Drum type washing machine

Abstract

To properly reduce vibration of a drum by allowing rolling elements to roll in an annular container even in the case where the weight of the rolling element is large.SOLUTION: A drum type washing machine includes: an outer tub; a drum constituted so as to rotate around an axis line extending in a horizontal direction or in an oblique direction in the outer tub; an annular container mounted on the drum and for storing a plurality of rolling elements and a liquid; and control means for controlling the rotational frequency of the drum. The weight of the rolling element is equal to or greater than 110 g. In the case where, in the middle of accelerating the rotational frequency of the drum toward high-speed dewatering rotation, the vibration of the drum exceeds a predetermined value at predetermined rotational frequency exceeding resonance rotational frequency, the control means performs rapid acceleration control for increasing the acceleration of the rotational frequency of the drum and then decreasing it.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a drum-type washing machine installed in, for example, a coin-operated laundry shop. [Background technology]

[0002] In conventional drum-type washing machines, when the spin cycle begins, if laundry becomes unbalanced inside the drum, which is rotatably arranged inside the housing, the drum may vibrate, making it impossible to start the spin cycle. For this reason, some drum-type washing machines are equipped with ball balancers at the front and rear ends of the drum to counteract the imbalance (see Patent Document 1).

[0003] A ball balancer typically has an annular container (a tubular guide member) attached around the side periphery of a drum, multiple rolling elements (metal balls) that fit inside the annular container and roll, and a liquid (a viscous fluid such as oil) stored inside the annular container to suppress sudden movement of the rolling elements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2011-125401 Summary of the Invention [Problem to be solved by the invention]

[0005] First, we will briefly explain how the ball balancer reduces drum vibration. When clothes become unbalanced inside the drum during spin drying, the center of vibration of the outer tub moves to a position closer to the clothes unbalance than the center of rotation of the drum. Meanwhile, during spin drying, centrifugal force acts on the rolling elements and liquid due to the rotation of the drum, causing them to move farther away from the center of vibration of the outer tub. Then, when the rolling elements and liquid begin to gather in a position symmetrical to the clothes unbalance, the clothes unbalance is canceled out and the outer tub vibration decreases, so the movement of the rolling elements stops, allowing spin drying to be performed with the vibration canceled out.

[0006] The inventors of the present invention attempted to use heavier rolling elements in the ball balancer that roll within the annular container so that clothing imbalance can be counteracted by the ball balancer in large drum washing machines installed in coin laundry shops, just like in conventional drum washing machines for home use.

[0007] However, when heavier rolling elements were used, the following two problems occurred. (Bug 1) If the clothing imbalance is relatively small, the rolling elements of the ball balancer do not move, and therefore the clothing imbalance is not canceled out. (Issue 2) Even when there is no clothing inside, the weight of the rolling elements in the ball balancer causes imbalance, resulting in vibration of the outer tub.

[0008] Therefore, an object of the present invention is to provide a drum-type washing machine that can appropriately reduce vibration of the drum even when using a ball balancer in which the weight of the rolling elements housed inside the annular container is increased. [Means for solving the problem]

[0009] After extensive research to determine the main cause of the above-mentioned problem, the inventors of the present invention discovered that the reason for this is that, due to the increased weight of the rolling elements, when the outer tub vibrates when there is relatively little clothing imbalance or when there is no clothing present, a force large enough to roll the heavy rolling elements is not applied to the rolling elements.

[0010] A drum-type washing machine according to one aspect of the present invention comprises an outer tub, a drum configured to be rotatable within the outer tub around an axis extending horizontally or inclined, an annular container attached to the drum and containing a plurality of rolling elements and a liquid, an acceleration sensor that detects vibration of the drum, and a control means for controlling the rotation speed of the drum, wherein the weight of the rolling elements is 110 g or more, and the control means performs rapid acceleration control to increase and then decrease the acceleration of the drum rotation speed when the vibration of the drum exceeds a predetermined value at a predetermined rotation speed that exceeds the resonant rotation speed while accelerating the rotation speed of the drum toward high-speed spin-drying rotation.

[0011] In this case, while the drum is slowly accelerating toward high-speed spin rotation, applying a sudden acceleration to the drum for a short period of time creates a sliding motion between the rolling elements and the liquid inside the annular container, causing the rolling elements to begin rolling within the annular container even when they are heavy. Once the rolling elements begin rolling, they then roll to a position symmetrical to the clothing imbalance, thereby enabling the vibration of the drum to be appropriately reduced. In particular, exceeding the resonant rotation speed causes the outer tub to vibrate around the clothing imbalance, making it easier for the rolling elements to move to a position opposite the clothing imbalance.

[0012] The acceleration is preferably of a magnitude that causes the rolling elements to move in a direction opposite to the rotation direction of the drum when the drum rapidly accelerates.

[0013] In this case, even if the weight of the rolling body is large, the rolling body can be moved appropriately to a position symmetrical to the clothing imbalance.

[0014] It is preferable that the control means performs the rapid acceleration control so as to increase the acceleration of the rotational speed of the drum and then decrease it after 0.1 to 0.5 seconds have elapsed.

[0015] In this case, even if the drum vibrates relatively slightly, it is possible to appropriately reduce the vibration of the drum.

[0016] It is preferable that the control means performs the rapid acceleration control when the vibration of the drum does not decrease to or below the predetermined value even after a predetermined time has elapsed after the vibration of the drum has exceeded the predetermined value.

[0017] In this case, if the vibration of the drum does not decrease even after a predetermined time has passed after the vibration of the drum exceeds a predetermined value, the rolling element will begin to roll within the annular container by applying a sudden acceleration to the drum for a short period of time. [Effects of the Invention]

[0018] The drum-type washing machine according to the present invention provides a drum-type washing machine that can appropriately reduce vibration of the drum even when the weight of the rolling elements housed inside the annular container is increased. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of a drum-type washing machine 1 according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the drum-type washing machine 1 of FIG. [Figure 3] FIG. 3(a) is a plan view of the ball balancer 30 of the first embodiment, FIG. 3(b) is a cross-sectional view taken along line III-III in FIG. 3(a), and FIG. 3(c) is an enlarged view of the area surrounded by the dotted line in FIG. 3(b). [Figure 4] FIG. 4(a) is a plan view of a conventional ball balancer 530, FIG. 4(b) is a cross-sectional view taken along line IV-IV in FIG. 4(a), and FIG. 4(c) is an enlarged view of the area surrounded by the dotted line in FIG. 4(b). [Figure 5]FIG. 5(a) is a plan view of a ball balancer 630 studied by the inventors of the present invention, FIG. 5(b) is a cross-sectional view taken along line VV in FIG. 5(a), and FIG. 5(c) is an enlarged view of the area surrounded by the dotted line in FIG. 5(b). [Figure 6] 10 is a diagram illustrating the shape of a protrusion 36. FIG. [Figure 7] 10 is a diagram illustrating the distance between two protrusions 36. FIG. [Figure 8] 10A and 10B are diagrams illustrating a method for reducing vibration of the drum 5 by the ball balancer 30. [Figure 9] 1 is a control block diagram of a drum type washing machine 1 according to an embodiment of the present invention. [Figure 10] 10 is a graph showing changes in the rotation speed of the drum 5 during dehydration. [Figure 11] 10 is a flowchart showing a control procedure when rapid acceleration control is performed in the drum type washing machine 1. [Figure 12] Figure 12(a) is a plan view of the ball balancer 30 of the second embodiment, Figure 12(b) is a cross-sectional view taken along line XII-XII in Figure 12(a), and Figure 12(c) is an enlarged view of the area surrounded by the dotted line in Figure 12(b). [Figure 13] Figure 13(a) is a plan view of the ball balancer 30 of the third embodiment, Figure 13(b) is a cross-sectional view taken along line XIII-XIII in Figure 13(a), and Figure 13(c) is an enlarged view of the area surrounded by the dotted line in Figure 13(b). [Figure 14] 10A and 10B are diagrams illustrating modified shapes of the protrusion 36. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] (First embodiment) A drum type washing machine 1 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of the drum type washing machine 1 according to the first embodiment of the present invention. Fig. 2 is a cross-sectional view of the drum type washing machine 1 of Fig. 1.

