92.

The inverter device 92 includes transistors 92U, 92V, 92W, 92 as switching elements.
X, 92Y, and 92Z are connected by a three-phase full-wave bridge, and a DC voltage is applied to an input of the X, 92Y, and 92Z from a power supply circuit 91, and transistors 92U, 92V, 92W, and 92
When X, 92Y, and 92Z are ON / OFF controlled in an appropriate firing order, a three-phase alternating current is generated at the output thereof and applied to the electric motor 9.

The operation of the control unit 13 for controlling the rotation of the motor 9 in the above configuration will be described.
Transistors 92U, 92V, 9 of inverter device 92
The 2W, 92X, 92Y, and 92Z are turned on / off in the firing pattern shown in FIG. 4, the firing interval is gradually shortened, and turned on / off at a predetermined firing interval over a predetermined time. As a result, the frequency of the three-phase alternating current output from the inverter device 92 increases to a predetermined frequency, so that the electric motor 9 driven by the inverter device 92 starts forward rotation, gradually increases in rotation speed, and reaches a steady rotation speed. Is maintained for a predetermined period of time.

Next, when the normal rotation period ends after a lapse of a predetermined time, the firing interval is increased while the firing pattern remains the same, and the output frequency of the inverter 92 is reduced. As a result, a negative slip occurs in the motor 9, that is, the synchronous rotation speed (original rotation speed as the motor) becomes lower than the actual rotation speed, the motor 9 acts as a generator, and the inertia of the drum 4 is reduced. The energy is absorbed by the power supply circuit 91 as electric energy, and a braking force is applied to the rotation of the electric motor 9. For example, as shown in FIG. 6, in the electric motor 9 rotating at a load torque point of a certain output frequency (frequency f) of the inverter device 92, the inverter device 9
When the output frequency of the motor 2 becomes lower (frequency f ′), the braking torque acts on the electric motor 9.

Then, the output frequency of the inverter 92 is gradually reduced so that the synchronous rotation speed and the actual rotation speed are kept at a constant interval. As a result, a constant negative slip is continuously generated in the electric motor 9, so that a constant braking force is always applied to the forward rotation of the electric motor 9, and the forward rotation of the electric motor 9 rapidly decelerates to stop.

The rotation speed of the motor 9 (actual rotation speed)
If the output frequency of the inverter device is reduced according to the detected actual rotational speed, the interval between the synchronous rotational speed and the actual rotational speed is more accurately kept constant. Thus, the rotation of the electric motor 9 can be stopped more quickly and more reliably.

In this way, when the forward rotation of the motor is stopped, the transistors 92U, 9
2V, 92W, 92X, 92Y, and 92Z are turned on / off in a firing pattern shown in FIG. 5, gradually shortening the firing interval, and turning on / off at a predetermined firing interval over a predetermined time.
Let it. As a result, the motor 9 starts reverse rotation, the rotation speed gradually increases, and the reverse rotation at the steady rotation speed is maintained for a predetermined time.

Next, when the reverse rotation period ends after a lapse of a predetermined time, the output frequency of the inverter device 92 is maintained at a constant interval between the synchronous rotation speed and the actual rotation speed while maintaining the same firing pattern. And gradually lower it. Accordingly, as described above, a constant braking force is always applied to the rotation of the electric motor 9, and the reverse rotation of the electric motor 9 is rapidly decelerated to stop.

By repeating the above operation, FIG.
As shown in FIG. 5, the rotation of the drum 4 is reversed. As described above, the inertia energy due to the rotation of the electric motor 9 is absorbed by the power supply circuit 91 as electric energy, thereby braking the rotation of the electric motor 9. Because
The braking force can be set large enough to prevent the constituent elements of the inverter device 92 from being damaged by a sudden increase in the power supply voltage, and the rotation of the electric motor can be stopped in a shorter time. Accordingly, the reversal of the drum 4 is performed in a shorter time, and the washing ability is improved, so that the washing time is reduced.

By the way, in the dehydration step, the steady-state rotation speed of the electric motor 9 is higher and the inertia energy is higher than in the washing step. Therefore, when the same initial braking force as the washing step is applied to the rotation of the electric motor 9, the power There is a possibility that the voltage may rise sharply and damage the components of the inverter device 92.

