Drum type drying/washing machine

Abstract: A drum type drying/washing machine performs drying without the flow of cooling water during a predetermined period of time or a period of time determined in accordance with an amount of clothes, and after the passage of the period of time, the machine starts the flow of the cooling water so as to perform drying with cooling-dehumidication. The drum type drying/washing machine, at the initial stage in the drying operation, also performs not only heating clothing but also rotating a drum at a high speed to dehydrate the clothing. A drum type drying/washing machine rotates a drum at an almost maximum rotational rate at which, in a low speed rotation, materials to be processed can roll over in the drum, or at a rotational rate above which, in the low speed rotation, the materials to be processed as a whole stick to the inner peripheral wall of the drum, and the drum is accelerated to a high speed rotation only when output from an unbalance detecting device is a predetermined level or less.

Description: BACKGROUND OF THE INVENTION (1) Field of the Invention The present invention relates to a drum type drying/washing machine which is able to perform washing and drying of laundry, and holds the laundry in a rotatable drum and dries it by cooling-dehumidification using cooling water while performing dehydration by a high speed rotation of the drum. Further, the present invention relates to a drum type drying/washing machine that performs washing and dehydrating (and optionally drying) fabrics such as clothes etc., as well as that only performs a drying operation. (2) Description of the Prior Art In conventional drum type driers, for example, drum type fully automatic drying/washing machines, a method called 'cooling-dehumidification' has been known in which drying is performed by using air ventilation, heating and water cooling as soon as the drying operation is started. In a known drum type drying/washing machine, detergent and water are supplied after laundry has been loaded to the loading port for laundry. Then, after washing, the washing liquid is drained and dehydrated. Subsequently, the laundry is supplied with water, rinsed and dehydrated. At the final stage, the laundry undergoes the heat drying treatment using a heater. A high-temperature, low-humidity air which is obtained by the heat treatment using the heater is supplied into the drum through an orifice located above the loading port of the drum type drying/washing machine so that, whilst the laundry is heated, damp contained in the laundry is removed to be exhausted from the drum. The exhausted air which now has become of high temperature and high humidity is transported through a duct around which cooling water is supplied from above the duct, so that the moisture in this air is condensed by the cooling water, thus the air becomes of low temperature and low humidity. This air is further sucked out by a fan to the drying heater. The thus delivered air is heated to be of high temperature and low humidity, then is blown into the drum through a blower port. The above conventional drum type drying/washing machine, however, needed a long running time. Specifically, for drying/washing a 2kg laundry load, it took 162 min. in total, 72 min. for washing and 90 min. for drying. For a 3kg laundry load, it took 222 min. in total, 80 min. for washing and 142 min. for drying. Japanese Patent Application Laid-Open Sho 61 No. 234897 has proposed an idea in which the dehydration rate is increased by taking in hot air which is discharged from a clothing drier into the dehydrating container of a two-tub washing machine. However, this proposal is not practical. DE 30 17 109 and EP-A-0 684 335 both disclose a drum type machine performing both washing and drying. In the drying phase the drum is briefly accelerated to an intermediate spin speed and then returned to normal drying speed. The above problem is not limited to the scope of the drum type washing machines, but drum type driers dedicated only to drying as well as other drum type rotary processing apparatuses have suffered from similar problems. The expression "drum type drying/washing machine" as used herein covers these various kinds of machine. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a drum type drying/washing, machine which is improved in the efficiency of dehydration in order to shorten the time for drying. In accordance with the invention, there is provided a drum type drying/washing comprising: a drum for accommodating laundry and having a number of holes on the peripheral wall thereof and a baffle for agitating laundry; an outer tank enclosing said drum and supporting said drum rotatably about a horizontal axis; a driving means for imparting driving force to rotate said drum in normal and reverse directions; a heating means for heating air to be supplied to said drum; and a control means for controlling said driving means to rotate said drum at at least two levels of low and high rotational speeds during a drying operation; characterized in that said control means is arranged to control said heating means so that when during said drying operation the drum is rotated at said high rotational speed the heating means temporarily operates