Patent Grant
7530243
The present invention relates to a drum type washing machine for performing washing, rinsing and water-extracting processes by rotating a rotary drum accommodating laundry therein.
With regard to a drum type washing machine, since a rotary drum is disposed in a water tub such that its rotational axis is horizontally oriented or slanted with respect to the horizontal direction with its front portion raised, laundry and water in the rotary drum tend to gather in the lower portion of the rotary drum when the rotary drum is rotated after loading laundry therein, the condition of which tends to cause excessive vibration of the rotary drum. Particularly, just as a water-extracting process is performed after the washing and rinsing processes, the laundry in the rotary drum contains water therein and may be unbalanced toward one portion of the rotary drum due to the rotation of the rotary drum depending on the types, materials and shapes of the laundry. If the laundry is placed in such an off-balanced state during the water-extracting process in which the rotary drum is rotated at a high rpm, the water tub accommodating the rotary drum therein would vibrate considerably, thereby causing abnormal vibration or noise. In case abnormal vibration occurs, a control process to remove the unbalanced distribution of the laundry in the rotary drum is performed by stopping the rotation of the rotary drum temporarily and then resuming the rotation thereof or by lowering the rpm of the rotary drum.
In order to perform a control operation in response to abnormal vibration, various methods have been proposed for detecting such abnormal vibration promptly. For example, Japanese Patent Laid-open Application No. H6-170080 (Reference 1; see pages 2 to 3, FIG. 1) discloses a method for detecting abnormal vibration of a washing machine. In this method, a warning of excessive vibration is outputted by detecting excessive vibration based on an output current of an inverter circuit, wherein the inverter circuit controls an induction motor which rotates the rotary drum.
Moreover, Japanese Patent Laid-open Application No. H61-098286 (Reference 2; see pages 1 to 3, FIG. 1) also discloses a method for operating a washing machine. In this method, the transition from the washing cycle to the water-extracting cycle is controlled based on a vibration detection output transmitted from a vibration detecting sensor for detecting the vibration of a water tub. Here, the water-extracting operation is stopped immediately once an abnormal vibration is detected during the water-extracting cycle.
However, the method of Reference 1, which detects abnormal vibration indirectly from variations in output currents of the inverter circuit, is based on the assumption that laundry's imbalanced state is reflected by an effective current of an induction motor and that the imbalanced state leads to abnormal vibration. However, the variations in the effective current of the induction motor can be caused not only by an unbalanced distribution of laundry in the rotary drum but also by various mechanical factors, e.g., a bearing of the induction motor or the like. Further, since a set value for current in detecting an excessive vibration is determined based on the variations of the effective current, excessive vibration warnings may be given unnecessarily, thereby stopping the rotary drum too frequently.
Further, in case of the method disclosed in Reference 2 in which a vibration of the water tub is detected by a vibration detecting sensor, during the balancing operation wherein the rotary drum is rotated at a low rpm, an abnormal vibration may not yet be detected due to small amplitudes of vibration, even if there is an unbalanced distribution of laundry in the rotary drum due to laundry's clinging to an inner surface of the rotary drum. Since the amplitudes of vibration are too small to be detected until the rotational speed of the rotary drum reaches a high rpm, it tends to be difficult to detect abnormal vibration until the rotary drum is rotated at a high rpm. Therefore, there is a greater risk that the laundry or the washing machine can be damaged by abnormal vibration as the rotary drum is brought to a stop, and it will take too much longer to decelerate the rotary drum spinning at a high rpm.
It is, therefore, an object of the present invention to provide a washing machine including a displacement detector for detecting vibration of a water tub accommodating a rotary drum therein with superior precision.
In accordance with a preferred embodiment of the present invention, there is provided a drum type washing machine including: a housing; a rotary drum for accommodating therein laundry, the rotary drum having a substantially horizontal or slanted rotational axis; a water tub, suspended in the housing, for accommodating therein the rotary drum; a controller for controlling an operation of the washing machine; and a displacement detecting unit disposed between the water tub and a base portion of the housing, for detecting displacement of the water tub, the displacement detecting unit having: a primary coil wound around a bobbin; a first secondary coil without overlapping the primary coil and a second secondary coil overlapping the primary coil, the first and the second secondary coils being wound coaxially with the primary coil; and a magnetic body vertically movable inside the bobbin corresponding to a displacement of the water tub.
