WASHING MACHINE

Description

Technical Field

[0001] The present invention relates to a washing machine for washing laundry.

Background Art

[0002] A washing machine in which steam is supplied into a storage tub storing laundry has been developed to make the laundry subjected to various processes (c.f. Patent Documents 1 and 2). The washing machines disclosed in Patent Documents 1 and 2 supply steam into a storage tub in synchronization with starting washing water supply for washing laundry. Since the washing water is heated by the steam, the washing machine shows high washing performance.

[0003] However, the techniques dependent on steam to cause a temperature rise of the washing water are inefficient in terms of time.

[0004] 

Patent Document 1: EP 1861534.

Patent Document 2: EP 2031114.

[0005] WO 2006/101362 A1 relates to a method for washing of washer. A washing method of a washing machine that is capable of performing a washing operation of laundry with reduced washing water consumption and low power consumption and, in addition, sterilizing the laundry is disclosed. The washing method includes supplying washing water containing detergent into a tub to perform a high-concentration washing process, and, before or after the high-concentration washing process, supplying steam into a drum.

Summary of the Invention

[0006] It is an object of the present invention to provide an improved and useful washing machine in which the above-mentioned problems are eliminated. In order to achieve the above-mentioned object, there is provided a washing machine according to claim 1. Advantageous embodiments are defined by the dependent claims.

[0007] Advantageously, a washing machine includes a storage tub configured to store washing water for washing laundry, a first heater configured to heat the washing water, a steam supply mechanism configured to supply steam to the storage tub, and a controller configured to control the steam supply mechanism and the first heater. The controller actuates the steam supply mechanism after stopping the first heater.

[0008]  The washing machine according to the present invention may use steam to show high washing performance.

[0009] The objects, features and advantages of the present invention will become more evident from the following detailed description and the accompanying drawings.

Brief Description of Drawings

[0010] 

Fig. 1 is a schematic vertical cross-sectional view of the washing machine according to the first embodiment

Fig. 2 is a schematic transparent perspective view of the washing machine shown in Fig. 1.

Fig. 3 is a schematic perspective view of a steam supply mechanism stored in a housing of the washing machine shown in Fig. 1.

Fig. 4A is a schematic perspective view of a steam generation portion of the steam supply mechanism shown in Fig. 3.

Fig. 4B is a schematic perspective view of the steam generation portion of the steam supply mechanism shown in Fig. 3.

Fig. 5 is a schematic perspective view of an attachment portion for connecting a lid of the steam generation portion shown in Figs. 4A and 4B to the housing.

Fig. 6 is a schematic perspective view of the steam generation portion, which is fixed to a housing top wall by the attachment portion shown in Fig. 5.

Fig. 7 is a schematic perspective view of a steam generation portion which is connected to first and second reinforcing frames.

Fig. 8A is a schematic perspective view of a steam generator of the steam generation portion shown in Figs. 4A and 4B.

Fig. 8B is a schematic perspective view of the steam generator of the steam generation portion shown in Figs. 4A and 4B.

Fig. 9 is a schematic perspective view of a main piece of the steam generator shown in Figs. 8A and 8B.

Fig. 10 is a schematic exploded perspective view of the steam generator shown in Figs. 8A and 8B.

Fig. 11 is a schematic perspective view of a lid piece of the steam generator shown in Fig. 10.

Fig. 12 is a schematic plan view of the main piece shown in Fig. 9.

Fig. 13 is a schematic view of a water supply mechanism of the steam supply mechanism shown in Fig. 3.

Fig. 14 is a schematic rear view of a front portion of a storage tub in the washing machine shown in Fig. 1.

Fig. 15 is a graph schematically showing a relationship between intermittent operation of a pump of the water supply mechanism shown in Fig 13 and a temperature inside a chamber space.

Fig. 16 is a schematic block diagram showing various elements of the washing machine used in a washing process.

Fig. 17 is a schematic flowchart showing control executed to adjust a temperature of washing water.

Fig. 18 is a graph schematically showing a change in a temperature of water supplied to a water tub of the washing machine shown in Fig. 1.

Fig. 19A is a schematic timing chart showing a timing for supplying steam in a spin-drying process.

Fig. 19B is a schematic timing chart showing a timing for supplying steam in the spin-drying process.

Fig. 19C is a schematic timing chart showing a timing for supplying steam in the spin-drying process.

Fig. 20 is a block diagram schematically showing control executed for a door in response to a temperature of the steam generator shown in Fig. 8B.

Fig. 21 is a schematic exploded perspective view of the steam generator used in the washing machine according to the second embodiment.

Fig. 22 is a schematic perspective view of the steam generator shown in Fig. 21.

Description of Embodiments

[0011] The washing machine is described below with reference to the drawings. Directional terms such as "up", "down", "left" and "right" are simply used in the description to clarify explanation without limiting principles of the washing machine. The principles of the washing machine may be applicable to devices with not only a washing function but also a drying function for drying laundry (washing and drying machine).

<First Embodiment>

<Washing Machine>

[0012] Fig. 1 is a schematic vertical cross-sectional view of a washing machine 100 according to the first embodiment. The washing machine 100 is described with reference to Fig. 1.

[0013] The washing machine 100 includes a housing 110 and a storage tub 200 configured to store laundry in the housing 110. The storage tub 200 includes a rotary drum 210, which has a substantially cylindrical peripheral wall 211 surrounding a rotational axis RX, and a water tub 220, which stores the rotary drum 210. The storage tub 200 is substantially cylindrical so that the storage tub 200 surrounds the rotational axis RX. In a washing process as described hereinafter, the storage tub 200 stores laundry and washing water used for washing the laundry. In a spin-drying process as described hereinafter, the washing water is discharged from the storage tub 200. Subsequently, the rotary drum 210 rotates at high speed.

[0014] The washing machine 100 includes a water heater 160 for heating the washing water. The water heater 160 is situated below the water tub 220. Control under usage of the water heater 160 is described hereinbelow. In the present embodiment, the first heater is exemplified by the water heater 160.

[0015] The housing 110 includes a front wall 111, which is provided with a feed opening 119 for feeding laundry into the storage tub 200, and a rear wall 112 opposite to the front wall 111. The housing 110 includes a housing top wall 113, which substantially horizontally extends between the front and rear walls 111, 112, and a housing bottom wall 114 opposite to the housing top wall 113. The rotary drum 210 and the water tub 220 are provided with openings 213, 227, respectively, in communication with the feed opening 119 formed in the front wall 111.

[0016] The washing machine 100 includes a door 120 which is attached to the front wall 111. The door 120 rotates between a closed position, at which the door 120 closes the feed opening 119 formed in the front wall 111, and an open position, at which the door 120 opens the feed opening 119. A user may rotate the door 120 towards the open position to feed laundry into the storage tub 200 through the feed opening 119 of the front wall 111. The user may then move the door 120 towards the closed position to wash the laundry in the washing machine 100. The door 120 shown in Fig. 1 is situated at the closed position.

[0017] The rotary drum 210 rotates about the rotational axis RX which extends between the front and rear walls 111, 112. The laundry fed into the storage tub 200 moves inside the rotary drum 210 due to rotation of the rotary drum 210, and is subjected to various processes such as washing, rinsing and/or spin-drying.

[0018] The rotary drum 210 includes a bottom wall 212 facing the door 120 at the closed position. The water tub 220 includes a bottom portion 221, which surrounds the bottom wall 212 of the rotary drum 210 and a part of the peripheral wall 211, and a front portion 222, which surrounds the other portion of the peripheral wall 211 of the rotary drum 210 between the bottom portion 221 and the door 120.