at a reduced power output. Preferably, the control means is arranged to cause said drum to be rotated for a predetermined period of time at said high rotational speed once or a plurality of times at an initial stage of the drying operation in order to dehydrate the laundry which has been heated by warm air. In an embodiment the control means is arranged to control the driving means so that after the completion of the dehydration by the high speed rotation, said drum is stopped, or is rotated in the reverse direction at a low speed in order to separate the laundry sticking to the peripheral wall of said drum. With this configuration of the drum type drying/washing machine, it is possible to shorten the time for drying using such a simple method that the drum is made to rotate at a high speed at the initial stage of the drying and heating operation. In this configuration, the motor and other components for rotating the drum are unlikely to be loaded because the drum is merely rotated at a high speed at the beginning of the drying and heating operation. The drum is stopped for a while after the high speed rotation, and it is then rotated in a reverse direction for some time. Therefore, the clothes will not stick to the drum and thus it becomes possible to perform the drying operation efficiently. Also, the dehydration operation is performed on laundry heated by warm air so as to lower the viscosity of water in the wet laundry. Accordingly, the laundry can be dehydrated more effectively as compared with the efficiency of unheated dehydration at a similar level of a rotational rate, and thus it is possible to shorten the time for drying. Some preferred embodiments of the invention will now be described by way of example with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall perspective view showing an embodiment of a drum type drying/washing machine of the invention; Fig. 2 is an overall sectional side elevation showing the drum type drying/washing machine of Fig. 1; Fig. 3 is a circuit block diagram for a drum type drying/washing machine of the invention; Fig. 4 is a time chart for a drum type drying/washing machine of the invention; Fig. 5 is a chart showing a relation between the pre-selected time and the determined amount of clothing in accordance with an embodiment of a drum type drying/washing machine of the invention; Fig. 6 is a chart showing a relation between the pre-selected time and the determined amount of clothing in accordance with another embodiment of a drum type drying/washing machine of the invention; Fig. 7 is an overall perspective view showing another embodiment of a drum type drying/washing machine of the invention; Fig. 8 is a schematic wiring diagram showing another embodiment of a drum type drying/washing machine of the invention; Fig. 9 is a graph showing change in the surface temperature of laundry with the passage of time during the drying operation; Fig. 10 is a graph showing how a viscosity of water will change depending on the temperature; Fig. 11 is an overall perspective view showing another embodiment of a drum type drying/washing machine of the invention; Fig. 12 is an overall sectional side elevation showing a drum type drying/washing machine of Fig. 11; Fig. 13 is a circuit block diagram showing a relation between a control circuit and peripheral devices of a drum type drying/washing machine of Fig. 11; and Fig. 14 is a graph showing change in the exhausted air temperature from the drum of Fig. 11 with the passage of time. DESCRIPTION OF THE PREFERRED EMBODIMENT One embodiment of the drum type drying/washing machine of the invention will hereinbelow be described with reference to the accompanying drawings. As shown in Figs.1 and 2, a drum type drying/washing machine of the invention includes a cylindrical water tank 2 which is elastically supported inside a machine body 1; and a cylindrical drum 3 which is supported in the water tank 2, rotatably by a shaft 6 provided on the back side of the water tank 2 and accommodates laundry and rotates on the shaft. Since the washing mechanism used in the drum type drying/washing machine of the embodiment is of a well-known type, the mechanism of drying will in particular be explained in detail. The drum 3 is formed with an exhaust duct 7 on which an exhausted air temperature sensor 8 is provided. The drum 3 further has an intake duct 9, on which an intake air temperature sensor 10 is provided. A controlling device 24 including a microcomputer (CPU) is disposed in the front part of the drum type drying/washing machine body 1. This controlling device controls the washing operation in accordance with input which is imparted through control keys (control switch) 20 of a control panel disposed on the front side of the machine body 1, output signals from various sensors such as exhausted air temperature sensor 8 and intake air temperature sensor 10 etc., as well as an internal timer. As shown in a block diagram of Fig.3, a control circuit 30 in controlling device 24 receives signals from exhausted air temperature sensor 8, intake air temperature sensor 10, switch 20 for selecting the type of clothing etc., a water level switch 29, a lid switch 31 and a tachometer 32, and controls a drum motor 4, a fan motor 14 (a