JP2014132916A - Drum type washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum type washing machine capable of minimizing vibrations of a drum when passing through a resonance rotation speed.SOLUTION: The drum type washing machine includes: a bottomed cylindrical drum 3 rotatably supported by a horizontal or inclined revolving shaft; a water tub 2 for accommodating the drum 3; a tubular container 17 arranged on a front side of the drum 3; a plurality of spheres 8 movable in the tubular container 17; a viscous liquid 18 stored in the tubular container 17; temperature detection means 20 for detecting an outside temperature; a drive motor 4 for rotationally driving the drum 3; and control means 6 for controlling the drive motor 4 on the basis of at least an output of the temperature detection means 20. The control means 6 controls a repeating operation of acceleration and deceleration of the rotation of the drum 3 in accordance with an outside temperature detected by the temperature detection means 20. Thus, vibrations of the drum 3 when passing through a resonance rotation speed can be minimized.

Description

  The present invention relates to a drum-type washing machine that includes a drum that can be rotated and accommodates laundry in an elastically supported water tub, and in which the laundry is washed, rinsed, and dewatered.

  In general, in a dewatering process of a drum-type washing machine having a horizontal or inclined rotating shaft, the laundry is often in a non-uniform state, that is, an unbalanced state in the drum. As a result, a biased force is applied to the rotating shaft during dehydration, and vibration is generated. The amplitude of vibration increases in proportion to the square of the rotational speed of the rotating drum. Due to the vibration, the washing machine itself moves, and the noise is so strong that it becomes impossible to drive at a certain rotational speed or higher.

  There is a ball balancer system using a metal ball (hereinafter referred to as a sphere) in order to reduce vibration due to unbalanced laundry. The ball balancer includes a plurality of spheres having a degree of freedom in the rotation direction (circumferential direction) in a tubular race portion attached to the inner periphery of the drum, and introduces a certain viscous liquid therein. The friction between the sphere and the race is limited. This ball balancer is a balance device that utilizes a dynamic phenomenon in which a sphere automatically moves to an opposing position with respect to an unbalanced body that generates an eccentric load.

  In addition to a single ball balancer in which a sphere is arranged on the front side of the drum, a double ball balancer in which a plurality of rolling elements are arranged at two locations on the front side and the bottom side of the drum is also known (for example, Patent Documents). 1).

  The single ball balancer and the double ball balancer are the same in principle, that is, both ball balancers have multiple spheres corresponding to the unbalanced amount of the laundry that changes over time in the dehydration process. It is a mechanism that changes the position and automatically corrects the unbalance.

  In Patent Document 1, the first rotation speed is rotated at a rotation speed equal to or lower than the resonance rotation speed, and the sphere moves to the in-phase position with respect to the eccentric load for a predetermined time, and is maintained at the in-phase position. After that, the drum gradually accelerates from the stopped state at the in-phase position and passes through the resonance rotational speed. Accordingly, the sphere is automatically moved to the unbalanced opposing position according to the principle of automatic balancing, thereby suppressing vibration.

  In addition, after increasing the drum rotation to the upper limit of the transient vibration rotation speed region near the resonance rotation speed, in order to move the sphere in the direction of canceling the unbalance, the rotation speed of the drum is rotated discontinuously. Some drums are controlled by slightly changing the speed (for example, see Patent Document 2).

JP 2010-125083 A JP2011-125401A

However, in the conventional configuration, since the required sphere motion differs depending on the outside air temperature and the unbalanced amount of the laundry, there is a problem that vibration may increase when passing through the resonance rotational speed in the same way of starting up. Was.

  The present invention solves the above-mentioned conventional problems, and by changing how the drum starts up at high speed rotation according to the outside air temperature and the unbalanced amount of laundry, the vibration of the drum is minimized when the resonance rotational speed is passed. An object of the present invention is to provide a drum-type washing machine that can be suppressed.

  In order to solve the above-described conventional problems, a drum-type washing machine of the present invention includes a bottomed cylindrical drum that is rotatably supported by a horizontal or inclined rotating shaft, a water tank that accommodates the drum, and the drum A tubular container disposed on the front side of the tube, a plurality of spheres movably provided in the tubular container, a viscous liquid stored in the tubular container, a temperature detecting means for detecting an outside air temperature, and A drive motor for rotating the drum; and a control means for controlling the drive motor based on at least an output from the temperature detection means, wherein the control means is responsive to the outside air temperature detected by the temperature detection means. The repetitive acceleration and deceleration operations of the drum are controlled.