[0021] The drum type washing machine 1 of this embodiment is used in, for example, a coin laundry shop, and is operated in the order of a washing process, a rinsing process, and a spin-drying process.

[0022] As shown in FIGS. 1 and 2 , a drum-type washing machine 1 has a box-shaped housing 2. Inside the housing 2, an outer tub 3 having a substantially cylindrical inner circumferential surface is disposed. Inside the outer tub 3, a drum 5 having a substantially cylindrical inner circumferential surface for storing laundry is disposed. The outer tub 3 is a bottomed, cylindrical member disposed inside the housing 2 and capable of storing wash water therein. As shown in FIG. 2 , an acceleration sensor 25 capable of detecting acceleration in three directions, namely, up-down, left-right, and front-to-rear, is attached to the outer periphery of the outer tub 3. Note that, in this embodiment, the acceleration of the outer tub 3 detected by the acceleration sensor 25 is substantially the same as the acceleration of the drum 5. An opening 5a is formed at the front end of the drum 5, and a ring-shaped loading port 3a is formed at the front end of the outer tub 3, located forward of the opening 5a of the drum 5. The drum 5 is supported by a main shaft 6 extending in the front-to-rear direction and is rotatable about a horizontal axis.

[0023] An operation panel 2a is provided on the upper front surface of the housing 2, and a front panel 10 is detachably attached below the operation panel 2a on the lower front surface of the housing 2. An operation unit 2a1 for user operation is arranged on the operation panel 2a. A clothing insertion opening 11 is formed on the front panel 10, facing the insertion opening 3a formed at the front end of the outer tub 3.

[0024] A door 12 for opening and closing the loading opening 3a is provided at the front end of the outer tub 3. When the front panel 10 is attached to the housing 2, the door 12 is located inside the clothes loading opening 11 of the front panel 10. In the drum type washing machine 1, opening the door 12 allows clothes (laundry) to be put into and taken out of the drum 5.

[0025] The main shaft 6 is rotatably supported by a bearing 6a attached to the rear wall of the outer tub 3, and a main pulley 13 is attached to the tip of the main shaft 6 that protrudes further rearward. A motor 14 is installed at the bottom of the housing 2, and a motor pulley 15 is attached to the rotating shaft of the motor 14. The rotational power of the motor pulley 15 is transmitted to the main pulley 13 via a timing belt 16. As a result, when the motor 14 is driven, the drum 5 rotates around the main shaft 6.

[0026] A water supply pipe 20 with a water supply valve 20a installed midway is connected to the upper part of the rear wall of the outer tub 3, and when the water supply valve 20a is opened, water supplied from outside is supplied to the outer tub 3 via the water supply pipe 20. A drain pipe 21 with a drain valve 21a installed midway is connected to a drain outlet installed at the bottom of the outer tub 3, and when the drain valve 21a is opened, the water in the outer tub 2 is discharged outside the machine through the drain pipe 21.

[0027] A ball balancer 30 is provided near the opening 5a at the front end of the drum 5. Fig. 3(a) is a plan view of the ball balancer 30, Fig. 3(b) is a cross-sectional view taken along line III-III in Fig. 3(a), and Fig. 3(c) is an enlarged view of the area surrounded by the dotted line in Fig. 3(b).

[0028] As shown in Fig. 3(a), the ball balancer 30 has an annular container 31. The annular container 31 is formed from an annular pipe, and contains a plurality of rolling elements 32 and a liquid 33 as moving elements inside the annular container 31. The annular container 31 is installed inside the drum 5, more inward than the opening 5a of the drum 5, so that its rotation axis coincides with the rotation axis of the drum 5.

[0029] The drum-type washing machine 1 of this embodiment is a large drum-type washing machine installed in a coin laundry. To enable the ball balancer 30 to counteract clothing imbalance, the rolling elements 32 are, for example, metal balls with a diameter of 30 mm. The rolling elements 32 are made of, for example, carbon steel. The weight of the rolling elements 32 is, for example, 110 g. However, the diameter and weight of the rolling elements 32 are not limited thereto. In this embodiment, the weight of the rolling elements is, for example, 110 g to 510 g, preferably 110 g to 340 g. The diameter of the rolling elements is, for example, 30 mm to 50 mm, preferably 30 mm to 45 mm. The liquid 33 is, for example, silicone oil. While oils such as silicone oil can be used as the liquid 33, the type of liquid is not limited. The cross-sectional shape of the circular tube forming the annular container 31 is, for example, a circular shape with a diameter of 34 mm. However, the diameter of the cross-sectional shape of the annular container 31 is not limited to these. As will be explained later, since the protrusions 36 are formed on the circular pipe forming the annular container 31, the cross-sectional shape of the circular pipe with the protrusions 36 formed thereon is not exactly circular. However, the cross-sectional shape of the circular pipe without the protrusions 36 formed thereon is the same as the cross-sectional shape of the annular container 631 shown in FIG. 5(c) when the cross-sectional shape is changed to a circular shape (round). In FIG. 3(c), the rolling elements 32 are illustrated as spherical with a diameter N1 mm, and the annular container 31 is illustrated as a circular pipe with a diameter N2 mm with the protrusions 36 formed thereon. This is also shown in FIGS. 5(c), 12(c), and 13(c).

[0030] Here, in the drum type washing machine 1 of this embodiment, a larger rolling element is used as the rolling element 32 that rolls inside the annular container 31, so naturally the space inside the annular container 31 also becomes larger, resulting in a technical problem in that the amount of liquid 32 sealed inside the annular container 31 increases significantly.

[0031] That is, in conventional ball balancer 530, annular container 531 has a rectangular cross section. Therefore, when a centrifugal force acts on rolling elements 532 toward outer peripheral wall 535 of annular container 531 due to the rotation of the drum, rolling elements 532 come into contact with outer peripheral wall 535, as shown in Fig. 4(c). At this time, a relatively large gap is formed at a corner near the outer peripheral wall of annular container 531 (between the outer peripheral surface of rolling elements 532 and outer peripheral wall 535), and a large amount of liquid 533 is stored in the gap.

[0032] The inventors of the present invention have considered a new ball balancer 630 in which, for example, metal balls having a diameter of more than 30 mm are used as the rolling elements 32 that roll within the annular container 31, and in order to reduce the amount of liquid 533 to be sealed in the conventional ball balancer 530, the cross-sectional shape of the annular container 531 of the conventional ball balancer 530 is changed to a circular (round) shape.

