JP3593243B2 - Drum type washing machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drum-type washing machine that performs washing to drying in a drum by rotating a drum alternately and forwardly and reversely, and particularly to a drum-type washing machine that drives an electric motor that rotates a drum using an inverter device. It is.
[0002]
[Prior art]
The drum-type washing machine has a structure in which the drum rotates around a horizontal axis in a water tank. By rotating the drum, the process from washing to drying is performed in the drum, and washing, rinsing, dehydrating, and so on are performed. This is a typical washing machine having a series of drying washing functions.
[0003]
Generally, in a drum type washing machine, in order to improve the washing performance, the rotation of the drum is reversed at a predetermined cycle such as forward rotation → reverse rotation → forward rotation → reverse rotation →. This uses a motor that can rotate 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, and after the reverse rotation of the motor is stopped, the motor is energized for a predetermined time so that the motor rotates forward. Then, as the time until the rotation of the electric motor stops is shorter, the drum is inverted in a shorter time, and the washing ability is improved, so that the washing time is shortened.
[0004]
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 rotation direction while the motor is rotating, an excessive load is applied to the motor, or This is because an impact force is exerted on the drive mechanism and the drive 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-off period, that is, the motor is coast-stopped. Is long, and the motor stops rotating in a so-called uncontrolled state, so the time from when power is supplied to rotate in one direction to when power is supplied to rotate in the other direction is started. Must be set to be longer than the time that is expected to be necessary until the rotation is stopped by the inertia stop, and the reversal of the drum cannot be performed in a short time. Therefore, the following drum-type washing machine has been proposed in order to solve this problem, to shorten the time required for washing by improving the washing ability by reversing the drum in a shorter time.
[0006]
For example, a method is provided in which a direct current is passed through an armature winding of a motor that rotates a drum to apply braking to the rotation of the motor (hereinafter, referred to as “to perform DC braking”) (Japanese Patent Laid-Open No. 63-24987). As shown in FIG. 9), and as shown in FIG. 9, motors for rotating drums are separately provided for washing and dewatering, and a washing motor 100 provided for washing is replaced by a dehydrating motor 200 provided for dewatering. Also, a large reduction ratio (the number of rotations of the electric motor / the number of rotations of the drum) is set large, and a larger braking force is obtained by performing DC braking using the washing motor 100 having a large reduction ratio. JP-A-2-252493).
[0007]
[Problems to be solved by the invention]
Here, when a direct current is applied to the armature winding of the electric motor, a static magnetic field is generated, and the magnetic flux is cut off by the rotor, thereby generating an overcurrent 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-described conventional drum-type washing machine that performs DC braking, the braking force cannot be set so large, and thus the time until the rotation of the electric motor stops is not significantly reduced. 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 concern 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.
[0009]
Therefore, an object of the present invention is to provide a drum type washing machine in which the washing time is further reduced.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the drum-type washing machine according to claim 1 has a drum for performing washing to drying inside by rotating the drum alternately in a forward / reverse direction. In a drum type washing machine in which an electric motor that rotates alternately is driven by an inverter device,
The inverter device is driven between DC power supply voltages in such a manner that when one is ON, the other is OFF, and first and second switching transistors that generate a motor drive output from their connection midpoint are connected in series. Transistor pairs corresponding to the respective phases of the electric motor. The ON / OFF periods of the respective transistors are extended during rotation of the electric motor to reduce the output frequency of the inverter device, thereby reducing the rotation of the electric motor. By applying a braking force to the , by performing control to reduce the output frequency of the inverter device so that the difference between the original rotation speed of the electric motor and the actual rotation speed corresponding to the lowered output frequency is constant. The inertia energy of the drum resulting from a constant rotation difference between the original rotation speed and the actual rotation speed of the motor is converted into electrical energy by the power supply circuit. To yield.
[0011]
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 (hereinafter, referred to as the motor). (Referred to as “synchronous rotation speed”), and the back electromotive voltage of the armature winding becomes higher than the terminal voltage, thereby acting as a generator.
[0012]
Therefore, according to the configuration of the present invention, the inertial energy due to the rotation difference of the motor is absorbed as electric energy in 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 temperature does not increase as in DC braking, so that a large braking force can be set.
[0013]
Further, in the drum type washing machine according to the second aspect, the drum type washing machine according to the first aspect, further comprising means for detecting the number of rotations of the electric motor, until the rotation of the electric motor stops. The output frequency of the inverter device is controlled according to the rotation speed of the electric motor.
