tructure analysis of traditional water meter

The internal structure of traditional water meter can be divided into three parts: shell, sleeve and inner core. The shell is made of pig iron. After water comes out of the water inlet, it passes through the lower annular space of the shell, which is called the "lower annular chamber". There is a "upper ring chamber" on the top of the circular space, which is connected with the water outlet. At the bottom of the sleeve is a filter screen with a small hole to filter out the sundries in the water. There are two rows of round holes on the side of the sleeve. The position of the holes is just opposite to the upper and lower ring chambers of the shell. Obviously, the lower row is the water inlet hole and the upper row is the water outlet hole. In particular, these two rows of holes are made obliquely along the tangent direction of the circle. Note that the direction of the upper and lower rows of holes is opposite. It is very important for the work of the water meter that the water flows in along the tangent direction from the lower drain hole, which is bound to form a rotating water flow. The inner core is divided into upper, middle and lower layers. From the glass window, you can see the upper layer, only the pointer and dial. In fact, the key is the lower layer. There is a plastic wheel in it. There are many plastic blades on the edge of the wheel, called "impeller".

The impeller is located in the rotating flow formed by the hole in the lower layer of the casing, and the water flow impacts the blades around the wheel to generate torque and make the impeller rotate. The larger the tap is, the faster the water flows, and the faster the impeller turns.

The shaft of the impeller reaches the middle layer vertically, and there is a pinion on the shaft. It is used to mesh with the "decimal number gear" to achieve the purpose of cumulative revolution. The function of "decimal number gear" is that every time a single digit gear turns ten turns, the ten digit gear turns one turn. In other words, a single digit gear turns a turn, and a ten digit gear turns a tenth of a turn. The single digit gear is the driver, which drives the ten digit gear. Actually, two pairs of gears are used to complete each decimal position, so as to make the rotation direction consistent. One pair of transmission ratio is 9:30, the other pair is 10:30. The two pairs are connected in series. The total transmission ratio is the product of the two, i.e. 0.099999, which can be approximately 0.1. According to this calculation, if you want to read seven digits (four digits before the decimal point is the black scale, three digits after the decimal point is the red scale), you have to use 12 pairs of gears. In addition to other uses, the small space in this middle layer is packed with 18 shafts and 34 gears, which is also a high-density installation. This kind of water meter with its simple and cheap, can be used in humid environment for a long time without maintenance, and without power supply, power failure does not affect the work of the advantages of long-term service.