WO2007138019A1

WO2007138019A1 - A drum washing machine and a control method for the same

Info

Publication number: WO2007138019A1
Application number: PCT/EP2007/055116
Authority: WO
Inventors: Ye Lv; Xiu Wan; Ping Ye
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2006-05-31
Filing date: 2007-05-25
Publication date: 2007-12-06
Also published as: CN101082161A; CN101680153B; EP2032757A1; EP2032757B1; CN101680153A; CN101082161B

Abstract

A drum washing machine with a drying program and a control method for the same, wherein said drum washing machine comprises a tub (1) to hold water, a drum (2) rotatably set in the tub, a heating drying tunnel (4) configured outside said tub, a first temperature detection unit (11) set in the said tub and a system control unit for controlling the said drying program based on the signals fed back from the said first temperature detection unit.

Description

A DRUM WASHING MACHINE AND A CONTROL METHOD FOR THE SAME

Field of the Invention

The present invention relates to a drum washing machine and a method of controlling the same, and, more particularly, to a drum washing machine with a drying function or a drum washer-dryer and a method of controlling a drying program therein.

Background of the Invention

Drum washing machines are popular with users due to their water saving feature and avoidance of damage to the laundry. In recent years, as technology progresses, drum washing machines with drying function, also known as washer- dryers, have become mainstream products in the market. When drying, such drum washing machine takes in air through a fan set on an outside of a tub containing the drum, heats the air with a heater, and then transfers the heated air to the tub and the inside of the drum. The heated air exchanges heat with the water contained in the laundry and takes away the moisture. The moisture is then condensed in a condensing unit mounted on an outside of the tub and drained out of the washing machine.

The existing washing machines with drying function typically dry the laundry at a substantially constant temperature and in a preset period of time. However, such kind of control method tends to overdry the laundry when the load of laundry to be dried is small and to underdry the laundry when the load of laundry is large. Therefore, it can hardly meet users' needs in general. To overcome these shortcomings, it has been proposed to provide temperature sensors or/and humidity sensors inside the washing machine to detect the temperature or/and humidity of the washing machine. The washing machine will determine the degree of dryness based on the signals sent from the sensors and thus achieve relatively accurate control over the drying effect. For example, GB 2 082 742 A provides a dryer which controls the drying time according to the internal temperature change rate in combination with considering the type of clothes being washed and predetermined degree of dryness.

CN 1 746 379 A discloses a drum washing machine with drying function which has an upper temperature sensor and a lower temperature sensor mounted respectively on an upper end and a lower end of a vertical part of a hot air circulating pipe, and which has a control unit that determines a degree of dryness reached based on the difference between temperature detected by the upper and lower temperature sensors, and thereby controls the drying process.

Another example is CN 1 503 864 A which discloses a control unit for detecting the dryness in an air exhaust dryer and a control method for using the same. The control unit disclosed determines the degree of dryness of the wash based on the signals detected by a humidity detection unit and a temperature detection unit and thereby controls the drying process.

In addition, CN 1 61 1 659 A discloses a drum washing machine system control device, which determines the load of the laundry to be dried according to data obtained by a humidity sensor set on a condensing pipe, and a drying device for drum washing machines which adjusts a temperature of a heater based on a laundry load, and a control method for the same.

The technologies disclosed in the above-mentioned documents pertain to configure sensors for the system so that the system can make judgment according to signals detected by the sensors and control the drying process. However, every sensor will inevitably have a certain error depending on its accuracy, installation location, and other factors. For example, in the said document CN 1 746 379 A, the result detected by the temperature sensor may not be accurate due to the effect of the condensed water. Further, the accuracy of the result detected by the temperature sensor in the said CN 1 61 1 659 A will also be affected by the condensed water during the condensing process. In addition, the judgment based on the difference between signals detected by a number of sensors located in different areas of the washing machine will lead to inaccurate result of final judgment due to aggregated errors of several sensors, which in turn affects the drying effect and results in inadequate drying or over-drying. Furthermore, excessive use of sensors will increase the cost of the washing machine and the complexity of the system control program.