blower fan 13), a low-mode heater 11, a high-mode heater 12, a drain pump 15, a cooling water solenoid valve 19 and a water supply solenoid valve 18. In Fig.2, the drying/washing machine further has a filter 16 for trapping lint etc. from waste water, a supply hose 21, a drain hose 22, a lid 23, a detergent supplying port 25, a spring 26 and a shock absorber 27. In Fig.3, the control system further has a rectifier circuit 33, an AC power supply 34, a driver 35, a driving circuit 36, a display circuit 37 and a buzzer circuit 38. In the above configuration, when laundry is loaded into the drum 3 through a clothing loading port 5 and the washing operation is started, the drum 3 is made to rotate at a high speed and then is stopped so that the weight of clothing in the drum 3 can be estimated by measuring the duration of the continuation of the rotation due to the inertia of the drum 3 until it stops. Then, water is supplied by releasing the water supply solenoid valve 18, and thereafter the drum 3 is rotated by means of the drum motor 4, to start the washing operation, which is followed by subsequent rinsing and dehydrating operations. When the operation enters the drying stage, the low-mode heater 11 and the high-mode heater 12 are turned on the electricity with the cooling water solenoid valve 19 closed and the drum 3 starts rotation at a low speed (50 rpm. in this embodiment). A circulating gas is circulated by the operation of the fan motor 14 through the passage of the low-mode heater 11, the high-mode heater 12, the drum 3 and the exhaust duct 7, in this order, so as to heat the clothing inside the drum 3 to evaporate the moisture. Next, when the temperature detected by the exhausted air temperature sensor 8 has reached a pre-selected temperature A (50 °C in this embodiment) or more, the high-mode heater 12 will be turned off to halve the power consumption while the drum 3 will be rotated at a high speed (1,000 rpm. in this embodiment) so that water in the clothing which is reduced in viscosity by heating will be centrifugally dehydrated for a predetermined time D (10 min. in this embodiment). After the predetermined time D has passed, the rotational rate of the drum 3 will be restored to the low speed, and the high-mode heater 12 will be turned on again so that the clothing inside the drum 3 will be heated and water can be evaporated. Then, when the temperature detected by the exhausted air temperature sensor 8 has reached a pre-selected temperature B (60 °C in this embodiment) or more, or when the temperature detected by the intake air temperature sensor 10 has reached a pre-selected temperature C (110 °C in this embodiment) or more, the drain pump 15 will be activated and the cooling water solenoid valve 19 will be opened so as to initiate the flow of the cooling water. A high-humidity circulating air that contains water vapor which was evaporated from the clothing and delivered from the exhaust port of the drum 3 enters a cooling dehumidication chamber 17 where the circulating air is made in contact with the cooling water and cooled. In this process, water vapor in excess of the saturated vapor is condensed to drops of water so that the water is discharged outside from the drum type drying/washing machine body 1 through a drain port 28 disposed at the bottom of the cooling dehumidication chamber 17. Thus, the clothing can be dried by dehumidifying the circulating air. In this case, tap water is used as the cooling water and is sprayed to the circulating air inside the cooling dehumidication chamber 17. In the course of the drying process, whenever a pre-selected time E (which will be determined depending upon the amount of clothing as shown in Fig.5, in this embodiment) elapses from the end of the high speed rotation operation, the high-mode heater 12 will be turned off to halve the power consumption while, with the cooling water solenoid valve 19 closed, the drum 3 will be rotated at a high speed (1,000 rpm. in this embodiment) for a pre-selected time F (3 min. in this embodiment) in order to centrifugally dehydrate water from the clothing, whose viscosity has been reduced by heating, and relocate the clothing inside the drum. Next, when the temperature detected by the exhausted air temperature sensor 8 has reached a pre-selected temperature G (65 °C in this embodiment) or more, the high-mode heater 12 will be turned off to halve the power consumption while the cooling water solenoid valve 19 will be opened and closed alternately at intervals of a pre-selected time (in this embodiment, the valve is alternately opened for 1 min. and closed for 1 min.) so as to allow intermediate flowing of cooling water. When the temperature detected by the exhausted air temperature sensor 8 has reached a pre-selected temperature H (70 °C in this embodiment) or more, or when the temperature detected by the intake air temperature sensor 10 has reached a pre-selected temperature (120 °C in this embodiment) or more, the drying of clothing will be judged as complete and the drying operation will be finished by turning off the low-mode heater 11, stopping the fan motor 14, shutting out the cooling water solenoid valve 19, stopping the drain pump 15, and stopping the drum motor 4. Fig. 4 shows a time