[0019] The storage tub 200 includes a rotary shaft 230 which is attached to the bottom wall 212 of the rotary drum 210. The rotary shaft 230 extends toward the rear wall 112 along the rotational axis RX. The rotary shaft 230 extends through the bottom portion 221 of the water tub 220 and appears between the water tub 220 and the rear wall 112.

[0020] The washing machine 100 further includes a motor 231 situated below the water tub 220, a pulley 232 attached to the rotary shaft 230 appearing outside the water tub 220, and a belt 233 for transmitting drive power of the motor 231 to the pulley 232. When the motor 231 operates, the drive power of the motor 231 is transmitted to the belt 233, the pulley 232 and the rotary shaft 230. Accordingly, the rotary drum 210 rotates inside the water tub 220.

[0021] The washing machine 100 further includes a packing structure 130 situated between the front portion 222 of the water tub 220 and the door 120. The door 120 compresses the packing structure 130 when the door 120 is rotated to the closed position. Accordingly, the packing structure 130 forms a water-tight sealing structure between the door 120 and the front portion 222.

[0022] The washing machine 100 further includes a water supply port 140 connected to a faucet (not shown), and a distribution portion 141 for distributing water supplied through the water supply port 140. The water supply port 140 appears on the housing top wall 113 situated above the storage tub 200. The distribution portion 141 is situated between the housing top wall 113 and the storage tub 200.

[0023] The washing machine 100 further includes a detergent storage portion (not shown), in which detergent is stored, and a steam supply mechanism 300 (described below), which sprays steam into the storage tub 200. The distribution portion 141 includes water supply valves for supplying water selectively to the storage tub 200, the detergent storage portion and the steam supply mechanism 300. Fig. 1 does not show water supply paths to the storage tub 200 and the detergent storage portion. Technologies used in a conventional washing machine may be suitably used for the water supply to the storage tub 200 and the detergent storage portion.

<Steam Supply Mechanism>

[0024] Fig. 2 is a schematic transparent perspective view of the washing machine 100. Fig. 3 is a schematic perspective view of the steam supply mechanism 300 which is stored in the housing 110. The housing 110 is indicated by dotted lines in Figs. 2 and 3. The storage tub 200 is not shown in Fig. 3. The arrows in Fig. 3 schematically show a water supply path. The steam supply mechanism 300 is described with reference to Figs. 1 to 3.

[0025] As shown in Fig. 3, the distribution portion 141 includes a first supply valve 310 used in the steam supply mechanism 300, a second supply valve 142 for opening and closing a water supply path, which leads to the detergent storage portion for storing detergent, and a third supply valve 143 for opening and closing a water supply path leading to the water tub 220. Water delivered to the detergent storage portion by opening operation of the second supply valve 142 is supplied to the storage tub 200 as the washing water (aqueous solution of detergent). Water delivered directly to the water tub 220 by opening operation of the third supply valve 143 may be used for adjusting detergent concentration in the washing water in the storage tub 200, a water level in the storage tub 200 or turbidity of the washing water.

[0026] In addition to the aforementioned first supply valve 310, the steam supply mechanism 300 includes a reservoir tank 320 situated below the storage tub 200. The first supply valve 310 is used for controlling water supply to the reservoir tank 320. Water is supplied from the water supply port 140 to the reservoir tank 320 when the first supply valve 310 opens. The water supply to the reservoir tank 320 is stopped when the first supply valve 310 closes.

[0027] The steam supply mechanism 300 further includes a pump 330, which is attached to the reservoir tank 320, and a steam generation portion 400, which receives water discharged from the pump 330. The pump 330 carries out an intermittent or continuous water supply operation to the steam generation portion 400. During the intermittent water supply operation, the pump 330 supplies an appropriately adjusted amount of water to the steam generation portion 400 to cause instantaneous steam generation. If the pump 330 supplies water continuously to the steam generation portion 400, impurities (scale) contained in the water used to generate steam are flushed from the steam generation portion 400.

[0028] The steam generation portion 400 is heated to a high temperature in order to generate steam which is sprayed into the storage tub 200. The storage tub 200 and the steam generation portion 400 are appropriately isolated from a user since the housing 110 stores the storage tub 200, which contains the rotary drum 210 configured to perform rotary movement, and a steam generation portion 400, which is heated to a high temperature. Consequently, the user may safely operate the washing machine 100.

[0029] As shown in Fig. 2, the steam supply mechanism 300 further includes a steam conduit 340 which extends downwards from the steam generation portion 400. As shown in Fig. 1, the front portion 222 of the water tub 220 includes a peripheral wall portion 223, which surrounds the peripheral wall 211 of the rotary drum 210, and an annular portion 224, which forms a water-tight sealing structure in conjunction with the packing structure 130. The steam conduit 340 is connected to the peripheral wall portion 223. Steam generated by the steam generation portion 400 is supplied to the storage tub 200 through the steam conduit 340. It is preferable that the steam conduit 340 may be bellows configured to transmit little vibration to the steam generation portion 400 under rotation of the storage tub 200.

[0030] Figs. 4A and 4B are schematic perspective views of the steam generation portion 400. The steam generation portion 400 is described with reference to Figs. 2 to 4B.

[0031] The steam generation portion 400 includes a substantially rectangular box-shaped case 410 and a steam generator 420 which is surrounded by the case 410. The case 410 includes a container 411 for storing the steam generator 420, and a lid 412 which closes the container 411.

[0032] The steam generator 420 is connected to the pump 330 by a connecting pipe 421 and a tube (not shown). The steam generator 420 is connected to the steam conduit 340 by an exhaust pipe 422. The container 411 includes a bottom wall portion 414 provided with an opening 413. The connecting pipe 421 and the exhaust pipe 422 project downwards through the opening 413.

[0033] The steam generator 420 is situated above the reservoir tank 320 since the pump 330 forcibly supplies water from the reservoir tank 320 to the steam generator 420 inside the steam generation portion 400. If water is supplied from the reservoir tank 320 to the steam generator 420 without the pump 330, the water in the reservoir tank 320 has to be supplied to the steam generator 420 by the action of gravity. In this case, the steam generator 420 has to be situated below the reservoir tank 320.

[0034] In the present embodiment, water supply from the reservoir tank 320 to the steam generator 420 is carried out by the pump 330. Since the water is supplied from the reservoir tank 320 to the steam generator 420 forcibly by a pressure of the pump 330, there are few restrictions on a vertical relationship about an arrangement design of the steam generator 420 and the reservoir tank 320. With increased freedom in a layout design of the reservoir tank 320 and the steam generator 420, an internal space of the housing 110 is used efficiently.

[0035] The pump 330 may appropriately supply water from the reservoir tank 320 to the steam generator 420 although the steam generator 420 is situated above the reservoir tank 320 as shown in Fig. 2.

[0036] If water flows accidentally into a steam generator because of unexpected failures or other problems, steam is generated unnecessarily. In the present embodiment, the reservoir tank 320 is situated below the steam generator 420 due to usage of
the pump 330. Even if the pump 330 is stopped by failures so that water supply to the steam generator 420 becomes uncontrollable, water remaining inside a hose connecting the reservoir tank 320/the pump 330 to the steam generator 420 does not flow into the steam generator 420 unnecessarily. Without the pump 330, the steam generator 420 has to be situated below the reservoir tank 320 as described above. For example, if there are failures of control parts such as on-off valves for controlling water supply from the reservoir tank 320 to the steam generator 420, water supply to the steam generator 420 becomes out-of-control so that water is supplied unnecessarily from the reservoir tank 320 to the steam generator 420 because of the action of gravity. In the present embodiment, unnecessary water supply to the steam generator 420 and the reservoir tank 320 is less likely to occur due to usage of the pump 330.

[0037] As shown in Fig. 2, the housing 110 includes a right wall 115 standing between the front and rear walls 111, 112, and a left wall 116 opposite to the right wall 115. The rotational axis RX extends along the right and left walls 115, 116 (i.e. the rotational axis RX extends substantially in parallel to the right and left walls 115, 116).

