AU749680B2 - Washing machine - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): SANYO ELECTRIC CO., LTD.

Invention Title: WASHING MACHINE r The following statement is a full description of this invention, including the best method of performing it known to me/us: A TITLE OF THE INVENTION Washing Machine FIELD OF THE INVENTION The present invention relates to a washing machine capable of draining wash water in a laundry tub to a high position by a drain pump.

BACKGROUND OF THE INVENTION In South America and Austria, a washing machine capable of draining wash water used for washing to a higher position, (for example, a sink on a cabinet), than the place where the washing machine is set, has been conventionally used. This type of washing machine is provided with a drain pump for sucking out the wash water accumulated in a laundry tub, and the wash water in the laundry tub is pumped by the function of the drain pump and is drained to the higher positioned sink on the cabinet or the like.

oS Such a washing machine is provided with a water level sensor for detecting the water level of the wash water in 20 the laundry tub. An example of the water level sensor is one connected to an air trap formed at the bottom one connected to an air trap formed at the bottom -2of the laundry tub through an air tube, to detect the water level in the laundry tub on the basis of the change in air pressure in the air tube. Consequently, the water level which can be detected by the water level sensor is limited. A water level which is not more than a predetermined lower-limit water level cannot be detected. In a conventional washing machine, therefore, it is judged that the wash water in the laundry tub is all drained at the time point where a previously determined time period has elapsed since the water level sensor detected that the water level in the laundry tub dropped to the lower-limit water level.

15 In the above-mentioned washing machine, however, in a case where laundry is spin-dried after the wash water is drained, wash water wrung out of the laundry may not, in some cases, be satisfactorily drained from the laundry tub. Specifically, when the driving of the drain pump is continued in a state where there is no wash water because the wash water in the laundry tub is all drained within the previously determined time period, air flows into the drain pump, so that the drain pump -3does not sufficiently function by the air flowing thereinto. When the spin-drying is started in the state, the wash water wrung out of the laundry is hard to be drained, so that the water obtained by the spin-drying is accumulated in the laundry tub because the drainage capabilities of the drain pump are decreased by the air flowing thereinto.

Particularly in the intermediate spindrying process carried out between the washing process and the rinsing process, when the water obtained by spin-drying the laundry is not satisfactorily drained, the water obtained by the spin-drying, including a detergent, is accumulated in the laundry tub. A spin-drying tub is rotated in the state, so that bubbles are produced in the water obtained by the spindrying which is accumulated in the laundry tub.

The produced bubbles prevent the spin-drying tub from being rotated. Accordingly, the number of revolutions of the spin-drying tub is not increased to a desired number of revolutions, so that the laundry may not, in some cases, be satisfactorily spin-dried.

Further, the produced bubbles prevent the spin- -4drying tub from being rotated, so that the power consumption of a motor for rotating the spin-drying tub is increased.

SUMMARY OF THE INVENTION At least preferred embodiments of the present invention solve the above-mentioned technical subject, and provide a washing machine capable of satisfactorily draining wash water in a laundry tub by a drain pump.

According to the present invention of the main construction, there is provided a washing machine comprising: an outer tub for storing wash water used for washing, a drainage port 15 formed at the bottom of the outer tub, an inner tub for containing laundry to be washed, provided in the outer tub, a pulsator for agitating laundry provided in the inner tub, a :':*"drain pump for pumping out wash water from the outer tub, the drain pump having a suction port connected to the drainage port of the outer tub and a drainage port connected to a drainage hose which leads water to a higher position, spin-drying performing means for rotating the inner tub and the pulsator at high speed after drainage of wash water in the outer tub, and drainage control means for activating the drain pomp to drain off water being accumulated in the outer tub in making the spin-drying, the drainage control means stops the drain pomp only for a predetermined time period during the spin-drying is being carried out.

When the wash water in the outer tub is all drained, and the drain pump is then driven, the wash water does not flow into the drain pump from the outer tub. Therefore, the drain pump sucks in air, to enter a state where it does .e.not sufficiently function by the air sucked in.