chart of the drying operation described above. Next, description will be made of another embodiment of a drum type drying/washing machine in accordance with the invention. In the above embodiment, in the course of the drying process, whenever a pre-selected time E (15 min. in this embodiment) elapses from the end of the high speed rotation operation, the high-mode heater 12 will be turned off to halve the power consumption while, with the cooling water solenoid valve 19 closed, the drum 3 will be rotated at a high speed (1,000 rpm. in this embodiment) for a pre-selected time F (3 min. in this embodiment). However, in this embodiment, the high speed rotation operation will be performed whenever a pre-selected time which is determined depending upon the amount of clothing as shown in Fig. 6 passes. In the above embodiment, although the description was made of the drum type fully automatic machine which performs both washing and drying, it is also possible to apply the invention to a drum type drier which only performs drying. Particularly, the present invention should not be limited to the mode of the above embodiment. Another embodiment of a drum type drying/washing machine of the invention will hereinbelow be described with reference to the drawings. Fig.7 is a schematic perspective diagram view showing a structure of the embodiment of a drum type drying/washing machine of the invention. In Fig.7, a reference numeral 41 designates a fan, 42 a motor, 43 a duct, 44 a drying heater, 45 a hot-air blower port, 46 a sealer, 47 a drum, 48 an outer tank, 49 a duct, 50 a water supply valve, 51 a detergent supplying port, 52 a condensation branch hose, 53 a water-cooling dehumidication hose, 54 a check valve, 55 a filter, 56 a drain pump, 57 a circulating pump, 58 a drain hose, 59 a nozzle, 60 a drum type drying/washing machine body, and 61a, 61b and 62 bellows hoses. Wound around the outer periphery of the drum 47 which accommodates laundry and rotates is a drum rotating belt for transmitting a rotational force from a drum rotating motor, so that the drum will rotate at about 50 to 60 rpm. for drying/washing and will revolve at about 1,000 rpm. for dehydration. The outer tank 48 is attached around the drum 47 so that no water will leak. The sealer 46 for protecting leakage of water is attached on the front side between the laundry loading port and the drum 47. Attached to the outer tank 48 is the bellows hose 61a for draining and circulating washing water as well as the bellow hose 61b for circulating a drying air. The bellow hose 61a to be used to drain and circulate washing water is attached to the filter 55 for trapping lint, dust etc., scattered in the water. The drain pump 56 and the drain hose 58 to be used for draining washing water and dehydrating are attached to one side of the filter 55. Attached on the other side of the filter 55 are the circulating pump 57 and the nozzle 59 for circulating washing water during washing so that washing water can forcibly be blown upon the laundry. The bellows hose 61b to be used for circulating drying air is connected to the duct 49, which is then followed by the fan 41, the duct 43 and the hot-air blower port 45. Performed in the duct 49 is exchange of heat between laundry drying circulating air (indicated by an outlined arrow B) and water (indicated by a solid arrow A) supplied from the water-cooling dehumidication hose 53 so as to condense some of water and produce a low-temperature high-humidity air. This heat-exchanged air is drawn by the fan 41 which is rotated by the motor 42, into the duct 43 where the air is heated to about 120 °C by means of the drying heater 44. The thus heated air is supplied again from the hot-air blower port 45 into the drum 47 to evaporate moisture of the laundry. In this way, the air is circulated in the machine. On the other hand, the water condensed in the duct 49, passing through hose 62, is discharged via the drain hose 58 by the function of the drain pump 56. In the figure, 50 indicates a water supplying valve for supplying tap water, 51 a detergent supplying port, 52 a condensation branch hose, and 54 a check valve. Here, these components are not of importance, so that the description will be omitted. Next, the operation of this drum type drying/washing machine will be described. After laundry is loaded into the machine via the laundry loading port in front of the sealer 46 for protecting leakage of water, a detergent suited to the laundry should be put into the detergent supplying port 51. As the start button is pressed, a suitable quantity of water to the amount of the laundry is passed through the water supplying valve 50 and is supplied to the drum 47 whilst solving the detergent loaded in the detergent supplying port. Then, the drum 47 will be rotated to beat-wash the laundry. During washing, washing water is circulated through the bellows hose 61a, the filter 55 and the circulating pump 57 and returned to the drum 47 from the nozzle 59. This procedure is repeated to perform washing. When washing is complete, the water is passed through the bellow hose 61a, the filter 55, the drain pump 56 so as to be discharged from the drain hose 58. Thereafter, the drum 47 is rotated at a high speed so that the washing