  Thereby, by controlling the repetition of the acceleration and deceleration of the rotation of the drum according to the outside air temperature, it is possible to arrange a plurality of spheres at an optimal position that always cancels the unbalance of the laundry, Since the arrangement of the spheres can be controlled to an appropriate position without depending on the outside air temperature, it is possible to reduce the unbalance of the laundry, and to start up to the resonance rotational speed with low vibration, and to reduce vibration and noise when passing through the resonance rotational speed. Can be minimized.

  The drum type washing machine of the present invention can always place the sphere at the optimal position with the laundry unbalance regardless of the amount of unbalance of the laundry, and at the same time, the sphere without depending on the outside air temperature. Since the arrangement can be controlled to an appropriate position, the unbalance of the laundry can be reduced, and vibration and noise at the resonance rotational speed can be reduced.

Side sectional view of the drum-type washing machine according to Embodiment 1 of the present invention. Schematic of ball balancer of drum type washing machine Control block diagram of drum type washing machine The figure showing the sequence of the rotational speed of the drum type washing machine

  A drum-type washing machine according to a first aspect of the present invention is a bottomed cylindrical drum that is rotatably supported by a horizontal or inclined rotating shaft, a water tank that houses the drum, and a tubular tube that is disposed on the front side of the drum. A container, a sphere movably provided in the tubular container, a viscous liquid stored in the tubular container, a temperature detecting means for detecting an outside air temperature, a drive motor for rotationally driving the drum, and at least Control means for controlling the drive motor based on an output from the temperature detection means, the control means for accelerating and decelerating the rotation of the drum according to the outside air temperature detected by the temperature detection means. The repetitive operation is controlled.

  With this configuration, by controlling the repeated acceleration and deceleration operations of the drum according to the outside air temperature, it is possible to arrange a plurality of spheres at an optimal position that always cancels the laundry imbalance. Because it can control the arrangement of the spheres to an appropriate position without depending on the outside air temperature, it can reduce the unbalance of the laundry, and can start up to the resonance rotation speed with low vibration, vibration and noise when passing through the resonance rotation speed Can be minimized.

  In the second aspect of the invention, in particular, the control means of the first aspect of the invention increases the repetition operation frequency of drum rotation acceleration and deceleration when the outside air temperature detected by the temperature detecting means is low and when the outside air temperature is high. Is designed to control less.

  With this configuration, when the outside air temperature is low, the viscous resistance of the viscous liquid in the tubular container is high. Therefore, the frequency of repeated acceleration and deceleration of the drum rotation is increased, and when the outside air temperature is high, the viscous resistance is increased. By reducing the frequency of repeated drum rotation acceleration and deceleration, it is possible to arrange a plurality of spheres at the optimal position that always cancels the laundry imbalance, regardless of the outside air temperature. .

  In a third aspect of the invention, in particular, in the first or second aspect of the invention, the apparatus further comprises a vibration detection means for detecting the vibration of the water tank, and the control means has a small amount of unbalance in the laundry detected by the vibration detection means. When the outside air temperature detected by the hour and the temperature detection means is low, the drum rotation is repeatedly accelerated and decelerated.

  With this configuration, when the amount of laundry unbalance is small, that is, considering the correction force of the sphere, the spheres are arranged in a dispersed state rather than all the spheres being put together and positioned in opposite phase to the laundry unbalance. Since the unbalance is reduced, the sphere can be rearranged in a dispersed state by once decelerating the rotation of the drum and accelerating it again. Furthermore, since the resistance value of the viscous liquid in the tubular container is higher than the normal temperature (20 ° C.) when the outside air temperature is low, if the drum rotation is decelerated and the repetition frequency of the acceleration is increased, the sphere Can be rearranged into a distributed state. Therefore, the ball balancer acts to reduce the laundry imbalance, and the drum vibration when passing through the resonance rotational speed can be minimized.

  According to a fourth aspect of the invention, in particular, the control means according to any one of the first to third aspects applies a rotational speed to the laundry in the drum during the operation of accelerating and decelerating the rotation of the drum. The rotation speed is such that gravity and centrifugal force are balanced.