[0038]  Single-dotted lines are used in Fig. 2 to depict a vertical plane VP which passes through the rotational axis RX. The reservoir tank 320 is situated in a space on the bottom left of the housing 110 (a space between the vertical plane VP and the left wall 116). The steam generator 420 is situated in a space on the top right of the housing 110 (a space between the vertical plane VP and the right wall 115). The steam generator 420 and the reservoir tank 320 are arranged at substantially symmetrical positions with respect to the central axis of the storage tub 200 (the rotational axis RX). The reservoir tank 320 is situated near the rear wall 112 whereas the steam generator 420 is closer to the front wall 111 than the rear wall 112.

[0039] With regard to a general washing machine, a detergent storage portion in which detergent is stored is situated in one of the left and right portions of an upper front portion of the housing. A space outside the substantially cylindrical storage tub 200 except for a position occupied by the detergent portion is used efficiently for arranging each of the reservoir tank 320 and the steam generator 420. For example, if the detergent storage portion is situated in a left portion of the upper front portion of the housing 110, the reservoir tank 320 is situated at a rear position in a left lower portion of the housing 110 as shown in Fig. 2. In this case, if the steam generator 420 is situated at a front position in an upper right portion of the housing 110, an internal space between an inner surface of the substantially rectangular housing 110 and an outer surface of the substantially cylindrical storage tub 200 is utilized efficiently for arranging the reservoir tank 320 and the steam generator 420. Consequently, the reservoir tank 320 and the steam generator 420 may be maximally sized in an acceptable space.

[0040] The reservoir tank 320 may be situated at a position substantially symmetrical with respect to the detergent storage portion about the central axis (rotational axis RX) of the storage tub 200 whereas the steam generator 420 may be arranged at a substantially symmetrical position to the reservoir tank 320 with respect to the horizontal plane HP containing the rotational axis RX of the storage tub 200 if the detergent storage portion is arranged at the aforementioned position. Like the aforementioned layout design, the internal space of the housing 110 is utilized efficiently.

[0041] If the detergent storage portion is arranged at the aforementioned position, the reservoir tank 320 may be situated below the detergent storage portion. In this case, the steam generator 420 may be situated above the reservoir tank 320. Accordingly, the steam generator 420 may be arranged in a substantially symmetrical position to the reservoir tank 320 with respect to the vertical plane containing the rotational axis RX of the storage tub 200. Accordingly, like the aforementioned layout design, the internal space of the housing 110 is utilized efficiently.

[0042] If the rotational axis RX of the storage tub 200 is inclined in the front/rear direction of the housing 110 (e.g. if the rotational axis RX of the rotary drum 210 is inclined upwards from the rear wall 112 towards the front wall 111), the reservoir tank 320 and the steam generator 420 may be arranged at substantially symmetrical positions with respect to the rotational axis RX of the storage tub 200 or the horizontal plane HP containing the rotational axis RX. If the reservoir tank 320 and the steam generator 420 are arranged at substantially symmetrical positions with respect to the vertical plane passing through the approximate centre of the housing 110 in the front/rear direction, an internal space between the inner surface of the housing 110 and the outer surface of the storage tub 200 is utilized efficiently for arranging the reservoir tank 320 and the steam generator 420.

<Attachment Structure to Housing>

[0043] Fig. 5 is a schematic perspective view of an attachment portion 150 which is attached to the lid 412. The attachment portion 150 is described with reference to Figs. 3 and 5.

[0044] The lid 412 includes a substantially rectangular upper wall 415, a lid peripheral wall 416, which extends downwards from the edges of the upper wall 415, and a projecting piece 417, which projects forwards from the lid peripheral wall 416. The washing machine 100 further includes the attachment portion 150 which is attached to the lid 412. The attachment portion 150 includes a first attachment piece 151, which is fixed to the upper wall 415, and a second attachment piece 152, which is fixed to the projecting piece 417. The first and second attachment pieces 151, 152 project upwards from the lid 412.

[0045] The first attachment piece 151 includes a first connecting plate 153, which is connected to the upper wall 415, a first upright plate 154, which projects upwards from the first connecting plate 153, and a pair of first engagement pieces 155, which project rightwards from the first upright plate 154. The second attachment piece 152 includes a second connecting plate 156, which is connected to the projecting piece 417, a second upright plate 157, which projects upwards from the second connecting plate 156, and a second engagement piece 158, which projects forwards from the second upright plate 157.

[0046] Fig. 6 is a schematic perspective view of the steam generation portion 400 which is fixed to the housing top wall 113 by the attachment portion 150. Attachment of the steam generation portion 400 to the housing top wall 113 is described with reference to Figs. 3 and 6.

[0047] As shown in Fig. 3, the housing 110 further includes a first reinforcing frame 117 situated along the upper edge of the right wall 115, and a second reinforcing frame 118 situated along the upper edge of the front wall 111.

[0048] As shown in Fig. 6, the reinforcing frame 117 is provided with openings 171. The first engagement pieces 155 of the first attachment piece 151 are inserted into the openings 171. Accordingly, the first attachment piece 151 is engaged with the first reinforcing frame 117.

[0049] The first attachment piece 151 includes first fins 159 which are formed at the corner between the first connecting plate 153 and the first upright plate 154. Since a large part of the heat from the steam generation portion 400 is radiated from the first fins 159, there is a small heat amount to be transmitted to the first reinforcing frame 117 and the housing top wall 113.

[0050] The second reinforcing frame 118 is provided with an opening. As shown in Fig. 6, the second engagement piece 158 of the second attachment piece 152 is inserted into the opening of the second reinforcing frame 118. Consequently, the second attachment piece 152 is engaged with the second reinforcing frame 118. Therefore, the steam generation portion 400 is fixed to the housing top wall 113 by the first and second attachment pieces 151, 152. The steam generation portion 400 is distant from the housing top wall 113 due to the first and second upright plates 154, 157 which stand upward. Consequently, there is an air layer between the lid 412 and the housing top wall 113. Therefore, there is little heat transfer from the steam generation portion 400 to the housing top wall 113.

[0051] The projecting piece 417 to which the second connecting plate 156 of the second attachment piece 152 is connected includes second fins 418 which project downwards. Since a large part of heat from the steam generation portion 400 is radiated from the second fins 418, there is a small heat amount to be transmitted to the second connecting plate 156. The second upright plate 157 is narrower than the second connecting plate 156. Therefore, there is a small amount of heat transfer from the second connecting plate 156 to the second upright plate 157. Accordingly, there is a small heat amount to be transmitted to the second reinforcing frame 118 and the housing top wall 113 through the second upright plate 157.

[0052] Fig. 7 is a schematic perspective view of the steam generation portion 400 which is connected to the first and second reinforcing frames 117, 118. The attachment of the steam generation portion 400 is described with reference to Fig. 7.

[0053] In Fig. 7, the contour of the housing 110 is represented by a single-dotted line. The first reinforcing frame 117 includes an outer edge 172 near the right wall 115, which extends downwards from the housing top wall 113, and an inner edge 173, which is more distant from the right wall 115 than the outer edge 172 is. The first reinforcing frame 117 further includes a rib 174 which extends downwards from the inner edge 173. The rib 174 is provided with the aforementioned openings 171. The first engagement pieces 155 of the first attachment piece 151 are inserted into the openings 171 and project towards the right wall 115. The first attachment piece 151 is connected along the right edge of the lid 412. Therefore, the steam generation portion 400 is distant appropriately from the right wall 115 of the housing 110 due to the first attachment piece 151. Accordingly, there is little heat transfer from the steam generation portion 400 to the right wall 115.