water remaining in the laundry can be dehydrated. The waste water during dehydration is also discharged through the same passage as above. At the completion of washing, water is supplied into the drum 47 through the detergent supplying port 51 from the water supplying valve 50, and rinsing is performed in the same manner as in the washing process. Then, the dehydration is performed in the same manner as above. Here, washing or rinsing water which goes into the duct 49 through the bellows hose 61b will be drained from the drain hose 58 with the help of the drain pump 56, the passing through hose 62 which is connected to a bottom exit of the duct 49, the circulating pump 57, the filter 55 and the drain pump 56. Next, the dehydrated laundry undergoes the drying process. In the drying process, first, the fan 41 is activated while the drying heater 44 is heated with 1,200 W so that the hot air can be blown out from the hot-air blower port 45 into the drum 47 which is rotating at 50 rpm. (by means of main motors 'b' and 'c' in Fig.8). After about 5 min., a heat switch 63 will be turned off in the circuit shown in Fig.8, reducing the power of the drying heater 44 to 700 W while the drum 47 will be rotated at approximately 1,000 rpm. (using main motors 'a' and 'b' in Fig.8) for 10 min. In this case, as shown in Fig.10, a characteristic has been known that the viscosity of water will become lower as the temperature of water becomes higher. Fig.9 shows a graph of change in the surface temperature of laundry. In this graph, during the period from 5 to 15 min., the laundry is heated to around 40 °C, and approximately 100 g of water is removed by the high speed dehydration. This dehydrated water, the water used for water cooling and condensed water are all discharged out from the drain hose 58 by the function of the drain pump 56, passing through the duct 49, the hose 62, the circulating pump 57, the filter 55 and the drain pump 56. When the drum 47 is rotated at a rate of 1,000 rpm., laundry will stick to the peripheral wall of the drum 47. Therefore, once stopped after the high speed rotation, the drum 47 is rotated in reverse direction at about 50 rpm. by the function of a rectifier board. This rotation causes the laundry stuck to the drum 47 to go down and roll over in harmony with the low speed turn. This operation is continued until the drying will be complete. Although it took about 45 min. to dry 1 kg of laundry in the conventional method, the drying time could be reduced by 10 %, that is, it took 40 min. to dry the same amount of laundry. In Fig.8, the drying heater 44 is composed of a drying heater 44a of 700 W and a drying heater 44b of 500 W. A reference numeral 70 designates a main motor for rotating the drum 47, 71 a rectifier circuit board having a rectifier circuit, 72 a drying temperature sensor, 73 a water supply valve for washing, 74 a water supply valve for drying, and 75 a control board having a microcomputer etc. In the above drum type drying/washing machine, the drum will be rotated at a high speed at the initial stage of the clothes drying operation when the viscosity of water has already started to become lower, so that the dehydrated level of laundry right after the dehydration can be improved further. Further, the laundry stuck to the drum can be separated from it by stopping or reversing it after the high speed rotation. Moreover, the total of the power of the drying heater and the power of rotational motor is controlled to be almost constant, regardless of whether drying is performed with the high speed rotation or with the low speed turn. Specifically, the power consumption of the drying heater is controlled between 700 to 1,200 W in accordance with the operating mode of the drum: the high speed rotation or the low speed turn, so that the total power consumption may be about 1,350 W. In this way, it is possible to quickly remove water from laundry and shorten the drying time, thus making it possible to save the energy. Fig.11 is a perspective view showing another embodiment of a drum type drying/washing machine of the invention. In Fig.11, a reference numeral 81 designates a fan, 82 a fan motor, 83 an intake duct, 84 a drying heater, 85 hot-air blower port, 86 a sealer, 87 a drum, 88 an outer tank, 89 an exhaust duct, 90 a solenoid-operated water supply valve for supplying tap water, 91 a detergent supplying port, 92 a condensation branch hose, 93 a water-cooling dehumidication hose, 94 a solenoid-operated cooling water valve, 95 a filter, 96 a drain pump, 97 a circulating pump, 98 a drain hose, 99 a nozzle, 100 a hatch, 101 a control key, 103 an exhausted air temperature sensor, 104 an intake air temperature sensor, 130 a drum type drying/washing machine body, and 131a, 131b and 132 bellows hoses. Fig.12 is a sectional side elevation showing the drum type drying/washing machine of Fig.11. In Fig.12, a reference numeral 102 designates a drum motor, 105 a water supply hose, 106 a lid, 107 a controlling device, 108 a spring, 109 a damper, and 116 a solenoid valve for hatch. Wound around the outer periphery of a rear end shaft of the drum 87 which accommodates laundry and rotates is a drum rotating belt for transmitting a rotational force from a drum rotating motor 102. The