ELECTRONIC CONTROL METHOD FOR DRAIN PUMPS USED IN ELECTRICAL HOME APPLIANCES

Abstract: The invention is related to a method that provides electronic control of working periods of the synchronous or asynchronous drain pump motors used in electrical home appliances such as dish washing machines and washing machines. During normal use of the home appliance, while the drain pump (2) is operating, the values of the current taken is audited by a microprocessor (1) and compared with the previous values of "rates of current drawn while operating loaded (while there is water in the machine) and without load (while there is no water)" which are loaded into the memory of the microprocessor and when the desired balance is attained, the drain pump, by arriving at a decision that operation is done without water, stops. To measure the current drawn by the drain pump (2), a circuit formed by a "resistance based on manganin" (3) an "op-amp" (4) and an "ac-dc converter" (5), is being used.

Description: ELECTRONIC CONTROL METHOD FOR DRAIN PUMPS USED IN ELECTRICAL HOME APPLIANCES The invention is related to a method that provides electronic control of working periods of the synchronous or asynchronous drain pump motors used in electrical home appliances such as dish washing machines and washing machines. In the control systems of the existing dish washing and washing machines, the drain pump is in operated along a fixed operating time period at places required by the washing program. This fixed time period, is over the time needed to drain the water out by the drain pump under normal conditions. For example, a drain pump of 16 liters/minute, can empty the water content of 5 liters of water in a washing machine in a short time period but, it is operated for a fixed time period of 1 minute. Similarly, drain pumps are operated half or more of the operating periods in the existing control systems without need for it. This unnecessary operation, despite water is drained by the drain pump, continues without water, to complete the operation period. The drain pump operating without water is forming the highest source of noise in the machine that is sucking air from it. Despite there is no water in the machine, the drain pump continues to operate and results in unnecessary energy consumption. For example, in "normal" program of dish washing machine, a drain pump of 34W power operating at an average of 5.5 minutes, uses 3.2 wH energy. The drain pump when operated without need for it at 50% of this period. 1.6 wH unnecessary energy consumption is faced with. The drain pump, during its operation, draws different currents from the network while there is water in the machine (loaded) and while there is no water in it (unloaded). For example, a drain pump of 34W, if started to operate with a load over 3.5 liters, draws more or less 125 mA current but after the water in the machine is drained, the current drawn by the pump from the network is decreased to about 110 mA. The objective of this invention, is to provide a method by taking the difference of current drawn from the network by the drain pump while operating with and without load as the base, is to control the pump operating time, the values of the current drawn by the pump with electronic control and in parallel to this, to prevent the energy consumption arising out of unnecessary operation, to decrease the noise and to shorten the duration of the program. In order to reach to these objectives, the proposed method will be explained herebelow with reference to the attached drawings, wherein; Figure 1 is the electronic circuit diagram that controls the pump with microprocessor 1) and measures the currents drawn by the drain pump (2). Figure 2 is the circuit diagram in which " current transformer" (6) is used instead of " Manganin based resistance" (3). Figure 3 is the circuit diagram in which a "Hall effect transistor" (7) is used instead of " Manganin based resistance" (3). In the method according to this invention, drain pump is controlled by a microprocessor 1). To realize this, laboratory experiments are carried out and the difference of the currents drawn by the pump while operating with and without load are recorded. These values are saved to the memory of a microprocessor (1). After this phase, current ratios with and without load (I, 0 , lded / I unloaded ) r e saved in a microprocessor along with the program to be used. During operation, to measure the current drawn by the drain pump(2), a circuit formed by a "manganin based resistance" (3), a " op-amp" (4) and a " AC-DC converter" (5) is used (Figure 1). In this circuit, instead of "manganin based resistance" (3), a " current transformer" (6) or a "Hall effect transistor" (7) can also be used. A directly proportional voltage is formed on the manganin based resistance (3) which is connected to the line from the drain pump (2) over the microprocessor (1). This voltage is transmitted to a op-amp (4) circuit such that the highest value is increased to 5V AC. The voltage increasing at 0-5 V AC level in Op-amp (4) circuit, is converted into direct voltage in the AC-DC converter (5) circuit and transmitted to the microprocessor(l).This information coming into the microprocessor 1) as analog is later converted into digital information. If the voltage transmitted to microprocessor (1) is constantly above 5V, it means that the drain pump (2) is blocked. During normal use of the dish washing machine, after 7 seconds from the moment of entrance into operation of the drain pump(2), the current drawn is started to be measured. This time period, being dependent on take off time of the pump, may change between 5-10 seconds. This measurement period changes depending on the microprocessor and software used. In the present method, the time required for this is 640μs with PIC 16C74 microprocessor. The values recorded during the first five seconds after starting the measurements are compared with each other and the largest value is saved in the memory as the operation loaded value (I'ι oaded )• To compare the values with each other, a time period which is different from five seconds, may be preferred. Following the saving of the current for operation loaded ((I'ι oaded ) with each measurement made the saved current for operation loaded is compared and the ratio determined (!' loaded / I easu i ed ) i s compared to the ratio of operation with and without load (Ii oaded / ^ unloaded ) which was saved in the memory of the microprocessor during previous laboratory studies after being determined. When the value I' loaded / I mea ured > (I loaded / I unloaded ) equivalence is obtained, it is understood that the drain pump is operating without load and it is stopped. In case the measurements taken reaches at 5V continuously, decision is reached that the pump is blocked(2) and in this case, the user is informed with a warning method.

