RU2493766C2 - Method for regulation of drying in dishwashing machines - Google Patents

Abstract

FIELD: personal use articles.

SUBSTANCE: invention relates to a method for optimisation of drying in a dishwashing machine with a washing chamber for objects being washed; according to this method, objects being washed are heated to the preset temperature (T₀) that exceeds that of the condensing surface communicating with the washing chamber; the method includes the following stages: a) one determines the graph of characteristic temperature (T) during drying of the objects being washed; b) one determines the indicator characterising the factor of water evaporation from the surface of the objects being washed (28a, 28b) relying on the characteristic temperature graph; the method specificity consists in the fact that characteristic temperature (T) represents the difference (DT) between the temperature (T₁) characterising the temperature of the objects being washed and the temperature (T₂) characterising the condensing surface temperature.

EFFECT: drying process discontinuation when a sufficient drying result is achieved.

8 cl, 4 dwg

Description

Technical field

The invention relates to a method according to the restrictive part of paragraph 1 of the claims.

State of the art

An important performance parameter of automatic dishwashers is the amount of energy spent on various work processes, as well as the duration of these processes. These parameters are not independent, but are closely related to each other, and partly even opposite in the sense that minimizing one parameter results in an increase in another parameter. The last workflow, as a rule, is the drying of washable items in the washing chamber. Various drying methods and principles are known.

According to one of the methods based on drying with its own heat, the heating device supplies heat to the interior of the washing chamber, but moisture is not removed. This raises the temperature of the air inside the washing chamber, as a result of which the relative humidity of the air may increase. A cold surface increases the drying effect. It can condense moisture from the air inside the chamber, so that the moisture capacity of the air inside the chamber remains at the same level or increases.

In traditional dishwashers with the function of drying with their own heat, a predetermined amount of energy (heat) is supplied to the washing chamber regardless of the load, that is, of the quantity and heat capacity of the objects to be dried. The drying process has a predetermined fixed duration. The amount of heat and duration are selected in such a way as to provide sufficient drying efficiency even with a large load. This method does not take into account the possibility of low load. Also, when drying with its own heat, humidity sensors are not applicable, since the degree of humidity in the washing chamber is constantly maintained during drying, and sometimes even exceeded.

Disclosure of invention

The task of the invention is to optimize the drying process (step) in the dishwasher. An optimized drying process should be inexpensive and technically easy to implement, in particular, it should not need technically sophisticated sensors and / or devices needed specifically for the drying process.

The invention proceeds from a method for optimizing the drying process, such as, for example, controlling the drying time in a dishwasher with a washing chamber for washable items, according to which washable items are heated to a predetermined initial temperature (T ₀ ) that exceeds the temperature of the condensing surface in communication with the washing chamber .

The objective of the invention is solved by the following steps:

a) taking a graph of the characteristic temperature (T) during drying of washable items.

b) determination of a characteristic characterizing the coefficient of evaporation of water from the surface of washable objects (28a, 28b), based on a graph of the characteristic temperature,

moreover, the characteristic temperature (T) is the difference (ΔT) between the temperature (T ₁ ), which characterizes the temperature of washable objects, and the temperature (T ₂ ), which characterizes the temperature of the condensing surface.

A sign characterizing the complete drying of washable objects may be the achievement, exceeding, or lowering below a suitably selected critical value characteristic of complete drying, that is, the threshold value of the characteristic temperature (T). Recognition of a characteristic may include recognition of the achievement of the final temperature or the onset of the asymptotic behavior of the dependence of the characteristic temperature on time. Thus, the onset of complete drying can be detected, the drying process can be stopped in a timely manner, that is, for example, before the expiration of the programmed drying time, and thus, time can be saved.

A characteristic feature can also be the achievement of the value of the derivative of the characteristic temperature with respect to time, which characterizes complete drying, that is, the threshold value dT (t) / dt. It can also be the achievement of the characteristic value of the difference (ΔТ = Т ₁ -Т ₂ ) of temperatures or the time derivative (d (ΔT) / dt) of the temperature difference T ₁ and T ₂ measured in two different positions, that is, the threshold value for ΔT or d (ΔT) / dt. The time derivative of the temperature signals can be calculated by a program processed in the processor of the central control device and provided for analysis.

