A method of washing laundry

Abstract: A method of washing laundry in a washing machine is disclosed. The method comprises the steps of heating water for washing and determining the temperature of the water whilst it is being heated. The method also includes the step of following one of a plurality of predetermined wash cycles selected in dependence on the determined temperature.

Description: The present invention relates to a method of washing laundry in a washing machine, comprising heating water for washing and, during the heating step measuring the temperature of the water whilst it is being heated, performing a predetermined sub-routine for carrying out a predetermined wash cycle selected in dependence on the measured temperature. The present invention also relates to a washing machine comprising a heater for heating water for washing, means for measuring the temperature of the water during the heating step, and control means configured to perform during the heating step, a predetermined sub-routine for carrying out a predetermined wash cycle in dependence on the measured temperature. A washing machine employing this method is known from EP 0742307 A. A method of controlling a washing machine is also known from FR 1171432A and GB 2043954A. A conventional drum type washing machine is illustrated in Figure 1 and comprises a housing 1, a tub 2 suspended in the housing 1, and a drum 3 rotatably mounted within the tub 2. A plurality of holes 3a and protrusions 3b are formed through and in the drum 3 respectively. A motor 5 for rotating the drum 3. is mounted on the tub 2, and a pump 7 for draining water from the drum 3 after the washing cycle has been completed is provided beneath the tub 2. A heater 9 for heating the washing water in the drum 3 is mounted on the top of the tub 2, and a door 8 for gaining access to the interior of the drum 3 is mounted on the housing 1. A water supply device 6 for supplying water to the drum 3 is mounted in the upper part of the housing 1. A detergent drawer 4 having a detergent container 4a is mounted in front of the water supply device 6, and a control panel 10 for controlling operation of the washing machine, is installed on the upper front face of the housing 1. The washing machine conducts a washing cycle, a rinsing cycle, and a spin-drying cycle. To use the machine, the door 8 is opened and laundry is placed in the drum 3. The required washing program is then selected from the control panel 10. A microprocessor (not shown) controls the washing cycle in accordance with the selected program. During the wash cycle, water and detergent is supplied to the drum 3 and, as the drum 3 is rotated in forward and reverse directions alternately by the motor 5, the laundry is agitated and washed. When hot water is required in the washing cycle, the heater 9 operates during rotation of the drum 3. A process for carrying out a wash cycle in a conventional washing machine is illustrated in Figure 2. Firstly, the water temperature is selected on the control panel 10 so that the water is heated during the wash cycle S102. A sensor (not shown) measures S103 the temperature of the washing water and the microprocessor detects S104 whether the measured temperature is higher than the selected temperature. If the measured temperature is lower than the selected temperature, the wash cycle continues and the heater 9 continues to heat the water. However, if the measured temperature is higher than the selected temperature, the heater is switched off S105. When the heater is switched off, the microprocessor measures S106 the duration of the wash cycle, and stops it when the measured time reaches S107 the set time. When the wash cycle is complete, the pump 7 drains water from the tub 2 and the rinsing cycle is initiated. When the rinsing cycle is complete, the pump 7 operates again to drain the water, and the spin-drying cycle is initiated. During the spin-drying cycle, the drum 3 is rotated at high speed to force the water out of the laundry. A disadvantage with the wash cycle of a conventional washing machine is that the wash cycle operates despite the water having not fully reached the selected temperature, thereby reducing the cleaning efficiency of the machine. Furthermore, the heater is only energised when all the washing water has been supplied to the drum 3, increasing the time taken before the water reaches the selected washing temperature and further reducing the efficiency of the washing machine. A method of washing laundry in a washing machine according to the present invention is characterised by the steps of stopping the heating step when the water for washing has reached a set temperature and performing another predetermined sub-routine for carrying out a predetermined wash cycle selected in dependence on a measured temperature of the water after completion of the predetermined sub-routine only if the set temperature has not been reached. Preferably, the method includes the step of switching off the heater and initiating a predetermined further sub-routine for carrying out a predetermined wash cycle selected in dependence on the selected temperature when said selected temperature has been reached or exceeded. In a preferred embodiment, the method includes the step of stopping the predetermined further sub-routine carried out in dependence on the related temperature when a selected washing time has been reached. According to the invention, there is also provided a washing machine characterised in that the control means is configured to stop heating the water when a set temperature has been reached and perform another predetermined sub-routine for carrying out a predetermined wash cycle selected in dependence on a measured temperature of the water after completion of the predetermined sub-routine only if the set temperature has not been reached. An embodiment of the invention will now be described, by way of example only, with reference to Figures 3 and 4 of the accompanying drawings, in which: Figure 1 is a perspective view of a prior art drum type washing machine; Figure 2 is a flow chart showing a prior art method for controlling the heating-washing operation; Figure 3 is a flow chart showing a method for controlling a heating and washing cycle according to the present invention; and Figure 4 is a graph illustrating an optimal amount of washing water optimal with respect to a variation in temperature of the washing water. Hereinafter, an exemplary embodiment will be described in detail with reference to the drawings. Parts identical to those in the prior art washing machine shown in Figure 1 will not be described, and will be referred to with the same reference numerals. A flow chart showing a method for controlling a heating and washing cycle of a washing machine is illustrated in Figure 3. The microprocessor is pre-programmed with a number of sub-routines that correspond to various different temperatures of the water. A particular subroutine is performed in dependence on the temperature of the washing water to provide optimal washing. When a time and a temperature is selected (S120) via the control panel 10, the heater heats the water (S202) and the sensor (not shown) detects (S203) the temperature of the water. If it is below 20°C (S204), the microprocessor controls the washing machine, such as the amount of water supplied to the drum 3 or its speed of rotation, to initiate a wash cycle according to a first subroutine (S205). If the detected temperature is below 30°C (S206), the microprocessor controls the washing machine to initiate a wash cycle according to a second subroutine (S207). If the detected temperature is below 40°C (S208), the microprocessor controls the washing machine so that the wash cycle is performed according to a third subroutine (S209). The temperature of the water is continually checked and a pre-programmed wash cycle is performed in accordance with an associated sub-routine. If the detected temperature is below 100 degrees centigrade (S210), for example, the ninth subroutine is performed (S211), and if the detected temperature is over 100 degrees centigrade, the tenth subroutine is performed (S212). The microprocessor checks (S213) if the water has reached the selected temperature whilst a subroutine is performed. If the detected temperature is below the selected temperature, the washing cycle continues and the heater continues to heat the water. If the detected temperature is above the selected temperature, the heater is switched off (S214). When the heater is switched off, the washing cycle is performed according to a subroutine that corresponds to the selected temperature. The microprocessor determines (S215) the washing time, and when the selected time (S216) is reached, the washing cycle stops, and the rinsing and spin-drying cycles are initiated consecutively. An example of how the washing machine is controlled in accordance with each of the subroutines is illustrated in Figure 4 which shows a graph between the amount of washing water and temperature of the water at which optimal washing effect is achieved. For example, if the temperature of the washing water is 20 degrees centigrade, it is preferable that the drum 3 is supplied with three litres of water. Thus, when the water is 20°C and the first subroutine is performed, the microprocessor controls the water supply device 6 to supply 3 litres of water to the drum 3. However, when the temperature of the water is 40 degrees centigrade, the drum 3 is supplied with seven litres of washing water. Thus, when the water is 40°C and the third subroutine is performed, the microprocessor controls the water supply device 6 to supply 7 litres of water to the drum 3. Similarly, in each of the subroutines, the optimal amount of washing water is set on the basis of the graph shown in Figure 4. The optimal amount of water to achieve the optimal washing effect is not always ascertained on the basis of the graph shown in figure 4 in all types of washing machines. Such data is obtainable experimentally in consideration of the type of the washing machine, washing capacity, energy consumption, or degree of agitation of the laundry during the rotation of the drum 3. As described above, the washing effect and the energy efficiency can be enhanced by increasing the amount of the washing water in proportion to its temperature. Furthermore, as only a small amount of water is supplied to the drum while the temperature is low, it can reach the selected temperature quickly. The subroutine may control other operating conditions of the washing machine, in addition to the amount of the washing water as shown in Figure 4. For example, the washing conditions may include data concerning a time for maintaining the water at a respective temperature, the number of revolutions of the drum 3, and the number of revolutions of the drum in each direction. This data can be determined experimentally in consideration of the aforementioned factors. For example, when the temperature of the water is low and only a small amount of water is supplied to the drum 3, it is preferably that the rotational speed of the drum 3 is slow but the direction of rotation of the drum changes often. As the temperature of the water approaches the selected temperature and the amount of water increases, it is preferable that the rotational speed of the drum 3 increases and whereas the period for changing the rotational direction reduces, thereby increasing the washing effect. Accordingly, the overall energy efficiency of the washing machine is improved and the washing effect is maximised. Furthermore, since the total operation time of the washing machine is confined to the time selected by the user, the water is at the selected temperature for as long as possible during the selected time period. As described above, each of the subroutines is a different wash cycle which is performed corresponding to respective temperatures of the washing water, so that optimal washing effect is achieved and energy efficiency is improved. The microprocessor controls the washing machine by performing a particular subroutine corresponding to a respective temperature.