The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:
Referring to
Cylindrical rotary drum 2 having a base is rotatably installed in water tub 3. Rotary drum 2 is driven to rotate by drum driving motor 5, disposed at the rear side of water tub 3, and a rotational direction and a rotational speed of rotary drum 2 can be varied. Further, rotary drum 2 is slantingly disposed such that its rotational axis is declined from the front side corresponding to its opening toward the rear side corresponding to its base portion. Therefore, without a user having to bend down, laundry can be loaded into or unloaded from rotary drum 2 through opening door 9 installed at an inclined surface formed on the front side of housing 6. Moreover, since the washing machine can be operated without too much clearance space in front of drum type washing machine 1, it can be installed in a small space like a bathroom etc.
Though not shown in the drawing, drum type washing machine 1 with the above configuration also has a drying function with a fan for circulating warm air into rotary drum 2 and a heater for generating warm air. Further, a control unit is provided for controlling a series of operations including washing, rinsing, water-extracting and drying processes in sequence based on a program input by a user and an operational status monitoring of each unit.
As shown in
Drum driving motor 5 is a brushless DC motor including a stator with three-phase coils 5a to 5c, a rotor with a bipolar permanent magnet and three position detectors 24a to 24c, and is rotated by PWM (pulse width modification) control inverter circuit 26 including switching devices 26a to 26f. Rotor position detection signals from position detectors 24a to 24c are inputted to controller 20, and based on the signals, PWM control of the on-off status of switching devices 26a to 26f is performed by driving circuit 25. Accordingly, by regulating electric current to three-phase coils 5a to 5c, the rotor is controlled to rotate as many times as a set rotation number.
With regard to drum type washing machine 1 with the above-described configuration, when laundry is loaded into rotary drum 2 through opening door 9 and an operational option is set or an input for an operation start is executed from input setting unit 21 provided at a top portion of housing 6, drum type washing machine 1 initiates its operations corresponding to the selected operation course under the control of controller 20. The amount of laundry loaded in rotary drum 2 is detected by laundry amount detector 30, and controller 20 controls the opening/closing of water supply valve 14 such that water enters rotary drum 2 up to a water level corresponding to the laundry amount. The water level in water tub 3 is detected by water level detector 16. Specifically, the current flowing in inverter circuit 26 fluctuates depending on the load exerted on drum driving motor 5 when rotary drum 2 is rotated at a preset rotational speed. Thus, current detecting circuit 29 detects the current value from voltages at both ends of resistor 28, which is connected in series to a current circuit, and laundry amount detector 30 detects the laundry amount in rotary drum 1 based on the detected current value. Moreover, the detection of laundry amount can also be performed by means of displacement sensor 36 to be described later. In such a case, current detector 27 including resistor 28 and current detecting circuit 29 can be configured to be used in detecting the torque of drum driving motor 5.
If laundry distribution is unbalanced toward one portion of rotary drum 2 during a water-extracting process in particular, rotary drum 2 would vibrate considerably, which in turn makes water tub unit 7 vibrate as well, causing abnormal vibration or noise. Thus, in case the vibration of water tub unit 7 increases beyond a predetermined level, it is necessary to perform a control for stopping the rotation of rotary drum 2 temporarily and then resuming the rotation thereof or reducing the speed of rotary drum 2 to remove the imbalanced distribution of laundry. In order to detect the vibration of water tub unit 7, displacement sensor (displacement detecting unit) 36 is installed between lower supporting part 74, on which vibration damper 70 for supporting water tub unit 7 is installed, and supporting table 73 fixed on a base portion of housing 6 of washing machine 1.
As shown in
As illustrated in
As for coil body 57 shown in
As shown in
Displacement rod unit 41, which is inserted into cylinder body 58 of detection coil unit 40 such that it is vertically movable, includes rod body 43 having a cylindrical shape with a base, as shown in
Moreover, since ferrite 42 is fabricated by molding of raw material powder by pressurizing it and then sintering the molded structure, ferrite 42 is vulnerable to impact or the like. However, even though ferrite 42 is broken inside rod body 43, for example, this has no effect on its electrical property because ferrite 42 is compressed towards the step of the hollow portion by pressing spring 49. Therefore, instead of using ferrite 42 with a predetermined standard length, it is also possible to use multiple shorter ferrites stacked on top of each other, so it becomes an option whether to use a single ferrite of a standard length or to use multiple but shorter ferrites. Therefore, it is possible to use a ferrite of a standard size or a broken ferrite of a shorter size. Further, pressing spring 49 is preferably fabricated with a non-magnetic material so that the spring will not interfere with the effect of ferrite 42 having a fixed length and formed of magnetic material by serving as an extension of ferrite 42. Here, in the preferred embodiment of the present invention, however, since ferrite 42 is biased by pressing spring 49 via non-magnetic spacer 48, it is permissible form pressing spring 49 with a magnetic body, that is, pressing spring 49 can be either a magnetic or non-magnetic body. Thus, there is more option to choose in terms of selecting the material for pressing spring 49. In addition, by providing a space in the internal end side of rod body 43 and forming water discharge hole 51 opened toward the outside from the space, it becomes possible to discharge condensed water out of rod body 43 in case condensed water is generated due to temperature variations.
