EP0255863B1 - Dishwashing machine - Google Patents

Description

The invention relates to a dishwasher according to the preamble of claim 1.

A known dishwasher of this type (US-A-3 888 269) is provided with a program switching device for controlling a multi-course overall wash cycle. The program switching device controls first of all the pre-rinsing from four successive pre-rinse cycles, a cleaning cycle with heated rinsing liquid and the addition of detergent into the rinsing liquid, two subsequent rinse cycles and finally a drying cycle. In the program steps for pre-rinsing, the cleaning cycle and the intermediate rinsing cycles, liquid is let into a rinsing container of the dishwasher, which is pumped around by a circulation pump via spray devices. The program switching device also has program steps by means of which a rinse liquid change is controlled between the aforementioned rinse cycles, which consists of completely pumping out the rinse liquid and the supply of fresh water for the following rinse cycle. A sensor for detecting the degree of contamination of the washing liquid is also connected to the program switching device and measures the turbidity of the washing liquid during the individual pre-wash cycles. If this sensor emits a signal during the pre-rinse cycle that is running, which signals less contamination of the rinsing liquid below a limit value, the program switching device immediately switches to the program step for the cleaning cycle. Here, the rinsing liquid change that usually follows after the rinsing cycle is hidden, so that the rinsing liquid is transferred from the pre-rinsing cycle into the cleaning cycle becomes. However, the measurement of the turbidity of the pre-rinse liquid takes place only in the second pre-rinse cycle and is repeated if necessary in the third pre-rinse cycle, with the result that if the pre-rinse liquid is less contaminated, the immediate switch back to the cleaning cycle takes place and if the soiling is above the limit value fourth pre-rinse cycle, including a rinsing liquid change. After the pre-rinsing has been completed, the subsequent rinsing cycles are no longer influenced by the sensor for detecting the degree of contamination. The subsequent cleaning cycle and the subsequent two intermediate rinsing cycles are then processed in each case. In this embodiment, considerable water consumption and at least the energy consumption required for the circulation of the washing liquid in these washing steps occurs.

A dishwasher is also known (EP-A-0 188 158), the program switching device of which controls a multi-course total rinse cycle consisting of three pre-rinse cycles, two cleaning cycles with heated washing liquid and addition of detergent and an intermediate rinse cycle, which is followed by a program step for a drying cycle. A program step is provided between the individual rinse cycles for carrying out a change of rinsing liquid. The program switching device is connected here to a sensor for detecting the degree of contamination of the rinsing liquid in the pre-rinse cycles. If the washing liquid in the respective pre-wash cycle is above a limit value, the pre-wash liquid is then pumped out and a new pre-wash cycle is carried out. If excessive contamination is also signaled in the third pre-rinse cycle, the program run is aborted because an error in the control must then be expected. If, on the other hand, the sensor does not detect any contamination above the limit value, the current pre-rinse cycle is carried out to the end and a rinsing liquid change is carried out in any case. Then the specified cleaning cycles and the intermediate rinsing cycle are carried out unchanged. Even with the so controlled Dishwasher has a high water consumption and at least the energy consumption required for pumping around the washing liquid.

Finally, a dishwasher is also known (FR-A-2 417 967) in which a pressure sensor for detecting the degree of contamination of the washing liquid is attached to the outlet line of a circulation pump for pumping washing liquid. This sensor controls the program switching device in such a way that in the respective rinsing cycle of a multi-course total rinsing cycle, liquid is initially let into the rinsing tank until the sensed pressure on the pump outlet line has a predetermined value. This ensures that the dishwasher can work with the minimum amount of water required for this pressure value. In the further course of the washing program, a second, higher pressure value is then specified. For this purpose, rinsing liquid is fed in again until the specified pressure value is reached at the pump outlet. This pressure value is therefore also achieved with the smallest possible amount of liquid. The pressure value detected by the sensor depends on the degree of contamination of the rinsing liquid in such a way that a larger quantity of rinsing liquid must be present with increasing degree of contamination until the respectively specified pressure value is reached. Measures can also be provided to extend or shorten the entire washing cycle as a function of whether the dishes are clean or not. Unnecessary filling circuits can then be switched off or additional circuits can be added. However, complete rinsing liquid changes are also provided here between the individual rinsing cycles.

