CN1148149C - Method for operating a dishwasher - Google Patents

Abstract

The invention relates to an energy-and water-saving method for a dishwasher for washing dishes to be washed with a washing liquid, the application of which does not require the following of special head conditions, wherein the washing liquid is conveyed by a gaseous conveying medium under pressure.

Description

How the dishwasher works

technical field

The invention relates to a method of operating a dishwasher for rinsing dishes to be washed with a washing liquid.

Background technique

In all previously known dishwashers, especially domestic dishwashers, the dishes to be washed are rinsed continuously with a washing liquid, which normally consists of water and possibly added detergent or Detergent composition.

This cleaning liquid is generally conveyed by a circulating pump, for example designed as a centrifugal pump, from a continuously filling liquid storage tank via a delivery line to the spray device, with which the cleaning liquid is applied to the tableware to be cleaned.

When the tableware to be cleaned is cleaned, by adding a certain amount of chemical additives to the cleaning solution, but mainly by rinsing the tableware for a long enough time and cleaning the dirt on the tableware to be cleaned during this entire time. The mechanical friction can achieve sufficient cleaning effect. This means that, in addition to the energy consumption for delivering the cleaning fluid, a long cleaning program is also required.

When a centrifugal pump is used, the separation of gas or solid particles is caused by centrifugal action, which affects the delivery capacity and efficiency of the pump.

In conventional pumping methods, such as with conventional pumps, the liquid must flow from a storage tank into the pump under its own static pressure. The active part of the pump, the moving part, in the case of a centrifugal pump, the impeller creates a negative pressure and draws liquid into the pump. This negative pressure is limited by the inlet of the liquid. If the static pressure on the suction side is insufficient to force a sufficient volume of liquid into the pump and limit the negative pressure mentioned above, the absolute pressure developed on the suction connection may drop below the vapor pressure of the liquid. As a result, the liquid evaporates and enters the pump with vapor instead of liquid. In this way, the delivery capacity of the pump is reduced to a small fraction of the specified delivery volume. Additionally, loud noises are generated during this process called cavitation, which is caused by condensation of vapor bubbles.

At higher temperatures and in the presence of solid particles, the so-called germination point (Keim), due to the increase in vapor pressure, i.e. shifting to near atmospheric pressure, when the pump sucks in hot and dirty liquids (especially in dishwashers), Such occurrences are particularly serious and frequent, which can lead to the above-mentioned serious disturbances in operation, and even to the destruction of the pump, and cause the above-mentioned excessive noise.

In order to avoid these disadvantages, as mentioned above, the liquid should be managed to flow into the pump under its own sufficient static pressure, for example from a liquid storage tank. For this, a minimum level of liquid, the so-called net suction head (NPSH), must be maintained on the suction side of the pump, for example in the reservoir, in order to generate the required static pressure. This minimum height of the liquid (usually referred to as head) cannot always be guaranteed because, for example, it is impossible in the space of the dishwasher and would necessarily make the structure of the dishwasher complex and expensive, or in other words, because for It is undesirable to have to reserve additional cleaning liquid which eventually disappears during operation.

Contents of the invention

It is therefore the object of the present invention to propose a method of operating a dishwasher of the above-mentioned type, which saves energy and water and whose application does not require special head conditions.

According to the invention, this object is achieved in that a method for operating a dishwasher in which the dishes to be cleaned are rinsed with a washing liquid in the dishwasher, wherein the washing liquid is supplied in a gaseous state under pressure. The conveying medium is conveyed in a pulsed manner at a certain time interval. It is characterized in that the cleaning liquid is conveyed by a rhythmic impact method. When using the rhythmic impact method, the cleaning liquid is applied with a pressure through the gaseous conveying medium. The pressure alternates between two pressure levels in such a way that at a low pressure level generating a negative pressure, the cleaning fluid is sucked in, and by applying a higher pressure level generating an overpressure, the cleaning liquid is drawn in the desired direction of delivery. transport within.

When conveying the cleaning liquid with a gaseous conveying medium under pressure, no special head and suction conditions are required, which leads to a simpler construction of the dishwasher. Since no pumps are used to deliver the cleaning liquid, no minimum injection volume of cleaning liquid is required and thus the water consumption can be reduced compared to the prior art described at the outset. In this way, less electrical energy is also used in delivering the cleaning fluid compared to prior art centrifugal pumps which operate continuously on electrical power. In other words, the present invention successfully proposes an energy-saving and water-saving operation method for the dishwasher, and its application does not need to follow special lift conditions.

