Flow rate measuring device

A flowmeter comprising:

• a main body;
• a membrane section which is fixed to the main body and defines a metering chamber used for housing and discharging a fluid;
• a movement conversion section for converting reciprocal movement of the membrane section into rotational movement;
• a member to be detected which is fixed to one of the main body and a mechanism section formed from the membrane section and the movement conversion section;
• a direction sensor which is fixed to another one of the main body and the mechanism section and which detects a position relative to the member to be detected;
• and
• a flow rate computing section which detects the position of the member to be detected by means of a detection signal output from the direction sensor and which computes a flow rate of the fluid.

A flowmeter comprising:

• a main body;
• a membrane section which is fixed to the main body and defines a metering chamber used for housing and discharging a fluid;
• a rotary member which performs rotational movement in synchronism with reciprocal movement of the membrane section;
• a member to be detected which is placed on the rotary member;
• a direction sensor which detects location of the member to be detected and movement thereof caused in association with rotational movement of the rotary member;
• a weighting coefficient computing section which detects variations in rotation of the rotary member from a detection signal output from the direction sensor and which computes an angular velocity achieved at an arbitrary position along a circumferential direction of the rotary member and a weighting coefficient in response to the angular velocity;
• and
• a flow rate computing section which detects the position of the member to be detected by means of a detection signal output from the direction sensor and which computes a flow rate of the fluid achieved at the arbitrary position by reference to the position of the member to be detected and the weighting coefficient.

A flowmeter comprising:

• a main body;
• a membrane section which is fixed to the main body and defines a metering chamber used for housing and discharging a fluid;
• a rotary member which performs rotational movement in synchronism with reciprocal movement of the membrane section;
• a member to be detected which is placed on the rotary member;
• a direction sensor which detects location of the member to be detected and movement thereof caused in association with rotational movement of the rotary member;
• and
• a flow rate computing section which detects from a detection signal output from the direction sensor variations in rotation of the rotary member and the position of the member to be detected and which computes a flow rate of the fluid,
• wherein the flow rate computing section measures a time required for one rotation of the rotary member at a plurality of positions in the rotational direction of the rotary member and computes a flow rate at each of the positions on the basis of the most-recently measured time.

A flowmeter comprising:

• a main body;
• a membrane section which is fixed to the main body and defines a metering chamber used for housing and discharging a fluid;
• a rotary member which performs rotational movement in synchronism with reciprocal movement of the membrane section;
• a magnet placed on the rotary member;
• a plurality of lead switches for detecting movement of the magnet associated with rotational movement of the rotary member;
• and
• a flow rate computing section which detects variations in rotation of the rotary member and the position of the magnet by means of a detection signal output from the plurality of lead switches and which computes a flow rate of the fluid,
• wherein the flow rate computing section measures a time required for one rotation of the rotary member at positions of the plurality of lead switches and computes a flow rate at each of the positions on the basis of the most-recently measured time.