With this configuration, when the outside air temperature is low, the resistance value of the viscous liquid in the tubular container is high. Therefore, by setting the rotational speed at which the gravity and the centrifugal force applied to the laundry are balanced, The sphere can be repositioned in the optimal position to counteract the laundry imbalance.
Therefore, the ball balancer acts to reduce the laundry imbalance, and the drum vibration when passing through the resonance rotational speed can be minimized.

  According to a fifth aspect of the present invention, when the control means of the third or fourth aspect of the invention repeats acceleration and deceleration of drum rotation, and the vibration amount of the water tank by the vibration detection means is smaller than a predetermined value, The drum is raised to a rotational speed higher than the resonant rotational speed.

  With this configuration, after repeatedly accelerating and decelerating the rotation of the drum, the spheres are rearranged in the optimal position to cancel the laundry imbalance, so the vibration detection means checks whether the vibration is small. By starting the drum at a high rotational speed after that, the vibration of the drum when passing through the resonant rotational speed can be reliably suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this plan is not limited by this embodiment.

(Embodiment 1)
1 is a side sectional view of a drum-type washing machine according to Embodiment 1 of the present invention. Inside the drum type washing machine 1, a bottomed cylindrical water tank 2 is accommodated. A bottomed cylindrical drum 3 is accommodated in the water tank 2. On the front side of the drum-type washing machine 1, an opening 3 a that communicates with the drum 3 through the opening 2 a of the water tank 2 is provided.

  The drum 3 is disposed such that a rotation shaft that rotatably supports the drum 3 is inclined downward from the front side toward the bottom side. The water tank 2 is inclined and arranged along the drum 3 with the opening 2a as the front side. By inclining the rotation axis, the opening on the front side of the water tub 2 can be arranged on the upper side, and the laundry in the drum 3 can be taken out without taking a posture of bending greatly.

  Moreover, compared with the case where a rotating shaft is made into a horizontal direction, the water supplied in the water tank 2 accumulates on the back side, and a deep water storage state can be obtained even with a small amount of water. That is, it becomes easy for the laundry to hydrate with a small amount of water supply. The water tank 2 is supported by a spring 10 and a damper 5. Note that the rotation axis may be horizontal if the ease of taking out the laundry and the amount of water supply are not taken into consideration.

  A baffle 16 that can lift and drop the laundry 13 is provided inside the drum 3. When the drum 3 is driven to rotate, the laundry lifted by the baffle 16 is struck against the water surface from the top of the drum 3 and is washed by tapping (mechanical force). Further, the drum 3 is provided with a plurality of through holes 15. Water can be passed from the water tank 2 into the drum 3 through the through holes 15.

  Moreover, the door 7 is provided in the opening part 3a so that opening and closing is possible. The opening 2a of the water tank 2 is fitted with a tubular sealing material at its mouth edge. Since the front surface side of the sealing material is in contact with the rear surface side of the door 7 and sealed, even if the opening 2a of the water tank 2 that swings up and down, right and left and back and forth moves, the sealing material is deformed and pressed to the rear surface side of the door 7. Airtightness is maintained.

  A ball balancer 30 is provided on the front side of the drum 3. FIG. 2 is a schematic diagram of the ball balancer 30 of the drum type washing machine 1 according to Embodiment 1 of the present invention.

  The ball balancer 30 includes a tubular container 17 disposed on the front side of the drum 3, a sphere 8 (sphere) made of metal that can move in the tubular container 17, and a viscous liquid 18 stored in the tubular container 17. Have. The tubular container 17 having a ring shape is installed so as to coincide with the drum 3 in the axis.

  In order to control the movement of the sphere 8, a viscous liquid 18 is stored inside the tubular container 17. In the first embodiment, silicon oil (viscosity resistance: 100 cst) is used. In addition, since the same effect will be acquired if it is another viscous liquid, it is not limited to silicone oil.

  A drive motor 4 for rotationally driving the drum 3 is attached to the inside of the drum type washing machine 1 and below the water tub 2. The rotational drive of the drive motor 4 is transmitted via a belt 23 to a drum pulley 24 provided on the same shaft of the drum 3. As a result, the drive motor 4 drives the drum 3 to rotate.

