Flow meter

A flow meter, comprising:

• a lower shell;
• an upper shell disposed on the lower shell;
• a running water cavity disposed between the lower shell and the upper shell;
• an impeller disposed in the running water cavity, the impeller comprising:
• an installation positioning hole disposed at a bottom portion of the impeller;
• and
• a rotating positioning hole disposed at a top portion of the impeller;
• an installation positioning shaft extending upward from the lower shell and configured to be inserted into the installation positioning hole;
• and
• a rotating positioning shaft extending downward from the upper shell and configured to be inserted into the rotating positioning hole.

A flow meter, comprising:

• a lower shell;
• an upper shell comprising:
• a shell body disposed on the lower shell, the shell body comprising a top opening;
• and
• a shell top lid detachably disposed on the top opening;
• a running water cavity disposed between the shell body and the lower shell;
• an impeller disposed in the running water cavity, the impeller comprising:
• an installation positioning hole disposed at a bottom portion of the impeller;
• and
• a rotating positioning hole disposed at a top portion of the impeller and coaxially arranged with the installation positioning hole;
• an installation positioning shaft extending upward from the lower shell and configured to be inserted into the installation positioning hole;
• and
• a rotating positioning shaft extending downward from the shell top lid and configured to be inserted into the rotating positioning hole.

A method for assembling a flow meter, the method comprising:

• forming a running water cavity by connecting a lower shell and an upper shell;
• installing an impeller in the running water cavity by inserting an installation positioning shaft extending upward from the lower shell into an installation positioning hole disposed at a bottom portion of the impeller;
• and
• in response to a non-floating state of the impeller, suspending a rotating positioning shaft extending downward from the upper shell above a rotating positioning hole disposed at a top portion of the impeller,
• wherein a radius of the rotating positioning hole is smaller than a radius of the installation positioning hole, and
• wherein a radius of the rotating positioning shaft is smaller than a radius of the installation positioning shaft.