The present invention relates to a coffee machine wherein the coffee is brewed by mixed with water.

Coffee machines that can brew Turkish coffee are known. In this type of machines, water and coffee are transferred to a brewing pot automatically or by the user and the coffee is brewed by heating the brewing pot. In the traditional Turkish coffee brewing method, the coffee is boiled with water, thus the coffee essence comes out. During the boiling, the coffee foams and the coffee pot is removed from the cooker and served before the foam overflows from the coffee pot. Since Turkish coffee can foam and overflow quickly during brewing, it is necessary to control the rise of the foam and stop the heating process before reaching the boiling point in order to prevent the foam from overflowing and to obtain the traditional taste and consistency of the Turkish coffee. While cooking traditional Turkish coffee with a coffee pot, the cooking pot is moved away from the fire a little by the cooking person at the time of rising, thus the rising time is extended such that the coffee particles are mixed better with water and the coffee is prevented from overflowing. It is known to control the amount of heat transferred to the brewing pot to increase the foaming time of the coffee while brewing Turkish coffee in the coffee machines. The use of level sensors such as infrared or time of flight is known to this end, and by turning off/turning on the heater as the sensor measures the foam level, the amount of foam is increased and the traditional brewing method is simulated. However, the moisture and the steam generated in the brewing pot cause the decision of turning off the heater at the wrong time to be taken. That the effect of these parameters is not equal, in other words linear, but is variable across all measurements causes a chaotic situation and adversely affects the decisions taken by the control unit of the coffee machine. If the sensor perceives the coffee as risen although it has not, the coffee remains uncooked, and otherwise, the coffee is overcooked, getting a bitter taste. In the state of the art International Patent Application No. W02006008583, a coffee machine is disclosed, which takes a first measurement taken by the sensor as the reference value.

In the state of the art International Patent Application No. W02007071567, a coffee machine is disclosed, wherein the traditional brewing method is simulated by controlling the heater.

In the state of the art International Patent Application No. WO2018174837, a coffee machine is disclosed, wherein the sensor errors are minimized by changing the calculation of the height of completing the brewing process.

The aim of the present invention is the realization of a coffee machine that provides the brewing of Turkish coffee with the traditional consistency.

The coffee machine realized in order to attain the aim of the present invention, explicated in the claims, comprises a control unit which determines the time for restarting the heater depending on the difference between a reference value taken at the beginning of the brewing process and a second reference value taken within a certain time after the heater is turned off, and which calculates a new second height value. Said difference is compared with a predetermined limit value, and if the difference is smaller than the limit value, it is understood that the decision of turning of the heater at the first time is correct and that at the second time the heater must be turned off when the coffee mixture reaches a predetermined second height value or a second value smaller than the same, and if the difference is higher than the limit value, it is understood that the decision of turning off the heater is taken due to the changes in the ambient conditions and is wrong, therefore at the second time the heater must be turned off after a longer period of time, in other words when the coffee mixture reaches a height value higher than the second height value. Thus, the changes in the ambient conditions are continuously monitored, and the brewing process is interfered with and the decision of completion of the brewing process is prevented from being erroneously taken. In an embodiment of the present invention, the control unit calculates the new second height value by using the predetermined second height value in direct proportion to said difference value. In a version of this embodiment, the new second height value is determined so as to be a linear function of the difference. By means of this embodiment, the changes in the ambient conditions are reflected to the algorithm of the decision of completion of the brewing process in the best manner.

In another embodiment of the present invention, the control unit determines a lower limit value and an upper limit value for the new second height value depending on the difference value. In this case, if the difference value is equal to or higher than a predetermined upper threshold value, the new second height value is selected as the maximum second height value. Similarly, if the difference value is equal to or smaller than a predetermined upper threshold value, the new second height value is selected as the minimum second height value. Thus, the heater is always turned on for a second time and the operational time is limited. Thus, the amount of foam is increased and the coffee is prevented from getting burnt.

In another embodiment of the present invention, the control unit determines the threshold values according to the amount of coffee or first height value expected to be realized before the first turning-off of the heater. By means of this embodiment, again the amount of foam is increased, and the consistency and the taste thereof are improved, preventing the coffee from getting burnt.

In another embodiment of the present invention, the control unit continuously takes measurements by the sensor instead of taking measures at certain times such that the effect of any change in the ambient conditions is included in the algorithm of taking the decision of completion of the brewing process.

