Patent Application
20240117809
The present invention refers to improvements in water pumps, both for those submersible well pumps, for water extraction, and for those centrifugal pumps, and in particular, a control and prevention system for the absence of water in the pump, to prevent deterioration and/or failure of the electric motor due to idle operation.
In order to avoid damage to the motor of the water pumps, due to the heat it produces when it works, it is necessary to cool it. The heat generated by the impeller against the pump casing is dissipated with the fluid to be transferred, and therefore the pump cannot work for a long time in a vacuum, since it is cooled by the liquid circulating inside it. Mainly, pumps are cooled by the liquid they drive and submersible pumps also do so when they are submerged below the level of the liquid. Hence the importance of preventing the pump from working without liquid and the need to control the minimum level of the well to ensure the proper functioning of the pump. Well pumps are usually hung from the discharge hose itself and from a strong rope as a safety measure, for this purpose.
For the detection of water levels in submersible pumps, three methods are commonly used. One method is detection by means of probes that are taped onto the discharge hose itself in order to prevent the cables from hindering the maneuver of inserting or removing the pump for installation and maintenance purposes. The probes are electrodes that are placed at the desired level of the liquid to be detected inside the well where the submersible pump lies. Two probes are usually used, one of which is placed at the minimum level height where the pump must stop, and another at a high level, which indicates the height at which the water must reach for the pump to start again. In order to avoid electrolysis, these probes must be powered by alternating current. The length of the probe cables also increases the resistance to be measured, and the values to be measured must be configured for each installation. Since the well pump is hanging from the hose, every time it starts and stops, it jerks. That pull causes the pump to bang against the walls of the well at each start or stop. Because of this, if your application allows it, it is preferable to start the pump gradually. This pulling effect can damage the sensors located at the height where the pump body is housed.
Another level detection method involves measuring the electrical consumption of the motor. When the motor is not cooled due to lack of liquid, the electrical consumption rises, and said electrical consumption is controlled by a panel that detects said excess consumption and interrupts the operation of the motor. What this system does not allow is knowing when the liquid has returned to the desired level to start again.
Another method consists of placing a flowmeter with its corresponding board for the purpose of measuring the flow rate extracted by the pump and configuring said board so that it interrupts operation from a minimum flow rate that guarantees the desired level of the liquid in the layer.
All these methods have in common that the detection elements are close to the pump motor and the control devices/boards are located on the surface. If we consider that the water tables can be between 8 meters to 200 meters depending on the geographical area, we understand that an expensive and complex installation is required for the purposes of its installation and maintenance.
Regarding self-priming pumps, these work by generating a pressure difference by separating air and water, but for this they require water to remain inside the turbine housing. When there are leaks in the connections and assemblies, the housing empties of water and the self-priming system fails to generate the pressure difference necessary for priming, and the motor overheats.
The present invention consists of a water pump that can be submersible or too, centrifugal—depending on the application—and that includes a sensor to detect the absence of liquid, said sensor connected and associated with an electronic controller board that is located inside the sealed compartment of the motor, the electronic board also controls the power supply of the motor. The sensor consists of two conductive metal parts that, when in contact with water, close the electrical circuit with the controller board, which in turn enables the power supply to the motor. The electronic board is isolated from the water, as the motor is, and the cables associated with the sensor come out of said isolated compartment through a hermetic hole. The sensor may preferably be placed on the internal wall of the cavity that houses the impellers, also called the volute, or at the inner or outer surface of the pump inlet or on the jacket or external wall of the pump. In the case of being placed in the volute, the liquid entry to the pump is directly controlled. If placed in the jacket, the level of the water table is controlled in the case of submersible pumps.
The control board has the motor stop and start functions linked to the sensor. Said control also contains a timer that will determine the times for stopping and starting based on the sensor values. When the sensor detects the absence of water—which may be due to the descent of the water from the groundwater or due to an air bubble in the cavity that houses the impellers, among other causes—the timer will stop the engine in a period set by the manufacturer and relative to the location of the sensor. Said time could be 1 minute, for example, in order to take advantage of the minimum level of the water table as long as the operation in empty does not matter. Said timer will also determine the reconnection of the system. For example, the control board may set reconnection times that may be variable and staggered in order to be able to determine the average times of replenishment of the level of the layer. Thus, for example, it could set every 10 minutes that the board requires the state of the sensor, as well as determine a time between the positive state of the sensor after a cut, as well as self-regulate the reconnection times based on the data accumulated between reconnection times and times between outages. It is convenient to set a time between stopping the motor and the average time for the replacement of the layer, because for the purposes of conservation of the motor, the number of starts per hour that it can carry out must be limited, as well as the interval between starts. Among the relevant advantages, among others already mentioned, by placing the sensor on the inner wall of the turbine housing, the risk of its damage due to blows from the pump body is eliminated, as well as maximizing the use of the sensor that It will not only measure the level of the water table, but also the effects of the behavior of the water inside the turbine, such as clogging or air bubbles, ensuring that the measurement of said sensor will protect the engine against damage caused by lack of circulation. of liquid, and not merely due to the absence of detection of water at the level of the layer where the pump is housed. In the case of self-priming pumps, the sensor makes it possible to detect the absence of the minimum quantity of water necessary for the self-priming operation.
Likewise, the controller board will be able to activate, based on these detections, various mechanisms associated with it. For example, there may be an additional water tank connected to the chamber that houses the impeller, and release the emergency water according to the indication of the controller board in order to achieve self-priming, and the filling of the water tank. emergency.
Thus, the new described mechanism presents notable advantages over the existing prior art, reducing installation and maintenance costs, and providing greater functional autonomy to the water pumps.
