Flow quantity controlling apparatus

Claim 2

A flow quantity controlling apparatus comprising a control valve for controlling a flow quantity of a liquid flowing through a conduit, a flowmeter for measuring the flow quantity of the liquid flowing through the conduit, a rotary shield plate rotated by rotations transmitted from said flowmeter in proportion to said flow quantity, said rotary shield plate being provided with slits, an air jet means for injecting air to said shield plate, an air pressure receiving means for receiving a pressure of the air jet injected from said air jet means and passed through said slits of said rotary shield plate, and a controlling means for controlling an opening and closing of said control valve by receiving the air pressure from said air pressure receiving means.

Claim 3

The flow quantity controlling apparatus as defined in claim 1 wherein said rotary shield plate comprises a plurality of shield plates which respectively have slits and are so constructed that the slits are adjustable in their mutual relative positions so that an area of an opening common to respective slits can be adjusted.

Claim 4

The flow quantity controlling apparatus as defined in claim 1 wherein said controlling means for controlling an opening and closing of said control valve comprises a first pressure supplying means for supplying a first pressure to said control valve, said first pressure determining a valve opening rate so that the flow quantity of the liquid becomes a first predetermined flow quantity Q1, a second pressure supplying Means for supplying a second pressure to said control valve in response to air pressure supplied from said air pressure receiving means, said second pressure determining the valve opening rate so that the flow quantity of the liquid becomes a second predetermined flow quantity Q2 larger than the flow quantity Q1, and a third pressure supplying means for supplying a third pressure to said control valve, said third pressure determining the valve opening rate so that the flow quantity of the liquid reaches a third predetermined flow quantity Q3 smaller than the flow quantity Q2.

Claim 5

The flow quantity controlling apparatus as defined in claim 3 wherein said controlling means further comprises a cam rotating by being transmitted the rotations from said flowmeter, and a changeover means for sequentially changing over the pressure supplyings of said first, second and third pressure supplying means to said control valve.

Claim 6

The flow quantity controlling apparatus as defined in claim 3 wherein said second pressure supplying means includes a constant flow quantity valve controlling means which is so constructed that the second pressure supplying means makes the opening rate of the flow quantity controlling valve to be constant by a predetermined pressure so that the flow quantity per unit time is maintained to be constant, said constant flow quantity valve controlling means performing a valve action to cancel variations of the received air pressure of said air pressure receiving means corresponding to the variation of the flow quantity.