[0033] However, if the cross-sectional shape of the annular container 631 in the ball balancer 630 is changed to a circular shape (round shape), when a centrifugal force toward the outer peripheral wall 635 of the annular container 631 acts on the rolling elements 632 due to the rotation of the drum, the rolling elements 632 come into contact with the outer peripheral wall 635, as shown in Fig. 5(c). At this time, almost no gap is formed between the outer peripheral surface of the rolling elements 632 and the outer peripheral wall 635 near the outer peripheral wall 635 of the annular container 631. The range of the outer peripheral wall 635 is a portion that connects the front end 631a and the rear end 631b of the annular container 631 on the outer periphery of the annular container 631. The inventors of the present invention have discovered that when a gap is formed between the outer peripheral surface of the rolling body 632 and the outer peripheral wall 635, the gap becomes a liquid passage portion through which liquid passes as the rolling body 632 moves, but if the liquid passage portion becomes small, the rolling body 632 will no longer roll properly within the annular container 631, resulting in a technical problem in that clothing imbalance cannot be properly counteracted.

[0034] As a result of extensive research conducted by the inventors of the present invention to solve the above-mentioned technical problem, they found that in order for the rolling elements in the annular container to properly move to a position that offsets the clothing imbalance, it is necessary to displace the liquid in the direction of the rolling elements' movement. In other words, when the cross-sectional shape of the annular container is conventionally square, when the rolling elements in the annular container move to a position that offsets the clothing imbalance, the liquid in the direction of the rolling elements' movement flows from the corners on the outer periphery of the rolling elements to the rear of the rolling elements. The inventors of the present invention found that if the cross-sectional shape of the annular container is circular (round), the gap (liquid passage) through which the liquid in the direction of the rolling elements' movement flows behind the rolling elements becomes narrower, and the liquid in the direction of the rolling elements' movement acts as a resistance to the ball's movement. As a result, the inventors of the present invention found that by increasing the gap (liquid passage) through which the liquid in the direction of the rolling elements' movement flows behind the rolling elements, the rolling elements in the annular container can properly move to a position that offsets the clothing imbalance.

[0035] As shown in FIG. 3(c), the outer periphery of the annular container 31 is provided with an outer peripheral wall 35 that is curved convexly outward. In FIG. 3(c), the outer peripheral wall 35 is curved convexly downward in the drawing, and this is also the case in FIGS. 5(c), 12(c), and 13(c). The outer peripheral wall 35 covers a portion of the outer periphery of the annular container 31 that connects the front end 31a and the rear end 31b of the annular container 31. Two protrusions 36 that protrude inward are formed along the entire periphery of the outer peripheral wall 35. That is, the two protrusions 36 are each formed in an annular shape and are provided on the outer peripheral wall 35 with a gap between them. The two protrusions 36 are provided symmetrically with respect to the outermost portion 35T of the annular container 31. The cross-sectional area of ​​the protrusions 36 decreases as they approach the tip.

[0036] The shapes of the two protrusions 36 formed on the outer peripheral wall 35 will be described with reference to Fig. 6. Since the two protrusions 36 have substantially the same shape, only the protrusion 36 shown on the right side of Fig. 3(c) will be described.

[0037] 6, in a cross section perpendicular to the axial center of the annular container 35, the protrusion 36 has an upper curved portion t1, a flat portion t2, and a lower curved portion t3 that are arranged above a straight line C that passes through the tip end (point contact portion 36a) of the protrusion 36, and an upper curved portion t4, a flat portion t5, and a lower curved portion t6 that are arranged below the straight line C. The upper curved portion t1 and the upper curved portion t4 are symmetrical with respect to the straight line C, the flat portion t2 and the flat portion t5 are symmetrical with respect to the straight line C, and the lower curved portion t3 and the upper curved portion t6 are symmetrical with respect to the straight line C.

[0038] The flat surface portions t2 and t5 are flat surfaces, whereas the upper curved surface t1, the lower curved surface t3, the upper curved surface t4, and the lower curved surface t6 are formed in an R-shape with a predetermined curvature. The flat surface portions t2 and t5 are inclined so that the distance between them decreases as they approach the tip of the protrusion 36. In this embodiment, the angle θ between the plane extending from the flat surface portion t2 and the plane extending from the flat surface portion t5 is 108 degrees. The angle θ is 160 degrees or less, and preferably 110 degrees or less.

[0039] In this embodiment, the diameter of the circular tube of the annular container 31 (the diameter of the circular tube when the protrusions 36 are not formed) is the same as the diameter of the annular container 631 shown in Figure 5, and the diameter of the rolling element 32 is the same as the diameter of the rolling element 632 shown in Figure 5.Therefore, the ball balancer 30 of this embodiment differs from the ball balancer 630 shown in Figure 5 in that two protrusions 36 are formed on the outer wall 35 of the annular container 31.

[0040] The inventors of the present invention found that when the cross-sectional shape of the annular container 631 is changed to a circular shape (round shape) as shown in Figure 5, the gap (liquid passage portion) formed between the outer surface of the rolling body 632 and the outer wall 635 becomes smaller, and the rolling body 632 no longer rolls properly inside the annular container 631. Therefore, they formed two protrusions 36 that protrude inward on the outer wall 35 of the circular tube of the annular container 631.

[0041] In this case, when the drum 5 is rotating and the rolling elements 32 are pressed toward the outer peripheral wall 35 by centrifugal force generated by the rotation of the drum 5, the outer peripheral surfaces of the rolling elements 32 and the outer peripheral wall 35 are in point contact at two point contact portions 36a, which are the tip ends of the two protrusions 36, as shown in FIG. 3(c). At this time, a liquid passage 40 through which the liquid 33 passes along the circumferential direction of the annular container 31 is formed between the outer peripheral surfaces of the rolling elements 32 and the outer peripheral wall 35. Specifically, the liquid passage 40a is formed closer to the front end than the two protrusions 36, the liquid passage 40b is formed between the two protrusions 36, and the liquid passage 40c is formed closer to the rear end than the two protrusions 36. The liquid passage 40b formed between the two protrusions 36 is the liquid passage formed between the two point contact portions 36a.

[0042] In this embodiment, Figure 3(c) and Figure 5(c) are compared, that is, the size of the liquid passage section 40 and the size of the liquid passage section 640 are compared when the diameter N1 of the rolling body 32 and the diameter N1 of the rolling body 632 are the same and the diameter N2 of the cross-sectional shape of the annular container 31 and the diameter N2 of the cross-sectional shape of the annular container 631 are the same.

[0043] 5(c), when a centrifugal force generated by the rotation of drum 5 acts on rolling element 632 toward outer peripheral wall 635, rolling element 632 comes into contact with outermost portion 635T of outer peripheral wall 635. At this time, liquid passing portion 640, through which liquid 633 passes along the circumferential direction of annular container 631, is formed between the outer peripheral surface of rolling element 632 and outer peripheral wall 635. Specifically, liquid passing portion 640a is formed on the front end side of outermost portion 635T, and liquid passing portion 640b is formed on the rear end side of outermost portion 635T.

[0044] Comparing cross sections perpendicular to the axial center of the annular container as shown in Figures 3(c) and 5(c), the liquid passage portion 40 formed between the outer peripheral surface of the rolling element 32 and the outer peripheral wall 35 in Figure 3(c) is larger than the liquid passage portion 640 formed between the outer peripheral surface of the rolling element 632 and the outer peripheral wall 635 in Figure 5(c). In other words, when the protrusion 36 is formed on the outer peripheral wall 35 of the annular container 32 as shown in Figure 3(c), the size of the liquid passage portion is larger than when no protrusion is formed on the outer peripheral wall 635 of the annular container 632 as shown in Figure 5(c).