Further, there occurs a state where the wash 15 water is accumulated in the drainage hose for introducing the water pumped by the drain pump to a high position.

In this construction, however, the drain pump is made stopped oyly for a predetermined time period during the spin-drying, so that the wash water accumulated in the drainage hose flows back, and flows into the drain pump.

Even if ,the drain pump does not sufficiently function by sucking in air, therefore, the air sucked in the drain pump is returned to the -6outer tub by the wash water flowing back from the drainage hose. As a result, the state where the drain pump does not sufficiently function by the air sucked in is canceled, so that the drain pump can be returned to its normal state.

Consequently, the wash water wrung out of the laundry by the subsequent spin-drying can be satisfactorily drained by the drain pump, so that the water obtained by spin-drying the laundry is not accumulated in the outer tub.

In intermediate spin-drying performed S: subsequently to the washing, for example, therefore, there is no possibility that bubbles 15 are produced during the spin-drying. Further, there, is no possibility that the bubbling o**prevents the inner tub from being rotated, to cause the problems that the number of revolutions of the inner tub is not increased to a desired number of revolutions, and power required to rotate the inner tub is increased.

In accordance with the invention described in the claim 2, there is provided the washing machine as set forth in the claim 1, wherein the spin-drying performing means rotates the -7inner tub and the pulsator at high speed when the spin-drying is carried out by increasing the number of revolution of them to a predetermined high speed, and the drainage control means controls the drain pump into onstate when the spin-drying is started by the spin-drying performing means, which controls the drain pump into off-state only for a predetermined time period during a rise-time for increasing the number of revolution of the inner tub and the pulsator to the predetermined high speed.

According to this construction, the drain pump is brought into an off state so that the 15 state where the drain pump does not sufficiently function due to the air sucked in is canceled, before a large quantity of wash water wrung out of the laundry by the spin- *drying where the inner tub and the pulsator is rotated at high speed. The drain pump has taken its normal state by the time when the water obtained by the spin-drying is accumlated in the outer tub. Accordingly, the drainage control of the water can be sufficiently made.

In accordance with the invention described -8in the claim 3, there is provided the washing machine as set forth in the claim 2, wherein the spin-drying performing means intermittentry activates the inner tub and the pulsator, for example, for slowly increasing the number of revolution of them to the predetermined high speed.

According to this construction, wash water is not wrung out of the laundry sufficiently because the inner tub and the pulsator is not rotated at high speed during the drain pump is in its off-state. Thus, wash water is not accumulated in the outer tub when the drain pump is in its off-state.

15 In accordance with the invention described in the claim 4, there is provided the washing machine as set forth in the claim 1i, wherein the spin-drying performing means rotates the inner tub and the pulsator at high speed when the spin-drying is carried out by increasing the number of revolution of them to a predetermined high speed, and the drainage control means controls the drain pump into offstate when the spin-drying is started by the spin-drying performing means, which controls -9the drain pump into on-state at a predetermined timing after the spin-drying started.

According to this construction, it is possible for the drain pump to quickly cancel such the state that it does not sufficiently function by the air sucked in, and retain its normal state because the drain pump has been turned off when the spin-drying is started.

Accordingly, the water accumlated during the subsequent spin-drying can be sufficiently drained off.

In accordance with the invention described in the claim 5, there is provided the washing machine as set forth in any one of the claims 1 to 4, further comprising water level detection means for detecting a water level in the outer tub when the water level therein is higher than a lower-limit water level, wherein the spindrying performing means starts the spin-drying 20 at the time point where a predetermined time •oooo period has elapsed since the drainage of water after washing or rinsing from the outer tub by the drain pump, and the water level in the outer tub dropped to the lower-limit water level which is detectable by the water level i detection means.

In accordance with the invention described in the claim 6, there is provided the washing machine as set forth in the claim 5, wherein the time point where a predetermined time period has elapsed since the water level dropped to the lower-limit water level is a predetermind timing at which water in the outer tub is not completely drained yet.