Summary of the Invention

Therefore, to overcome these problems, the present invention is intended to provide a drum washing machine with a drying program, the drum washing machine comprising a tub to hold water, a drum rotatably set in the tub, a heating drying tunnel configured outside said tub, a first temperature detection unit mounted in said tub, and a system control unit for controlling the drying program based on signals fed back from the said first temperature detection unit.

Preferably, said heating drying tunnel is provided with a second heating unit and a second temperature detection unit, and the said system control unit controls said second heating unit based on a signal fed back from the said second temperature detection unit to prevent said heating drying tunnel from damage by over- temperature of the second heating unit.

More preferably, the outlet of said heating drying tunnel is connected with said tub to lead the air heated by said second heating unit into the inside of the tub and the drum so that the laundry is dried by heat exchange between the heated air and the moisture contained in the laundry.

Further preferably, a fan is provided at an appropriate location inside the heating drying tunnel. Said fan draws the air into the heating drying tunnel through the inlet of said heating drying tunnel, and then transports the air heated by said second heating unit to the inside of the tub and drum.

Also preferably, said drum washing machine further comprises a condensing unit and a pump, whereby the high-temperature and low-humidity air heated by the said second heating unit having taken away the moisture contained in the laundry after heat exchange and been converted into low-temperature and high-humidity air is drained out of the tub and drum. The low-temperature and high-humidity air, after being condensed by the condensing water in the said condensing unit, will be separated from the condensate obtained and recirculated to the drum, and the condensate obtained pumped to the outside or a collector through the said pump.

Preferably, said tub is provided with a first heating unit so that it will heat water during the washing process to improve washing efficiency. The said system control unit relies on the said first temperature detection unit to control the said first heating unit to prevent damage to the wash due to excessively high water temperature during washing.

More preferably, the said first temperature detection unit and the said second temperature detection unit are temperature sensors, and are preferably NTC (Negative Temperature Coefficient) temperature sensors to enhance detection accuracy.

Another objective of the present invention is to provide a control method for a drying program of a drum washing machine. Said drum washing machine comprises a tub, a rotatable drum set in the tub, a heating drying tunnel configured outside said tub, a first temperature detection unit mounted in said tub and a system control unit. The said control method comprises the following step: a drying phase, during which a temperature is detected by the said first temperature detection unit and a corresponding temperature signal is transferred to the system control unit; the system control unit comparing temperatures and controlling the drying program based on the comparison results.

Preferably, said control method further comprises a step being a preheating phase, during which a temperature inside said drum is heated to a preset preheating temperature and the system control unit determines a weight of the laundry based on the time spending in raising the temperature to the preheating temperature, as the weight of the laundry is in direct proportion to the time required for heating to the preheating temperature.

Also preferably, within the drying phase, when the load is less than a normal laundry load, the system control unit compares the current temperature of the drum with a preset drying termination temperature. When the current temperature is higher than or equal to the said drying termination temperature, the drying phase is completed; otherwise, the drying process continues. When the load is equal to or more than the normal laundry load, the system control unit compares the current temperature of the drum with a minimum temperature for the drying phase. When the difference between the current temperature and the minimum temperature for the drying phase is greater than or equal to a preset reference temperature and the said current temperature is greater than or equal to the said drying termination temperature, the drying phase is completed; otherwise, the drying process continues.

Preferably, a condensing unit and a pump are further provided outside the tub and a second heating unit, a second temperature detection unit and a fan are further provided at respective appropriate locations inside the said heating drying tunnel, and the said control method further comprises a step being a cooling phase during which the system control unit controls the second heating unit to stop working while controlling the said fan, condensing unit, and pump to work as usual during the drying step.

The said cooling phase preferably lasts for a preset period of time.