[0014]
With the above configuration, if the output frequency of the inverter device is appropriately controlled, for example, a constant braking force can be applied to the rotation of the motor until the motor stops.
[0015]
According to a third aspect of the present invention, in the drum type washing machine according to the first or second aspect, the drum type washing machine further includes means for detecting the number of rotations of the electric motor, and an inverter according to the number of rotations of the electric motor. By lowering the output frequency of the device, 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.
[0016]
With the above-described 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 a component element of the inverter device is damaged.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described 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.
[0018]
The water tank 3 is suspended by the support 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.
[0019]
At the center of the front of the main body, a lid 7 for taking in and out the laundry with respect to the drum 4 is provided, and the space between the lid 7 and the water tub 3 is sealed by a packing 8. The electric motor 9 rotates the drum 4. The drain pump 10 discharges washing liquid and the like in the water tub 3 to the outside of the machine. A lint filter case 11 is provided in a piping route between the water tank 3 and the drain pump 10 to remove lint such as lint contained in the liquid discharged outside the machine.
[0020]
An operation unit 12 is provided on the upper part of the lid 7, and the operation unit 12 allows a user to perform various inputs from the operation unit 12 and check a washing state based on information displayed there. In addition, a switch for selecting an operation course, a start switch for starting operation, display means, and the like are provided.
[0021]
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, and performs washing and drying. Controls a series of steps up to.
[0022]
In the above-described configuration, the washing process is performed such that the detergent contained in the detergent case 14 is poured from above while being dissolved by water supply, is included in the laundry in the drum 4, and the drum is rotated while repeating reversal between normal rotation and reverse rotation. 4 at low speed. The water level of the washing liquid is detected by a water level sensor 15.
[0023]
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 through a small hole provided on the entire peripheral wall of the drum 4. It is guided to the lower part along the inner surface, and is discharged out of the machine by the drainage pump 10.
[0024]
The drying step 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.
[0025]
For safety, when the operation is started, the fitting claw of the lid 7 main body is locked by a lid lock mechanism (not shown) provided in the washing machine main body, so that the lid 7 cannot be opened. I have. However, after the operation is completed, the lid 7 can be easily opened by operating a handle (not shown) formed integrally with the lid 7 main body.
[0026]
Here, a drive circuit of the electric motor 9 for rotating the drum 4 is shown in FIG. In the figure, reference numeral 91 denotes a power supply circuit, and 92 denotes an inverter device. The power supply circuit 91 includes, for example, a rectifier circuit and a smoothing capacitor, and converts an AC voltage from a commercial AC power supply into a DC voltage. Then, the DC voltage is applied to the inverter device 92.
[0027]
The inverter device 92 is configured by connecting transistors 92U, 92V, 92W, 92X, 92Y, and 92Z as switching elements in a three-phase full-wave bridge, and receives a DC voltage from a power supply circuit 91 at its input. The ON / OFF control of 92U, 92V, 92W, 92X, 92Y, and 92Z is performed in an appropriate firing order, so that a three-phase alternating current is generated at its output and applied to the electric motor 9.
[0028]
In the above configuration, an operation performed by the control unit 13 to control the rotation of the electric motor 9 will be described. The transistors 92U, 92V, 92W, 92X, 92Y, and 92Z of the inverter device 92 are turned on / off in the firing pattern shown in FIG. 4, and the firing interval is gradually shortened, and the predetermined firing is performed over a predetermined time. ON / OFF at intervals. 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.
[0029]
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 device 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, when the output frequency of the inverter device 92 decreases (frequency f '), the braking torque Work on the electric motor 9.
[0030]
Then, the output frequency of the inverter device 92 is gradually reduced so that the synchronous rotation speed and the actual rotation speed maintain 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 is rapidly decelerated to stop.
[0031]
In addition, if means for detecting the rotation speed (actual rotation speed) of the electric motor 9 is provided, and the output frequency of the inverter device is reduced according to the detected actual rotation speed, the synchronous rotation can be more accurately performed. The interval between the number and the actual number of rotations can be kept constant, and the rotation of the electric motor 9 can be stopped more quickly and more reliably.
[0032]
When the forward rotation of the electric motor is stopped in this way, the transistors 92U, 92V, 92W, 92X, 92Y, and 92Z of the inverter device 92 are turned on / off in the firing pattern shown in FIG. It is shortened and is turned ON / OFF at a predetermined firing interval over a predetermined time. 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.
[0033]
Next, when the reverse rotation period ends after a lapse of a predetermined time, the output frequency of the inverter device 92 is gradually increased so that the synchronous rotation speed and the actual rotation speed are maintained at a constant interval while the firing pattern remains the same. To lower. Thus, 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.