[0054] The front wall 111 adjacent to the right wall 115 projects downwards from the housing top wall 113. The second attachment piece 152 suspended from the second reinforcing frame 118 bends in the opposite direction to the front wall 111 and is connected to the steam generation portion 400. Therefore, the steam generation portion 400 is distant appropriately from the front wall 111 of the housing 110 due to the second attachment piece 152. Accordingly, the steam generation portion 400 is distant from the housing 110 and is held by the attachment portion 150.

<Steam Generator>

[0055] Figs. 8A and 8B are schematic perspective views of the steam generator 420. The steam generator 420 is described with reference to Figs. 8A and 8B.

[0056] The steam generator 420 includes a substantially rectangular main piece 423, a lid piece 424, which is situated above the main piece 423, and a linear heater 425, which is situated on the main piece 423. In the present embodiment, the main piece 423 and the lid piece 424 are made from aluminium. Consequently, the main piece 423 and the lid piece 424 are heated appropriately by the heater 425.

[0057] The steam generator 420 further includes a thermistor 426. The thermistor 426 is also attached to the main piece 423, in addition to the abovementioned connecting pipe 421, exhaust pipe 422 and heater 425. The heater 425 is controlled by means of the thermistor 426, on the basis of temperature information which is obtained by the thermistor 426. Therefore, the main piece 423 and the lid piece 424 are kept substantially at a certain temperature. Instead of the thermistor 426, a thermostat which controls to turn on and off the heater 425 at a certain temperature may be used to obtain similar effects.

[0058] Fig. 9 is a schematic perspective view of the main piece 423. The main piece 423 is described with reference to Figs. 8B and 9.

[0059] The main piece 423 includes a main piece lower surface 427, to which the connecting pipe 421, the exhaust pipe 422 and the thermistor 426 are attached, a peripheral surface 428, to which the heater 425 is attached, and an upper surface 429 opposite to the main piece lower surface 427. The main piece 423 further includes an outer chamber wall 431, which stands from the upper surface 429 towards the lid piece 424 to define a substantially triangular chamber space 430, and a substantially J-shaped inner chamber wall 432, which defines a flow path of the steam in the chamber space 430.

[0060] Fig. 10 is a schematic exploded perspective view of the steam generator 420. Fig. 11 is a schematic perspective view of the lid piece 424. The steam generator 420 is described with reference to Figs. 2, 3, 8B to 11.

[0061] The steam generator 420 includes a packing ring 433 which is attached to the main piece 423 so as to surround the outer chamber wall 431. The packing ring 433 is made from heat-resistant rubber.

[0062] The lid piece 424 includes a lower surface 434 facing the main piece 423 and an outer shield wall 435 which has substantially the same shape as the outer chamber wall 431. The lid piece 424 is pressed against the main piece 423. Accordingly, the outer shield wall 435 compresses the packing ring 433 to keep the chamber space 430 airtight.

[0063] The main piece 423 is provided with an inflow port 437, through which water supplied via the connecting pipe 421 flows into the chamber space 430. The inflow port 437 formed at substantially the centre of the chamber space 430 is surrounded by the inner chamber wall 432. If the pump 330 supplies a prescribed amount of water to the steam generator 420, the water is injected upwards via the connecting pipe 421 and the inflow port 437. Consequently, the water hits the inner chamber wall 432, the upper surface 429 of the main piece 423, which is surrounded by the inner chamber wall 432, and/or the lower surface 434 of the lid piece 424, which is situated above the inflow port 437. The steam generator 420 is heated by the heater 425 (e.g. to approximately 200°C) so that the steam generator 420 has high thermal energy. The pump 330 which executes intermittent water supply operation supplies a suitable amount of water for the thermal energy of the steam generator 420 (e.g. about 2 cc every dosage). Therefore, the water injected upwards from the inflow port 437 evaporates instantaneously. In the present embodiment, the chamber is exemplified by the chamber space 430 used for generating steam. The wall surface is exemplified by the inner chamber wall 432, the upper surface 429 of the main piece 423, which is surrounded by the inner chamber wall 432, and/or the lower surface 434 of the lid piece 424, which is situated above the inflow port 437 since the water supplied through the inflow port 437 hits the inner chamber wall 432, the upper surface 429 of the main piece 423 and/or the lower surface 434 of the lid piece 424. The second heater is exemplified by the heater 425.

[0064] Impurities contained in water supplied to the steam generator 420 may adhere or be precipitated at water vaporization onto the wall surfaces which form the chamber space 430. Since an internal pressure of the chamber space 430 rises suddenly as a result of the instantaneous evaporation of the water, the adhering or precipitated impurities are easily discharged from the chamber space 430 by an action of a pressure caused at the vaporization.

[0065] As shown in Fig. 2, the steam generator 420 is situated above the storage tub 200. As described above, impurities contained in water, which is supplied to the steam generator 420, may adhere or be precipitated at vaporization onto the wall surfaces forming the chamber space 430 such as the outer chamber wall 431 of the main piece 423, the inner chamber wall 432, the upper surface 429 and the lower surface 434 of the lid piece 424. Accumulation of the impurities worsens thermal conductivity between the wall surfaces and the supplied water. Accordingly, less water evaporates. However, if the steam generator 420 is situated above the storage tub 200, the adhering or precipitated impurities are discharged or drop down below the steam generator 420 under a pressure at the vaporization and the action of gravity. Consequently, the impurities are easily discharged from the chamber space 430 to the storage tub 200. Accordingly, the accumulation of adhering or precipitated impurities inside the chamber of the steam generator 420 is removed appropriately. Therefore, a resultant decline from the accumulation of impurities is less likely to happen to vaporization capability.

[0066] Fig. 12 is a schematic plan view of the main piece 423. The main piece 423 is described with reference to Figs. 8B and 12.

[0067] The heater 425 extends along a substantially U-shaped path inside the main piece 423. Therefore, the heater 425 surrounds the inflow port 437 to which the connecting pipe 421 is connected. Consequently, the inner chamber wall 432 and the region surrounded by the inner chamber wall 432 become the highest temperature in the chamber space 430. Therefore, the water injected through the inflow port 437 evaporates instantaneously.

[0068] Since the substantially J-shaped inner chamber wall 432 extends in the chamber space 430, which is defined by the outer chamber wall 431, the chamber space 430 draws a whorl flow path. The main piece 423 is provided with an exhaust port 438 formed at the terminal end of the flow path. Steam generated in the space surrounded by the inner chamber wall 432 flows towards the exhaust port 438 with an internal pressure rise in the chamber space 430. The exhaust pipe 422 is connected to the exhaust port 438. The steam arriving at the exhaust port 438 is discharged downward through the exhaust pipe 422.

[0069] The heater 425 extends in a U-shape along the outer path of the whorl flow path. Consequently, steam generated in the space surrounded by the inner chamber wall 432 flows towards the exhaust pipe 422 while being heated. Therefore, hot steam is exhausted.

[0070] Since the steam generator 420 injects water onto the heated wall surfaces to evaporate the water instantaneously, it takes less power to generate a certain amount of steam, in comparison with conventional technologies with a heater immersed in water for steam generation.

[0071]  <Water Supply Mechanism>

[0072] Fig. 13 is a schematic view of the water supply mechanism 500. The water supply mechanism 500 is described with reference to Fig. 13.

[0073] The water supply mechanism 500 which injects water into the chamber space 430 of the steam generator 420 includes the aforementioned first supply valve 310, reservoir tank 320, pump 330 and connecting pipe 421. The water supply mechanism 500 further includes a level sensor 321 configured to measure a water level in the reservoir tank 320. The first supply valve 310 may supply water to the reservoir tank 320 or stop the water supply to the reservoir tank 320 in response to the water level detected by the level sensor 321.