The invention has for its object to take measures in a dishwasher according to the preamble of claim 1, by means of which a further reduction in water and energy consumption is made possible with little contamination of the dishes to be washed.

This object is achieved by the invention characterizing features of claim 1.

In one embodiment of a dishwasher according to the invention, it is assumed that in the single pre-wash cycle the dirt particles adhering to the dishes to be cleaned are removed, which are usually detached with a washing liquid without the addition of detergent. A much larger part of these initially detachable dirt parts cannot be removed from the dishes in a further pre-wash cycle, so that the water and energy expenditure for further pre-wash cycles is saved. The dirt portions remaining on the dishes after the pre-wash cycle, which can essentially only be removed by adding detergent to the heated washing liquid, then lead to contamination of the cleaning washing liquid in the corresponding subsequent cleaning cycle. If the resulting contamination is above a predetermined limit value, the cleaning process is carried out completely, whereby a program step is provided during the cleaning process in which a subset of the dirty washing liquid is removed from the area of the sieves provided for filtering the washing liquid, where the dirt particles are piled up in concentrated form. The removed part of the rinsing liquid is then replaced by fresh water. Due to the high level of contamination in the cleaning cycle, two subsequent intermediate rinsing cycles are then carried out. If, on the other hand, the sensor detects a lower degree of contamination of the rinsing liquid in the cleaning cycle, partial emptying is not carried out in the cleaning cycle and only a single intermediate rinsing cycle is carried out. If the dishes to be cleaned are very slightly soiled, the cleaning liquid provided for the pre-rinse cycle is taken over into the cleaning cycle and used there for heating and the addition of detergents for the cleaning cycle. There is also no partial emptying in the cleaning cycle and only a single intermediate rinse cycle. In this way, the amount of liquid required for the cleaning cycle and the amount of liquid required as a replacement for partial emptying as well as the Quantity of liquid saved for an intermediate rinse. The duration of the program can also be shortened accordingly.

If the level of contamination is only low in the cleaning cycle, partial emptying in the cleaning cycle and an intermediate rinsing cycle and the amount of liquid required are saved after performing a complete pre-rinse cycle. The limit value for the signal supplied by the sensor can be adjustable so that different degrees of soiling can also be predetermined in different rinse cycles as a starting point for the determination of a reduced or increased degree of soiling. If the sensor also detects a low degree of contamination, the program control assigned to the dishwasher is influenced in such a way that the program sections which can be shortened in this case are skipped or the emptying pump is prevented from being switched on.

The invention is explained in more detail below with the aid of sketches of an exemplary embodiment.

• Figur 1: Eine Prinzipdarstellung einer Geschirrspülmaschine mit Steuereinrichtungen für einen verkürzten Programmablauf und
• Figur 2: Ein Schema eines ungekürzten Programmablaufs sowie
• Figur 3 ein Schema für einen verkürzten Programmablauf.

Show it:

• Figure 1: A schematic diagram of a dishwasher with control devices for a shortened program and
• Figure 2: A schematic of an unabridged program flow as well
• Figure 3 is a schematic for a shortened program flow.

In the washware container (1) of a dishwasher there is an upper spray arm (2) and a lower spray arm (3), which are fed with washing liquid via associated pressure lines (4 and 5). The pressure lines (4, 5) branch off from a flow reversing device (6), for example a continuously rotating rotary valve, which is connected to the pressure port (7) of a circulation pump (8). From the circulating pump (8), an intake (9) leads into a drain pan (10) provided in the bottom (11) of the washware container (1) and through funnel-shaped fine sieve (12) towards the interior (13) of the washware container (1) is covered. The fine sieve (12) merges in the lower part into a cylindrical fine sieve cylinder (14) directed vertically downwards, which opens into a drainage shaft (15). A drain connection (16) leads from the drain shaft (15) to an emptying pump, not shown. A coarse sieve (17) is located within the fine sieve cylinder (14). The washware container is filled with liquid via a water line (18) with the controllable valve (19) switched on, which is controlled by a program switching device (20) that also controls the circulation pump (8) and other electrical components.