[0045] That is, if the area of ​​the liquid passage section 640 (the sum of liquid passage section 640a and liquid passage section 640b) formed between the outer peripheral surface of the rolling body 632 and the outer peripheral wall 635 in the cross-sectional view of Figure 5(c) is T0, the area of ​​the liquid passage section 40 (the sum of liquid passage section 40a, liquid passage section 40b, and liquid passage section 40c) formed between the outer peripheral surface of the rolling body 32 and the outer peripheral wall 35 in the cross-sectional view of Figure 3(c) is larger than T0.

[0046] As shown in FIG. 3( c), the two protrusions 36 are formed on the outer peripheral wall 35 at a distance (circumferential distance) such that, in a drum rotation state in which the rolling element 32 is pressed against the outer peripheral wall 35, the outer peripheral surface of the rolling element 32 and the outer peripheral wall 35 are in point contact at the tips of the two protrusions 36, and the outer peripheral surface of the rolling element 32 does not come into contact with the outer peripheral wall 35 between the two protrusions 36. For example, if the distance (circumferential distance) between the two protrusions 36 is too large, as shown in FIG. 7, in a drum rotation state in which the rolling element 32 is pressed against the outer peripheral wall 35, the outer peripheral surface of the rolling element 32 comes into contact with the outer peripheral wall 35 between the two protrusions 36. Therefore, the two protrusions 36 are formed on the outer peripheral wall 35 at a distance such that, in a drum rotation state in which the rolling element 32 is pressed against the outer peripheral wall 35, the outer peripheral surface of the rolling element 32 does not come into contact with the outer peripheral wall 35 between the two protrusions 36.

[0047] A brief description will now be given of how the ball balancer 30 of this embodiment reduces vibration of the drum 5. When clothes become unbalanced in the drum during spin-drying, the center of vibration of the outer tub 3 moves to a position closer to the clothes unbalance than the center of rotation of the drum 5, as shown in FIG. 8. Meanwhile, during spin-drying, centrifugal force acts on the rolling elements 32 and liquid 33 due to the rotation of the drum 5, causing them to move farther away from the center of vibration of the outer tub. When the rolling elements 32 and liquid 33 begin to gather at positions symmetrical to the clothes unbalance, the clothes unbalance is canceled out and the outer tub vibration decreases, so the movement of the rolling elements 32 stops, allowing spin-drying to be performed with the vibration canceled out.

[0048] 9 is a control block diagram of the drum type washing machine 1 of this embodiment. As shown in FIG. 9, the control unit 50 of the drum type washing machine 1 is configured with, for example, a microcomputer, and includes a CPU, a ROM storing a program for controlling the operation of the drum type washing machine 1, and a RAM for temporarily storing data used when executing the program. The operation of the drum type washing machine 1 is controlled by this control unit 50. The motor 14 and the acceleration sensor 25 are connected to the control unit 50.

[0049] Control unit 50 stores various parameters for performing rapid acceleration control, which increases and then decreases the acceleration of the rotation speed of drum 5. In drum type washing machine 1 of this embodiment, rapid acceleration control is performed if, after spin-drying has started, the vibration of drum 5 (output value output from acceleration sensor 25) exceeds a predetermined value when the rotation speed of drum 5 reaches a predetermined rotation speed that exceeds the resonance rotation speed, and if the acceleration of drum 5 continues to exceed the predetermined value for a predetermined period of time after the rotation speed of drum 5 exceeds the predetermined rotation speed.

[0050] FIG. 10 is a graph showing changes in the rotation speed of the drum 5 during spin drying. As shown in FIG. 10, when spin drying begins, the rotation speed of the drum 5 increases at a constant acceleration toward the maximum spin drying rotation speed of 900 rpm. If the vibration of the drum 5 exceeds a predetermined value when the rotation speed of the drum 5 reaches 300 rpm, which exceeds the resonance rotation speed, the drum performs rapid acceleration control (rapid increase in the drum rotation speed) for a short period of time, as shown by the solid line, and then immediately returns to the original acceleration and increases the rotation speed toward 900 rpm at the original acceleration. If the vibration of the drum 5 is below the predetermined value when the rotation speed of the drum 5 reaches 300 rpm, the drum increases at a constant acceleration toward the maximum spin drying rotation speed of 900 rpm, as shown by the dotted line.

[0051] Therefore, specifically, the control unit 50 sets the maximum dehydration rotation speed (for example, 900 rpm) of the dehydration operation, and a constant acceleration (for example, 150 rad / s) for increasing the rotation speed of the drum 5 toward the maximum dehydration rotation speed at the start of dehydration. 2 ), a predetermined value for the vibration (acceleration) of the drum 5, a predetermined rotation speed of the drum 5 when determining whether the rotation speed of the drum 5 exceeds the resonance rotation speed and the vibration of the drum 5 exceeds a predetermined value (for example, 300 rpm), a maximum acceleration when performing rapid acceleration control (for example, 700 rad / s 2 The control unit 50 also stores a predetermined time period for determining that the vibration of the drum 5 will not be reduced to a predetermined value or less unless rapid acceleration control is performed after the rotation speed of the drum 5 exceeds a predetermined rotation speed.

[0052] A method for determining the maximum acceleration and the maximum acceleration time in the "rapid acceleration control" will be described below.

[0053] First, regarding maximum acceleration, the acceleration at the center of gravity of the ball caused by the maximum acceleration must satisfy the following formula. M×a > μ×M×ω 2 ×r M: Mass of rolling element 32 (ball) (kg) a: Acceleration (m / s) of the center of gravity of the rolling element 32 (center of gravity of the ball) generated by the maximum acceleration 2 ) μ: Coefficient of static friction occurring between the rolling element 32 (ball) and the annular container 31 in an oil lubricated state ω: Angular velocity of drum 5 when acceleration a occurs (rad / s) r: Center radius (m) of the contact area between the rolling element 32 (ball) and the annular container 31

[0054] Next, the maximum acceleration time depends on the power of the motor 14. For example, a constant acceleration of 150 rad / s 2 , maximum acceleration 700rad / s 2 In this case, the angular velocity of the drum is actually 700 rad / s 2 Instead of increasing to 700 rad / s 2 After changing to , a slight delay occurs, 700rad / s 2 This delay depends on the power of the motor 14.

[0055] In the drum-type washing machine 1 of this embodiment, acceleration a refers to the magnitude of acceleration at which the rolling elements 32 move in the direction opposite to the rotation direction of the drum 5 when the drum 5 suddenly accelerates. In this embodiment, it takes 0.3 seconds to reach the acceleration a at which the rolling elements 32 (balls) start to move. Therefore, this maximum acceleration time is a value that is experimentally determined depending on the power of each motor 14.

[0056] Furthermore, the greater the motor's power, the higher the cost, so a motor with a power that can produce a certain level of acceleration is usually selected. The maximum acceleration is achieved by overloading the motor for a short period of time. The overload operation time is kept as short as possible to prevent damage to the motor.

[0057] In this embodiment, "rapid acceleration control" refers to accelerating the rotation speed of the drum 5 at the maximum acceleration for 0.3 seconds and then returning to the original acceleration. In other words, "rapid acceleration control" refers to control that rapidly accelerates the drum 5 to obtain the acceleration required to move the rolling elements 32 in the direction opposite to the rotation direction of the drum 5. Note that it is preferable that the control unit 50 performs rapid acceleration control such that, after increasing the acceleration of the rotation speed of the drum 5, the acceleration is reduced 0.1 to 0.5 seconds later.