Preferably, said tub is further provided in the inside with a first heating unit which heats the water during the washing process. The system control unit controls said first heating unit based on the signal fed back from said first temperature detection unit.

More preferably, said first temperature detection unit and said second temperature detection unit are temperature sensors, and are preferably NTC temperature sensors to enhance the accuracy of detection signal.

The present invention achieves control over the drying process through the first temperature detection unit set in the tub. Furthermore, said first temperature detection unit can also be used to control the heating by the first heating unit during the washing process. This means that the same temperature detection unit addresses two different functional requirements. This not only effectively reduces drying control error but also cuts production costs and simplifies the system control program since no additional sensor is needed. Brief Description of the Drawings

The invention will be further illustrated without setting any limitation of its scope below in conjunction with the drawings and preferred embodiments.

FIG. 1 is a structural diagram of the drum washing machine with a drying program of the present invention;

FIG. 2 is a temperature change curve detected by the first temperature detection unit when the load is equal to or more than the normal wash load;

FIG. 3 is a temperature change curve detected by the first temperature detection unit when the load is less than the normal wash load; and

FIG. 4 is a drying flow chart of the drum washing machine with a drying program.

Embodiments

As shown in FIG. 1 , the washing machine mainly comprises a tub 1 , which is used to hold water and is housed in an enclosure (not shown in the figure) of the washing machine through a support device (not shown in the figure) and a suspension device (not shown in the figure), a drum 2 which is rotatably set in the tub 1 for washing the laundry and is provided with through holes which allow passage of water and air, and a system control unit (not shown in the figure). The drum 2 rotates when driven by a drive unit (not shown in the figure) on the rear of the tub 1 and lifts the laundry to a certain height through lifting devices (not shown in the figure) configured in the drum 2, and then the laundry falls due to gravity. This combined with the action of the water and detergent completes the washing process.

Furthermore, a first heating unit 10 is configured inside the lower part of the tub 1 , which heats the water to a certain temperature during the washing process to increase the cleaning ability of the washing water and enhance the washing effect. The system control unit controls said first heating unit 10 based on the signal fed back from the first temperature detection unit 1 1 , which is an NTC temperature sensor or other temperature detector and configured near said first heating unit 10 to prevent any damage to the laundry caused by excessively high water temperature.

A heating drying tunnel 4 is configured outside the said tub 1 , for example, on the top and the inlet 41 of the heating drying tunnel 4 is connected with the outlet of a condensing unit 5. Said condensing unit 5 is configured in the vertical direction outside the tub 1 , with its inlet connected with the tub 1. A fan 42 is set in an appropriate location inside the heating drying tunnel 4 to force air into the heating drying tunnel 4. A second heating unit 40 is provided inside the heating drying tunnel 4 at the far end from the condensing unit 5 to heat the inlet air into high- temperature and low-humidity hot air. Preferably, a second temperature detection unit 43, for example, NTC temperature sensor or other temperature detector, is configured near the second heating unit 40. The system control unit controls the second heating unit 40 based on a signal fed back from the second temperature detection unit 43 to prevent any damage to the heating drying tunnel 4 caused by excessively high temperature. The outlet 44 of the heating drying tunnel 4 is connected with the tub 1 so that the high-temperature and low-humidity hot air is transferred to the inside of the tub 1 and drum 2. The hot air will exchange heat with the moisture contained in the laundry in the inner drum 2, carry away the moisture, and change into low-temperature and high-humidity air. After being condensed in the condensing unit 5, the moisture in the said low-temperature and high-humidity air will be condensed into water and drained out of the washing machine or into a removable container through the pump 6 configured on the bottom of the outer drum 1. This cycle repeats until the laundry is dried.

The drying process and the control method of the washing machine will be detailed below in conjunction with FIG. 2, FIG. 3, and FIG. 4.