In accordance with the invention described in the claim 9, there is provided the washing machine characterized by comprising: an outer tub for storing wash water used for washing, a drainage port formed at the bottom of the outer tub, an inner tub for containing laundry to be washed, provided in the outer tub, a pulsator for agitating laundry provided in the inner tub, a drain pump for pumping out wash water from the outer tub, the drain pump having a suction port connected to the drainage port of the outer tub and a drainage port connected to a drainage hose which leads water to a higher position, spin-drying performing means for rotating the inner tub and the pulsator at high speed after drainage of wash water in the outer -11tub, drainage control means for activating the drain pump to drain off water being accumulated in the outer tub in making the spin-drying, and water level detection means for detecting a water level in the outer tub when the water level therein is higher than a lower-limit water level, wherein the spin-drying performing means starts the spin-drying at the time point where a predetermined time period has elapsed since the drainage of water after washing or rinsing from the outer tub by the drain pump, and the water level in the outer tub dropped to the lower-limit water level which is detectable by the water level detection means.

15 In accordance with the invention described o.

in the claim 10, there is provided the washing machine as set forth in the claim 9, wherein *e SS the time point where a predetermined time period has elapsed since the water level 20 dropped to the lower-limit water level is a o••oo predetermind timing at which water in the outer tub is not completely drained yet.

According to these constructions above, the spin-drying is started before the wash water in the outer tub is all drained. Therefore, the -12spin-drying can not be made in such a state that the drain pump does not sufficiently function by the air sucked in. Consequently, the wash water wrung out of laundry by the spin-drying can be smoothly drained off by the drain pump.

In accordance with the invention described in the claim 7, there is provided the washing machine as set forth in either one of the claims 5 or 6, further comprising time measuring means for measuring a time period required for the water level in the outer tub 0* 06 to drop from the first water level A to the ~second water level B which are both higher than 15 the lower-limit water level, wherein the spindrying start timing by the spin-drying @0° performing means is determined in a oo 0 relationship with the measured time.

.e In accordance with the invention described bOO• in the claim 8, there is provided the washing machine as set forth in the claim 7, wherein the relationship with the measure time includes making proportional to the measured time.

In accordance with the invention described in the claim 11, there is provided -13the washing machine as set forth in either one of the claims 9 or 10, further comprising time measuring means for measuring a time period required for the water level in the outer tub to drop from the first water level A to the second water level B which are both higher than the lower-limit water level, wherein the spindrying start timing by the spin-drying performing means is determined in a relationship with the measured time.

In accordance with the invention described in the claim 12, there is provided the washing machine as set forth in the claim 11, wherein the relationship with the measured time "00 15 includes making proportional to the measured °ooo..

time.

to i eeoc.

SIn a case where large amount of laundry is contained in the laundry tub, also in a case o where the laundry in the laundry tub has a 20 large amount of wash water soaks thereinto, the 0 0 water level in the outer tub is slowly droping 0 down. In the washing machine of the present invention, however, the timing at which the spin-drying is started is determined in relation to the time period required for the -14water level in the outer tub to drop from the water level to the water level B" thereby making it possible to start the spin-drying immediately before that the water in the outer tub is all drained. In other words, the water is being drained by the drain pump when the spin-drying is started. Therefore, the drain pump does not enter the state where it can not sufficiently function by air sucked in.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view schematically showing the construction of a washing machine according to one embodiment of 15 the present invention; oooo Fig. 2 is a block diagram showing the electrical configuration of the washing machine; Fig. 3 is a timing chart showing a state S 20 where a drain pump and a motor are turned on/off in the drainage process and the spin- S•drying process; Fig. 4 is a diagram showing circumstances in which wash water is moved in the vicinity of a drain pump in the drainage process and the spin-drying process; and Fig. 5 is an illustration for explaining a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a cross-sectional view schematically showing the configuration of an automatic washing machine according to one embodiment of the present invention. The automatic washing machine comprises a boxshaped housing 1 having an opening on its upper 15 surface. On the upper surface of the housing o 1i, an opening/closing cover 2 for opening or closing the opening on the upper surface is mounted. In the housing i, an outer tub 3 in which wash water is to be accumulated is 20 supported by a suspension bar with a spring.