[0034]
By repeating the above operation, the rotation of the drum 4 is reversed as shown in FIG. 7, but as described above, the inertial energy due to the rotation of the electric motor 9 is absorbed by the power supply circuit 91 as electric energy. By doing so, the rotation of the motor 9 is braked, so that the braking force can be set large enough to prevent the power supply voltage from sharply rising and damaging the components of the inverter device 92, and the rotation of the motor 9 is stopped in a shorter time. Will be able to do that. Therefore, the reversal of the drum 4 is performed in a shorter time, and the washing ability is improved, so that the washing time is shortened.
[0035]
By the way, in the dehydration process, the steady-state rotation speed of the electric motor 9 is higher and the inertia energy is larger than in the washing process. However, the components of the inverter device 92 may be damaged.
[0036]
In order to prevent such a problem, the negative slip value is reduced as the rotation speed of the electric motor 9 is increased, and the negative slip value is increased as the rotation speed of the electric motor 9 is decreased. By lowering the output frequency of the inverter device 92 during rotation, when the rotation speed of the electric motor 9 is high as in the dehydration process, the rotation of the electric motor 9 is performed more than when the rotation speed of the electric motor 9 is low as in the washing process. Reduce the initial braking force.
[0037]
In this manner, the initial braking force applied to the rotation of the electric motor 9 is varied. Usually, since the steady rotation speed is determined for each stroke, it is determined whether the stroke is a washing stroke or a dehydration stroke. Alternatively, means for detecting the number of rotations of the electric motor 9 may be provided, and the detection may be performed 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]
【The invention's effect】
As described above, according to the drum-type washing machine according to claim 1, the inverter such that the difference between the original rotation speed and the actual rotation speed of the electric motor corresponding to the decreasing output frequency is always constant. by controlling the decrease in the output frequency of the device, with the amount of inertial energy generated by the rotation difference of the motor can be stabilized, it can be stably absorbed into the power supply circuit of the inertial energy as electric energy. In addition, since the rotation of the electric motor is braked, 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 drum is inverted 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 electric motor and increasing the current consumption, which is a concern when DC braking is performed, is also solved.
[0039]
According to the drum-type washing machine of the second aspect, by appropriately controlling the inverter frequency, the braking force applied to the rotation of the motor can be kept constant until the rotation of the motor stops. Thus, 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.
[0040]
Further, in the drum-type washing machine according to the third aspect, it is possible to obtain the effect obtained by the drum-type washing machine according to the first or second aspect without causing a problem that the components of the inverter device are damaged. it can.
[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.
FIG. 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 while the electric motor 9 is rotating.
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 showing a forward / reverse rotation state when the rotation of the electric motor is stopped by inertia.
FIG. 9 is a diagram illustrating 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 unit 13 Control unit 14 Detergent case 15 Water level sensor 91 Power supply circuit 92 Inverter device 100 Washing motor 200 Dehydration motor

Claims (3)

In a drum type washing machine that has a drum that performs washing to drying inside by rotating it forward and reverse alternately, and a motor that drives this drum alternately and reversely is driven by an inverter device,
The inverter device is driven between DC power supply voltages in such a manner that when one is on, the other is off, and first and second switching transistors that generate a motor drive output from their connection midpoint are connected in series. Transistor pairs corresponding to the respective phases of the electric motor, and by increasing the ON and OFF periods of the respective transistors during the rotation of the electric motor to reduce the output frequency of the inverter device, the rotation of the electric motor is reduced. with applying a braking force to the,
By performing control to reduce the output frequency of the inverter device so that the difference between the original rotation speed of the motor and the actual rotation speed corresponding to the reduced output frequency is constant, the rotation speed of the motor and the actual rotation speed are reduced. A drum type washing machine characterized in that a power supply circuit absorbs, as electrical energy, inertial energy of a drum resulting from a certain rotation difference with the number of rotations of a drum. 2. The apparatus according to claim 1, further comprising: a unit configured to detect a rotation speed of the electric motor, and that controls an output frequency of the inverter device according to the rotation speed of the electric motor until the rotation of the electric motor stops. 3. Drum type washing machine. Means for detecting the number of revolutions of the electric motor, and by reducing the output frequency of the inverter device according to the number of revolutions of the electric motor, the initial braking force applied to the rotation of the electric motor is increased, and the number of revolutions of the electric motor is increased. The drum type washing machine according to claim 1, wherein the smaller the number of rotations, the larger the number of rotations of the electric motor.

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