When the drying program starts, it enters a preheating phase. The fan 42 will draw air into the heating drying tunnel 4, and the second heating unit 40 will heat the air to any desired temperature. The heated high-temperature and low-humidity air will be transferred to the tub 1 and drum 2 by the fan 42 to exchange heat with moisture contained in the laundry. The air will then change into low-temperature and high-humidity air. The system control unit, according to the second temperature detection unit 43, determines whether the preheating phase is completed based on the fact that the current temperature T_current of the heating drying tunnel is equal to or greater than the preheating temperature T_dΘfaUιt. The preheating temperature T_defauit varies with different types of clothes contained in the laundry. In the case of cotton fabric, the preheating temperature T_defauιt is set to 78°C; in the case of chemical fibre clothes, the preheating temperature T_defauιt is set to 66⁰C. If the current temperature T_current is equal to or greater than the preheating temperature T_defauι_t, the preheating phase is completed. Meanwhile, the system control unit records the time f taken by the second heating unit 40 to heat the air to the preheating temperature T_defauι_t, and then determines whether the laundry is less than, more than, or equal to the normal laundry load W₀ according to the time t. When the laundry load is small, it will take only a short period of time to reach the preheating temperature T_defauιt, as shown in FIG. 3. When the laundry load is large, it will take a relatively long period of time to reach the preheating temperature T_defauit, as shown in FIG. 2. The time required is in direct proportion to the laundry load.

Upon completion of the preheating phase, the drying program will enter a drying phase under the control of the system control unit. The fan 42 and the second heating unit 40 continue to work to transfer the heated high-temperature and low- humidity air to the tub 1 and drum 2. Based on the the laundry load determined at the preheating phase, when the laundry load W is less than the rated laundry load W₀, the temperature change curve of the tub 1 and drum 2 detected by the first temperature detection unit 1 1 is shown in FIG. 3. Since the laundry load is light and the moisture contained in the laundry is low, the temperature change is not great even after heat exchange between the high-temperature and low-humidity air and the moisture contained in the laundry and it is a slowly rising process. During this phase, the first temperature detection unit 1 1 detects the current temperature T_current inside the drum and feeds it to the system control unit. The system control unit has a preset termination temperature T_termι_naii which depends on the materials of clothes contained in the laundry. In the case of cotton fabric, the termination temperature T_termιnaii is set to 85°C; in the case of chemical fibres, the termination temperature T_termιnaii is set to 71⁰C. The system control unit compares the current temperature T_current with the preset termination temperature Ttermman- When the current temperature T_current is equal to or greater than the preset termination temperature T_termι_naii, the second heating unit 40 stops working and the drying phase is completed; otherwise, the drying process continues.

When the laundry load W is equal to or greater than the normal laundry load W₀, the temperature change curve for the tub 1 and drum 2 detected by the first temperature detection unit 1 1 is shown in FIG. 3. Since the load is large and the moisture contained in the laundry is high, the temperature will first drop at the beginning of the heat exchange between the high-temperature and low-humidity air and the moisture contained in the laundry. As the heat exchange progresses, the moisture contained in the laundry reduces and the temperature will gradually rise. At this phase, the first temperature detection unit 1 1 detects the current temperature T_current inside the drum 2 and feeds it back to the system control unit. The system control unit has a reference temperature T_refe_re_nce, which is preferably set to 6°C. The system control unit compares the current temperature T_current with the preset termination temperature T_termιnai2- The termination temperature T_termιnai2 depends on the materials of the clothes being washed. In the case of cotton fabric, the termination temperature T_terminai2 is set to 78°C; in the case of chemical fibres, the termination temperature T,_ermι_nai₂ is set to 68°C. Meanwhile, the system control unit checks whether the difference ΔT between the current temperature T_current and the minimum temperature for the drying phase is equal to or greater than the reference temperature T_he_nce- When the current temperature T_current is equal to or greater than the preset termination temperature T_termmai₂ and the said temperature difference ΔT is equal to or greater than the reference temperature Treference, the drying phase is completed; otherwise, the drying process continues.