The determination of these characteristic features of the characteristic temperature allows you to automatically determine the drying. Due to the appropriate selection of the characteristic temperature and characteristic, the automatic determination of drying may not depend or to the maximum depend on the heat and noise insulation of the washing chamber, environmental conditions, in particular, ambient temperature (for example, in summer or winter) and the specific conditions at the installation site of the automatic dishwasher machines (for example, a freestanding machine or a machine built between adjacent elements of kitchen furniture).

The advantage of the method is that the drying process can be controlled depending on the load. That is, with a small load, energy can be saved, and with a large load, sufficient drying efficiency can nevertheless be achieved. Optimization consists, first of all, in stopping the drying process when a sufficient drying result is achieved. For this, according to the invention, only a technically simple and inexpensive temperature sensor with appropriate signal analysis is required. Of course, two or more temperature sensors can be used, which are installed in different positions, and their signals of the measured temperature are combined to obtain a characteristic temperature, as is done, for example, when forming a temperature difference.

In traditional dishwashers, a fixed duration of the drying process and its initial temperature are set in a programmable control device, and these parameters are calculated for a given standard load.

In a further embodiment of the invention, the dishwasher comprises means for determining a load or a load volume. The initial temperature for the drying process with its own heat is determined before drying, depending on the specific load. For this, a suitable initial temperature and / or the amount of thermal energy that must be used to heat washable objects can be set before heating washable objects depending on the load. In this case, the load can be expressed, for example, by the quantity, heat capacity and / or total surface area of washable objects. Thus, the drying process can be optimized depending on the load, for example, reduced at low load.

The characteristic temperature can, in principle, be determined at various points in the dishwasher. It can characterize, for example, the temperature of the condensing surface. Characteristic temperature can also characterize the temperature of washable objects.

The temperature difference can be formed, for example, on the basis of the temperature characterizing the temperature of washable objects, and the temperature characterizing the temperature of the condensing surface. For the temperature of the condensing surface, if necessary, you can take the temperature of the heat accumulator. Based on the analysis of the temperature difference, the influence of the ambient temperature and / or the conditions of the installation site and / or the heat and noise insulation surrounding the washing chamber is reduced or eliminated, so that the recognition of the characteristic feature can be improved.

To solve the above problem, a dishwasher with a washing chamber for washing objects, with a condensing surface in communication with the washing chamber, and with means for heating washing objects in the washing chamber are also proposed.

According to the invention, the dishwasher also contains means for determining the time dependence (T (t)) of the characteristic temperature (T) and means for determining the sign of the time dependence of the characteristic temperature, characterizing the degree of evaporation of water from the surface of washable objects. Thanks to this, the actual end of the drying process can be calculated. That is, its end can be determined depending on the load, that is, the drying process is completed as needed.

A condensing surface may be, for example, a loading door. Since the loading door in traditional dishwashers already contains electronic components and process controls, a temperature sensor can be integrated into it with minimal additional technical costs and inexpensively. Preferably, the condensing surface is in heat-conducting connection with an element having a high heat capacity, for example, a water storage tank or a heat accumulator operating at a relatively low temperature. The condensing surface may also be the surface of a heat accumulator in communication with the washing chamber. The temperature of the condensing surface changes slightly during heating of washable objects, which contributes to effective condensation and, therefore, drying. Due to the large heat capacity of the water storage tank or heat accumulator, the influence of the ambient temperature (for example, in winter or summer) or the conditions of the installation site (for example, near other heat-generating devices) on the characteristic temperature is at least reduced.

The recording device can be made in such a way that it is able to determine the time dependence of the temperature characterizing the temperature of the condensing surface, and can be, for example, a temperature sensor thermally connected to the condensing surface. Alternatively, the recording device may be designed so that it is able to determine the time dependence of the temperature characterizing the temperature of washable objects, and may be, for example, a temperature sensor thermally connected to the water pumped through the washing chamber. A suitable installation location may be, for example, a sump pump of an automatic machine.