In the outer tub 3, an inner tub 4 in which clothes to be washed can be contained is rotatably provided.

A detergent containing portion 5 in which a detergent used for washing is to be contained -16is formed above the outer tub 3. A water supply line 6 is connected to the detergent containing portion 5. A water supply hose 7 extending from water supply installation, for example, a water faucet is connected to the water supply line 6. A water supply valve 8 composed of an electromagnetic valve, for example, is interposed in an intermediate part of the water supply line 6. Consequently, tap water flowing out from the water supply installation can be supplied to the detergent containing portion 5 by opening the water supply valve 8, and the supply of the tap water to the detergent containing portion 5 can be S15 stopped by closing the water supply valve 8.

oooo The tap water supplied to the detergent Scontaining portion 5 flows into the inner tub 4, and is accumulated in the outer tub 3 through a lot of small holes formed in the 20 inner tub 4.

A drainage port 9 for draining the wash o* o water accumulated in the outer tub 3 outward is formed at the bottom of the outer tub 3. The drainage port 9 is communicated to a suction port of a drain pump 10 provided below the -17outer tub 3 through a connecting pipe 11. A drainage hose 13 extending outward from the housing 1 and having its end inserted into a sink 12 on a cabinet is connected to an outlet of the drain pump 10. Consequently, the wash water accumulated in the outer tub 3 can be drained to the sink 12 through the drainage port 9, the connecting pipe 11 and the drainage hose 13 by driving the drain pump An air trap 14 is provided at one corner of the bottom of the outer tub 3. The air trap 14 is connected to a water level sensor provided in an upper part of the housing 1 through an air tube 16. When the wash water is 15 supplied to the outer tub 3, the wash water enters into the air tube 16 from the air trap S" 14 as the water level of the wash water in the outer tub 3 rises, thereby air pressure rises in the air tube 16. Contrary to this, when the 20 wash water is drained from the outer tub 3, air pressure in the air tube 16 drops as the water -level of the wash water in the outer tub 3 drops. The water level sensor 15 can detect the water level in the outer tub 3 on the basis of the change of the air pressure in the air -18tube 16.

The inner tub 4 also serves as a spindrying tub, and a lot of microscopic holes (dehydration holes) are formed on its peripheral surface. A pulsator 17 for agitating the wash water to produce a water current is provided at the bottom of the inner tub 4. The inner tub 4 and the pulsator 17 are supported so as to be rotatable forward and backward by an output shaft 19 of a bearing 18 provided below the outer tub 3.

A motor 20 for producing a driving force for rotating the inner tub 4 and the pulsator 17 and a transmission mechanism 21 for transmitting torque generated by the motor to the bearing 18 are further provided below the outer tub 3. The transmission mechanism 21 comprises a motor pulley 23 fixed to an output shaft 22 of the motor 20, a pulley 25 fixed to 20 a lower end of an input shaft 24 of the bearing 18, and a belt 26 stretched between the motor pulley 23 and the pulley 25. Consequently, the torque generated by the motor 20 is transmitted to the pulley 25 through the motor pulley 23 and the belt 26, and is further transmitted to -19the bearing 18 through the input shaft 24.

A clutch is contained in the bearing 18, and the output shaft 19 of the bearing 18 is constituted by a double shaft in order that the inner tub 4 and the pulsator 17 can be individually driven. For example, at the time of washing and rinsing, the driving force of the motor 20 is transmitted to the pulsator 17 through the bearing 18. Accordingly, the pulsator 17 is rotated forward and backward, so that a water current is produced in the inner tub 4. At the time of spin-drying, the driving force of the motor 20 is transmitted to both the inner tub 4 and the pulsator 17.

15 Accordingly, both the inner tub 4 and the pulsator 17 are rotated in one direction at high speed, so that laundry in the inner tub 4 is spin-dried by a centrifugal force.