Upon completion of the drying phase, the drying program enters the cooling phase. The system continuously introduces cool air into the drum 2 for a certain period time to cool the laundry down. At the cooling phase, the second heating unit 40 stops working while the fan 42, the condensing unit 5, and the pump 6 continue to work. Preferably, the cooling phase lasts for a certain period of time Tde_fauit, for example, 10 minutes. Upon the completion of the cooling phase, the whole drying process is completed.

Claims

1 . Drum washing machine with a drying program, comprising: a tub, used to hold water; a drum rotatably set in said tub; a heating drying tunnel configured outside said tub; a first temperature detection unit set in the said tub; and a system control unit which controls the said drying program based on the signals fed back from the said first temperature detection unit.

2 . Drum washing machine with a drying program according to Claim 1 , in which the said heating drying tunnel further comprises a second heating unit and a second temperature detection unit, and said system control unit controls the said second heating unit based on a signal fed back from said second temperature detection unit.

3 . Drum washing machine with a drying program according to Claim 2, in which the outlet of said heating drying tunnel is connected with said tub so as to lead the air heated by the said second heating unit into the tub and the drum.

4 . Drum washing machine with a drying program according to Claim 1 , in which a fan is provided inside said heating drying tunnel to draw air into the heating drying tunnel through the inlet of said heating drying tunnel.

5 . Drum washing machine with a drying program according to Claim 1 , which further comprises a condensing unit and a pump, whereby the air exhausted from the tub and the drum is condensed by said condensing unit and recirculated to the drum and condensate obtained is drained out of the washing machine through said pump.

6 . Drum washing machine with a drying program according to any of Claims 1 to 5, in which said tub is further provided with a first heating unit and during the washing phase, said system control unit relies on said first heating unit to control said first temperature detection unit.

7 . Drum washing machine with a drying program according to Claim 6, in which said first temperature detection unit and the second temperature detection unit are temperature sensors, in particular NTC temperature sensors.

8 . Control method for a drying program of a drum washing machine, in which said drum washing machine comprises a tub, a drum rotatably set in the tub, a heating drying tunnel configured outside said tub, a first temperature detection unit set in said tub and a system control unit, said control method comprising the following step: a drying phase, during which the temperature is detected using said first temperature detection unit, and a corresponding temperature signal is transferred to the system control unit, which then compares temperatures and controls a degree of dryness of laundry being dried based on comparison results.

9 . Control method according to Claim 8, which further comprises a preheating phase during which the temperature inside the said inner drum is heated to a preset preheating temperature and the system control unit determines a weight of laundry based on a time spending in raising the temperature to the preheating temperature.

10 . Control method according to Claim 9, in which, when a laundry load is less than a normal laundry load, the system control unit will compare a current temperature of the drum with a preset drying termination temperature and, when the current temperature is higher than or equal to the said drying termination temperature, the drying phase is completed, otherwise the drying process continues; when the laundry load is equal to or more than the normal laundry load, the system control unit compares the current temperature of the drum with the minimum temperature for the drying phase; when the difference between the current temperature and the minimum temperature for the drying phase is greater than or equal to a preset reference temperature and said current temperature is greater than or equal to the said drying termination temperature, the drying phase is completed; otherwise, the drying process continues.

11 . Control method according to Claim 8, in which, a condensing unit and a pump are further provided outside the tub and a second heating unit, a second temperature detection unit, and a fan are further provided inside the said heating drying tunnel, the said control method further comprising a cooling phase, during which the system control unit controls the second heating unit to stop working while controlling the said fan, condensing unit, and pump to work as in the drying step.

12 . Control method according to Claim 1 1 , in which said cooling phase lasts for a preset period of time.

13 . Control method according to any of Claims 8 to 12, in which said tub is further provided with a first heating unit so that it will heat water during washing and the system control unit controls the said first heating unit based on the signal fed back by the first temperature detection unit.

14 . Control method according to Claim 13, in which said first temperature detection unit and said second temperature detection unit are temperature sensors, in particular NTC temperature sensors.