In the coffee machine of the present invention, the values measured by the sensor are calculated again by taking into account the effect of the ambient conditions, and important changes which may affect the taste and consistency of the coffee are prevented. Thus, it becomes possible to brew coffee with the same taste and consistency under any condition. The coffee machine realized to attain the aim of the present invention is illustrated in the attached figure, where:

Figure 1 - is the schematic view of a coffee machine.

The elements illustrated in the figures are numbered as follows:

1. Coffee machine

2. Body

3. Brewing pot

4. Heater

5. Level sensor

6. Control unit

The following symbols are used so that the present invention is understood better: t - predetermined time

refdeltal - First predetermined reference height value

refdelta2 - Second predetermined reference height value

refl - First predetermined reference level value

ref2 - Second predetermined reference level value

teta - Difference between refl and ref2

limtetat - predetermined limit value

delta 1 - First height value

delta2 - Second height value

esika - Lower threshold value

esiku - Upper threshold value

delta2max - Maximum second height value

delta2min - Minimum second height value The coffee machine (1) comprises a body (2); at least one brewing pot (3) which is placed into/onto the body (2) and wherein water, coffee and as per the preference additional ingredients such as sugar are put and brewed; a heater (4) which is disposed in the body (2) and which enables the brewing port (3) to be heated; a level sensor (5) which is disposed on the body (2) and which measures the level of the water-coffee mixture in the brewing pot (3); and a control unit (6) which ensures that if the mixture in the brewing pot (3) reaches a predetermined first reference height value (refdeltal), the heater (4) is turned off and a predetermined time (t) is waited out afterwards the heater (4) is operated until the mixture in the brewing pot (3) reaches a predetermined second reference height value (refdelta2).

In the coffee machine (1), the user puts water and coffee into the brewing pot (3) and places the same onto the body (2) or water and coffee are automatically taken into the brewing pot (3), and then the user starts the brewing process by pressing the start button (not shown in the figures). In the brewing process, the heater (4) contacts the brewing pot (3) preferably from below and provides the brewing of Turkish coffee. The level sensor (5) will be referred to as the sensor (5) hereinafter. By means of the sensor (5), the raising of the foam on the coffee is detected and it is decided if the brewing process is completed. While brewing coffee, especially brewing Turkish coffee, the control of the amount of heat transferred to the brewing receptacle (3) is very important. The control unit (6) controls the heater (4) according to the data received from the sensor (5). When the height (deltal) of the mixture in the brewing pot (3) reaches a predetermined first reference height value (refdeltal), the heater (4) is turned off and/or the contact between the brewing pot (3) and the heater (4) is interrupted and thus the rising foam is enabled to come down, the heater (4) is restarted after a certain time (t) and the brewing process is completed when the height of the mixture reaches a predetermined second reference height (refdelta2). Thus, the amount of foam is increased and the consistency of the coffee brewed is improved.

The coffee machine (1) of the present invention comprises the control unit (6) which ensures that a first reference level value (refl) at the beginning of the brewing process and a second reference level value (ref2) within the predetermined time (t) after the heater (4) is turned off are measured by the level sensor (5), and that if the difference (teta) between the first reference level value (refl) and the second reference level value (ref2) is smaller than a predetermined limit value (limteta), a second height value (delta2) smaller than the second reference height value (refdelta2) is determined and if it is higher, a second reference value (delta2) higher than the second reference height value (refdelta2) is determined. In the memory of the control unit (6), the producer saves the expected values for the difference (teta) between the first reference value (refl) and the second reference value (ref2) obtained as a result of numerous experiments and related to the amount of coffee, hence to the number of cups as the predetermined limit value (limteta). The limit values (limteta) can be a value or can be used to define a value range.

If the difference (teta) is different from a predetermined limit value (limteta), there can be two possibilities. If the level of the coffee mixture, in other words the second reference value (ref2) is closer to the first reference value (refl), in other words smaller than the limit value (limteta), within a certain time (t) after the heater (4) is turned off, it is understood that the decision of turning of the heater (4) is corrent, in other words the coffee mixture has risen to the first reference height value (refdeltal) as desired and that the foam has come down to the previous level (refl) as the heater (4) is turned off. Therefore, it is not required to brew the coffee mixture to the predetermined second reference height value (refdelta2) while the heater (4) is operated for the second time, and it is sufficient to brew the coffee mixture to a second height value (delta2) smaller than said level (refdelta2). Here, by determining a smaller value (delta2), it is aimed to prevent the coffee from being overcooked so as to cause the foam to burst and so as to get burnt and have a bitter taste.