According to a preferred feature of the invention, the cleaning liquid is conveyed at regular time intervals by means of a gaseous conveying medium under pressure. During the water supply time interval of the tableware to be washed, the pressure of the supplied washing liquid rises every time the water supply starts, and the pressure of the supplied washing liquid decreases every time the water supply ends. Practice has shown that by this alternate rise and fall of the pressure of the cleaning liquid and thus the alternate rise and fall of the mechanical force acting on the dirt of the tableware to be cleaned, it is possible to achieve a shorter water supply duration than the above-mentioned prior art. In this case, a sufficient cleaning effect can be achieved and the duration of the cleaning program can be shortened.

According to another feature of the invention, the delivery of the cleaning liquid is pulsed, so that in a very short time an alternating rise and fall of the pressure of the cleaning liquid and thus a mechanical force acting on the dishes to be cleaned can be produced. alternating rise and fall. Practice has shown that a further noticeable improvement in the cleaning effect can thus be achieved with a shorter rinse time for the dishes to be cleaned.

According to a preferred embodiment of the invention, the ratio of the duration of the delivery interval of the cleaning liquid to the delivery duration of the cleaning liquid is approximately 3:1, wherein according to an advantageous embodiment of the invention, the delivery duration of the cleaning liquid for 0.5 seconds. With this very short pulse duration, the cleaning effect of the cleaning liquid applied under pressure to the dishes to be cleaned is optimized.

According to a preferred embodiment of the invention, in order to realize the rinsing of the dishes to be washed in a simple manner, the above-mentioned gaseous conveying medium is conveyed by means of a pulsed pumping method.

According to an advantageous embodiment, this clocked pumping method is realized in that a clocked pump, for example a piston pump or a diaphragm pump, etc., is used to transport the gaseous pumping medium.

As an alternative solution, the gaseous conveying medium can also be used to convey the cleaning liquid in a timed manner from a gas source.

According to a preferred embodiment, the cleaning liquid is conveyed using a clocked impact method in which the cleaning liquid is exerted by a gaseous conveying medium at a pressure which alternates between two pressure stages such that Change, that is, at a low pressure level that generates a negative pressure, the cleaning liquid is sucked in and by applying a higher pressure level that generates an overpressure, the cleaning liquid is conveyed in the desired conveying direction. By applying low pressure, a sufficient volume can be inhaled despite the low suction head. With the next application of a higher pressure, the cleaning liquid is forced to be conveyed by displacement. Since a gaseous conveying medium must also be sucked in for the compression, this measure can also be used to convey this negative pressure which is present anyway, the liquid, in particular to accelerate the delivery of the wake of the new quantity of cleaning liquid to be conveyed.

The gaseous conveying medium is preferably air, so that this most common gas is used for conveying cleaning.

Liquid According to a preferred embodiment of the invention, during a subprogram step "blow dry", the gaseous conveying medium is introduced into the treatment chamber of the dishwasher, so that the gaseous conveying medium (air) which is present anyway is blown The blow-drying effect is improved and the duration of the "Blow-Dry" subprogram step is considerably shortened by drying residual humidity from the dishes to be washed.

The present invention will be described in detail below in conjunction with the embodiments shown in the accompanying drawings.

Description of drawings

Fig. 1 has the schematic diagram of the domestic dishwasher of a device that implements the method of the present invention;

Fig. 2 implements the schematic diagram of the device of the inventive method;

FIG. 3 shows the time course of an injection pulse according to the method according to the invention.

Detailed ways

In the exemplary embodiment, the method according to the invention is described using a domestic dishwasher 25 shown in FIG. 1 in which a device 1 for carrying out the method according to the invention is installed. In this domestic dishwasher 25, the tableware to be washed, not shown in the dishwasher 25, is rinsed with a washing liquid, in which water as washing liquid is optionally mixed with detergent or cleaning agent, possibly also with washing Dropped food residue.

The domestic dishwasher 25 has a rinsing tank 26 for placing and rinsing unillustrated tableware to be cleaned, and this rinsing tank can be provided with a door not described in detail which generally rotates around a horizontal axis in a domestic dishwasher. closure. In this rinsing tank 26 are placed crockery baskets 27, 28, in which are placed unshown crockery such as boxes, plates, cups, bowls, etc., which are passed through a spraying device such as a so-called spraying device with a cleaning liquid. The shower arms 29, 30 are rinsed according to the method of the present invention, and the cleaning liquid returned from the unshown tableware to be cleaned in the cutlery basket is collected in the lowermost section of the rinse tank 26. The lowermost section of the rinse tank is generally called Pump tank or drain tank.