[0058] The control procedure when the sudden acceleration control is performed in the drum type washing machine 1 of this embodiment will be described with reference to Fig. 11. Fig. 11 is a flowchart showing the control procedure when the sudden acceleration control is performed in the drum type washing machine 1.

[0059] <Step S1> In step S1, the control unit 50 controls the motor 14 so that the rotation speed of the drum 5 gradually increases at a constant acceleration.

[0060] <Step S2> In step S2, the control unit 50 determines whether the rotation speed of the drum 5 has reached a predetermined rotation speed. If the control unit 50 determines that the rotation speed of the drum 5 has reached the predetermined rotation speed, the process proceeds to step S3. If the control unit 50 determines that the rotation speed of the drum 5 has not reached the predetermined rotation speed, the process proceeds to step S1.

[0061] <Step S3> In step S3, the control unit 50 determines whether the vibration of the drum 5 exceeds a predetermined value. If the control unit 50 determines that the vibration of the drum 5 exceeds the predetermined value, the process proceeds to step S4. If the control unit 50 determines that the vibration of the drum 5 is equal to or less than the predetermined value, the process proceeds to step S5.

[0062] <Step S4> In step S4, the control unit 50 repeatedly determines whether a predetermined time has elapsed since the vibration of the drum 5 exceeded a predetermined value. If the control unit 50 determines that the predetermined time has elapsed since the vibration of the drum 5 exceeded the predetermined value, the process proceeds to step S6.

[0063] <Step S5> In step S5, the control unit 50 controls the motor 14 so that the rotation speed of the drum 5 gradually increases at a constant acceleration rate. Then, the process proceeds to step S3.

[0064] <Step S6> In step S6, the control unit 50 determines whether the vibration of the drum 5 has become equal to or less than a predetermined value. If the control unit 50 determines that the vibration of the drum 5 has exceeded the predetermined value, the process proceeds to step S7. If the control unit 50 determines that the vibration of the drum 5 has become equal to or less than the predetermined value, the process proceeds to step S5.

[0065] <Step S7> In step S7, the control unit 50 controls the motor 14 to perform rapid acceleration control, which increases and then decreases the acceleration of the rotation speed of the drum 5. In this embodiment, the control unit 50 rapidly accelerates the rotation speed of the motor 14 that rotates the drum 5 at the maximum acceleration at which the rotation speed of the motor 14 can be increased, and then returns the acceleration to the original value. Then, the process proceeds to step S8.

[0066] <Step S8> In step S8, the control unit 50 determines whether the vibration of the drum 5 has become equal to or less than a predetermined value. If the control unit 50 determines that the vibration of the drum 5 has become equal to or less than the predetermined value, the process proceeds to step S5. If the control unit 50 determines that the vibration of the drum 5 has exceeded the predetermined value, the process proceeds to step S9.

[0067] <Step S9> In step S9, the control unit 50 controls the motor 14 to stop the rotation of the drum 5.

[0068] As described above, the drum-type washing machine 1 of this embodiment includes the outer tub 3, the drum 5 configured to be rotatable around an axis extending horizontally or inclined within the outer tub 3, the annular container 31 attached to the drum 5 and containing a plurality of rolling elements 32 and a liquid 33, and the control unit 50 (control means) that controls the rotation speed of the drum 5, wherein the weight of the rolling elements 32 is 110 g or more, and the control unit 50 performs rapid acceleration control to increase and then decrease the acceleration of the rotation speed of the drum 5 when the vibration of the drum 5 exceeds a predetermined value at a predetermined rotation speed that exceeds the resonant rotation speed while accelerating the rotation speed of the drum 5 toward high-speed dehydration rotation.

[0069] As a result, by applying a sudden acceleration to the drum 5 for a short period of time while the drum 5 is slowly accelerating toward high-speed spin rotation, a sliding motion is added to the rolling elements 32 and liquid 33 in the annular container 31 as a whole, so that the rolling elements 32 start to roll within the annular container 31 even if the rolling elements 32 are heavy. After that, once the rolling elements 32 start to roll, they roll to a position symmetrical to the unbalanced clothes, making it possible to appropriately reduce the vibration of the drum 5.

[0070] The acceleration is the magnitude of the acceleration that causes the rolling element 32 to move in the direction opposite to the rotation direction of the drum 5 when the drum 5 suddenly accelerates.

[0071] In this case, even if the weight of the rolling element 32 is large, the rolling element 32 can be moved appropriately to a position symmetrical to the clothing imbalance.

[0072] The control unit 50 performs rapid acceleration control such that the acceleration of the rotation speed of the drum 5 is increased and then decreased after 0.1 to 0.5 seconds have elapsed.

[0073] This makes it possible to appropriately reduce the vibration of the drum 5 even when the vibration of the drum 5 is relatively small.

[0074] The control unit 50 performs rapid acceleration control when the vibration of the drum 5 does not decrease to a predetermined value or less even after a predetermined time has elapsed after the vibration of the drum 5 exceeds a predetermined value.

[0075] As a result, if the vibration of the drum 5 does not decrease even after a predetermined time has elapsed after the vibration of the drum 5 exceeds a predetermined value, the rolling body 32 starts rolling inside the annular container 31 by applying a sudden acceleration to the drum 5 for a short period of time.

[0076] Furthermore, the drum-type washing machine 1 of this embodiment comprises an outer tub 3, a drum 5 configured to be rotatable around an axis extending horizontally or inclined within the outer tub 3, and an annular container 31 attached to the drum 5 and containing a plurality of rolling elements 32 and a liquid 33, wherein the rolling elements 32 are spherical, and the annular container 31 is an annular circular tube having a protrusion 36 formed on its outer peripheral wall 35 that protrudes inward, and when the drum is in a rotating state in which the rolling elements 32 are pressed toward the outer peripheral wall 35 by centrifugal force generated by the rotation of the drum 5, the outer peripheral surface of the rolling elements 32 and the outer peripheral wall 35 are in point contact at two point contact portions 36a, and a liquid passage portion 40b is formed between the two point contact portions 36a.

[0077] In this case, even if the annular container 31 is a circular tube, by forming the protrusions 36 on its outer wall 35, the outer surface of the rolling elements 32 and the outer wall 35 come into point contact at two point contact areas 36a when the drum 5 is rotating, and a liquid passage 40b is formed between the two point contact areas 36a. This prevents the liquid 33 in the direction of the rolling elements' movement from acting as a resistance to the movement of the rolling elements 32. As a result, even if the annular container 31 is a circular tube, the rolling elements 32 inside the annular container 31 can be moved appropriately to a position that offsets the imbalance in the clothes, and the vibration of the drum 5 can be appropriately reduced.

[0078] Furthermore, the drum-type washing machine 1 of this embodiment includes an outer tub 3, a drum 5 configured to be rotatable around an axis extending horizontally or inclined within the outer tub 3, and an annular container 31 attached to the drum 5 and containing a plurality of rolling elements 32 and a liquid 33, wherein the rolling elements 32 are spherical and the annular container 31 is an annular circular tube having a protrusion 36 protruding inward on its outer wall 35. When the diameters of the rolling elements 32 and the diameters of the circular tubes are the same, when comparing cross sections perpendicular to the axial center of the circular tubes, in a drum rotation state in which the rolling elements 32 are pressed toward the outer wall 35 by centrifugal force generated by the rotation of the drum 5, the liquid passage 40 formed between the outer surface of the rolling elements 32 and the outer wall 35 is larger than the liquid passage portion formed between the outer surface of the rolling elements 32 and the outer wall 35 when the protrusion 36 is not formed on the outer wall 35 of the annular container 31.