The determining device may contain one or more of the following means (modules):

(i) means for determining the achievement of the final value,

(ii) Means for determining the onset of asymptotic behavior when approaching the final value of the characteristic temperature,

(iii) Means for determining the achievement of the threshold value of the time dependence and / or

(iv) A means for determining a threshold value of a time derivative or a time derivative of a time dependence of a characteristic temperature.

These tools can be implemented in the form of software modules that analyze the temperature signals of the recording device. For this, a central control device (controller) can be provided with a processor that can be programmed using software.

In addition, the dishwasher may contain means for calculating the first derivative of the time dependence of the characteristic temperature over time. The determining device may comprise means for determining the achievement of the final value or the onset of asymptotic behavior when approaching the final value of the time derivative of the characteristic temperature. Alternatively, it may comprise means for determining whether the threshold value of the time dependence or the threshold value of the time derivative of the time dependence of the characteristic temperature is reached. These tools may also be implemented as software modules executed by a processor.

To calculate the temperature difference, the temperature characterizing the temperature of washable objects and the temperature characterizing the temperature of the condensing surface or the surface of the heat accumulator can be used. To measure the temperature of washable objects, the first temperature sensor can be placed in the water circuit through the washing chamber, for example, in a circulation pump. Alternatively, the temperature of the medium involved in the heat exchange with the washed objects, for example, the basket into which the washing objects are placed, or the temperature in the washing chamber, for example, near the place where the washing objects are laid, can be measured. To measure the temperature of the condensing surface, a second temperature sensor may be provided which is in thermal contact with the condensing surface or the surface of the heat accumulator. By calculating and analyzing the temperature difference, the influence of environmental conditions or the installation site on the control of the drying process can be reduced or eliminated.

In addition, it is preferably provided that the temperature is recorded and analyzed, characterizing the washed items and / or the condensing surface. For this, the various measured values can be variously evaluated before analysis.

According to one embodiment of such a recording and calculating device, in a dishwasher with a heat accumulator, the first temperature sensor may be, for example, in said battery. The second sensor can be installed in the washing chamber, and the third in the device for supplying detergents in the loading door. For each of the simultaneously measured values of the second and third sensors, the calculation device generates a relative value (coefficient), which is derived from the simultaneously measured temperature value of the first sensor. Measurements at several points in time within the same time interval allow us to construct a graph with a falling characteristic, which asymptotically approaches the threshold temperature value. The threshold value indicates complete drying. If the characteristic has approached it to a certain extent, or if a threshold value has been reached, the control device will receive an appropriate signal by which the control device will complete the drying process.

Brief Description of the Drawings

The main idea of the invention is explained in detail below on the basis of the figures. The figures depict:

Figure 1: time dependence of temperature during working processes in the washing chamber of a dishwasher with drying by its own heat.

Figure 2: time dependence of the temperature in the washing chamber of the dishwasher during washing and drying for various loading options.

Figure 3: schematic section of a dishwasher (side view).

Figure 4: schematic section of a dishwasher with a heat accumulator (front view).

The implementation of the invention

The figure 1 presents the working processes in the dishwasher with the function of drying with its own heat, according to the state of the art. These include pre-washing 2, first cleaning 4, second cleaning 6, intermediate washing 8, final washing 10 and drying 12 to complete work processes. During pre-flushing 2, cold clean water (in the amount of about 3.4-3.9 l) is supplied to the chamber and circulated through the washing chamber 14 (see figures 3 and 4) for a predetermined period of time (approximately 15 minutes) using a circulation pump 20 installed under the washing chamber 14. During subsequent cleaning 4, detergent is introduced into the washing chamber 14, and the water supplied during the preliminary washing is heated to the initial cleaning temperature (about 51 ° C) for about 13-14 minutes . A heating device (not shown in the figure), placed in the hydraulic circuit, heats the circulating water to the temperature necessary for the current working process. During subsequent cleaning 6, the circulation of heated water with detergent is performed. Cleaning 6 is the main process for cleaning dishes 28 placed in the washing chamber 14.