outer tank 88 is attached around the drum 87 so that no water will leak. The sealer 86 for protecting leakage of water is attached on the front side between the laundry loading port and the drum 87. Attached to the outer tank 88 is the bellows hose 131a for draining and circulating washing water as well as the bellow hose 131b for circulating drying air. The bellow hose 131a to be used to drain and circulate washing water is attached to the filter 95 for trapping lint, dust etc., scattered in the water. The drain pump 96 and the drain hose 98 to be used for draining washing water and dehydrating are attached to one side of the filter 95. Attached on the other side of the filter 95 are the circulating pump 97 and the nozzle 99 for circulating washing water during washing so that washing water can forcibly be blown upon the laundry. The bellows hose 131b to be used for circulating drying air is connected to the exhaust duct 89, which is then followed by the fan 81, the intake duct 83 and the hot-air blower port 85. Performed in the duct 89 is exchange of heat between laundry drying circulating air (indicated by an outlined arrow B) and water (indicated by a solid arrow A) supplied from the water-cooling dehumidication hose 93 so that the circulating air inside the exhaust duct 89 will be condensed to become a low temperature low-humidity air. This low-temperature low-humidity air is drawn by the fan 81 which is rotated by the fan motor 82, into the intake duct 83 where the air is heated to become a high-temperature low-humidity air. This high-temperature low-humidity air is again supplied from the hot-air blower port 85 into the drum 87 in order to evaporate moisture of the laundry. In this way, the air is circulated in the machine. On the other hand, the water condensed in the exhaust duct 89, passing through the hose 132, is discharged via the drain hose 98 by the function of the drain pump 96. The controlling device 107 including a microcomputer (CPU) is disposed in the front part of the drum type drying/washing machine body 130. This controlling device controls the washing operation in accordance with the input which is imparted through control keys (control switch) 101 of a control panel disposed on the front side of the machine body 130, the output signals from various sensors such as the exhausted air temperature sensor 103 and the intake air temperature sensor 104 etc., as well as an internal timer. As shown in a block diagram of Fig.13, a control circuit 110 in the controlling device 107 receives signals from the exhausted air temperature sensor 103, the intake air temperature sensor 104, the control keys 101 for selecting the type of clothing etc., a lid switch 111 and a tachometer 112, and controls the drum motor 102, the fan motor 82, the drying heater 84, the solenoid valve 116, the drain pump 96, the circulating pump 97, the cooling water valve 94 and the water supply valve 90. In Fig.13, a reference numeral 115 designates a rectifier circuit, 117 a driver, 118 a driver circuit, 119 a display circuit, 120 a buzzer circuit and 121 an AC power supply. In the above configuration, when laundry is loaded into the drum 87 and the washing operation is started, the controlling device 107 controls the drum motor 102 so that the drum 87 rotates at a predetermined high speed and then stops. The controller detects the duration of the continuation of the rotation due to the inertia of the drum 87 until it stops so as to estimate the weight of clothing in the drum 87. Then, water is supplied by releasing the water supply solenoid valve 90, and thereafter the drum 87 is rotated by means of the drum motor 102, to start the washing operation, which is followed by subsequent rinsing, dehydrating and drying operations. When the operation enters the dehydrating stage, driving state of drum 87 is shifted from a low speed turn (at about 50 rpm.) to a high speed rotation (at about 1,000 rpm.) by means of the drum motor 102 while the drying heater 84 is turned on the electricity in the low-mode (with about 700 W). Heat from this drying heater 84 will be able to improve the dehydration ratio by about 2 % and raise the surface temperature of laundry by 5 to 10 °C. Here, it is possible to determine whether the drying heater 84 should be turned on after the completion of the dehydrating operation, through the control keys 101. When the operation enters the drying stage, the surface temperature of clothing during drying varies depending upon the amount of laundry. Variations of the clothing surface temperature is shown in Fig.14. Therefore, the remaining-heat drying time, the normal-rate drying time, the reduced-rate drying time should be set different depending upon the amount of laundry. Specifically the remaining-heat drying should finish for about 10 min., when the amount of laundry is 1 kg. It will finish for about 15 min. for a 2 kg laundry and it will finish for about 20 min. for a 3 kg laundry. During this time alone, the cooling water valve 94 is closed to further increase the temperature of clothing. In the normal-rate drying, it will take about 35 min. for a 1 kg laundry, about 65 min. for 2 kg, and about 95 min. for 3 kg. Finally, in the reduced-rate drying, it will take about 44 min. for 