Claims: A method of washing laundry in a washing machine comprising heating water for washing and, during the heating step: (a) measuring the temperature of the water whilst it is being heated; (b) performing a pre-determined sub-routine for carrying out a predetermined wash cycle selected in dependence on the measured temperature characterised by the steps of (c) stopping the heating step when the water for washing has reached a set temperature, and (d) performing another predetermined sub-routine for carrying out a predetermined wash cycle selected in dependence on a measured temperature of the water after completion of the predetermined sub-routine only if the set temperature has not been reached. A method according to claim 1, including the step of performing a predetermined further sub-routine for carrying out a predetermined wash cycle selected in dependence on the set temperature when said set temperature has been reached or exceeded. A method according to claim 2 wherein the method includes the step of stopping the predetermined further sub-routine carried out in dependence on the set temperature when a selected washing time has been reached. A method according to any of claims 1 to 3, wherein the step of performing a predetermined sub-routine for carrying out a predetermined wash cycle or a further predetermined sub-routine for carrying out a predetermined wash cycle includes controlling the amount of water for washing. A method according to any of claims 1 to 4, wherein the step of performing a predetermined sub-routine for carrying out a predetermined wash cycle or a further predetermined sub-routine for carrying out a predetermined wash cycle includes controlling the rotational velocity of a drum in which the laundry is washed. A method according to any of claims 1 to 5, wherein the step of performing a predetermined sub-routine for carrying out a predetermined wash cycle or a further predetermined sub-routine for carrying out a predetermined wash cycle includes controlling the direction of rotation of a drum in which the laundry is washed. A washing machine comprising a heater (9) for heating water for washing, means for measuring the temperature of the water during the heating step, and control means configured to perform during the heating step, a predetermined sub-routine for carrying out a predetermined wash cycle in dependence on the measured temperature, characterised in that the control means is configured to stop heating the water when a set temperature has been reached and perform another predetermined sub-routine for carrying out a predetermined wash cycle selected in dependence on a measured temperature of the water after completion of the predetermined sub-routine only if the set temperature has not been reached.

Inventors: CHO SUNG-WON, CHO, SUNG-WON
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1998
Main classification: D06F35
IPC codes: D06F35, D06F33