What is the internal structure of the spray bottle?

Update:04 Jan 2020
Summary:

A spray bottle is a very useful device, it is a good ex […]

A spray bottle is a very useful device, it is a good example of the basic principle of pipe pumping. The head of the spray bottle consists of only a few parts. It has a trigger that triggers a small pump. The pump is connected to a plastic tube, which sucks the cleaning liquid from the bottom of the reservoir. This pump presses the liquid into a narrow cavity and sprays them out of the small hole of the sprayer nozzle. This hole, or nozzle, enables the flowing liquids to come together and become a concentrated stream of water. The only complex in this design is the hydraulic pump, but its structure is also very simple. Its main moving element is a piston located in a cylindrical hydraulic chamber. In the hydraulic chamber, there is a small spring. To run the hydraulic pump, you must first pull the wrench back to push the piston into the hydraulic chamber. The moving piston compresses the spring. When the wrench is released, the piston is pushed out of the hydraulic chamber. The two strokes of the piston into and out of the hydraulic chamber constitute a complete pump cycle.

During the downward stroke, the piston is pushed inward, compressing the volume of the hydraulic chamber, thereby pushing the liquid out of the pump. During the upward stroke, the spring pushes the piston outwards, expanding the volume of the hydraulic chamber, thereby drawing liquid into the pump. When using a spray bottle, it is necessary to suck up the cleaning liquid from the lower reservoir, and then squeeze it out of the upper cavity. In order to get all the liquid flowing into the cavity, the pump can only press the liquid upwards-it cannot press the liquid back into the reservoir. In other words, the liquid can only flow through the pump in one direction.

The device that realizes this function is called a check valve. The spray bottle has two non-return valves in its pumping system: one between the pump and the reservoir and the other between the pump and the nozzle. Normally, the check valve located between the pump and the reservoir contains a small rubber ball that is lightly placed in a small capsule. The edges of the sealing tube have edges and corners, so the rubber ball will not fall from the sealing tube. According to the design, when no water is pumped, the small ball relies on its own gravity or the elastic force of a small spring to bear against the sealing cylinder, thereby blocking the passage of water. When the piston moves outward (when the wrench is released), the enlarged hydraulic chamber will suck the small rubber ball away from the cylinder and suck up the liquid from below. As the pellets are lifted, liquid can flow from the reservoir unhindered. When you press down on the wrench, the external force of the flowing liquid pushes the ball back onto the gland, blocking the channel between the pump and the reservoir. Therefore, the pressurized liquid can only flow to the small cavity above.
The non-return valve located between the pump and the nozzle is a cup-shaped device that is placed at the end of the cavity. During the upward stroke, because the pressure in the pump is less than the outside air pressure, the cup-shaped device is tightly attached to the cavity, so air cannot flow in from the nozzle. During the downward stroke, the squeezed liquid pushes the cup-shaped device slightly away from the cavity and then flows out of the nozzle. Without a second check valve, the pump system would not be able to draw liquid from the reservoir due to lack of suction (no pressure drop). At this time, the upward stroke does not reduce the air pressure in the pump; it only sucks more air to maintain the pressure inside the pump.