1 kg, about 71 min. for 2 kg, and about 110 min. for 3 kg. After the completion of the normal-rate drying to the end of the drying process, the cooling water valve 94 is opened so as to perform the cooling-dehumidication. Explaining in further detail, when the amount of laundry is 1 kg, from 0 (the start of drying) to 7 min., the drum 87 is rotated at about 50 rpm. while the drying heater 84 is turned on the electricity in the high mode (1,200 W) to heat the laundry (so-called tumbling operation). Thereafter, from 7 min. to 10 min., the drum 87 is rotated at 1,000 rpm. to perform dehydration while the drying heater 84 is turned on in the low mode (about 700 W) to heat the laundry. During the period from 10 min. to 44 min., the tumbling operation (at about 50 rpm. heated with 1,200 W) is performed. During this operation, from 15 min. to 35 min., the drum 87 is rotated at about 1,000 rpm. for 15 sec. at intervals of 5 min. in order to dehydrate the laundry. During this time, the drying heater 84 is turned on in the low mode (about 700 W) to heat the laundry. When the reduced-rate drying stage starts, the drum 87 turns at about 50 rpm. and the drying heater 84 uses about 1,200 W to heat the laundry until the drying operation is complete. Here, when the dehydration is not performed from 15 min. to 35 min., the drum 87 turns at about 50 rpm. and the drying heater 84 uses approximately 1,200 W to heat the laundry. Finally, when the exhausted air temperature sensor 103 detects a predetermined temperature (approximately 70 °C), the whole drying operation will finish. When the amount of laundry is 2 kg, from 0 (the start of drying) to 12 min., the drum 87 is rotated at about 50 rpm. while the drying heater 84 is turned on in the high mode (1,200 W) to heat the laundry and perform tumbling. Thereafter, from 12 min. to 15 min., the drum 87 is rotated at 1,000 rpm. to perform dehydration while drying heater 84 is turned on in the low mode (about 700 W) to heat the laundry. During the period from 15 min. to 71 min., the tumbling operation (at about 50 rpm. heated with 1,200 W) is performed. During this operation, from 20 min. to 60 min., the drum 87 is rotated at about 1,000 rpm. for 15 sec. at intervals of 5 min. in order to dehydrate the laundry. During this time, the drying heater 84 is turned on in the low mode (about 700 W) to heat the laundry. When the reduced-rate drying stage starts, the drum 87 turns at about 50 rpm. and the drying heater 84 uses about 1,200 W to heat the laundry until the drying operation is complete. Here, when the dehydration is not performed from 20 min. to 60 min., the drum 87 turns at about 50 rpm. and the drying heater 84 uses approximately 1,200 W to heat the laundry. Finally, when the exhausted air temperature sensor 103 detects a predetermined temperature (approximately 70 °C), the whole drying operation will finish. When the amount of laundry is 3 kg, from zero (the start of drying) to 15 min., the drum 87 is rotated at about 50 rpm. while the drying heater 84 is turned on in the high mode (1,200 W) to heat the laundry and perform tumbling. Thereafter, from 15 min. to 20 min., the drum 87 is rotated at 1,000 rpm. to perform dehydration while the drying heater 84 is turned on in the low mode (about 700 W) to heat the laundry. During the period from 20 min. to 110 min., the tumbling operation (at about 50 rpm. heated with 1,200 W) is performed. During this operation, from 25 min. to 100 min., the drum 87 is rotated at about 1,000 rpm. for 15 sec. at intervals of 5 min. in order to dehydrate the laundry. During this time, the drying heater 84 is turned on in the low mode (about 700 W) to heat the laundry. When the reduced-rate drying stage starts, the drum 87 turns at about 50 rpm. and the drying heater 84 uses about 1,200 W to heat the laundry until the drying operation is completed. Here, when the dehydration is not performed from 25 min. to 100 min., the drum 87 turns at about 50 rpm. and the drying heater 84 uses approximately 1,200 W to heat the laundry. Finally, when the exhausted air temperature sensor 103 detects a predetermined temperature (approximately 70 °C), the whole drying operation will finish. Table 1 below shows the conditions of the operations of dehydrating and drying stages when the amounts of laundry are 1 kg, 2 kg and 3 kg. Here, when the exhausted air temperature sensor 103 has detected a predetermined temperature and the operation enters the reduced-rate drying stage, the openable hatch 100 which is provided for the intake duct 83 may be opened by activating the solenoid valve 116. This will cause the high temperature air that contains vapor, to discharge outside the drying/washing machine body 130, therefore it becomes possible to further reduce the drying time. However, if the hatch 100 is opened, the room may be filled with the moisture which has come out from the clothing. Therefore, the activation of the solenoid valve 116 for opening and closing this hatch 100 is made to be selected. When the hatch 100 is closed, it should be done manually. Thus, when drying is performed in this drum type drying/washing machine of the invention, it is possible to reduce the drying time by about 20 %, compared to that in the conventional configuration.