  A water supply valve 11 is provided at the top of the drum type washing machine 1. Water from the water supply valve 11 flows into the detergent case 9 and is supplied into the water tank 2 while dissolving the detergent. In the rinsing process, since there is no detergent in the detergent case 9 even through the detergent case 9, rinsing water containing no detergent component is supplied. In addition, a drain pump 19 is provided at the lower part of the drum type washing machine 1, and by driving the drain pump 19, washing water and rinsing water in the water tank 2 are drained. In the present embodiment, the drainage pump 19 drains the washing water and the rinsing water in the water tank 2, but it may be a drain valve.

  Next, the details of the control means 6 for controlling the driving motor 4 and the like, and controlling the steps such as washing, rinsing and dehydration will be described with reference to FIG. FIG. 3 is a control block diagram of the drum type washing machine in the first embodiment of the present invention. The control means 6 uses a timer for all input / output control including various sensor outputs such as vibration detection means 12 and a water level sensor (not shown) as well as instructions for driving the water supply valve 11, drain pump 19 and drive motor 4. A system that can be managed is provided, and the time required for each operation and timing can be known.

  The vibration detecting means 12 for detecting the vibration of the water tank 2 is provided at the upper part on the back side of the water tank 2. The vibration detection means 12 detects vibration of the water tank 2 in a series of steps of washing, rinsing and dehydration. After the control means 6 analyzes the vibration value in each step, the motor is optimally controlled by issuing a command to the drive motor 4.

  The vibration detection means 12 has at least one acceleration sensor (not shown) and detects vibration in at least one of the vertical direction, the horizontal direction, and the front-rear direction of the water tank 2. The acceleration sensor may be a semiconductor acceleration sensor, a piezoelectric acceleration sensor, or the like, and may be a multi-axis (two-axis or three-axis) acceleration sensor.

  A temperature detecting means 20 comprising a thermistor or the like capable of detecting the outside air temperature is provided on the front side of the water tank 2 (upper part of the tubular container 17 of the ball balancer 30). Based on the outside air temperature detected by the temperature detecting means 20, the tubular container The control means 6 issues a command to the drive motor 4 so that the drum 3 can be accelerated and decelerated so that the position of the sphere 8 within the 17 is uniform with the unbalance of the laundry 13.

  The control means 6 is an electric circuit having a CPU, a memory, a driver circuit and the like as a hardware configuration, and moves peripheral devices such as the drive motor 4 in accordance with a program stored in the memory in the control means 6. In the present embodiment, the temperature detection means 20 comprising a thermistor or the like for detecting the outside air temperature is attached to the front side of the water tank 2, but the present invention is not limited to this embodiment as long as the temperature of the basic outside air can be detected. Absent.

  For example, the vicinity of the damper 5 in the lower part of the water tank 2, the vicinity of the vibration detecting means 12, and the like can be mentioned. In addition, it is desirable not to employ the temperature in the vicinity of the control means 6 and the drive motor 4 because it is greatly affected by temperature.

  The dehydration process of the drum type washing machine configured as described above will be described with reference to the drawings for the operation and action. FIG. 4 is a diagram illustrating a rotation speed sequence of the drum-type washing machine according to the first embodiment of the present invention.

  First, when the drum type washing machine 1 performs dehydration after draining, a drive voltage is applied to the drive motor 4 according to a command from the control means 6. The drive motor 4 is operated from low speed rotation to high speed rotation, and the rotation speed of the drum 3 is gradually increased. At this time, since the drive motor 4 is a permanent magnet synchronous motor, the rotor position of the drive motor 4 is detected. Thereby, it is possible to increase the rotational speed safely and at high speed by preventing the drive motor 4 from stepping out.

  Next, the control means 6 rotates the drum 3 at a rotational speed at which the gravity applied to the laundry 13 and the sphere 8 is smaller than the centrifugal force generated by the rotation of the drum 3. The rotational speed at which the laundry 13 sticks to the inner wall of the drum 3 is most desirable so that the vibration detection means 12 can detect the vibration of the water tank. When the drum 3 is rotated at this rotational speed, an unbalance of the laundry 13 is easily formed, and vibration due to the unbalance of the laundry 13 can be detected within one rotation (one cycle) of the drum 3, In this embodiment, it is 80 rpm.

  Next, the unbalanced position and amount detection of the laundry 13 will be briefly described. In the present embodiment, the vibration detection means 12 is a triaxial acceleration sensor. The up / down direction, left / right direction, and front / rear direction of the aquarium 2 are detected, and the unbalance amount of the laundry is detected by the phase difference of each axis based on the position of the unbalance of the laundry 13.