In the other possible case, if the difference (teta) is higher than the limit value (limteta), it is understood that the decision of turning off the heater (4) is affected by the changes in the ambient conditions and actually the heater (4) is turned off before the coffee mixture reaches the first reference height value (refdeltal). In other words, the coffee has not risen and has not been brewed as desired. By determining a longer time for the second operation of the heater (4) or determining a higher level (delta2) for the expected level of the mixture than the second reference height value, the coffee mixture is enabled to be brewed better in the second round, in other words when the heater (4) is operated for the second time.

In an embodiment of the present invention, the control unit (6) determines the second height value (delta2) in direct proportion to the difference (teta) between the first reference level value (refl) and the second reference level value (ref2). In a version of this embodiment, the control unit (6) determines the second height value (delta2) as a linear function of the difference (teta) between the first reference level value (refl) and the second reference level value (ref2). By means of these embodiments, an adjustment is made in proportion to the magnitude of the effects of the changes in the ambient conditions.

In another embodiment of the present invention, the control unit (6) ensures that if the difference (teta) between the first reference level value (refl) and the second reference level value (ref2) is higher than a predetermined upper threshold value (esiku), a predetermined maximum second height value (delta2max) is used as the second height value (delta2). If there is no acceptable rising during the first operation of the heater (4), the coffee mixture is enabled to rise to a maximum height (delta2max) in the second round, thus providing the desired amount of foam for the coffee and preventing the same from being overcooked and getting burnt.

In another embodiment of the present invention, the control unit (6) ensures that if the difference (teta) between the first reference level value (refl) and the second reference level value (ref2) is smaller than a predetermined lower threshold value (esika), a predetermined minimum second height value (delta2min) is used as the second height value (delta2). If there is excessive rising during the first operation of the heater (4), the coffee mixture is enabled to rise to a minimum height (delta2min) in the second round, thus enabling the coffee to foam again and preventing the same from being overcooked so as to cause the foam to burst.

In another embodiment of the present invention, the control unit (6) determines the threshold values (esiku, esika) according to the first reference height value (refdeltal). By determining the threshold values (esiku, esika) depending on the amount of rising of the coffee in the first round, a dynamic brewing algorithm is performed and the coffee is enabled to be brewed with the same taste and consistency without being affected by the changes in the ambient conditions.

In another embodiment of the present invention, the control unit (6) determines the threshold values (esiku, esika) according to the amount of coffee desired to be brewed. In the above-disclosed embodiment, the changes in the ambient conditions are included in the brewing algorithm, and in this embodiment the amount of coffee, which is one of the natural parameters of the brewing process, is included in the algorithm and the threshold values (esiku, esika) of the difference value (teta) are determined according to the amount of coffee to be brewed.

In a version of this embodiment, the control unit (6) continuously takes measurements by the sensor (5) instead of taking measurements at certain times, and uses the continuously-taken measurements in the above-disclosed embodiments. Said values can be calculated by continuously taking measurements and averaging said measurements or the iteration method can be used by using the previous measurements so as to continuously update the values.

The Turkish coffee brewing method of the present invention comprises the following steps executed by the control unit (6) in the coffee machine (1) comprising the above- described control unit (6):

- measuring the level of the coffee-water mixture in the brewing pot at the beginning of the brewing process and saving the value measured as the first reference level value (refl) in the memory of the control unit (6),

- turning off the heater (4) when the mixture in the brewing pot (3) reaches a predetermined first reference height value (refdeltal),

- waiting for a predetermined time (t),

- measuring a second reference level value (ref2) within the predetermined time (t),

- comparing the difference (teta) between the first reference level value (refl) and the second reference level value (ref2) with a predetermined limit value (limteta), and - determining a second height value (delta2) different than the second reference height value (refdelta2) depending on the difference (teta).

In a version of the Turkish coffee brewing method, the second height value (delta2) is calculated as a positive linear function of the difference (teta) so as to remain between a lower threshold value (esika) and an upper threshold value (esiku).

In the Turkish coffee machine (1) of the present invention, in cases the height, in other words the level, of the coffee-water mixture is erroneously measured due to the ambient conditions, the deviation of the level sensor (5) is determined, and the decision of completion of the brewing process is calculated for every brewing process. Especially, taking into account that the steam and moisture over the mixture increases when the temperature of the coffee mixture increases and hence the sensor (5) data deviates, taking measurements when the temperature is low gives better results. In other words, taking the measurement of the second reference level value (ref2) when the heater (4) is turned off improves the precision of the decision of completion of the brewing process.