In the period between cleaning 6 and intermediate washing 8, the washing solution is pumped out of the washing chamber 14 and clean cold water is supplied to it. During the intermediate washing 8, clean water circulates through the washing chamber for about 5 minutes, while it is heated by contact with objects in the washing chamber 14 that have retained heat after the cleaning process 6, for example, with washing objects 28, 28a, 28b, a basket 30, a pivoting console 24 with nozzles, walls of the washing chamber 14, as well as parts 22a, 20, 22b of the hydraulic circuit. In the transition from intermediate washing 8 to final washing 10, the water used in the intermediate washing is pumped out of the washing chamber 14, after which pure water is supplied there.

In known dishwashers with the function of drying with their own heat, clean water, pumped for the final rinse 10, during this process circulates through the chamber for a given fixed period, for example, about 15 minutes, while it is heated due to a given fixed power of the heating device to the initial temperature THAT (for example, approximately 65 ° C) required for the subsequent drying process 12.

Figure 2 shows the temporal temperature characteristic or the time dependence of the temperature in the washing chamber for different volumes of loading during the final washing 10 and drying 12. The temperature shown in figure 2 may be the aforementioned characteristic temperature. It can also be the temperature of the load item 28a or 28b, or the temperature T _{1 of the} circulating water measured by the first temperature sensor 32. Figure 2 shows the time characteristic T _n (t) for a normal load containing a certain amount of dishes and cutlery, and the time characteristic T _n- (t) for the load n-, reduced compared to the normal load, and the time characteristic T _{n +} (t) for the load n +, increased compared to the standard load. When the heating device is turned on, the temperature in the washing chamber 14 and, thereby, the temperature of the washing objects 28a, 28b during the final washing 10 rises, in general, in proportion to the time t. The temperature rise shown in FIG. 2, which is less than proportional, is caused by heat transfer losses, in particular, through the walls of the washing chamber 14 and the loading door 16 to machine parts located outside the washing chamber 14. During normal loading n, the temperature during the final washing 10 rises in accordance with the Central curve T _n (t) to a temperature T ₀ , the initial temperature of the subsequent drying process 12. With a reduced load n- or increased load n +, the temperature at the same power of the heating device rises more strongly in accordance with the upper curve T _n- (t) or weaker in accordance with the lower curve T _{n +} (t) to the corresponding initial temperatures T _{0, n-} or T _{0, n +} subsequent drying process 12.

After turning off the heating device, the drying process 12 begins. Under normal loading n, the temperature characteristic T _n (t) changes, in general, in accordance with the falling exponent. As the characteristic temperature T _n decreases, drying of the loaded items is accelerated, that is, the moisture film present on the washing items 28a, 28b evaporates and condenses on a cold surface, for example, a cold wall or the inside of the loading door 16 in the washing chamber 14. At time t _{12, n, the} temporal temperature characteristic T _n (t) reaches a temperature T _{12, n} , which subsequently changes only slightly and indicates the achievement of an asymptotic state. That is, the moisture film on the washing items 28 completely evaporated. The drying process 12 of the load n can be stopped at time t _{12, n} .

In this example, the temperature characteristic T _n (t) corresponds to a characteristic characteristic characteristic of the evaporation coefficient. The achievement of the asymptotic state is a characteristic sign of the complete drying of washable objects 28. By determining the time characteristic T (t) of the characteristic temperature T, it is possible to recognize the end of the drying process 12 and complete the drying process 12. For example, an optical or acoustic signal “Drying complete” can be generated or an internal control signal can be generated to complete the drying process 12 and turn off the automatic dishwasher and / or put it in a state of readiness to open the loading door 16 and empty the washing chamber 14.

In the example shown in figure 2, with a reduced load n- the temperature T _n- (t) drops at the beginning of the drying process faster than with a normal load n, and the asymptotic state at a temperature T _{12, n-} at the time t _{12, n-} It is reached earlier than during normal loading. The reason is that with a reduced load n- the total amount of moisture to be evaporated from the surfaces of washable objects 28 is reduced. Conversely, with an increased load n +, the temperature T _{n +} (t) at the beginning of the drying process decreases more slowly than with a normal load n, and the asymptotic state at a temperature T _{12, n +} at the time t _{12, n + is} reached later.