  When the unbalanced amount of the laundry 13 is on the front side of the drum 3, the phase difference between the left and right directions and the front and rear direction of the water tank 2 becomes large. When the unbalanced amount of the laundry 13 is on the rear side of the drum 3, the phase difference in the two directions is small. Therefore, the control unit 6 determines the unbalanced amount of the laundry 13 based on the signal detected by the vibration detecting unit 12. It becomes possible to judge.

  Moreover, about the unbalance amount of the laundry 13, the unbalance amount of the laundry 13 is detected using the signal amplitude of the left-right direction of the water tank 2. FIG. This means that when clothes are present in the drum 3, the SN ratio in the left-right direction is the largest as the shaking of the water tank 2. Therefore, the left-right direction is adopted in this embodiment.

  Next, how to start up to the resonance rotational speed when the outside air temperature is low and when the unbalance amount of the laundry 13 is small will be described with reference to FIG. Here, the low outside air temperature of the present embodiment is 5 ° C. to 15 ° C., which is lower than the normal temperature (20 ° C.), and the unbalance amount of the laundry 13 is 300 g or less.

  First, when the dehydration process is started, the rotational speed of the drum 3 is increased to 80 rpm, and the unbalance amount of the laundry 13 is detected.

  When it is determined that the outside air temperature is low and the unbalance amount of the laundry 13 is small based on the outputs of the temperature detection means 20 and the vibration detection means 12, the control means 6 accelerates the rotation of the drum 3 to 120 rpm, Rotate at 120 rpm for a certain time (1 s). Thereafter, the rotational speed of the drum 3 is again reduced to 80 rpm and rotated at 80 rpm for a certain time (6 s).

  In the present embodiment, the external air temperature is low, and the frequency of repetition of the acceleration and deceleration of the drum rotation is increased to 4 times. However, the frequency set by the external air temperature is 3 times. If it is within the range of ˜5 times, the same effect as this embodiment can be obtained. In a state where the outside air temperature is high (a state higher than the normal temperature (20 ° C.)), the frequency of the repetition of the drum rotation acceleration and deceleration can be reduced. The same effect can be obtained.

  Thereafter, the vibration detection means 12 detects the vibration of the water tank 2 again, and when the vibration amount is smaller than a predetermined value, the drum is raised to a rotational speed higher than the resonance rotational speed.

  As described above, when the outside air temperature is low and the amount of unbalance of the laundry 13 is small, the resistance value increases due to the low viscosity resistance of the viscous liquid 18 (for example, silicon oil) in the tubular container 17. In response to this, by increasing the frequency of the repetition of the acceleration and deceleration of the rotation of the drum, it is possible to arrange the plurality of spheres at the optimum position to cancel the unbalance of the laundry.

In the silicone oil of the present embodiment, since the current viscous resistance 100 cst becomes the viscous resistance 153 cst at an outside air temperature of 5 ° C., the ball balancer itself can be unbalanced in the laundry. By repeating the operation of decelerating, the sphere can be rearranged in a dispersed state.
By doing this, the unbalance of the laundry as the ball balancer can be reduced, and the vibration of the drum can be minimized when the resonance rotational speed is passed.

  In addition, although the rotational speed to decelerate is set to 80 rpm in this embodiment, the same result as this embodiment can be obtained if the rotational speed is 67 rpm to 80 rpm. However, if the rotational speed is set to 80 rpm or more, the centrifugal force of the laundry 13 becomes larger than the gravity, and the viscosity resistance value of the silicone oil is high when the outside air temperature is low. Can not do it.

  Further, after the acceleration / deceleration of the drum 3 is repeated, when the vibration amount by the vibration detecting means 12 is smaller than a predetermined value, the sphere 8 is rearranged in a dispersed state in which the unbalance amount of the laundry is reduced. In this state, even if the drum 3 is raised to a rotational speed higher than the resonance rotational speed, the sphere 8 remains in a dispersed state in which the amount of laundry unbalance is reduced.

  For this reason, it is possible to reliably suppress the vibration of the drum 3 when passing through the resonance rotational speed by raising the drum 3 to a high rotational speed after confirming whether the vibration is small by the vibration detecting means 12.