At least one sensor (21) is arranged in the washing system in order to determine the degree of contamination of the washing liquid which is generated by the addition of washing agent to the filled water in the successive washing steps of the overall washing program controlled by the program switching device (20) during the cleaning of contaminated goods. which outputs a control signal dependent on the determined degree of contamination to the program switching device. Different degrees of soiling can also be predetermined in different rinse cycles as a starting point for the determination of a reduced or increased degree of soiling.

The sensor (21) can be designed as a pressure sensor (21.1) which is connected to the pressure port of the circulation pump. However, pressure sensors (21.2 or 21.3) can also be connected to the pressure lines (4) or (5) to the spray arms (2) or (3). A pressure sensor (21.4) can also be assigned to the intake port (9) of the circulation pump (8). However, the sensor (21) can also be designed as an optical sensor and respond to the turbidity of the rinsing liquid. In addition, it is also possible to use the sensor (21) to record the weight of the washing liquid or the flow rate of the washing liquid. However, the speed of the spray arms (2 or 3) can also be scanned with a sensor (21.5). Likewise, the power-dependent speed of the circulation pump (8) or the current consumption of the drive motor for the circulation pump (8) can be detected with a sensor (21.6). Finally, it is also possible to adjust the dynamic working level of the liquid level in the drain pan (10) during flushing operation. to sense that changes with the degree of pollution. Furthermore, a bypass path can be provided in the flushing liquid path, in particular in the pipe system, in which a filter screen is arranged, a pressure sensor measuring the pressure loss or dynamic pressure occurring on the filter screen. This filter screen must be rinsed free after each rinse cycle in order to avoid falsification of the measurement result from previous rinse cycles.

At the beginning of a rinse cycle, the rinsing liquid with a pollution degree of 0 is practically pumped around in the rinsing system. If, for example, the pressure sensor (21.1) is used to determine the degree of contamination, then the maximum achievable pressure in the flushing system is present. If this pressure falls below a predetermined value in the course of the respective rinse cycle to be processed, which can be different in the pre-rinse cycle than in the cleaning cycle, this means normal or increased contamination of the items to be rinsed. There is then no reason to change a normal basic washing program according to FIG. 2. Accordingly, after the inflow of water for the pre-rinse cycle, the complete pre-rinse cycle specified by the program switching device is carried out. After the pressure measurement followed in the course of the pre-rinse cycle signals a normal to high degree of contamination, the pre-rinse cycle is processed to the end. The dirt-laden rinsing liquid is emptied there and fresh water is added again for the subsequent cleaning cycle. If the pressure measurement, which preferably takes place at the end of the heating process for the cleaning liquid, again results in a normal to increased degree of contamination, a partial emptying of the washing liquid is carried out via the emptying pump. In particular, the main part of the dirt collected in the coarse sieve and in the drain shaft is removed from the rinsing liquid and then the rinsing liquid level is refilled to the initial level, as well as the ongoing cleaning cycle up to the maximum end specified by the program switching device (20). continued. Then, for example, two intermediate rinse cycles and a rinse cycle, for example after each emptying and re-supplying of water, are added, the rinsing liquid being heated up again in the latter, so that this increases washing good for the subsequent drying cycle at the end of the total washing cycle can be removed from the dishwasher.