[0074] The first supply valve 310 may be controlled in response to an operating time and/or an operation pattern of the pump 330 (the intermittent water supply operation and/or continuous water supply operation). For example, a water dosage from the first supply valve 310 may be adjusted so that the reservoir tank 320 becomes empty at the end of the operation of the pump 330. Therefore, the water is less likely to freeze in the reservoir tank 320.

[0075] The pump 330 supplies water stored in the reservoir tank 320 to the chamber space 430 through the connecting pipe 421. The intermittent water supply operation of the pump 330 is adjusted so as to cause instantaneous evaporation of the water injected into the chamber space 430.

[0076] As a result of the evaporation of the water in the chamber space 430, impurities contained in the water may accumulate inside the chamber space 430. The continuous water supply operation of the pump 330 is adjusted so that water flows into the chamber space 430 at a sufficient flow rate to flush the accumulated impurities.

[0077] The exhaust pipe 422 is connected to the steam conduit 340. Steam generated in the chamber space 430 by the intermittent water supply operation of the pump 330 and water flowing into the chamber space 430 under the continuous water supply operation of the pump 330 flows into the storage tub 200 through the exhaust pipe 422 and the steam conduit 340.

<Supply of Steam and Water to Storage Tub >

[0078] Fig. 14 is a schematic rear view of the front portion 222 of the storage tub 200. Supply of steam and water to the storage tub 200 is described with reference to Figs. 1, 13 and 14.

[0079] As shown in Fig. 1, the annular portion 224 of the front portion 222 includes an inner surface 225 facing the rotary drum 210 and an outer surface 226 facing the front wall 111 of the housing 110. Fig. 14 mainly shows the inner surface 225.

[0080] The steam supply mechanism 300 includes a branching pipe 351 and a nozzle 352 which are fixed to the inner surface 225. The steam supply mechanism 300 further includes a steam tube 353 which connects the branching pipe 351 to the nozzle 352. The steam conduit 340 is connected to the branching pipe 351 via the peripheral wall portion 223.

[0081] Steam generated in the chamber space 430 flows into the steam conduit 340 through the exhaust pipe 422 with a pressure rise inside the chamber space 430. Subsequently, the steam reaches the branching pipe 351 from the steam conduit 340. The nozzle 352 is situated above the branching pipe 351. Since the steam arriving at the branching pipe 351 is hot, the steam is guided to the steam tube 353 and then reaches the nozzle 352. Eventually, the steam is sprayed downwards from the nozzle 352. Accordingly, the steam is blown directly onto the laundry stored in the storage tub 200 via the opening 213 of the rotary drum 210. In the present embodiment, the steam generated in the chamber space 430 is led to the nozzle 352 by the exhaust pipe 422, the steam conduit 340, the branching pipe 351 and the steam tube 353.

[0082] As described above, since the pump 330 injects a suitable amount of water into the hot chamber space 430 under the intermittent water supply operation, the water evaporates instantaneously. Therefore, there is a rapid increase in an internal pressure in the chamber space 430. Consequently, the steam is sprayed at a high pressure from the nozzle 352 so that the steam vertically traverses the internal space of the storage tub 200. Laundry is likely to gather near the lower end of the rotary drum 210 due to the gravity. Since the steam sprayed from the nozzle 352 attached to an upper portion of the storage tub 200 gets around to the lower end of the rotary drum 210, the steam is supplied efficiently to the laundry.

[0083] The branching pipe 351 includes a trunk pipe 354 connected to the steam conduit 340, an upper subsidiary pipe 355, which bends upwards from the trunk pipe 354, and a lower subsidiary pipe 356, which bends downwards from the trunk pipe 354. The steam or water flows into the trunk pipe 354 through the steam conduit 340. The upper subsidiary pipe 355 is connected to the steam tube 353 to define an upward path of the steam towards the nozzle 352.

[0084] Unlike the upper subsidiary pipe 355, the lower subsidiary pipe 356 defines a downward path. The water flowing into the branching pipe 351 through the steam conduit 340 under the continuous water supply operation of the pump 330 flows down via the lower subsidiary pipe 356 due to the action of gravity.

[0085] Fig. 14 shows an included angle θ1 between the trunk pipe 354 and the upper subsidiary pipe 355. Fig. 14 also shows the included angle θ2 between the trunk pipe 354 and the lower subsidiary pipe 356. The included angle θ1 is obtuse whereas the included angle θ2 is acute. Since the included angle θ2 is acute, there is relatively large flow loss from the trunk pipe 354 to the lower subsidiary pipe 356. Therefore, steam flowing into the trunk pipe 354 is less likely to flow into the lower subsidiary pipe 356 so that the steam mainly flows into the upper subsidiary pipe 355. On the other hand, since the upper subsidiary pipe 355 defines an upward flow path, water flowing into the trunk pipe 354 is less likely to flow into the upper subsidiary pipe 355 so that the water mainly flows into the lower subsidiary pipe 356 due to the action of gravity. Consequently, the flow path of the steam is separated from the flow path of the water appropriately.

<Intermittent Pump Operation>

[0086] Fig. 15 is a graph schematically showing a relationship between the intermittent operation of the pump 330 and a temperature in the chamber space 430. The intermittent operation of the pump 330 is described with reference to Figs. 10, 13 and 15.

[0087] As shown in Fig. 15, a time length during which the pump 330 is operated (ON period) is set to be shorter than a time length during which the pump 330 is stopped (OFF period). Consequently, an appropriate amount of water is injected into the chamber space 430.

[0088] A prescribed amount of water is supplied to the chamber space 430 during the ON period. Consequently, the water is evaporated and becomes steam. Vaporization heat resultant from the phase change from water to steam causes a temporal decrease in a temperature in the chamber space 430. Since the OFF period is set to be relatively long as described above, the heater 425 may increase a temperature of the chamber space 430 sufficiently during the OFF period. Therefore, steam supply at a high pressure to the storage tub 200 continues under the intermittent operation of the pump 330. In short, the chamber space 430 is heated sufficiently during the OFF period, and a suitable amount of water for thermal energy of the steam generator 420 including the chamber space 430 is supplied in the ON period to cause instantaneous evaporation (e.g. approximately 2 cc/dosage), so that steam supply at an appropriately high pressure to the storage tub 200 continues.

<Use of Steam in Washing Process>

[0089] Fig. 16 is a schematic block diagram showing various elements of the washing machine 100 used in the washing process. Operations of the washing machine 100 in the washing process are described with reference to Figs. 1, 13 and 16.

[0090] The washing machine 100 includes a controller 122, a water temperature detector 161, and a level detector 162, in addition to the distribution portion 141, the water heater 160 and the heater 425. The water temperature detector 161 detects a temperature of the washing water stored in the storage tub 200. A temperature sensor (not shown) attached to the water tub 220 is exemplified as the water temperature detector 161. The level detector 162 detects a level of the washing water in the storage tub 200. The level detector 162 may be a level sensor (not shown) attached to the water tub 220, a flowmeter attached to a path extending from the second and/or third supply valve 142, 143 to the water tub 220 or a timer for measuring a time period from an opening time at which the second and/or third supply valves 142, 143 are opened. In the present embodiment, the detection element is exemplified by the water temperature detector 161.

[0091] The controller 122 controls the distribution portion 141 to open the second and third supply valves 142, 143 and supply washing water to the storage tub 200. Meanwhile, the controller 122 may heat the steam generator 420 under feedback control between the thermistor 426 and the heater 425.

[0092] Detection signals containing information about a level of the washing water in the storage tub 200 are output from the level detector 162 to the controller 122. The controller 122 determines whether or not the water heater 160 is submerged in the washing water, on the basis of the detection signals from the level detector 162. If the water heater 160 is submerged in the washing water, the controller 122 activates the water heater 160.