[0079] In this case, even if the annular container 31 is a circular pipe, by forming the protrusions 36 on the outer wall 35, the liquid passages 40 formed between the outer surfaces of the rolling elements 32 and the outer wall 35 become relatively large, and the liquid 33 in the direction of movement of the rolling elements 32 flows behind the rolling elements 32 through the liquid passages 40. This prevents the liquid 33 in the direction of movement of the rolling elements 32 from acting as a resistance to the movement of the rolling elements 32. As a result, even if the annular container 31 is a circular pipe, the rolling elements inside the annular container 31 can be moved appropriately to positions that cancel out the imbalance in the clothes, and the vibration of the drum 5 can be appropriately reduced.

[0080] In the drum type washing machine 1 of this embodiment, the protrusion 36 has two flat surfaces t2 and t4 whose distance decreases toward the tip, and the angle between the two flat surfaces t2 and t4 is 160 degrees or less.

[0081] In this case, the liquid passage 40 formed between the outer surface of the rolling body 32 and the outer wall of the outer periphery 35 becomes sufficiently large, allowing the rolling body 32 inside the annular container 31 to move appropriately to a position that offsets the clothing imbalance.

[0082] As shown in FIG. 5, in a drum-type washing machine having a new ball balancer 630 in which the cross-sectional shape of annular container 631 is changed to a round shape, rolling element 632 cannot be moved properly within annular container 631 even when rapid acceleration control is performed. However, as shown in FIG. 4, in a drum-type washing machine having ball balancer 530 in which the cross-sectional shape of annular container 531 is square, when heavier rolling element 532 is used, rapid acceleration for a short period during spin-dry acceleration makes it possible for rolling element 532 to move properly even with relatively small outer tub vibrations, thereby counteracting clothing imbalance.

[0083] (Second embodiment) The drum type washing machine 101 of this embodiment differs from the drum type washing machine 1 of the first embodiment in the shape of the annular container of the ball balancer. Other configurations of the drum type washing machine 101 of this embodiment are similar to those of the drum type washing machine 1 of the first embodiment, and therefore detailed description thereof will be omitted.

[0084] In the ball balancer 130 of the drum-type washing machine 101 of the second embodiment, as shown in FIG. 12(c), an outer peripheral wall 135 that is curved in a convex shape toward the outside is provided on the outer periphery of the annular container 131. The range of the outer peripheral wall 135 is a portion that connects the front end 131a and the rear end 131b of the annular container 131 on the outer periphery of the annular container 131. A single protrusion 136 that protrudes toward the inside is formed along the entire periphery of the outer peripheral wall 135. That is, the protrusion 136 is formed in an annular shape and is provided on the rear end 131b side of the outermost portion 135T of the outer peripheral wall 135 of the annular container 131. The cross-sectional area of ​​the protrusion 136 decreases toward the tip.

[0085] In this embodiment, the diameter of the circular tube of the annular container 131 (the diameter of the circular tube when the protrusion 136 is not formed) is the same as the diameter of the annular container 631 shown in Fig. 5, and the diameter of the rolling element 132 is the same as the diameter of the rolling element 632 shown in Fig. 5. Therefore, the ball balancer 130 of this embodiment differs from the ball balancer 630 shown in Fig. 5 in that one protrusion 136 is formed on the outer peripheral wall 135 of the annular container 131.

[0086] The inventors of the present invention found that when the cross-sectional shape of the annular container 631 was changed to a circular shape (round shape) as shown in Figure 5, the gap (liquid passage portion) formed between the outer surface of the rolling body 632 and the outer peripheral wall 635 became smaller, and the rolling body 632 no longer rolled properly within the annular container 631. Therefore, they changed the cross-sectional shape of the annular container 31 to a circular shape (round shape) and further formed one protrusion 136 that protrudes inward on the outer peripheral wall 35.

[0087] In this case, when the drum 5 is rotating and the centrifugal force generated by the rotation of the drum 5 presses the rolling elements 132 toward the outer peripheral wall 135, the rolling elements 132 come into point contact with the outermost portion 135T of the outer peripheral wall 135 of the annular container 131 at a portion 135Ta on the front end side end 131a side and at the tip of the protruding portion 136, as shown in FIG. 12(c). At this time, a liquid passing portion 140 through which the liquid 133 passes along the circumferential direction of the annular container 131 is formed between the outer peripheral surface of the rolling elements 132 and the outer peripheral wall 135. Specifically, a liquid passing portion 140a is formed on the front side of the portion 135Ta of the outer peripheral wall 135, a liquid passing portion 140b is formed between the portion 135Ta of the outer peripheral wall 135 and the protruding portion 36, and a liquid passing portion 140c is formed on the rear side of the protruding portion 36.

[0088] In this embodiment, Figure 12(c) is compared with Figure 5(c), that is, when the diameter N1 of the rolling body 132 and the diameter N1 of the rolling body 632 are the same, and the diameter N2 of the cross-sectional shape of the annular container 131 and the diameter N2 of the cross-sectional shape of the annular container 631 are the same, the size of the liquid passage section 140 and the size of the liquid passage section 640 are compared.

[0089] When comparing cross sections perpendicular to the axial center of the annular container as shown in Figure 12(c) and Figure 5(c), the liquid passage portion 140 formed between the outer peripheral surface of the rolling element 132 and the outer peripheral wall 135 in Figure 12(c) is larger than the liquid passage portion 640 formed between the outer peripheral surface of the rolling element 632 and the outer peripheral wall 635 in Figure 5(c). In other words, when the protrusion 136 is formed on the outer peripheral wall 135 of the annular container 132 as shown in Figure 12(c), the size of the liquid passage portion is larger than when no protrusion is formed on the outer peripheral wall 635 of the annular container 632 as shown in Figure 5(c).

[0090] That is, if the area of ​​liquid passage section 640 (the sum of liquid passage section 640a and liquid passage section 640b) formed between the outer peripheral surface of rolling body 632 and outer peripheral wall 635 in the cross-sectional view of Figure 5(c) is T0, the area of ​​liquid passage section 140 (the sum of liquid passage section 140a, liquid passage section 140b, and liquid passage section 140c) formed between the outer peripheral surface of rolling body 132 and outer peripheral wall 135 in the cross-sectional view of Figure 12(c) is larger than T0.

[0091] As described above, in the drum type washing machine 101 of this embodiment, as in the first embodiment, by applying a sudden acceleration to the drum 5 for a short period of time while the drum 5 is slowly accelerating toward high-speed spin-drying rotation, the rolling body 32 rolls to a position symmetrical to the clothing imbalance, thereby making it possible to appropriately reduce the vibration of the drum 5.