If contamination in the pre-rinse cycle that is below a predetermined value is determined by the sensor (21), then according to FIG. If the degree of contamination is very low, the rinsing liquid from the pre-rinse cycle can be used immediately for the subsequent cleaning cycle. There is then no need to change the water from emptying and supplying. If the degree of soiling is higher but below the normal value, it is advisable to change the water. In any case, however, the duration of the program will be reduced by the hidden part of the pre-wash cycle. If a degree of soiling below the normal value is determined in the subsequent cleaning cycle at the time of the pressure measurement, then the partial water change after heating up the cleaning liquid can be omitted and at least the program time period required for the water change can be hidden. If necessary, the period in which the dishes are washed further after the end of the heating phase can also be shortened. This rinsing time can be selected depending on the degree of contamination. At the end of the cleaning cycle, the water is changed again, one of the intermediate rinsing cycles being hidden. This is followed by the final rinse and drying cycle in the same program. Insofar as no heating energy is saved in the hidden parts of the rinsing cycles, the correspondingly shortened running of the circulation pump results in a reduction in the drive energy for the circulation pump and a shortened washing program sequence in addition to the water saved.

Since the speed of the flushing liquid also changes with changing pressure conditions in the flushing system, the degree of contamination can be determined by a sensor that responds to the flow speed.

With changing pressure conditions in the flushing system, however, the rotational speed of the spray arms driven by recoil also changes, so that their rotational speed can also be a measure of the degree of contamination. In addition, the power requirement for the drive motor of the circulating pump changes with the density of the rinsing liquid, which is dependent on the degree of contamination, so that the degree of contamination can also be determined by appropriate sensors via its speed or current consumption. Furthermore, the liquid level in the drain pan changes with different delivery volumes of the circulating pump, so that the level of contamination can be determined from this using a level sensor (21.7).

Claims (4)

1. Dishwasher, having a programmer (20) for controlling a multi-cycle total washing cycle, which programmer controls at least consecutive program stages for pre-rinsing, a cleaning cycle with heated cleaning fluid, and intermediate rinsing cycles, in which fluid is allowed into a rinsing container (1,13) and is pumped round by a circulating pump (8) via spray devices (2, 3), a change of fluid taking place between the individual rinsing cycles, which involves complete evacuation of the fluid and the supply of fresh water into the next rinsing cycle. and having a sensor (21) for detecting the dirt level of the fluid, which, in the case of a low dirt level in the rinsing fluid of below a certain limit value, during pre-rinsing transmits a signal to the programmer (20), which suppresses the change of rinsing fluid after pre-rinsing or moves the programmer (20) on beyond the immediately following program stage for the change of rinsing fluid, characterised in that the programmer (20) has a program stage for only one single pre-rinsing cycle, in that in the program stage for the cleaning cycle the sensor (21) is switched on, in that in the program stage for the cleaning cycle a partial change of fluid is provided, in which only some of the dirty cleaning fluid is discharged and the fluid level is filled up to the starting level, and in that the signal transmitted by the sensor (21) to the programmer (20) in the case of a low dirt level of the cleaning fluid in the cleaning cycle blocks the partial change of fluid and only releases the program stage for a single intermediate rinsing cycle.
2. Dishwasher according to claim 1, characterised in that the limit value for the signal supplied by the sensor (21) is adjustable.
3. Dishwasher according to claim 1 or 2, characterised in that the further intermediate rinsing cycle is temporarily jumped by the programmer in the case of a low dirt level in the cleaning cycle.
4. Process for operating a dishwasher according to claim 1, 2 or 3, having a multi-cycle total washing program, which consists at least of pre-rinsing, a cleaning cycle and intermediate rinsing cycles, between each of which a complete change of rinsing fluid takes place, wherein during pre-rinsing, the dirt level of the rinsing fluid is detected and, if the level of dirt is less than a preset dirt level, the subsequent change of rinsing fluid is blocked and the pre-rinsing fluid is taken over into the cleaning cycle, characterised in that a single pre-rinsing cycle is carried out, in that in the cleaning cycle the dirt level is measured, in that in the cleaning cycle a partial change of fluid is provided, in which only some of the dirty cleaning fluid is discharged and the fluid level is filled to the starting level, and in that in the cleaning cycle, in the case of a low dirt level, the partial change of fluid is blocked and then only one intermediate rinsing cycle is carried out with a preliminary, complete change of fluid.

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