Claims: CLAIMS 1. A control method for drain pumps used in electrical home appliances characterized by ; • determining the characteristic between the currents used by the drain pump while operating loaded and unloaded; • Saving the obtained difference value in form of ratio like (Iι oaded I u ._i oaded> mt0 the microprocessor (1) along with the program to be used; • Starting to measure the drawn current during the use of the machine as of the take off period such as (5 to lOseconds) of the drain pump; • Saving the highest value which is obtained by comparison of the values obtained within the first five seconds or in a different time period as of the measurement, as loaded operating current (I'| oaded ) into the memory • Comparing the loaded operating current (I'ι oaded ) with each measured value and comparing the obtained ratio ((I' loaded / I measured ) with the values saved previously into the microprocessor as a result of the laboratory experiments; • Stopping the machine when the I' loaded / I measured > (I, oaded / I unloaded ) equivalence is provided assuming that the drain pump is working unloaded. 2. A method according to claim 1 wherein in order to measure the current used by the said drain pump; • a circuit comprising of an " op-amp" (4) and "AC-DC converter" (5) is used along with a " manganin based resistance" (3) or a " current transformer" (6) or a " Hall effect transistor" (7) serially connected to the electric line of the drain pump (2); • the voltage formed on "manganin based resistance" (3) or "current transformer" (6) or " Hall effect transistor" (7) is raised so that the maximum value is 5 V on the " op-amp" (4); • The raised current 0 - 5 V AC on the Op-amp (4) circuit is converted to direct current (DC) and transmitted to the microprocessor (1); • This analog data is converted to digital data. 3. A method according to claim 2 characterized by that when the voltage supplied to the microprocessor 1) permanently exceeds 5V, it is decided that the drain pump (2) is blocked and the user is informed by any means of warning.

Inventors: EKSERT SEMSETTIN, TAN FARUK, UGURLU IBRAHIM, EKSERT, SEMSETTIN, TAN, FARUK, UGURLU, IBRAHIM
Applicants: ARCELIK AS, EKSERT SEMSETTIN, TAN FARUK, UGURLU IBRAHIM, ARCELIK A.S., EKSERT, SEMSETTIN, TAN, FARUK, UGURLU, IBRAHIM
Application year: 1998
Main classification: F04D13
IPC codes: D06F39, F04D15