Fig. 2 is a block diagram showing the 20 electrical configuration of the automatic washing machine. The automatic washing machine comprises a microcomputer 30 for controlling the operation of each of the portions of the washing machine. The microcomputer 30 contains a ROM 31 storing an operation program of each 0* of the portions of the washing machine, a RAM 32 functioning as a work area when the program stored in the ROM 31 is executed, and a timer 33 for measuring operation time or the like.

A water level sensor 15 for detecting the water level in the outer tub 3 is connected to the microcomputer 30, so that a detection signal of the water level sensor 15 is inputted thereto.

The water supply valve 8, the drain pump and the motor 20 are connected to the microcomputer 30. The microcomputer controls the opening or closing of the water supply valve 8 and controls the on/off of the 15 drain pump 10 and the motor 20 in accordance with the program stored in the ROM 31 on the basis of an input signal from the water level sensor Fig. 3 is a timing chart showing the on/off states of the drain pump 10 and the motor 20 in the drainage process and the spin-drying process. Fig. 4 is a diagram showing circumstances in which the wash water is moved in the vicinity of the drain pump 10 in the drainage process and the spin-drying process.

*0 @0 *o 0 o 0 0* 00 0000 0 0 0 0 0 0 00* 0* 00* 00 00 0 0000 O 0 0 0 0f ft* tf gotf -21- When the laundry is contained in the inner tub 4 by a user, and a start key disposed on the upper surface of the housing 1, for example, is then depressed, to start a washing operation, a suitable amount of wash water is accumulated in the outer tub 3, so that the washing process is first carried out. When the washing process is terminated, the drain pump is turned on in order to drain the wash water in the outer tub 3, so that the drainage process is started (tl, see Fig. 4 While the drainage process is being executed, an output of the water level sensor 15 is always referred to by the microcomputer 15 30, and it is always examined whether or not the water level in the outer tub 3 drops to a lower-limit water level C which can be detected by the water level sensor 15. When it is detected that the water level in the outer tub 3 drops to the lower-limit water level C (t2), an added drainage time T which has been previously set and stored in the ROM 31 is set in the timer 33, so that the measurement of the added drainage time T is started.

The added drainage time T is set to a time 0 00 o 0 oo 0o °ooo o.: o 0 0 0000 -22period necessary-and-sufficient for the wash water accumulated to the lower-limit water level C in the outer tub 3 to be completely drained from the outer tub 3 by the drain pump 10. At the time point where the added drainage time T has elapsed since the water level in the outer tub 3 dropped to the lower-limit water level C, therefore, the drainage of the wash water accumulated in the outer tub 3 is completed (see Fig. 4 The motor 20 is turned on in response to time-up of the timer 33, so that the spin-drying process for removing the wash water included in the laundry is started (t3).

15 In the spin-drying process, the motor 20 is *°*ooo intermittently driven, to slowly start the 9* rotation of the inner tub 4 (intermittent spindrying), and the motor 20 is then continuously driven, to rotate the inner tub 4 at high 20 speed, so that the laundry is spin-dried.

Specifically, the on/off of the motor 20 is repeated in a period of six(6) seconds/ four(4) seconds, for example, for a predetermined time period (t3-t6) elapsed since the spin-drying process was started. Consequently, the -23rotation of the inner tub 4 is slowly started, so that the laundry in the inner tub 4 is pressed against an inner peripheral surface of the inner tub 4 without being unevenly distributed in the inner tub 4. After an elapse of the predetermined time period since the spin-drying process was started (t6) the motor 20 is continuously driven only for a previously set time period, so that the laundry in the inner tub 4 is spin-dried.

As also described in the prior art, in the washing machine capable of draining the wash water by the drain pump 10, when the wash water in the outer tub 3 is completely drained within 15 the added drainage time T, the drain pump St.oo ~sucks in air, so that the drain pump 10 does Ott S not sufficiently function by the air sucked in.

When the laundry is spin-dried in that state, e the wash water wrung out of the laundry is not 20 satisfactorily drained, so that the water obtained by the spin-drying is accumulated in 4* the outer tub 3.

