Twin-fluid nozzle spray apparatus
A twin-fluid nozzle spray apparatus according to one aspect includes a gas regulator that outputs compressed gas at a predetermined pressure in a compressed-gas supply system, a positive displacement pump that includes a relief valve configured to feed pressurized liquid at a pressure exceeding a predetermined pressure in a pressurized-liquid supply system back to a liquid supply side, and outputs the pressurized liquid, a liquid regulator or a needle valve that outputs the pressurized liquid output by the positive displacement pump while maintaining a pressure of the pressurized liquid at a discharge pressure having a predetermined value, and a twin-fluid nozzle that mixes and sprays the compressed gas output by the gas regulator and the pressurized liquid output by the liquid regulator or the needle valve.
1. A twin-fluid nozzle spray apparatus, comprising:
a first gas regulator that outputs a compressed gas at a first gas pressure that is a predetermined gas pressure in a compressed-gas supply system;
a positive displacement pump that includes a diaphragm pump configured to output a pressurized liquid and a relief valve configured to feed the pressurized liquid back to a liquid supply side when a first liquid pressure of the pressurized liquid exceeds a predetermined liquid pressure in a pressurized-liquid supply system;
a liquid control valve configured to output the pressurized liquid output by the positive displacement pump while maintaining a second liquid pressure of the pressurized liquid at a discharge pressure;
a twin-fluid nozzle that mixes and sprays the compressed gas output by the first gas regulator and the pressurized liquid output by the liquid control valve;
a second gas regulator in parallel to the first gas regulator in the compressed-gas supply system and configured to output a compressed gas at a second gas pressure, lower than the predetermined gas pressure;
a pipe having elasticity through which the compressed gas or the pressurized liquid is supplied toward the twin-fluid nozzle; and
a control circuit configured to
perform time proportional control of a spray amount of the twin-fluid nozzle by switching between permitting and blocking supply of the pressurized liquid to the liquid control valve, and
stop spray from the twin-fluid nozzle by blocking supply of the pressurized liquid and supply the compressed gas at the second gas pressure output by the second gas regulator to the twin-fluid nozzle.
2. The twin-fluid nozzle spray apparatus according to claim 1 , wherein
the twin-fluid nozzle mixes internally and sprays the compressed gas at the first gas pressure and the pressurized liquid while transmitting a pressure of the compressed gas output by the first gas regulator to the pressurized liquid output by the liquid control valve in a counter-flow direction to a liquid flow.
3. The twin-fluid nozzle spray apparatus according to claim 1 , wherein
the control circuit is configured to control a spray characteristic of the twin-fluid nozzle by controlling at least any of a pressure of the compressed gas output from the first gas regulator, a pressure of the pressurized liquid, and an opening degree of the liquid control valve.
4. The twin-fluid nozzle spray apparatus according to claim 1 , further comprising:
a discharge valve that discharges the pressurized liquid output from the liquid control valve from the pressurized-liquid supply system using an atmospheric pressure from the twin-fluid nozzle or a pump head difference when spray from the twin-fluid nozzle is stopped.
5. The twin-fluid nozzle spray apparatus according to claim 1 , wherein the liquid control valve is a liquid regulator.
6. The twin-fluid nozzle spray apparatus according to claim 1 , wherein the liquid control valve is a needle valve.
7. A control method for a twin-fluid nozzle spray apparatus, comprising:
generating a compressed gas at a first gas pressure through a first flow path;
generating a compressed gas at a second gas pressure, lower than the first gas pressure, through a second flow path, parallel to the first flow path;
outputting one of the compressed gas at the first gas pressure and compressed gas at the second gas pressure to a twin-fluid nozzle;
outputting a pressurized liquid, and otherwise feeding a pressurized liquid back to a liquid supply side when a first liquid pressure exceeds a predetermined pressure in a pressurized-liquid supply system;
controlling a liquid control valve that receives the pressurized liquid output by the pressurized-liquid supply system to maintain a second liquid pressure of the pressurized liquid at a discharge pressure;
outputting the pressurized liquid at the discharge pressure to the twin-fluid nozzle;
performing time proportional control of a spray amount of the twin-fluid nozzle by switching between permitting and blocking supply of the pressurized liquid to the liquid control valve, and
stopping spray from the twin-fluid nozzle by blocking supply of the pressurized liquid while suppling the compressed gas at the second gas pressure to the twin-fluid nozzle.