[0093]  Detection signals containing information about a temperature of the washing water in the storage tub 200 are output from the water temperature detector 161 to the controller 122. The controller 122 determines whether or not the washing water reaches a first threshold temperature, which is set for the temperature of the washing water, on the basis of the detection signals from the water temperature detector 161. If the washing water becomes the predetermined temperature, the controller 122 stops the water heater 160. The controller 122 then activates the pump 330 (the steam supply mechanism 300: water supply mechanism 500). While the pump 330 is activated, the controller 122 supplies water to the reservoir tank 320 as needed under feedback control between the level sensor 321 and the first supply valve 310.

[0094] Fig. 17 is a schematic flowchart showing control executed to adjust a temperature of the washing water. The control for adjusting a temperature of the washing water is described with reference to Figs. 1, 15 to 17.

(Step S110)

[0095] In step S110, the controller 122 opens the second and/or third supply valves 142, 143 to supply water to the storage tub 200. Step S120 is then executed.

(Step S120)

[0096] Information about a threshold "LTH" defined for a level of the washing water in the storage tub 200 is stored in the controller 122 in advance. In step S120, the controller 122 uses detection signals output from the level detector 162 to compare a level of the washing water in the storage tub 200 with the threshold "LTH". When the level of the washing water exceeds the threshold "LTH", step S130 is executed. Otherwise, step S110 is executed. The threshold "LTH" is set appropriately so that the water heater 160 is submerged in washing water when a level of the washing water exceeds the threshold "LTH". In the present embodiment, the water level represented by the threshold "LTH" is exemplified as the predetermined water level.

(Step S130)

[0097] In step S130, the controller 122 activates the water heater 160. Accordingly, the washing water is heated rapidly. Once the heating of the washing water is started, step S140 is executed.

(Step S140)

[0098] Information about a first threshold temperature "TTH" defined for a temperature of the washing water in the storage tub 200 is stored in the controller 122 in advance. In step S140, the controller 122 uses the detection signals output from the water temperature detector 161 to compare a temperature of the washing water in the storage tub 200 with the first threshold temperature "TTH". If the temperature of the washing water exceeds the first threshold temperature "TTH", step S150 is executed. Otherwise, step S130 is executed. In the present embodiment, the water temperature represented by the first threshold temperature "TTH" is exemplified as the predetermined temperature.

(Step S150)

[0099] In step S150, the controller 122 stops the water heater 160. Step S160 is then executed.

(Step S160)

[0100] In step S160, the controller 122 activates the pump 330. Operation of the pump 330 in step S160 is intermittent, as described with reference to Fig. 15. The intermittent operation of the pump 330 may be continued until the washing process is ended.

[0101] The operation of the pump 330 in step S160 may be controlled in response to a temperature of the washing water. For example, when the water temperature detector 161 detects a temperature, which is lower than a second threshold temperature defined for a temperature of the washing water, the controller 121 may cause the pump 330 to start the intermittent operation. After the pump 330 performs the intermittent operation for a predetermined period of time under the control by the controller 121, the washing water is heated appropriately. If the pump 330 is stopped by the controller 121 after the pump 330 executes the intermittent operation for a predetermined period of time under the control by the controller 121, the pump 330 consumes less power.

[0102] Fig. 18 is a graph schematically showing a change in a temperature of the water supplied to the water tub 220 in the washing process. Effects of steam used in the washing process are described with reference to Figs. 1, 10, 13 and 18.

[0103] As shown in Fig. 18, when the washing process is started, water is supplied to the water tub 220. Meanwhile, a temperature of the water contained in the laundry in the water tub 220 is substantially uniform. The water in the water tub 220 is then heated by the water heater 160. Since a large amount of heat is generated by the water heater 160, the temperature of the water contained in the laundry in the water tub 220 rises rapidly. Heating the water in the water tube 220 is then stopped at a prescribed temperature.

[0104] In Fig. 18, the dotted line shows a change in a temperature of water contained in the laundry after the water heater 160 stops heating the water without steam supply. The solid line shows a change in a temperature of water contained in the laundry after the water heater 160 stops heating with steam supply to the storage tub 200.

[0105] As described above, since hot steam into the storage tub 200 is supplied directly to the laundry, a temperature decrease is less likely to happen to the water contained in the laundry in the water tub 220. The heater 425 used in the steam generator 420 consumes a smaller power amount than the water heater 160 attached to the water tub 220 does. In comparison to maintaining a water temperature in the water tub 220 by means of the water heater 160, the steam supply may achieve smaller power consumption to maintain a temperature. Therefore, it is preferable that the pump 330 carries out the intermittent water supply operation after the water heater 160 stops.

<Usage of Steam in Spin-Drying Process>

[0106] Effects of steam used in the spin-drying process are described with reference to Figs. 1, 13 and 14.

[0107] In the spin-drying process, the rotary drum 210 rotates at high speed. As shown in Fig. 1, the peripheral wall 211 of the rotary drum 210 is provided with a lot of small holes 219. The laundry stored in the rotary drum 210 is pressed against the peripheral wall 211 due to a centrifugal force resultant from rotation of the rotary drum 210. Consequently, moisture contained in the laundry is discharged from the rotary drum 210 through the small holes 219. Therefore, the laundry is suitably spin-dried.

[0108] Fibres of the spin-dried laundry are likely to form hydrogen bonds. The hydrogen bonds between the fibres result in wrinkles in the laundry. If steam is supplied into the rotary drum 210, the steam removes the hydrogen bonds between the fibres. Therefore, there are decreased wrinkles of the laundry. Accordingly, it is preferable that the pump 330 carries out the intermittent water supply operation while the laundry is subjected to the spin-drying process. As a result of the intermittent water supply operation, the steam is sprayed from the nozzle 352 into the rotary drum 210. Since the steam sprayed from the nozzle 352 traverses the storage tub 200 as described above, the steam is blown uniformly onto the whole of the laundry which is stuck over the rotating peripheral wall 211. Therefore, few wrinkles happen to the whole of the laundry in the rotary drum 210.

[0109] Figs. 19A to 19C are schematic timing charts showing steam supply timings during the spin-drying process. The timings of the steam supply is described with reference to Fig. 1, 19Ato 19C.

[0110] As shown in Fig. 19A, the steam supply mechanism 300 may start steam supply a prescribed time period (T1) after the start of the spin-drying process. In this case, since little water is contained in the laundry, the laundry is humidified efficiently by heat and moisture of the steam. As shown in Figs. 19B and 19C, the steam supply mechanism 300 may start steam supply in synchronization with the start of the spin-drying process. In this case, since the laundry is heated at the start of the spin-drying process, the laundry is humidified efficiently at high temperature. As shown in Figs. 19A and 19B, the steam supply mechanism 300 may supply steam during a part of a period of the spin-drying process. As shown in Fig. 19C, the time period during which the steam supply mechanism 300 supplies steam may coincide with the time period from the start to the end of the spin-drying process.

<Cooling of Steam Generator>

[0111] The cooling process of the steam generator 420 is described with reference to Figs. 10 and 13.

[0112] It is preferable that the steam generator 420 is cooled at the end of processing laundry with steam. If the steam generator 420 is cooled, hot steam is prevented from unnecessarily being sprayed into the storage tub 200.

[0113] Power supply to the heater 425 is stopped in order to cool the steam generator 420. The pump 330 then starts the continuous water supply operation. Consequently, water flows into the chamber space 430 continuously from the reservoir tank 320. The water flowing into the chamber space 430 absorbs heat from the steam generator 420, and then flows into the storage tub 200. Therefore, the steam generator 420 is cooled in a short period of time.

[0114] Fig. 20 is a block diagram schematically showing control for the door 120 on the basis of a temperature of the steam generator 420. The control for the door 120 is described with reference to Figs. 1, 8B and 20.