In the present embodiment, therefore, the drain pump 10 is turned off for a predetermined time period (for example, two(2) to four(4) -24seconds) at predetermined timing after starting the spin-drying process, so that the air flowing into the drain pump 10 is removed, to return the state of the drain pump 10 to its normal state. Specifically, the drain pump is turned off after an elapse of a predetermined time period since the spin-drying process was started (t4) after the drainage process was terminated. The drain pump 10 is brought into an off state only for a predetermined off time, for example, four(4) seconds, and is then switched to an on state again (t5) As hatched in Fig. 4 in a state where

SS

15 the wash water accumulated in the outer tub 4 is all drained, and the drain pump 10 is then further driven, because there is no wash water flowing into the drain pump 10, so that the S 4 wash water is accumulated in the drainage hose 20 13 extending from the drain pump 10 to the sink oboe 12. When the drain pump 10 is turned off after •the spin-drying process is started, therefore, the wash water accumulated in the drainage hose 13 flows back, and flows into the drain pump 10. Even if the drain pump 10 does not sufficiently function by sucking in air, therefore, the air sucked in by the drain pump is returned to the outer tub 3 by the wash water flowing back from the drainage hose 13 (see Fig. 4 As a result, a state where the drain pump 10 does not sufficiently function by the air sucked in is canceled, so that the drain pump 10 is returned to its normal state.

Consequently, the wash water wrung out of the laundry after that can be satisfactorily drained by the drain pump 10, so that the water obtained by spin-drying the laundry is not e accumulated in the outer tub 3. Accordingly, 15 there is no possibility that bubbles are produced during the spin-drying process as in the conventional washing machine. Further, there is no possibility that the bubbling prevents the inner tub 4 from being rotated, to .ee.

20 cause the problems that the number of 0a..

revolutions of the inner tub 4 is not increased to a desired number of revolutions, and the power consumption of the motor 20 for rotating the inner tub 4 is increased.

The timing at which the drain pump 10 is -26turned off in order to solve the state where the drain pump 10 does not sufficiently function by the air sucked in is preferably the timing at which the number of revolutions of the motor 20 reaches 200 to 300 rpm, for example. By turning the drain pump 10 off at this timing, the state where the drain pump does not sufficiently function by the air sucked in can be reliably canceled before the bubbles are produced in the outer tub 3.

The timing at which the drain pump 10 is turned off in order to cancel the state where the drain pump 10 does not sufficiently function by the air sucked in needs not necessarily to be the timing after starting the spin-drying process. If the drain pump 10 is turned on again after starting the spin-drying process (after turning on the motor 20), the drain pump 10 may be turned off after the water 20 level in the outer tub 3 drops to the lowerlimit water level C which can be detected by the water level sensor 15 and before the spindrying process is started.

Furthermore, although in the present embodiment, a case where the number of times -27the drain pump 10 is turned off only once during the spin-drying process is taken as an example, the drain pump 10 may be turned off several times. For example, when the torque generated by the motor 20 is relatively small, while the drainage capabilities of the drain pump 10 are relatively high, the amount of the wash water wrung out of the laundry is small particularly when the motor 20 is started, resulting in the possibility that the drain pump 10 which has left once the state where it does not sufficiently function by the air sucked in does not sufficiently function by sucking in air again. In such a case, therefore, it is preferable that the drain pump is turned off a plurality of times during the spin-drying process, preferably before the inner tub 4 is rotated at high speed.

Consequently, it is possible to prevent the drain pump 10 from being continuously driven in the state where it does not sufficiently function by the air sucked in.

Fig. 5 is an illustration for explaining a second embodiment of the present invention. In Fig. 5, portions respectively corresponding to p.

p p p.

I

(I

-28the portions shown in Fig. 1 are assigned the same reference numerals and hence, the detailed description thereof is not repeated.

The feature of the second embodiment is not that a state where a drain pump 10 does not sufficiently function by sucking in air is canceled during the spin-drying process as in the above-mentioned first embodiment but that the spin-drying process is started after the water level in an outer tub 3 drops below the bottom surface of an inner tub 4 and before wash water accumulated in the outer tub 3 is completely drained, to prevent the drain pump 10 from entering a state where it does not 15 sufficiently function by sucking in air.