Since rod body 43 of displacement rod unit 41 having the above configuration is inserted into cylinder body 58 of detection coil unit 40 to move up and down therein like a piston moving in a cylinder, a friction coefficient between rod body 43 and cylinder body 58 should be small. In general, though reduction of friction coefficient is achieved by coating a lubricant such as grease on parts that are sliding against each other, it has a drawback in that fiber powder or dust particles would stick to the coated lubricant, making it impossible to maintain its performance for an extended period of time. Thus, in the preferred embodiment, rod body 43 and cylinder body 58 are formed by a combination of materials having small friction coefficients and high abrasion resistance relative to each other. For example, one of the rod body 43 and cylindrical body 58 may be formed of polyacetal while the other may be formed of polyamide, whereby friction between rod body 43 and cylinder body 58 can be reduced when rod body 43 moves relative to cylinder body 58. Further, since these materials have high abrasion resistance, endurance capacity can be improved. Further, when rod body 43 moves up and down rapidly inside cylinder body 58, air inside cylinder body 58 is compressed or expanded. Thus, in order to prevent the resistance against the vertical movement of displacement rod unit 41 due to air, it is preferred to provide in the lower end side of cylinder body 58 air discharge hole 80 opened from the inner hollow portion therein toward the outside. Air discharge hole 80 can also be used to discharge moisture or condensed water inside cylinder body 58 externally.
As described in
As shown in
As described above, since detection coil unit 40 is provided with connector 65 and the lead is connected to connector 65, when detection coil unit 40 rotates, there is a risk that the lead connected to connector 65 may be cut off or the connection itself may be separated. Therefore, lower connection member 44 has an anti-rotation structure for preventing the rotation of detection coil unit 40 while maintaining its free movement.
As shown in
As for globoid 44a and bowl-shaped body 44b forming lower connection member 44 jointly, and globoid 45a and bowl-shaped body 45b forming upper connection member 45 jointly, globoids 44a and 45a and bowl-shaped bodies 44b and 45b are formed of combinations of materials allowing for low friction coefficient therebetween, as in the case of cylinder body 58 and rod body 43 slidingly moving therein. In the preferred embodiment of the present invention, since globoid 44a is formed at one end of cylinder body 58 as one body therewith, lower attachment table 46 having bowl-shaped body 44b formed as one body therewith and cylinder body 58 are formed of different materials allowing for a small friction coefficient therebetween. As a result, globoid 44a and bowl-shaped body 44b can be coupled to each other such that their smooth sliding movements relative to each other are allowed without having to coat a lubricant such as grease on the sliding portions. Likewise, in the case of upper connection member 45, upper attachment table 47 having bowl-shaped body 45b formed as one body therewith and cap 50 having globoid 45a formed as one body therewith are formed of different materials. One example of the combination of those materials allowing for a small friction coefficient therebetween is a set of polyacetal and polyamide.
In order to form facing members of sliding contact portions using combinations of materials allowing for a small friction coefficient as described above, it is preferable to select a material for each part of displacement sensor 36 as will be described hereinafter. Here, the sliding contact portions refer to upper and lower connection members 44 and 45, and, also, sliding portions of rod body 43 and cylinder body 58.
As described, bowl-shaped body 44b formed on lower attachment table 46 is provided with engagement grooves 53a and 53b to prevent the rotation of detection coil unit 40. Here, even if bowl-shaped body 45b installed on upper attachment table 47 is configured to have engagement grooves 53a and 53b, it does not hinder the free movement of globoid 45a. Accordingly, it is possible to use same parts for upper and lower attachment tables 47 and 46. Hereinafter, for simplicity, characters will be used such that the material for resin-forming upper and lower attachment table 47 and 46 is material B while the material for plastic molding cylinder body 58 and cap 50 formed as one body with globoids 44a and 45b corresponding to bowl-shaped bodies 44b and 45b, respectively, is material C. Further, the material for resin-forming rod body 43 slidingly moving inside cylinder body 58 is material B different from the material for forming cylinder body 58. Since rod body 43 has cap 50 and globoid 45a is formed as one body with cap 50, the above distinction of materials becomes possible, and the facing members of the sliding contact portions can be formed of materials B and C, respectively, which allows for small friction coefficients therebetween. For example, material B may be polyacetal while material C may be polyamide.