According to the invention, the cleaning liquid is conveyed in pulses at regular time intervals by means of a gaseous conveying medium under pressure, according to an embodiment of the method according to the invention. The gaseous conveying medium is air in the present embodiment. The method according to the invention uses a pulsed pumping method, in the above-described exemplary embodiment a pulsed injection method, for conveying in a device 1 described below, which can be clearly seen from FIG. 2 .

In the exemplary embodiment shown, the device 1 for conveying cleaning liquid has a container 10 in which the gaseous conveying medium is kept at a certain pressure by means of a compressor 2 . In the direction of flow of the gaseous conveying medium, downstream of the compressor 2 , ie at its pressure outlet 3 , a pressure tank 4 is connected, into which the gaseous conveying medium is fed and stored.

In this embodiment, the container 10 has a pressure chamber 11 in fluid communication with the pump tank 9 . The gaseous conveying medium is fed controllably into the pressure chamber 11 via a valve 5 . In the present exemplary embodiment, the valve 5 for controlling the feeding of the gaseous conveying medium into the pressure chamber 11 is arranged in a connecting line 21 between the pressure tank 4 and the inlet 20 for the gaseous conveying medium into the pressure chamber 11 . A liquid discharge pipe 12 communicates with the pressure chamber 11 and the pump tank 9 . In the present exemplary embodiment, a liquid line 13 runs from the pump tank 9 to a liquid discharge line 12 which has a branch line 14 leading to the pressure chamber 11 . In this embodiment, a valve 15 is arranged between the pump tank 9 and the pressure chamber 11 to open and close the connection between the pump tank 9 and the pressure chamber 11. In this embodiment, the valve is a valve with a spherical The check valve of the closing body closes the flow of liquid from the pump tank 9 when a flow towards the pump tank 9 is generated. In this embodiment, a valve 16 for opening and closing the liquid discharge pipe 12 is arranged between the pressure chamber 11 and the liquid discharge pipe 12. The valve is a check valve with a spherical closing body. The valve closes the liquid discharge pipe 12 during the pump tank 9 or the flow in the direction of the liquid discharge pipe 12 . The pressure chamber 11 has a further inlet 18 , controlled by a valve 17 , to which a vent line 19 is connected. The inlet 20 of the gaseous conveying medium into the pressure chamber 11 is arranged above in the position of use, ie, looking at FIGS. 1 and 2 from the front, while the inlet of the liquid pipe 13 , the branch pipe 14 , is arranged below. In the illustrated embodiment, this arrangement is between the liquid discharge line 12 and the compressor 2 for the gaseous conveying medium. In the illustrated embodiment, there is a further connecting line 22 between the liquid discharge line 12 and the pressure tank 4 . A further valve 6 for controlling the flow of a gaseous conveying medium into the liquid outlet line 12 is arranged in the connecting line 22 . Furthermore, between the pressure chamber 11 and the suction pipe 7 of the compressor 2, the device has a connecting pipe 23, wherein in the flow direction of the gaseous conveying medium, the suction pipe 7 of the compressor 2 is connected to the pressure chamber 11 by another The branch of the connection pipe 23 of the valve 17 controlled inlet 20 is preceded by a further valve 8 in order to open or close the suction pipe 7 to the atmosphere.

In the embodiment with the above-described device 1, the inventive operating method of the dishwasher 25 and the pulsed conveying of the washing liquid through the gaseous conveying medium alternately with negative pressure and at certain time intervals with overpressure is carried out as follows :

Initially, valves 5, 6, 8 and 16 are closed and valves 15 and 17 are open. The liquid expands in the pump tank 9 to the level N1, and in the pressure chamber 11, due to the suction effect of the negative pressure to be described below, the liquid expands to a much higher level N1'. By closing valve 17 and opening valve 5 at the same time, the gaseous conveying medium under negative pressure enters pressure chamber 11 and thereby squeezes the liquid to a low level N2. The valve 15 is now closed and the valve 16 is opened, whereby the liquid is pressed further into the liquid discharge pipe 12 and the same amount of liquid flows from the liquid discharge pipe 12 to the spray arms 29 , 30 . At about the same time, as valve 5 is opened, valve 8 is also opened so that compressor 2 can suck in gas and balance the pressure and volume of gas. The valve 5 is now closed and the other valve 6 for controlling the flow of the gaseous conveying medium into the liquid discharge pipe 12 is opened - or the other valve for controlling the flow of the gaseous conveying medium into the liquid discharge pipe 12 can be opened first in the reverse order 6, then close the valve 5-, so the gaseous conveying medium flows into the liquid discharge pipe 12 according to one of the above two alternative procedures, and apply a higher pressure level for the second time to carry out the liquid supply with overpressure, This causes a pressure on the liquid located in the liquid discharge pipe 12 , so that the liquid again flows to the spray arms 29 , 30 . Valve 16 is closed. At this time, valve 6 and valve 8 are also closed and valve 17 is opened, so that the gaseous conveying medium in pressure chamber 11 flows to compressor 2 through discharge pipe 19 and suction pipe 7, and negative pressure is generated in pressure chamber 11. Valve 15 is now opened by means of this negative pressure, or by external control if valve 15 is not a non-return valve, so that liquid is sucked from pump tank 9 into pressure chamber 11 by the negative pressure built up in pressure chamber 11 . Valve 16 remains in the closed position. Valve 17 is now closed and valve 8 is reopened at the same time. The process is repeated for as long as the fluid needs to be delivered. In the above-described embodiment of the method according to the invention, an interval of about half a second was inserted before the valve 5 was reopened to allow the gaseous conveying medium under pressure to flow into the pressure chamber 11 .