Specifically, when the drain pump 10 is turned on after the washing process is terminated, for example, the drainage of the 9 wash water accumulated in the outer tub 3 is started, so that the water level in the outer tub 3 starts to drop. When the water level in the outer tub 3 drops to a previously determined start water level A (see Fig. the measurement of an elapsed time period after that is started, and a time period -29elapsed until the water level in the outer tub 3 reaches a predetermined stop water level B (see Fig. 5 is measured.

A time period required for the water level in the outer tub 3 to drop from the start water level A to the stop water level B is measured in order to suitably set a delay time elapsed from the time when the water level in the outer tub 3 drops to not more than a lower-limit water level C which can be detected by a water level sensor 15 (see Fig. 1) until the spindrying process is started on the basis of the measured time period.

Circumstances in which the wash water is drained vary depending on the condition of the laundry contained in the inner tub 4. That is, in a case where laundry superior in water absorption is contained and a case where a large amount of laundry is contained, a large amount of wash water soaks into the laundry, so that it takes long to drain the wash water. On the other hand, when laundry inferior in water absorption is contained in the inner tub 4, the wash water is drained in a short time.

It is possible to judge the condition of

S

the laundry contained in the inner tub 4 by measuring a time period required for the water level in the outer tub 3 to drop from the start water level A to the stop water level B. The condition of the laundry in the inner tub 4 is judged, so that the delay time can be set to a time period during which the spin-drying process is started after the water level in the outer tub 3 drops below the bottom surface of the inner tub 4 and before the wash water accumulated in the outer tub 3 is completely drained.

When the delay time is thus set, a motor (see Fig. 1) for rotating the inner tub 4 is turned on at the time point where the set delay time has elapsed since the water level in the outer tub 3 reached the lower-limit water level C (see Fig. 5 At this time, as hatched in Fig. 5 a small amount of wash water remains in the outer tub 3, thereby eliminating the possibility that the spin-drying process is started in a state where the drain pump 10 does not sufficiently function by sucking in air.

Consequently, the wash water wrung out of the laundry during the spin-drying process can be -31satisfactorily drained by the drain pump Therefore, the same effect as that in the above-mentioned first embodiment can be produced.

Although description was made of the two embodiments of the present invention, the present invention is not limited to the abovementioned two embodiments. For example, in each of the above-mentioned embodiments, description was made by taking as an example control at the time of the drainage process and the intermediate spin-drying process which are carried out between the washing process and the rinsing process, the present invention may be 15 applied to control at the time of the drainage process and the final spin-drying process which are carried out after the rinsing process.

The present invention can be widely applied to an automatic washing machine comprising a 20 drain pump and draining wash water in an outer tub to a high position by the drain pump. For example, the present invention may be applied to a double-sink type washing machine which has an automatic sink capable of performing washing, rinsing and spin-drying and an -32auxiliary laundry tub having a pulsator arranged on its side surface and capable of performing washing and rinsing provided adjacent to each other.

In addition thereto, various design changes can be made in the range of the technical matters described in the scope of Claim for Patent.

In the claims which follow and in the preceding summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

of the invention.

e

Claims (11)

1. A washing machine comprising: an outer tub for storing wash water used for washing, a drainage port formed at the bottom of the outer tub an inner tub for containing laundry to be washed, provided in said outer tub a pulsator (17) for agitating laundry provided in the inner tub a drain pump (10) for pumping out wash water from the outer tub the drain pump having a suction port connected to the drainage port of said outer tub and a 15 drainage port connected to a drainage hose (13) which leads water to a higher position, spin-drying performing means (20, 30) for rotating the inner tub and the pulsator (17) at high speed after drainage of wash water in the outer tub and drainage control means (30) for activating the drain pomp (10) to drain off water being accumulated in the outer tub in making the spin-drying, -34- said drainage control means (30) stops the drain pomp (10) only for a predetermined time period during the spin-drying is being carried out.