Displacement sensor 36 having the above-described configuration is installed between supporting table 73 and lower supporting part 74, on which vibration damper 70 is installed, as shown in
Further, since displacement sensor 36 can detect displacement in a direction substantially identical to the axial direction of vibration damper 70, it can detect the vibration of water tub unit 7 precisely. Moreover, since the installation of displacement sensor 36 can be accomplished by sharing the components for installing vibration damper 70, it is possible to install displacement sensor 36 securely without having to use additional components. Specifically, the attachment of displacement sensor 36 to lower supporting part 74 and supporting table 73 can be done simply by fitting engaging member 54 and hook member 55 into engagement holes provided at lower supporting part 74 and supporting table 73, wherein engaging member 54 and hook member 55 has the same structure and are formed on each of upper and lower attachment table 47 and 46, as shown in
The drum type washing machine in accordance with the preferred embodiment of the present invention employs a vibration dampening structure in which water tub unit 7 is slantingly disposed with its front portion raised, and vibration damper 70 supports water tub unit 7 at a location closer to the front portion of the washing machine than the center of gravity of water tub unit 7, and first and second coil spring 71 and 72 suspend water tub unit 7 at a predetermined position elastically. Since the function of vibration damper 70 becomes particularly noticeable in the above configuration, more precise detection of water tub unit 7's displacement can be done by installing displacement sensor 36 in the direction substantially identical to vibration dampening direction of vibration damper 70 as in the preferred embodiment of the present invention.
Detection of displacement of water tub unit 7 by displacement sensor 36 can be accomplished by connecting oscillation circuit 81 and detection circuit 82 to connector 65 installed in detection coil unit 40. In case water tub unit 7 is at a predetermined position without making a displacement, ferrite 42 locates itself at a reference position where no displacement of displacement rod unit 41 is made with respect to detection coil unit 40. Accordingly, if an triggered magnetic signal of a certain output is transmitted to primary coil 61 from oscillation circuit 81, signal outputs produced with respect to first secondary coil 62 and second secondary coil 63 are maintained at a certain level. Oscillation circuit 81 applies a sine wave or a chopping wave of a predetermined frequency to primary coil 61 as an excited magnetic signal, and detection coil circuit 82 rectifies and smoothes the signal outputs excited to first and second secondary coil 62 and 63 as a result of applying the excited magnetic signal to primary coil 61, to thereby obtain a voltage output corresponding to a displacement of water tub unit 7.
Here, the reference position refers to ferrite 42's position where its lower end locates at a position identical to the lower end of primary coil 61 when no laundry is loaded in rotary drum 2. In setting the reference position, the position of ferrite 42 within the coil can be adjusted by controlling the height position of detection coil unit 40, which is biased upward by spring 78, with respect to displacement rod unit 41 by rotating nut 79, as shown in
When displacement rod unit 41 moves vertically within detection coil unit 40 in response to the displacement of water tub unit 7, the position of ferrite 42 changes, so that the voltage obtained by detection circuit 82 from the output signal excited to first secondary coil 62 fluctuates as shown in graph Al in
Meanwhile, the output voltage obtained by detection circuit 82 from the output signal excited to second secondary coil 63 fluctuates as shown in graph A2 in
By inputting the two voltage variations obtained by detection circuit 82 to controller 20 (see
In accordance with the present invention as described above, since two displacement information of the water tub are obtained from one displacement detecting unit, vibration generation based on the laundry amount loaded into the rotary drum accommodated in the water tub or slope of the laundry position can be detected with superior precision. Therefore, abnormal vibration can be prevented without causing damage on laundry loaded or the washing machine itself by performing control operations based on the displacement detection, and there is provided a drum type washing machine not causing abnormal vibration or noise.
While the invention has been shown and described with respect to the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-264996 | Sep 2004 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3152462 | Elliott et al. | Oct 1964 | A |
| 5445970 | Rohr | Aug 1995 | A |
| 5767670 | Maher et al. | Jun 1998 | A |
| 6470751 | Baek | Oct 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 1510195 | Jul 2003 | CN |
| 1132005 | Dec 2003 | CN |
| 294014 | Dec 1988 | EP |
| 61-98286 | May 1986 | JP |
| 6-170080 | Jun 1994 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20060053839 A1 | Mar 2006 | US |
