How to make a simple piston pump model?
The principle of this "piston pump model" is the same as the principle of the "pressurizer" on the "pressing well" commonly used in rural areas, and the structure is basically the same. Friends who have lived in the countryside believe it is easy to understand.
It uses the principle of atmospheric pressure. When the piston moves upward, the volume of the space under the piston increases and the air pressure decreases. The pressure on the water surface inside is less than the atmospheric pressure, so the water moves upward under the action of the external atmospheric pressure; when the piston moves upwards During the downward movement, the one-way valve was closed, and the water lifted up could not flow back, so it was "squeezed out". Repeating this action, we can see the water being lifted out of the well.
The following is the schematic diagram:
One cylinder is immersed in water, and there is a one-way valve at the bottom of the cylinder. There is a piston that can move up and down, and there is also a one-way valve on the piston. When the piston is lifted up by the piston rod, the one-way valve on the piston is closed under the action of atmospheric pressure, and the atmospheric pressure below becomes lower. At this time, the one-way valve under the cylinder is opened by the water and the water is lifted up.
The piston moves to the top of the cylinder and begins to move downward. At this time, the valve at the bottom of the cylinder is closed under the pressure of water, and the water cannot flow out; and the valve on the piston is pushed open, and the water is tightened to the piston. When the piston moves upward again, while the water below is lifted up, the water above is pushed by the piston to flow out of the water outlet. Repeat this action, and the water will continue to be pumped up.
This is a very good scientific and technological small production topic. It can not only demonstrate the principle of atmospheric pressure, but also make a very practical tool. Perhaps in the future, it can help you solve difficulties at critical moments.
Materials and tools used:
1 cylindrical plastic bottle, the one used in the picture below is for tennis balls; 1 metal rod, and piston made of round plastic sheet; 1 section of straw to make nozzle; 1 pair of scissors; 1 some transparent tape (here The yellow one that is not too transparent is used);
The large-cylinder plastic bottle is the outer cylinder of this self-made piston pump. We first make the one-way valve at the bottom of the cylinder. Remove the lid of the plastic bottle, drill a round hole, and then take a piece of scotch tape and stick it on the inside of the lid, next to the round hole. Keep the tape longer, and then fold it in half to glue the sticky sides together.
In other words, the piece of tape covering the round hole is double-layered and has no stickiness on the outside. This makes a one-way valve that can be opened or closed at any time under the action of external pressure.
The figure below shows the structure of the piston. The method of making the one-way valve above is the same.
The piston is required to be a perfect circle, and the edge fits with the plastic barrel to ensure smooth up and down movement and good airtightness. It is difficult to make pistons with ordinary plastic sheets. Using the foam soles of plastic slippers or other foam materials that are easy to process will greatly reduce the difficulty of making pistons.
This is the detailed picture of the foam piston:
Assemble this piston pump model according to the schematic diagram:
Put the small hole at the bottom of the pump into the water, pull the piston up and down, and the water will be pumped up.
But the actual situation is that the sealing performance between the piston and the cylinder is often not good, and it cannot cause a sufficient air pressure difference to lift the water up. Therefore, it is generally necessary to install a part of water on the piston first, and use the water to strengthen the sealing performance of the piston. Anyone who has used "pressurized water wells" knows that a water press that has not been used for a long time must be filled with some water before it can be pumped out.
The piston was repeatedly twitched, and the water was pumped up. The model of this piston pump was successfully made!
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