Claims: A drum type drying/washing machine, comprising: a drum (3; 47; 87; 143; 203) for accommodating laundry and having a number of holes (143a; 203a) on the peripheral wall thereof and a baffle for agitating laundry; an outer tank (2; 48; 88; 142; 202) enclosing said drum and supporting said drum rotatably about a horizontal axis; a driving means (4; 70; 102; 148; 208) for imparting driving force to rotate said drum in normal and reverse directions; a heating means (11, 12; 44; 84) for heating air to be supplied to said drum; and a control means (24; 75; 107; 180; 300) for controlling said driving means to rotate said drum at at least two levels of low and high rotational speeds during a drying operation; characterized in that said control means is arranged to control said heating means so that when during said drying operation the drum is rotated at said high rotational speed the heating means temporarily operates at a reduced power output. A drum type drying/washing machine according to claim 1 wherein said control means (24; 75; 107; 180; 300) is arranged to cause said drum to be rotated for a predetermined period of time at said high rotational speed once or a plurality of times at an initial stage of the drying operation in order to dehydrate the laundry which has been heated by warm air. A drum type drying/washing machine according to claim 2, wherein said control means is arranged to control the driving means so that after the completion of the dehydration by the high speed rotation, said drum is stopped, or is rotated in the reverse direction at a low speed in order to separate the laundry sticking to the peripheral wall of said drum. A drum type drying/washing machine according to claim 2, wherein said. control means is arranged to control the driving means so that after the completion of the dehydration by the high speed rotation said drum is stopped for a predetermined period of time and then is rotated in the reverse direction at a low speed in order to separate the laundry sticking to the peripheral wall of said drum. A drum type drying/washing machine according to claim 2, wherein said control means is arranged to control said heating means and said driving means such that the total of the output power from said heating means and the output power of said driving means is equal to or less than a predetermined value both while the drying operation is performed with the high rotational speed of the drum and while the drying operation is performed with the low rotational speed of the drum. A drum type drying/washing machine according to claim 1, further comprising: an air-blowing means (13; 41; 81) disposed on a circulating passage extending between an exhaust port and an intake port of said drum; a dehumidifying means (17) for dehumidifying air inside the circulating passage by cooling the air using cooling water; and a water-flowing means (19; 54; 94) for controlling flow of the cooling water; wherein said heating means is arranged for heating the air dehumidified by said dehumidifying means; and wherein said control means is arranged to control said water-flowing means such that the operation of said dehumidifying means is stopped temporarily during the drying operation. A drum type drying/washing machine according to claim 1, further comprising: an air-blowing means (13; 41; 81) disposed on a circulating passage extending between an exhaust port and an intake port of said drum; a dehumidifying means (17) for dehumidifying air inside the circulating passage by cooling the air using cooling water; and a water-flowing means (19; 54; 94) for controlling flow of the cooling water; wherein said heating means is arranged for heating the air dehumidified by said dehumidifying means; and wherein said control means is arranged to control said driving means to rotate said drum at the start of the drying operation, said air-blowing means to blow out dry air, said heating means to heat the dry air and said water-flowing means to stop flowing the cooling water during a predetermined period of time or during a period of time predetermined in accordance with an amount of clothes so as to perform drying and to start flowing the cooling water after the period of time passes so as to perform drying with cooling-dehumidification. A drum type drying/washing machined according to claim 7, wherein said control means is arranged to control said water-flowing means so that after the start of the drying operation, the flow of the cooling water is initiated when a temperature sensor disposed near the exhaust port of said drum detects a temperature equal to or more than a predetermined value or when a temperature sensor disposed near the intake port of said drum detects a temperature equal to or more than a predetermined value. A drum type drying/washing machine according to claim 8, wherein said control means is arranged to control said driving means so as to rotate said drum at a high speed when the temperature sensor disposed near the exhaust port of said drum detects a temperature equal to or more than a predetermined value. A drum type drying/washing machine according to claim 9, wherein said control means is arranged to control said driving means during the drying operation to rotate said drum at a high speed at intervals of a predetermined period of time. A drum type drying/washing machine according to claim 10, wherein said control means is arranged to determine the predetermined period of time in accordance with the amount of the clothes being dried. A drum type drying/washing machine according to claim 10, wherein said control means is arranged so that when during the drying operation the drum is rotated at said high rotational speed, said water-flowing means stops the flow of the cooling water. A drum type drying/washing machine according to claim 9, wherein said control means is arranged so that after the passage of a predetermined period of time from the start of the drying operation, when the temperature sensor disposed near the exhaust port of said drum detects a temperature equal to or more than a predetermined value, said heating means is controlled so as to reduce power consumption and said water-flowing means is controlled so as to flow the cooling water intermittently.

Inventors: MATSUMOTO TSUYOSHI, NAKAGAWA HIROYASU, TANIGAWA MASANOBU, MATSUMOTO, TSUYOSHI, NAKAGAWA, HIROYASU, TANIGAWA, MASANOBU
Applicants: SHARP KK, SHARP KABUSHIKI KAISHA
Application year: 1996
Main classification: D06F58
IPC codes: D06F35, D06F39, D06F58, D06F33, D06F37, D06F25