[0115] The washing machine 100 includes a locking mechanism 121, which locks the door 120 at the closed position, and a controller 122 for controlling locking and unlocking of the locking mechanism 121. Mechanical and electrical mechanisms of the locking mechanism 121 may be a structure used in a generally known washing machine.

[0116] As shown in Fig. 8B, the steam generator 420 includes the thermistor 426. The thermistor 426 detects a temperature of the main piece 423 so that signals in correspondence to the detected temperature are output to the controller 122.

[0117] The controller 122 keeps the door 120 locked by the locking mechanism 121 until the signals output from the thermistor 426 indicates that a temperature is no more than a prescribed value. Accordingly, the internal space of the storage tub 200 is isolated from the outside until the steam generator 420 reaches the prescribed temperature or lower. Therefore, the washing machine 100 becomes very safe.

<Second Embodiment>

[0118] Fig. 21 is a schematic exploded perspective view of a steam generator 420A used in the washing machine according to the second embodiment. The washing machine according to the second embodiment has a similar structure to the washing machine 100 according to the first embodiment except for a structure of the steam generator 420A. Therefore, differences from the first embodiment are described below. Except for the differences described below, the description in the first embodiment is applicable to the washing machine according to the second embodiment. Elements which are the same as the first embodiment are labelled with the same reference numerals. Therefore, the description of the first embodiment is also applicable to the elements which are labelled with the same reference numerals.

[0119]  The steam generator 420A includes a main piece 423A, a lid piece 424A, and a packing ring 433 which is sandwiched between the main piece 423A and the lid piece 424A. Unlike the main piece 423 described in the context of the first embodiment, no heater is attached to the main piece 423A. Instead, a heater 425A is attached to the lid piece 424A.

[0120] Fig. 22 is a schematic perspective view of a lid piece 424A. An attachment structure of the heater 425A is described with reference to Figs. 21 and 22.

[0121] The lid piece 424A includes an inner shield wall 436 which is surrounded by an outer shield wall 435. The inner shield wall 436 has substantially the same shape as the inner chamber wall 432 of the main piece 423A. The inner shield wall 436 may overlap with the inner chamber wall 432. Consequently, a whorl flow path is formed in the chamber space 430. A region of the lower surface 434 which is surrounded by the inner shield wall 436 faces the inflow port 437 formed in the main piece 423A. Therefore, the region is called "facing region 439" in the following description. The heater 425A is situated inside the lid piece 424A so as to surround the facing region 439. If a flow rate of the water is adjusted so that water flowing from the inflow port 437 reaches the lid piece 424A, there is instantaneous evaporation since the facing region 439 is a very high temperature.

[0122] The aforementioned embodiments mainly include the following features.

[0123] A washing machine according to one aspect of the aforementioned embodiments includes a storage tub configured to store washing water for washing laundry; a first heater configured to heat the washing water; a steam supply mechanism configured to supply steam to the storage tub; and a controller configured to control the steam supply mechanism and the first heater. The controller actuates the steam supply mechanism after stopping the first heater.

[0124] According to the aforementioned configuration, the storage tub stores washing water for washing laundry. The first heater heats the washing water in the storage tub. Therefore, there is a more effective temperature rise of the washing water in terms of time than techniques which depend on steam to cause a temperature rise.

[0125]  The controller controls not only the first heater but also the steam supply mechanism configured to supply steam to the storage tub. Since the controller actuates the steam supply mechanism after stopping the first heater, the washing water is appropriately kept at a certain temperature. Consequently, the washing machine may show high washing performance over a long period of time.

[0126] In the aforementioned configuration, the controller may actuate the first heater when the washing water exceeds a predetermined water level in the storage tub.

[0127] According to the aforementioned configuration, since the controller actuates the first heater when the washing water exceeds a predetermined water level in the storage tub, the first heater spends a short time to warm the washing water due to the first heater.

[0128] In the aforementioned configuration, the washing machine may further include a detection element configured to detect a temperature of the washing water. The controller may stop the first heater when the temperature detected by the detection element exceeds a first threshold temperature.

[0129] According to the aforementioned configuration, since the controller stops the first heater when the temperature detected by the detection element exceeds the first threshold temperature, the first heater is less likely to consume power excessively. Since the controller actuates the steam supply mechanism after stopping the first heater, the washing water is appropriately kept at a certain temperature. Consequently, the washing machine may show high washing performance over a long period of time.

[0130] In the aforementioned configuration, the steam supply mechanism may include a steam generator with a wall surface defining a chamber for generating the steam, a second heater, which heats the wall surface, and a water supply mechanism, which injects water onto the wall surface. The controller may actuate the water supply mechanism after stopping the first heater.

[0131] According to the aforementioned configuration, since the controller actuates the water supply mechanism after stopping the first heater, water is injected onto the wall surface heated by the second heater. Accordingly, the water supplied from the water supply mechanism is instantaneously evaporated. Therefore, hot steam flows at high speed into the storage tub. Consequently, the steam may efficiently transfer thermal energy to the washing water.

[0132] In the aforementioned configuration, the controller may actuate the steam generation mechanism to supply the steam to the storage tub when the temperature detected by the detection element is lower than a second threshold temperature.

[0133] According to the aforementioned configuration, since the controller actuates the steam generation mechanism to supply the steam to the storage tub when the temperature detected by the detection element is lower than the second threshold temperature, the washing water is appropriately heated by the steam.

[0134] In the aforementioned configuration, the water supply mechanism may include a reservoir tank, which stores the water, and a pump, which supplies the water from the reservoir tank to the steam generator. The controller may actuate the pump after stopping the first heater.

[0135] According to the aforementioned configuration, since the controller actuates the pump after stopping the first heater, water is injected onto the wall surface heated by the second heater. Accordingly, the water supplied from the pump is instantaneously evaporated. Therefore, hot steam flows at high speed into the storage tub. Consequently, the steam may efficiently transfer thermal energy to the washing water.

[0136] In the aforementioned configuration, the controller may actuate the pump intermittently.

[0137] According to the aforementioned configuration, since the controller actuates the pump intermittently, a small amount of water is injected onto the wall surface. Accordingly, the water supplied from the pump is instantaneously evaporated. Therefore, hot steam flows at high speed into the storage tub. Consequently, the steam may efficiently transfer thermal energy to the washing water.

[0138] In the aforementioned configuration, a water supply period, during which the pump supplies the water from the reservoir tank to the steam generator, may be shorter than a time length in which the pump is stopped while the pump operates intermittently.

[0139] According to the aforementioned configuration, a water supply period, during which the pump supplies the water from the reservoir tank to the steam generator, may be shorter than a time length in which the pump is stopped while the pump operates intermittently. Therefore, the wall surface is maintained at a high temperature by the second heater. Accordingly, the water supplied from the pump is instantaneously evaporated. Consequently, hot steam flows at high speed into the storage tub. Therefore, the steam may efficiently transfer thermal energy to the washing water.

Industrial Applicability

[0140] The principles of the aforementioned embodiments may be applied suitably to devices which use steam to process laundry.

Claims

1. A washing machine (100) comprising:

a storage tub (200) configured to store washing water for washing laundry;

a first heater (160) configured to heat the washing water;

a steam supply mechanism (300) configured to supply steam to the storage tub (200); and

a controller (122) configured to control the steam supply mechanism (300) and the first heater (160), wherein

the steam supply mechanism (300) includes a pump (330) configured to supply water for generating the steam, characterized in that

the controller (122) actuates the first heater (160) when the washing water exceeds a predetermined water level in the storage tub (200), and then the steam supply mechanism (300) after stopping the first heater (160) so that the steam is injected to the washing water.