The time course of the injection pulses generated by the above method is shown in FIG. 3, which shows the time course from the opening of the valve 17 to the suction of the cleaning liquid into the pressure chamber 11 and the resulting water pressure. The time interval to inhalation is denoted by Ts in FIG. 3, which is about 1 second. In the described embodiment, a time interval Tp of about half a second is inserted. In the present invention, by opening the valve 5 a pulsed delivery of cleaning liquid with a pulse height If of approximately 310 mbar is carried out together with an additional head pressure with a pulse height In of approximately 90 mbar by opening the valve 6. The duration Ti of half a second is delivered. That is, in the present embodiment, the ratio of the duration of the time interval (Ts+Tp) of cleaning liquid delivery to the duration Ti of cleaning liquid delivery is about 3:1. With this very short pulse duration Ti, the cleaning effect of the cleaning liquid applied under pressure to the dishes to be cleaned is optimized.

During the water supply time interval of the tableware to be washed, the pressure of the supplied washing liquid rises every time the water supply starts, and the pressure of the supplied washing liquid decreases every time the water supply ends. Practice has shown that, especially when the cleaning liquid is conveyed in pulses, by this alternate rise and fall of the pressure of the cleaning liquid and thus the alternate rise and fall of the mechanical force acting on the dirt of the tableware to be cleaned, it can be compared A sufficient cleaning effect is achieved with the shorter duration of the water supply of the prior art described above, wherein the pressure of the cleaning liquid alternately rises and falls and thus induces an alternating rise and fall of the mechanical force acting on the dirt of the dishes to be cleaned. The dips occur over a short duration and are therefore intense.

In addition, in the above-described exemplary embodiment of the present invention, the gaseous conveying medium flows into the rinsing tank 26 of the domestic dishwasher 25 during a subroutine step "drying", so that the gaseous conveying medium (air) that exists anyway By drying residual moisture from the dishes to be washed, the drying effect can be improved and the duration of the "blow drying" subprogram step can be significantly shortened.

When the cleaning liquid is conveyed by a gaseous conveying medium under pressure, no special head and suction conditions are required, so that the dishwasher can be constructed relatively simply. Since the cleaning liquid is not pumped, a minimum injection volume of the cleaning liquid is not required, thereby reducing the water consumption as compared with the prior art described above. In this way, less electrical energy is also used in delivering the cleaning fluid compared to prior art centrifugal pumps which operate continuously on electrical power. In this way, the present invention successfully proposes an energy-saving and water-saving operation method for the dishwasher, and its application does not need to follow special lift conditions.

Claims (6)

1. The operation method of the dishwasher in which the tableware to be cleaned is rinsed with a cleaning liquid in the dishwasher, wherein the cleaning liquid is conveyed by a gaseous conveying medium under pressure at certain time intervals and pulsed , which is characterized in that the cleaning liquid is conveyed by a pulsed impact method, in which the cleaning liquid is subjected to a pressure through the gaseous conveying medium, which changes alternately between two pressure levels in this way , that is, at a low pressure level that generates a negative pressure, the cleaning liquid is sucked in, and by applying a higher pressure level that generates an overpressure, the cleaning liquid is transported in the required delivery direction. 2. The method according to claim 1, characterized in that the gaseous medium is air. 3. The method according to claim 1, characterized in that the gaseous conveying medium is conveyed by a pulsed pumping method. 4. The method according to claim 3, characterized in that the gaseous conveying medium is fed periodically from a gas storage source to the cleaning liquid. 5. The method according to claim 3, characterized in that the gaseous conveying medium is conveyed by a clocked pump. 6. The method according to claim 1, characterized in that, during a subprogram step "blow drying", the gaseous medium flows into a treatment chamber (26) of the dishwasher (25).