[0092] Furthermore, the drum-type washing machine 101 of this embodiment includes an outer tub 3, a drum 5 configured to be rotatable around an axis extending horizontally or inclined within the outer tub 3, and an annular container 131 attached to the drum 5 and containing a plurality of rolling elements 132 and a liquid 133, wherein the rolling elements 132 are spherical, and the annular container 131 is an annular circular tube having a protrusion 136 formed on its outer peripheral wall 135 that protrudes inward. When the diameters of the rolling elements 132 and the diameters of the circular tubes are the same, when comparing cross sections perpendicular to the axial center of the circular tubes, in a drum rotation state in which the rolling elements 132 are pressed toward the outer peripheral wall 135 by the centrifugal force generated by the rotation of the drum 5, the liquid passage portion 140 formed between the outer peripheral surface of the rolling elements 132 and the outer peripheral wall 135 is larger than the liquid passage portion formed between the outer peripheral surface of the rolling elements 132 and the outer peripheral wall 635 when the protrusion 136 is not formed on the outer peripheral wall 135 of the annular container 131.

[0093] In this case, even if annular container 131 is a circular pipe, by forming protrusion 136 on its outer circumferential wall 135, liquid passing portion 140 formed between the outer circumferential surface of rolling element 132 and outer circumferential wall 135 becomes relatively large, and liquid 133 in the direction of movement of rolling element 132 flows behind rolling element 132 through liquid passing portion 140. This prevents liquid 133 in the direction of movement of rolling element 132 from acting as resistance to the movement of rolling element 132. As a result, even if annular container 131 is a circular pipe, the rolling element inside annular container 131 can be appropriately moved to a position that cancels out the imbalance in the clothes, and vibration of drum 5 can be appropriately reduced.

[0094] (Third embodiment) The drum type washing machine 301 of this embodiment differs from the drum type washing machine 1 of the first embodiment in the shape of the annular container of the ball balancer. Other configurations of the drum type washing machine 301 of this embodiment are similar to those of the drum type washing machine 1 of the first embodiment, so detailed description thereof will be omitted.

[0095] In a ball balancer 330 of a drum-type washing machine 301 of the third embodiment, as shown in FIG. 13( c), an outer peripheral wall 335 that is curved in a convex shape toward the outside is provided on the outer periphery of the annular container 331. The range of the outer peripheral wall 335 is a portion that connects a front end 331a and a rear end 331b of the annular container 331 on the outer periphery of the annular container 331. A single recess 336 that is recessed toward the outside is formed along the entire periphery of the outer peripheral wall 335. That is, the recess 336 is formed in an annular shape and is provided so as to correspond to an outermost portion 335T of the outer peripheral wall 335 of the annular container 331. Note that because the recess 336 recessed toward the outside of the outer peripheral wall 336 forms a liquid passage portion 340b, resistance from the wall surface is reduced, and the liquid 333 flows more easily than when a protrusion that protrudes toward the inside is formed on the outer peripheral wall.

[0096] In this embodiment, the diameter of the circular tube of the annular container 331 (the diameter of the circular tube when the recess 336 is not formed) is the same as the diameter of the annular container 631 shown in Fig. 5, and the diameter of the rolling element 332 is the same as the diameter of the rolling element 632 shown in Fig. 5. Therefore, the ball balancer 330 of this embodiment differs from the ball balancer 630 shown in Fig. 5 in that one recess 336 is formed in the outer peripheral wall 335 of the annular container 331.

[0097] The inventors of the present invention found that when the cross-sectional shape of the annular container 631 is changed to a circular shape (round shape) as shown in Figure 5, the gap (liquid passage portion) formed between the outer surface of the rolling body 632 and the outer wall 635 becomes smaller, and the rolling body 632 no longer rolls properly within the annular container 631. Therefore, for the circular tube of the annular container 631, a single recess 336 recessed outward in the outer wall 35 is formed.

[0098] In this case, when the drum 5 is rotating and the centrifugal force generated by the rotation of the drum 5 presses the rolling elements 332 toward the outer peripheral wall 335, the rolling elements 332 come into point contact at two point contact portions 336a, which are both edge portions of the recessed portion 336 in the outer peripheral wall 335 of the annular container 331, as shown in FIG. 13(c). At this time, a liquid passage 340 through which the liquid 333 passes along the circumferential direction of the annular container 331 is formed between the outer peripheral surface of the rolling elements 332 and the outer peripheral wall 335. Specifically, the liquid passage 340a is formed on the front side of the recessed portion 336 in the outer peripheral wall 335, the liquid passage 340b is formed within the recessed portion 336 in the outer peripheral wall 335, and the liquid passage 340c is formed on the rear side of the recessed portion 336 in the outer peripheral wall 335. The liquid passage 340b formed between both edge portions of the recessed portion 336 is the liquid passage formed between the two point contact portions 336a.

[0099] In this embodiment, Figure 13(c) is compared with Figure 5(c), that is, when the diameter N1 of the rolling body 332 and the diameter N1 of the rolling body 632 are the same, and the diameter N2 of the cross-sectional shape of the annular container 331 and the diameter N2 of the cross-sectional shape of the annular container 631 are the same, the size of the liquid passage section 340 and the size of the liquid passage section 640 are compared.

[0100] When comparing cross sections perpendicular to the axial center of the annular container as shown in Figure 13(c) and Figure 5(c), the liquid passage portion 340 formed between the outer peripheral surface of the rolling element 332 and the outer peripheral wall 335 in Figure 13(c) is larger than the liquid passage portion 640 formed between the outer peripheral surface of the rolling element 632 and the outer peripheral wall 635 in Figure 5(c). In other words, when the recess 336 is formed in the outer peripheral wall 335 of the annular container 332 as shown in Figure 11(c), the size of the liquid passage portion is larger than when no recess is formed in the outer peripheral wall 635 of the annular container 632 as shown in Figure 5(c).

[0101] That is, if the area of ​​liquid passage section 640 (the sum of liquid passage section 640a and liquid passage section 640b) formed between the outer peripheral surface of rolling body 632 and outer peripheral wall 635 in the cross-sectional view of Figure 5(c) is T0, the area of ​​liquid passage section 340 (the sum of liquid passage section 340a, liquid passage section 340b, and liquid passage section 340c) formed between the outer peripheral surface of rolling body 332 and outer peripheral wall 335 in the cross-sectional view of Figure 13(c) is larger than T0.

[0102] As described above, in the drum type washing machine 301 of this embodiment, as in the first embodiment, by applying a sudden acceleration to the drum 5 for a short period of time while the drum 5 is slowly accelerating toward high-speed spin-drying rotation, the rolling body 32 rolls to a position symmetrical to the unbalanced clothes, thereby making it possible to appropriately reduce the vibration of the drum 5.

[0103] Furthermore, the drum-type washing machine 301 of this embodiment includes an outer tub 3, a drum 5 configured to be rotatable around an axis extending horizontally or inclined within the outer tub 3, and an annular container 331 attached to the drum 5 and containing a plurality of rolling elements 332 and a liquid 333, wherein the rolling elements 332 are spherical, and the annular container 331 is an annular circular tube having an outer peripheral wall 335 on which a recess 336 recessed outward is formed, and when the drum is in a rotating state in which the rolling elements 332 are pressed toward the outer peripheral wall 335 by centrifugal force generated by the rotation of the drum 5, the outer peripheral surface of the rolling elements 332 and the outer peripheral wall 335 come into point contact at two point contact portions 336a, and a liquid passage portion 340b is formed between the two point contact portions 336a.