2. The washing machine (100) according to claim 1, further comprising:

a detection element (161) configured to detect a temperature of the washing water, wherein

the controller (122) stops the first heater (160) when the temperature detected by the detection element (161) exceeds a first threshold temperature.

3. The washing machine (100) according to claim 2, wherein
the steam supply mechanism (300) includes a steam generator (420; 420A) with a wall surface (432) defining a chamber (430) for generating the steam, a second heater (425), which heats the wall surface (432), and a water supply mechanism (500), which injects water onto the wall surface (432); and
the controller (122) actuates the water supply mechanism (500) after stopping the first heater (160).

4. The washing machine (100) according to claim 3, wherein
the controller (122) actuates the steam supply mechanism (300) to supply the steam to the storage tub (200) when the temperature detected by the detection element (161) is lower than a second threshold temperature.

5. The washing machine (100) according to claim 3 or 4, wherein
the water supply mechanism (500) includes a reservoir tank (320), which stores the water, the pump (330) supplies the water from the reservoir tank (320) to the steam generator (420; 420A).

6. The washing machine (100) according to claim 5, wherein
the controller (122) operates the pump (330) intermittently.

7. The washing machine (100) according to claim 6, wherein
a water supply period, during which the pump (330) supplies the water from the reservoir tank (320) to the steam generator (420; 420A), is shorter than a time length in which the pump (330) is stopped while the pump (330) operates intermittently.

Ansprüche

1. Waschmaschine (100), umfassend:

einen Aufbewahrungsbottich (200), der konfiguriert ist, Waschwasser für das Waschen von Wäsche aufzubewahren;

eine erste Heizvorrichtung (160), die konfiguriert ist, das Waschwasser zu erwärmen;

einen Dampfzufuhrmechanismus (300), der konfiguriert ist, dem Aufbewahrungsbottich (200) Dampf zuzuführen; und

eine Steuervorrichtung (122), die konfiguriert ist, den Dampfzufuhrmechanismus (300) und die erste Heizvorrichtung (160) zu steuern, wobei der Dampfzufuhrmechanismus (300) eine Pumpe (330) umfasst, die konfiguriert ist, Wasser für das Erzeugen des Dampfes zuzuführen, dadurch gekennzeichnet, dass die Steuervorrichtung (122) die erste Heizvorrichtung (160) betätigt, wenn das Waschwasser einen festgelegten Wasserpegel im Aufbewahrungsbottich (200) übersteigt und anschließend nach dem Anhalten der ersten Heizvorrichtung (160) den Dampfzufuhrmechanismus (300) betätigt, so dass der Dampf in das Waschwasser eingespeist wird.

2. Waschmaschine (100) nach Anspruch 1, ferner umfassend:

ein Erkennungselement (161), das konfiguriert ist, eine Temperatur des Waschwassers zu erkennen, wobei

die Steuervorrichtung (122) die erste Heizvorrichtung (160) anhält, wenn die vom Erkennungselement (161) erkannte Temperatur eine erste Schwellentemperatur übersteigt.

3. Waschmaschine (100) nach Anspruch 2, wobei
der Dampfzufuhrmechanismus (300) einen Dampferzeuger (420; 420A) mit einer Wandfläche (432), die eine Kammer (430) für das Erzeugen des Dampfes definiert, eine zweite Heizvorrichtung (425), die die Wandfläche (432) erwärmt und einen Wasserzufuhrmechanismus (500) umfasst, der Wasser auf die Wandfläche (432) einspeist; und
die Steuervorrichtung (122) den Wasserzufuhrmechanismus (500) nach dem Anhalten der ersten Heizvorrichtung (160) betätigt.

4. Waschmaschine (100) nach Anspruch 3, wobei
die Steuervorrichtung (122) den Dampfzufuhrmechanismus (300) betätigt, um den Dampf dem Aufbewahrungsbottich (200) zuzuführen, wenn die vom Erkennungselement (161) erkannte Temperatur niedriger ist als eine zweite Schwellentemperatur.

5. Waschmaschine (100) nach Anspruch 3 oder 4, wobei
der Wasserzufuhrmechanismus (500) einen Vorratsbehälter (320) umfasst, der das Wasser aufbewahrt, wobei die Pumpe (330) das Wasser vom Vorratsbehälter (320) dem Dampferzeuger (420; 420A) zuführt.

6. Waschmaschine (100) nach Anspruch 5, wobei
die Steuervorrichtung (122) die Pumpe (330) mit Unterbrechungen bedient.

7. Waschmaschine (100) nach Anspruch 6, wobei
ein Wasserzufuhrzeitraum, während dem die Pumpe (330) das Wasser vom Vorratsbehälter (320) dem Dampferzeuger (420; 420A) zuführt, kürzer ist als eine Zeitdauer, in der die Pumpe (330) angehalten wird, während die Pumpe (330) mit Unterbrechungen arbeitet.

Revendications

1. Lave-linge (100) comprenant :

un bac de stockage (200) conçu pour stocker l'eau de lavage destinée à laver du linge ;

un premier chauffage (160) conçu pour chauffer l'eau de lavage ;

un mécanisme d'alimentation en vapeur (300) conçu pour alimenter le bac de stockage (200) en vapeur; et

un dispositif de commande (122) conçu pour commander le mécanisme d'alimentation en vapeur (300) et le premier chauffage (160), dans lequel

le mécanisme d'alimentation en vapeur (300) comprend une pompe (330) conçue pour fournir de l'eau permettant de générer de la vapeur, caractérisé en ce que

le dispositif de commande (122) déclenche le premier chauffage (160) lorsque l'eau de lavage excède un niveau d'eau prédéterminé dans le bac de stockage (200), et ensuite le mécanisme d'alimentation en vapeur (300) après l'arrêt du premier chauffage (160) de manière à ce que de la vapeur soit injectée dans l'eau de lavage.

2. Lave-linge (100) selon la revendication 1, comprenant en outre :

un élément de détection (161) conçu pour détecter une température de l'eau de lavage,

le dispositif de commande (122) arrêtant le premier chauffage (160) lorsque la température détectée par l'élément de détection (161) excède une première température de seuil.

3. Lave-linge (100) selon la revendication 2, dans lequel
le mécanisme d'alimentation en vapeur (300) comprend un générateur de vapeur (420 ; 420A) avec une surface de paroi (432) définissant une chambre (430) destinée à générer de la vapeur, un deuxième chauffage (425) qui chauffe la surface de la paroi (432) et un mécanisme d'alimentation en eau (500) qui injecte de l'eau sur la surface de la paroi (432) ; et
le dispositif de commande (122) déclenche le mécanisme d'alimentation en eau (500) après l'arrêt du premier chauffage (160).

4. Lave-linge (100) selon la revendication 3, dans lequel
le dispositif de commande (122) déclenche le mécanisme d'alimentation en vapeur (300) pour fournir de la vapeur au bac de stockage (200) lorsque la température détectée par l'élément de détection (161) est inférieure à la température du deuxième seuil.

5. Lave-linge (100) selon la revendication 3 ou 4, dans lequel
le mécanisme d'alimentation en eau (500) comprend une cuve de réserve (320), qui stocke l'eau, la pompe (330) fournit l'eau provenant de la cuve de réserve (320) au générateur de vapeur (420 ; 420A).

6. Lave-linge (100) selon la revendication 5, dans lequel
le dispositif de commande (122) déclenche la pompe (330) par intermittence.

7. Lave-linge (100) selon la revendication 6, dans lequel
une période d'alimentation en eau, pendant laquelle la pompe (330) fournit l'eau provenant de la cuve de réserve (320) au générateur de vapeur (420 ; 420A), est plus courte qu'une durée pendant laquelle la pompe (330) est arrêtée pendant que la pompe (330) fonctionne par intermittence.

Drawing