In the presence of a dishwasher, disputes about who to wash the dishes do not arise in principle. Moreover, the dishes after that look as if they had just been taken out of the store packaging. How the dishwasher manages to do this, what components and mechanisms are involved – we will analyze in the material.
Before proceeding with the virtual disassembly of the dishwasher , let’s see what stages the dishes go through during the washing process. In fact, there are not many of them:
Pre-soaking. The jets of water knock food remnants from the dishes, it is prepared for further processing;
The washing up. The dishes are washed with jets of hot water with a special agent dissolved in it.
Rinsing. Use hot water to remove residual detergent from the dishes. Depending on the algorithm of the control program or information received from the sensors, the water during rinsing can change several times.
Drying. Moisture is removed from the surface of the dishes. The result is a completely washed and dried crockery that you just have to put back in its usual place.
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Although the dishwasher is impressive in size, there are not many executive units inside. The main volume is occupied by the washing chamber, into which the dishes are loaded.
A typical diagram of a dishwasher is shown in the figure.
As shown in the diagram, the dishwasher has two independent circuits. One of them is provided for the circulation of water, the other for the circulation of air necessary for drying dishes.
In addition, a dishwasher usually includes:
water treatment system, in which water softening occurs;
a water circulation system in which the prepared water or cleaning solution is heated and supplied to the sprinklers;
a system of filters that cleanse the circulating liquid from food debris and debris;
a system of sensors that ensure uninterrupted operation of the device and monitor key parameters during its operation;
dirty water drainage system.
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The purpose of each element of the dishwasher will be described in more detail below when considering its principle of operation.
How the dishwasher works
At the start of the wash cycle, the control board gives a command to open the solenoid valve. The dishwasher starts to draw in water. Tracking the amount of water is entrusted to the pressure switch, which, when the required level is reached, closes its contacts, as a result of which the control board locks the solenoid valve. At the same time, the water collection process stops.
Before entering the dishwasher pan, water passes through a heat exchanger (its purpose will be revealed a little later) and an ion exchanger, which is a key component of the water softening system, since dishes are washed better in soft water. In addition, the use of softened water protects the components of the dishwasher from limescale and deposits.
The node consists of two chambers connected to each other. One of them contains a specialized filter filled with ion exchange resin. The second acts as a hopper for regenerating salt.
At the heart of water softening is the ion-exchange process, in which the cations of calcium Ca 2+ and magnesium Mg 2+ , which are present in excess in hard water, are replaced by more harmless sodium ions, which are rich in ion-exchange resin. The chemical properties of the resin are such that it has the ability to regenerate. This is helped by salt, rich in sodium cations. Of course, the resin does not reach its original composition and properties, but its ability to recover remains for a long time. Typically, the service life of the ion exchange resin is 5-8 years. The specific “life cycle” time depends on the hardness of the water and the intensity of use of the dishwasher.
Contrary to popular belief, salt does not soften the water, but regenerates the ion exchange resin!
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After the water has been drawn into the dishwasher pan, it must be heated. There are two approaches to performing this operation:
heating with a heating element installed at the bottom of the pallet;heating by means of an instantaneous water heater.The second type of design is commonly used in new models of dishwashers. This solution saves time, since there is no need to wait for the water to heat up. Dishwashing starts almost immediately, and the water continues to heat up during the cycle.
At this stage, a circulation pump comes into play, which ensures the forced movement of water in a closed loop.
In the circulation system, at its lowest point, a filter is installed that cleans the water from food debris and debris, thereby protecting the internal lines from blockages, and the pump from jamming.
The circulating pump creates pressure in the system, and the water rushes to the sprinklers, also called impellers.
The sprinkler has a hollow body in which special holes are made – nozzles. Through them, jets of water wash the dishes installed in the baskets. During operation, the sprinklers constantly rotate, covering the entire area of the basket with water.
An interesting design feature is that the impeller does not have its own drive motors. Its rotation is provided by the jet thrust of water jets escaping from the extreme nozzles. In order for them to provide rotation, their sockets are made at an angle to the axis of rotation of the sprinkler.
The lock of the detergent container is activated during the dishwashing. This happens at the command of the control board. The product dissolves in hot water. It turns out a washing solution, which is used to wash the dishes.
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Water circulates in the circuit until one of the washing stages is complete, after which it is removed from the dishwasher into the sewer using a drain pump. Its design is identical to the device of the drain pump of the washing machine .
After the dishes have been washed and rinsed, they must be dried. This is where the heat exchanger mentioned earlier comes in handy. As a rule, dishwashers use a condensation drying type.
Its essence is simple. Moisture naturally evaporates from the surface of hot dishes, because they were washed in very hot water. Inside the dishwasher, a convection movement of moist air occurs, which rushes through the channels to a heat exchanger filled with cold water. Contacting the walls of the heat exchanger, excess moisture condenses from the heated air, the drops of which flow down the chute into the pan, and the cooled air returns to the washing chamber. This process continues until the time “laid down” in the control program expires, or until the humidity sensor, which is the prerogative of expensive models, is triggered.
Condensation drying takes quite a long time, since the process of evaporation and condensation of moisture is not fast. To speed it up, some manufacturers place a fan heater in the dishwasher case. It provides forced ventilation of hot air and significantly reduces drying time.
The safety of the washing process is ensured by several sensors:
a pressure switch that monitors the presence of water in the washing unit and its level;
door lock, which does not allow starting the wash cycle when the machine door is open or not tightly closed;
a leakage sensor that turns off the device when water leaks from its hydraulic circuit. The triggering of the sensor leads to the closure of the water supply in order to save users from having to make repairs in their kitchen and in the kitchen of neighbors below.
The dishwasher can be equipped with other sensors that optimize the dishwashing process and give the unit intelligent functions. A striking example is a water turbidity sensor. Based on its readings, the device controller decides when to stop rinsing the dishes or, conversely, decides to change the water and continue the cycle.
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The dishwasher is a rather complex device from a technical point of view, but despite this, it has a simple logic of operation. The user is only required to carefully place the dishes in the baskets, load the detergent and activate the desired program. After that, the dishwasher will tirelessly get down to business, and the owner can safely go about their business, singing Seryozha Syroezhkin’s song about the delights of technological progress.