Here, the necessity of repeating acceleration and deceleration of the rotation of the drum 3 when the outside air temperature is low and when the unbalance amount of the laundry 13 is small will be described.
First, when the outside air temperature is low (for example, 5 ° C.), the viscous resistance value in the tubular container 17 becomes high, the stress (propulsive force) on the sphere increases, and the sphere moves as a solid in the tubular container 17. In addition to the unbalance of the object 13, an unbalance as a sphere occurs.

  Further, the ball balancer 30 disposed on the front side of the drum 3 cannot exert the correction force to the maximum when the unbalance amount of the laundry 13 is small. Therefore, in the present embodiment, the acceleration and deceleration of the rotation of the drum 3 are repeated, and the spheres 8 are dispersed in the tubular container, whereby the unbalance of the laundry 13 in the drum 3 and the spheres 8 are matched. It is possible to prevent diagonal imbalance caused by being located at a corner.

  When the unbalanced amount of the laundry 13 changes and the vibration by the vibration detecting means 12 is reduced, the unbalanced amount of the sphere 8 and the laundry 13 is detected by the vibration detecting means 12, and the drum is in reverse phase. 3 is rotated to a rotational speed equal to or higher than the resonant rotational speed. Thereby, the vibration of the drum can be minimized when the resonance rotational speed is passed.

  As described above, the vibration detecting means 12 detects the vibration of the water tub 2, the temperature detecting means 20 detects the outside air temperature, the unbalance amount of the laundry and the outside air temperature are determined based on the detection result, and the drum By changing the frequency of repetition of acceleration and deceleration of the rotation 3, it becomes possible to control the position of the plurality of spheres 8 in a dispersed state to reduce the unbalance amount of the laundry, and to maintain the low vibration. It is possible to start up to the resonance rotational speed, and it is possible to minimize vibration and noise when passing through the resonance rotational speed.

  In the above description of the embodiment, the mode in which the frequency of repetition of the acceleration and deceleration of the rotation of the drum is changed according to the outside air temperature has been described. However, as another embodiment, the drum speed is changed according to the outside air temperature. The same effect can be obtained by changing the rotation speed and the speed ratio of rotation acceleration and deceleration.

Since the washing machine according to the present invention changes how the drum is started up at high speed rotation depending on the outside air temperature and the amount of unbalance due to the laundry, the unbalance can be further reduced, and vibration at startup can be suppressed. It is useful as a drum-type washing machine and a cleaning device for home use and business use.

DESCRIPTION OF SYMBOLS 1 Drum type washing machine 2 Water tank 3 Drum 4 Drive motor 6 Control means 8 Sphere 12 Vibration detection means 13 Laundry 17 Tubular container 18 Viscous liquid 20 Temperature detection means 30 Ball balancer

Claims (5)

A bottomed cylindrical drum rotatably supported by a horizontal or inclined rotating shaft;
A water tank containing the drum;
A tubular container disposed on the front side of the drum;
A plurality of spheres movably provided in the tubular container;
A viscous liquid stored in the tubular container;
Temperature detecting means for detecting the outside air temperature;
A drive motor for rotationally driving the drum;
Control means for controlling the drive motor based on at least the output from the temperature detection means,
The drum-type washing machine, wherein the control means controls the repetitive operations of acceleration and deceleration of the rotation of the drum according to the outside air temperature detected by the temperature detection means. The control means controls the frequency of repeated acceleration and deceleration of the rotation of the drum when the outside temperature detected by the temperature detecting means is low and less when the outside temperature is high. A drum-type washing machine as described in 1. Equipped with vibration detection means to detect the vibration of the aquarium,
The control means repeats acceleration and deceleration of the rotation of the drum when the unbalance amount of the laundry detected by the vibration detection means is small and when the outside air temperature detected by the temperature detection means is low. The drum type washing machine according to claim 1 or 2. The control means is configured such that, in the operation of accelerating and decelerating the rotation of the drum, the decelerating rotational speed is set to a rotational speed at which gravity and centrifugal force applied to the laundry in the drum are balanced. The drum type washing machine of any one of 1-3. After repeatedly accelerating and decelerating the rotation of the drum, the control means raises the drum to a rotational speed higher than the resonance rotational speed when the vibration amount of the water tank by the vibration detecting means is smaller than a predetermined value. The drum type washing machine according to claim 3 or 4.