Determining the achievement of the asymptotic state of the temperature characteristic makes it possible to recognize the complete drying of washable objects 28 depending on the load. This can be used to complete the drying process 12 upon reaching full drying and to ensure constant drying efficiency (full drying) depending on the load. Thereby, the drying process is optimized in comparison with the drying process with fixed programmed parameters (fixed initial temperature, fixed drying time), since with a reduced load, the drying process 12 can be completed earlier than in conventional automatic dishwashers with a fixed drying time.

In the above description, it was assumed that the characteristic temperature is the temperature in the washing chamber 14, for example, the temperature of washable objects 28a, 28b. However, another measured temperature can be taken as the characteristic temperature, as is the case, for example, in embodiments of the invention according to figures 3 and 4.

The dishwasher according to figure 3 contains a washing chamber 14, in which washable items 28 are placed in the basket 30, namely plates and cups, a loading door 16 that is hinged to the washing chamber 14, which is closed during execution of the working processes shown in figure 1, pivoting console 24 with several nozzles 26 mounted rotatably in the washing chamber 14, a circulation pump 20 mounted under the bottom 19 of the washing chamber 14, a bypass pipe inlet 22a connecting the pressure outlet of the circulation pump CA 20 with a rotary console 24 with nozzles, a discharge section 22b of the bypass pipe leading to the suction side of the circulation pump 20, as well as the first temperature sensor 32 and the second temperature sensor 34, which are electrically or optically connected to the corresponding temperature sensing devices that analyze the temperature signals, measured by temperature sensors 32, 34.

The first temperature sensor 32 is installed in the circulation pump 20. It serves to measure the temperature T1 or to record the time dependence T1 (t) of the washing solution in the circulation circuit. It can be located in other places of the circulation circuit, for example, in the inlet section 22a, outlet section 22b or in the recess of the bottom of the washing chamber 14 near the outlet 22b.

The second temperature sensor 34 is installed so that it is in contact with the inner wall, that is, with the wall of the loading door 16 facing the washing chamber 14. It serves to measure the reference temperature T2 or to record the time dependence of the reference temperature T2 (t), which is characteristic of the temperature of the cold surface in the washing chamber 14. The sensor can also be installed in other positions, for example, on the control panel 18 to determine the temperature of the loading door 16. At this point, at strength already available are electric cables, it can be easily connected to a respective temperature sensing device.

The temperature T (t), which is characteristic for determining the characteristic, is the temperature difference T1 and T2, that is, T (t) = ΔT ₁₂ (t) = T ₁ (t) -T ₂ (t). The water temperature T1, measured by the first temperature sensor 32 in the circulation circuit, drops after the heating device is turned off at the end of the final washing process with the start of the drying process. The temporal response T1 (t) can be represented as a curve that decreases over time. The shape of this curve will be similar to the curve shown in Figure 2. The temperature T2, measured by the second temperature sensor 34 on the condensing surface, rises during the final washing process due to heat transfer to and through the walls of the washing chamber, but slower than temperature T1. After the start of the drying process, the temperature T2 rises further due to the heat of condensation released during condensation of moisture evaporated from washing objects on the cold surface of the washing chamber. This additional rise of T2, however, is weaker than the fall of T1, so that the temporal characteristic of the temperature difference ΔT ₁₂ (t) = T1 (t) -T2 (t), in general, shows a falling dynamics. A sign characterizing the achievement of complete drying of washable items is the lowering of a suitably selected critical value that is characteristic of complete drying, that is, a threshold value for ΔT ₁₂ .

The dishwasher shown in figure 4, in contrast to the machine according to figure 3, additionally contains a heat accumulator 38 adjacent to the side wall of the washing chamber 14. The heat accumulator 38 is made in the form of a container located parallel to the side wall of the washing chamber 14. This container contains, in general, two parallel walls, a supply pipe 40a with an adjustable supply valve 42, designed to fill the heat accumulator 38 with water, and a discharge pipe 40b, designed to empty the heat accumulator cumulator. As in the embodiment according to figure 3, the first temperature sensor 32, designed to measure the temperature T1 or to record the time dependence T1 (t) of the washing solution, is installed in the circulation circuit. Instead of a second temperature sensor 34 (see FIG. 3) mounted on the loading door 16, a third temperature sensor 36 is provided in contact with the wall of the heat accumulator 38 facing the washing chamber 14. It serves to measure the reference temperature T3 or to record the time dependence reference temperature T3 (t), which is characteristic of the temperature of the water in the heat accumulator 38.