In order to prevent such a problem, the negative slip value is decreased as the rotation speed of the motor 9 is increased, while the negative slip value is increased as the rotation speed of the motor 9 is decreased. By lowering the output frequency of the inverter device 92 during the rotation of the motor 9, when the rotation speed of the electric motor 9 is high as in the dehydration process, the output of the electric motor 9 is lower than when the rotation speed of the electric motor 9 is low as in the washing process. Reduce the initial braking force applied to rotation.

The initial braking force applied to the rotation of the electric motor 9 is varied as described above. Usually, since the steady rotation speed is determined for each stroke, this is the washing stroke or the dehydration stroke. Or a means for detecting the number of rotations of the electric motor 9 may be provided, and the number of rotations may be determined based on the detected number of rotations. However, when the latter method is adopted, the initial braking force can be controlled more accurately, and the components of the inverter device 92 can be more reliably prevented from being damaged.

[0038]

As described above, according to the drum type washing machine of the first aspect, the rotation of the motor is braked by absorbing the inertial energy due to the rotation of the motor as electric energy in the power supply circuit. Therefore, the braking force can be set to be larger than in the case of performing DC braking with a rise in temperature. Therefore, the rotation of the electric motor can be stopped in a shorter time, the reversal of the drum is performed in a shorter time, and the washing ability is improved, so that the washing time can be reduced. In addition, the problem of shortening the life of the motor and consuming a large amount of current, which is a concern when performing DC braking, is also solved.

According to the drum type washing machine of the present invention, the braking force applied to the rotation of the motor is kept constant until the rotation of the motor is stopped by appropriately controlling the inverter frequency. Therefore, the rotation of the electric motor can be reliably stopped in a shorter time. Therefore, the effect obtained by the first aspect can be further ensured.

Further, in the drum-type washing machine according to the third aspect, the effect obtained by the drum-type washing machine according to the first or second aspect can be obtained without the disadvantage that the components of the inverter device are damaged. Obtainable.

[Brief description of the drawings]

FIG. 1 is a front view of a drum type washing machine according to an embodiment of the present invention.

FIG. 2 is a side view of the drum type washing machine according to one embodiment of the present invention.

FIG. 3 is a diagram showing a drive circuit of the electric motor 9;

FIG. 4 is a diagram showing a firing order of components of the inverter device 92 when the electric motor 9 is rotated forward.

FIG. 5 is a diagram showing a firing order of components of the inverter device 92 when the motor 9 is rotated in the reverse direction.

6 is a diagram showing that a braking force is applied to the rotation of the electric motor 9 by lowering the output frequency of the inverter device 92 during the rotation of the electric motor 9. FIG.

FIG. 7 is a diagram showing a forward / reverse rotation state of the electric motor 9 according to the present invention.

FIG. 8 is a diagram illustrating a forward / reverse rotation state when the rotation of the electric motor is stopped by inertia.

FIG. 9 is a diagram showing a conventional drum-type washing machine that performs DC braking using an electric motor with a large reduction ratio.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer box 2 Support lot 3 Water tank 4 Drum 41 Small hole 5 Drying unit 6 Circulation duct 7 Lid 8 Packing 9 Electric motor 10 Drain pump 11 Lint filter case 12 Operation part 13 Control part 14 Detergent case 15 Water level sensor 91 Power supply circuit 92 Inverter device 100 Washing motor 200 Dehydration motor

Claims (3)

[Claims] 1. A drum type washing machine having a drum for performing washing and drying inside by rotating the drum forward and reverse, and driving an electric motor for rotating the drum forward and reverse by an inverter device. A drum-type washing machine wherein a braking force is applied to the rotation of the electric motor by lowering the output frequency of the inverter device during the rotation of the drum-type washing machine. 2. The apparatus according to claim 1, further comprising means for detecting a rotation speed of the motor, wherein an output frequency of the inverter device is controlled in accordance with the rotation speed of the motor until the rotation of the motor stops. The drum type washing machine according to claim 1. 3. An electric motor, comprising: means for detecting the number of revolutions of the electric motor; and reducing an output frequency of an inverter device in accordance with the number of revolutions of the electric motor to reduce an initial braking force applied to the rotation of the electric motor. The drum type washing machine according to claim 1 or 2, wherein the lower the number of rotations of the electric motor, the lower the number of rotations, while the lower the number of rotations of the electric motor, the higher the number of rotations.