2. The washing machine as set forth in claim 1, wherein said spin-drying performing means (20, rotates the inner tub and the pulsator (17) at high speed when the spin-drying is carried out by increasing the number of revolution of them to a predetermined high speed, and said drainage control means (30) controls the drain pump (10) into on-state when the spin-drying is started by said spin-drying performing means (20, 30), which controls the drain pump (10) into off-state only for a predetermined time period during a rise-time for increasing the number of revolution of the inner tub and the pulsator (17) to the predetermined high speed. e• S.

3. The washing machine as set forth in claim 2, wherein said spin-drying performing means (20, intermittentry activates the inner tub and the pulsator for example, for slowly increasing the number of revolution of them to the predetermined high speed.

4. The washing machine as set forth in claim 1, wherein said spin-drying performing means (20, rotates the inner tub and the pulsator (17) at high speed when the spin-drying is carried out by increasing the number of revolution of them to a predetermined high speed, and said drainage control means (30) controls the drain pump (10) into off-state when the 15 spin-drying is started by said spin-drying performing means (20, 30), which controls the drain pump (10) into on-state at a predetermined timing after the spin-drying started. The washing machine as set forth in any one of claims 1 to 4, further comprising water level detection means (15) for detecting a water level in said outer tub (3) when the water level therein is higher than a -36- lower-limit water level, wherein said spin-drying performing means (20, starts the spin-drying at the time point where a predetermined time period has elapsed since the drainage of water after washing or rinsing from the outer tub by the drain pump and the water level in the outer tub (3) dropped to the lower-limit water level which is detectable by said water level detection means S 15 S S S S. S. S

6. The washing machine as set forth in claim wherein said the time point where a predetermined time period has elapsed since the water level dropped to the lower-limit water level is a predetermind timing at which water in the outer tub is not completely drained yet. S S S

7. The washing machine as set forth in claims 5 or 6, further comprising Time measuring means for measuring a time period required for the water level in the outer tub to drop from the first water level A to the second water level B which are -37- both higher than the lower-limit water level, wherein the spin-drying start timing by said spin- drying performing means is determined in a relationship with the measured time.

8. The washing machine as set forth in claim 7, wherein the relationship with the measure time includes making proportional to the measured time.

9. A washing machine comprising: an outer tub for storing wash water used for washing, *0 15 a drainage port formed at the bottom of the outer tub an inner tub for containing laundry to be washed, provided in said outer tub a pulsator (17) for agitating laundry 20 provided in the inner tub a drain pump (10) for pumping out wash a water from the outer tub the drain pump having a suction port connected to the drainage port of said outer tub and a drainage port connected to a drainage hose (13) -38- which leads water to a higher position, spin-drying performing means (20, 30) for rotating the inner tub and the pulsator (17) at high speed after drainage of wash water in the outer tub drainage control means (30) for activating the drain pump (10) to drain off water being accumulated in the outer tub in making the spin-drying, and water level detection means (15) for detecting a water level in said outer tub (3) when the water level therein is higher than a lower-limit water level, wherein :said spin-drying performing means (20, 15 starts the spin-drying at the time point where a predetermined time period has elapsed since S the drainage of water after washing or rinsing from the outer tub by the drain pump and the water level in the outer tub (3) 20 dropped to the lower-limit water level which is detectable by said water level detection means .i The washing machine as set forth in claim 9, wherein -39- said time point where a predetermined time period has elapsed since the water level dropped to the lower-limit water level is a predetermind timing at which water in the outer tub is not completely drained yet.

11. The washing machine as set forth in claims 9 or 10, further comprising time measuring means for measuring a time period required for the water level in the outer tub to drop from the first water level A to the second water level B which are both higher than the lower-limit water level, 6 wherein 15 the spin-drying start timing by said spin- drying performing means is determined in a relationship with the measured time.

12. The washing machine as set forth in claim 20 11, wherein the relationship with the measured time includes making proportional to the measured time.

13. A washing machine substantially as herein described with reference to the accompanying drawings. Dated this 21st day of June 1999 SANYO ELECTRIC CO.. LTD. By their Patent Attorneys GRIFFITH HACK