Electrostatic spraying device

Patent metadata

Field	Value
Publication number	US-10994292-B2
Application number	US-201716330159-A
Country	US
Kind code	B2
Filing date	Sep 4, 2017
Priority date	Sep 5, 2016
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

An electrostatic spraying device includes: a high-voltage generation device for applying a voltage between a spray electrode and a reference electrode; and a controller that controls an output power of the high-voltage generation device based on operation environment information indicating at least one of (i) a surrounding environment of the device and (ii) an operation state of a power supply that supplies power to the device, independently of a current value and a voltage value at the spray electrode and the reference electrode.

First claim

The invention claimed is:

1. An electrostatic spraying device that, by applying a voltage between a first electrode and a second electrode, sprays liquid from a tip of the first electrode, the electrostatic spraying device comprising:
a voltage applicator for applying the voltage between the first electrode and the second electrode; and
a controller that controls an output power of the voltage applicator based on operation environment information indicating at least one of (i) a surrounding environment of the device and (ii) an operation state of a power supply that supplies power to the device, wherein the controller is configured to control the output independently from a current value and a voltage value at the first electrode and the second electrode.

2. The electrostatic spraying device according to claim 1 , wherein:
the voltage applicator comprises:
an oscillator for converting a direct current supplied from the power supply into an alternating current;
a transformer connected to the oscillator and converting a magnitude of a voltage; and
a converter circuit connected to the transformer and converting an alternating current into a direct current, wherein the controller outputs to the oscillator a PWM signal (pulse width modulation signal) of which a duty cycle is set to be constant.

3. The electrostatic spraying device according to claim 1 , wherein the controller controls the output power according to a duty cycle of a PWM signal (Pulse Width Modulation signal).

4. The electrostatic spraying device according to claim 1 , wherein the operation environment information includes information indicating at least one of air temperature, humidity and pressure around the device, and viscosity of the liquid, as information indicating the surrounding environment.

5. The electrostatic spraying device according to claim 4 , wherein:
the operation environment information includes information indicating the air temperature around the device; and
the controller controls the output power according to a duty cycle of a PWM signal,
increases the duty cycle of the PWM signal in response to rising of the air temperature, and
reduces the duty cycle of the PWM signal in response to dropping of the air temperature.

6. The electrostatic spraying device according to claim 5 , wherein:
the controller determines a spray interval for which a period of time during which the device sprays the liquid and a period of time during which it stops spraying are one cycle, based on a following formula (1),

[

Math
.

⁢
1

]

⁢

Sprayperiod
⁡

(
T
)

=

(

1
+

T
-

T
0

100

*
Sprayperiod_compensation
⁢
_rate

)

*

Sprayperiod
⁡

(

T
0

)

(
1
)

where,
Sprayperiod(T): Spray interval (s) for which the period of time during which the device sprays the liquid and the period of time during which it stops spraying at temperature T are one cycle
T: Air temperature (° C.)
T 0 : Initial setting temperature (° C.)
Sprayperiod_compensation_rate: Spray time compensation rate (-)
Sprayperiod(To): Spray interval (s) for which the period of time during which the device sprays the liquid and the period of time during which it stops spraying at the initial setting temperature T 0 are one cycle.

7. The electrostatic spraying device according to claim 5 , wherein:
the controller determines a period of time for turning on the PWM signal based on a following formula (2),

[

Math
.

⁢
2

]

⁢

PWM_ON
⁢
_time
⁢

(
T
)

=

(

1
+

T
-

T
0

100

*
PWM_compensation
⁢
_rate

)

*
PWM_ON
⁢
_time
⁢

(

Assignees

• Sumitomo Chemical Co

Inventors

• Dau Van Thanh
• Harada Akiko

Classifications

• B05B5/025

  Discharge apparatus, e.g. electrostatic spray guns · CPC title

• B05B5/08

  Plant for applying liquids or other fluent materials to objects · CPC title

• B05B5/053 Primary

  Arrangements for supplying power, e.g. charging power · CPC title

• B05B5/057

  Arrangements for discharging liquids or other fluent material without using a gun or nozzle · CPC title

• B05B12/12

  responsive to conditions of ambient medium or target, e.g. humidity, temperature {position or movement of the target relative to the spray apparatus (B05B12/082, B05B12/084 take precedence)} · CPC title