[0104] In this case, even if the annular container 331 is a circular tube, by forming a protrusion 336 on its outer peripheral wall 335, the outer peripheral surface of the rolling element 332 and the outer peripheral wall 335 come into point contact at two point contact portions 336a when the drum 5 is rotating, and a liquid passage portion 340b is formed between the two point contact portions 336a. This prevents the liquid 333 in the direction of the rolling element's movement from acting as a resistance to the movement of the rolling element 332. As a result, even if the annular container 331 is a circular tube, the rolling element 332 inside the annular container 331 can be moved appropriately to a position that offsets the imbalance in the clothes, and the vibration of the drum 5 can be appropriately reduced.

[0105] Furthermore, the drum-type washing machine 1 of this embodiment includes an outer tub 3, a drum 5 configured to be rotatable around an axis extending horizontally or inclined within the outer tub 3, and an annular container 331 attached to the drum 5 and containing a plurality of rolling elements 332 and a liquid 333. The rolling elements 332 are spherical, and the annular container 331 is an annular circular tube having an outer peripheral wall 335 on which a recess 336 recessed outward is formed. When the diameters of the rolling elements 332 and the diameters of the circular tubes are the same, when comparing cross sections perpendicular to the axial center of the circular tubes, in a drum rotation state in which the rolling elements 332 are pressed toward the outer peripheral wall 335 by centrifugal force generated by the rotation of the drum 5, the liquid passage portion 340 formed between the outer peripheral surface of the rolling elements 332 and the outer peripheral wall 335 is larger than the liquid passage portion formed between the outer peripheral surface of the rolling elements 332 and the outer peripheral wall 335 when the recess 336 is not formed in the outer peripheral wall 335 of the annular container 331.

[0106] In this case, even if the annular container 331 is a circular tube, by forming a recess 336 in its outer wall 335, the liquid passage 340 formed between the outer surface of the rolling element 332 and the outer wall 335 becomes relatively large, and the liquid 333 in the direction of movement of the rolling element 332 flows behind the rolling element 332 through the liquid passage 340. This prevents the liquid 333 in the direction of movement of the rolling element 332 from acting as a resistance to the movement of the rolling element 332. As a result, even if the annular container 331 is a circular tube, the rolling element inside the annular container 331 can be appropriately moved to a position that offsets the imbalance in the clothes, and the vibration of the drum 5 can be appropriately reduced.

[0107] Although the embodiments of the present invention have been described above, the specific configurations of the various components are not limited to the above-described embodiments.

[0108] For example, in the first to third embodiments, the rolling elements used are metal balls with a diameter of 30 mm and a weight of 110 g, but this is not limited to this. The rolling elements of the present invention may be any rolling elements having a weight of 110 g or more. Therefore, the specific gravity and material of the rolling elements are arbitrary.

[0109] In the first to third embodiments, sudden acceleration control is performed when the acceleration of drum 5 exceeds a predetermined value when the rotation speed of drum 5 reaches a predetermined rotation speed after spin-drying is started, and when the vibration of drum 5 continues to exceed a predetermined value for a predetermined period of time after the rotation speed of drum 5 exceeds the predetermined rotation speed. However, this is not limiting. The timing of the sudden acceleration control of the present invention is arbitrary. For example, sudden acceleration control may be performed to check whether the drum-type washing machine is operating properly during a test run that is performed after installation and before the start of actual operation.

[0110] In the first to third embodiments, examples of various parameters stored in control unit 50 are shown, but the various parameters stored in control unit 50 are arbitrary. That is, the maximum spin rotation speed of the spin operation, the constant acceleration by which the rotation speed of drum 5 is increased toward the maximum spin rotation speed at the start of spin drying, the predetermined value for vibration of drum 5, the predetermined rotation speed exceeding the resonance rotation speed, the maximum acceleration when rapid acceleration control is performed, the maximum acceleration time for which the maximum acceleration is applied, etc. may be changed arbitrarily. The predetermined time until it is determined that the vibration of drum 5 will not be reduced to or below the predetermined value unless rapid acceleration control is performed after the rotation speed of drum 5 exceeds the predetermined rotation speed may be changed arbitrarily.

[0111] In the first to third embodiments, examples of liquid passages formed between the outer peripheral surfaces of the rolling elements and the outer peripheral wall when the drum is rotating and the rolling elements are pressed toward the outer peripheral wall by centrifugal force generated by the rotation of the drum have been described, but the liquid passages are not limited to these. The number, size, shape, and arrangement of liquid passages formed between the outer peripheral surfaces of the rolling elements and the outer peripheral wall are arbitrary. Furthermore, the number, size, shape, and arrangement of protrusions or recesses for forming liquid passages between the outer peripheral surfaces of the rolling elements and the outer peripheral wall are arbitrary.

[0112] 14, in a cross section perpendicular to the axial center of the annular container 35, the protrusion 36 has an upper curved portion t1 and a lower curved portion t3 arranged above a straight line C passing through the tip end (point contact portion 36a) of the protrusion 36, and an upper curved portion t4 and a lower curved portion t6 arranged below the straight line C. The upper curved portion t1 and the upper curved portion t4 have shapes symmetrical with respect to the straight line C, and the lower curved portion t3 and the upper curved portion t6 have shapes symmetrical with respect to the straight line C.

[0113] The upper curved portion t1, the lower curved portion t3, the upper curved portion t4, and the lower curved portion t6 are formed into an R-shape with a predetermined curvature. In this embodiment, the angle θ between the tangent to the connection portion Ta between the upper curved portion t1 and the lower curved portion t3 and the tangent to the connection portion Tb between the upper curved portion t4 and the lower curved portion t6 is 108 degrees. The angle θ is 160 degrees or less, and preferably 110 degrees or less. Therefore, the protrusion 36 does not need to have two inclined flat portions whose distance decreases as it approaches the tip of the protrusion 36.

[0114] In the above first to third embodiments, a drum type washing machine having a ball balancer has been described, but the present invention is not limited to this, and the drum type washing machine of the present invention may also be a drum type washer-dryer. [Explanation of symbols]

[0115] 1. Drum washing machine 2. Case 3 Outer tank 5 Drums 25 Accelerometer 30 Ball Balancer 31 Annular container 32 rolling elements 33 liquid 50 control unit (control means) 101 Drum washing machine 130 Ball Balancer 131 Annular container 132 rolling elements 133 Liquid 301 Drum washing machine 330 Ball Balancer 331 Annular container 332 Rolling elements 333 Liquid

Claims

1. The outer tank and a drum configured to be rotatable around an axis extending horizontally or in an inclined direction within the outer tub; an annular container attached to the drum and containing a plurality of rolling elements and a liquid; an acceleration sensor that detects vibrations of the drum; a control means for controlling the rotation speed of the drum; The weight of the rolling element is 110 g or more, The control means performs rapid acceleration control to increase and then decrease the acceleration of the drum rotation speed when vibration of the drum exceeds a predetermined value at a predetermined rotation speed that exceeds a resonance rotation speed while accelerating the rotation speed of the drum toward high-speed spin rotation.

2. 2. The drum-type washing machine according to claim 1, wherein the acceleration is a magnitude of acceleration that moves the rolling element in a direction opposite to the rotation direction of the drum when the drum is suddenly accelerated.

3. 3. The drum-type washing machine according to claim 1, wherein the control means performs the rapid acceleration control so as to decrease the acceleration of the rotation speed of the drum after 0.1 to 0.5 seconds have elapsed since the acceleration of the rotation speed of the drum was increased.

4. 3. The drum-type washing machine according to claim 1, wherein the control means performs the rapid acceleration control when the vibration of the drum does not decrease to or below the predetermined value even after a predetermined time has elapsed after the vibration of the drum has exceeded the predetermined value.

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