The heat accumulator 38 at the beginning of the final washing process or the drying process is filled with clean water, the temperature of which is lower than the temperature of the circulating washing solution. The temperature T3 in the heat accumulator 38 rises during the final washing process due to heat transfer to and through the walls of the washing chamber 14, however, more slowly than the temperature T1. The rise in temperature T3 from the start of the drying process is provided by the heat generated by the condensation of the water evaporated from the washing objects 28a, 28b on the cold side wall of the washing chamber 14, to which the heat accumulator 38 adheres. The temperature T (t) characterizing the determination of the characteristic feature is temperature T3 in the heat accumulator, that is, T (t) = T3 (t). A sign characterizing the complete drying of the washed item is the excess of a suitably selected critical value that is characteristic of complete drying, that is, the threshold value for T3.

A suitable control device does not allow to open the loading door 16 during the final washing 10 and drying 12. Thus, wetting of washing objects due to back condensation when opening the loading door is prevented.

Claims (8)

1. A method of optimizing the drying process in a dishwasher with a washing chamber for washable items, according to which washable items are heated to a predetermined initial temperature (T ₀ ), which exceeds the temperature of the condensing surface in communication with the washing chamber, comprising the following steps:
a) determine a graph of the characteristic temperature (T) during drying of washable items;
b) determine the characteristic characterizing the coefficient of evaporation of water from the surface of washable objects (28a, 28b), based on the characteristic temperature graph, characterized in that the characteristic temperature (T) is the difference (ΔT) between the temperature (T ₁ ) characterizing the temperature of the wash objects, and temperature (T ₂ ), which characterizes the temperature of the condensing surface. 2. The method according to claim 1, characterized in that said sign is the achievement of a final temperature (T (t → ∞)) or the beginning of the asymptotic behavior of the dependence (T (t)) of the characteristic temperature on time. 3. The method according to claim 1, characterized in that to determine the specified attribute, an analysis of the increases in the characteristic temperature curve is performed. 4. The method according to one of claims 1 to 3, comprising measuring a temperature characterizing the temperature of washable objects, and / or recording a characteristic (T ₁ (t)) of temperature (T ₁ ) characterizing the temperature of washable objects. 5. The method according to one of claims 1 to 3, characterized in that the dishwasher contains a heat accumulator (38) and that the temperature (T ₂ ) characterizing the temperature of the condensing surface is a temperature (T ₂ = T _WT ), which characterizes the temperature of the heat battery (38). 6. The method according to claim 5, characterized in that the registration and analysis of the temperature (T ₁ ), characterizing the temperature of washable objects, and / or temperature (T ₂ ), characterizing the temperature of the condensing surface. 7. Dishwasher with a washing chamber for washing objects and a condensing surface in communication with the washing chamber, as well as with means for heating washing objects in the washing chamber to a predetermined initial temperature exceeding the temperature of the condensing surface, characterized in that it contains means for determining the time dependence ( T (t)) of the characteristic temperature (T), containing the first temperature sensor (32), designed to record the time dependence of temperature (T ₁ ), characterizing the temperature a round of washable objects, and a second temperature sensor (34), designed to record the time dependence of temperature (T ₂ ), characterizing the temperature of the condensing surface, and means for determining the sign of the dependence of the characteristic temperature, characterizing the degree of evaporation of water from the surface of washable objects (28a, 28b) . 8. Dishwasher according to claim 7, characterized in that the means for determining may include one or more of the following means:
i) means of determining the achievement of the final value,
ii) means for determining the onset of asymptotic behavior when approaching the final value of the characteristic temperature,
iii) means for determining the achievement of a threshold value of a time dependence and / or
iv) means for determining the threshold value of the derivative of the time dependence of the characteristic temperature over time.

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