US3795839A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preventing arcing in an electrostatic coating system
Assignee: Graco Inc
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Filing: 1971-11-03
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Granted: 1974-03-05
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Expires: 1991-11-03
Abstract
Abstract A method for setting up and using a safety circuit for an electrostatic coating system. A sensing circuit is connected to a source of potential to sense the current flow between the gun electrode and work to be coated. A delay circuit normally delays de-energization of the current to the electrode unless the sensing circuit senses a predetermined value in which case deenergization occurs without delay. A resistance may be connected to the electrode to aid in reducing disruptive arch and also to the sensing circuit. The sensing circuit may be set to sense the current through the electrode at different predetermined values after determining the maximum length of disruptive arc between the electrode and work to be coated and also the amount of current that would cause such an arc. Before the predetermined value in the sensing circuit is exceeded, the source of high potential is de-energized. The potential source may be prevented from being energized until control means are recycled.
Inventors
- 👤 A Walberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:37
CPC Classifications
B; B05; B05B; B05B5/00; B05B5/025; B05B5/03; B05B5/08; B05B5/10; H; H02; H02H; H02H7/00; H02H7/003
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
121 words
A method of preventing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated comprising: providing first means to terminate the spraying operation normally for short periods of time and control means operable in response to operation of said first means to deenergize said source of high potential after a time period which normally exceeds the short periods of time during which said spraying operation is terminated, determining the amount of current flowing between the gun electrode and the work to be coated, and deenergizing said source of high potential without the delay of said time period whenever such current exceeds a predetermined value.
Claim 2
Independent Claim
121 words
A method of preventing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated comprising: providing first means to terminate the spraying operation normally for short periods of time and control means operable in response to operation of said first means to deenergize said source of high potential after a time period which normally exceeds the short periods of time during which said spraying operation is terminated, determining the amount of current flowing between the gun electrode and the work to be coated, and deenergizing said source of high potential without the delay of said time period whenever such current exceeds a predetermined value.
Claim 3
Dependent Claim
51 words
A method of operating an electrostatic coating system in accordance with claim 1, which includes reducing the maximum length of a disruptive arc between said electrode and said work to be coated by increasing the series resistance of said source of high potential, said electrode and said work to be coated.
Claim 4
Dependent Claim
42 words
The method of claim 1 in which the reenergization of said source of high potential is prevented until said control means is recycled when such source of high potential has been deenergized as a result of said current exceeding said predetermined value.
Claim 5
Dependent Claim
46 words
The method of claim 1 in which said gun has an air supply for supplying air to the paint in the gun and propelling the same towards the work to be coated and in which said first means is a means for interrupting said air supply.
Claim 6
Independent Claim
110 words
A method of reducing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated comprising: reducing the maximum length of a disruptive arc between the electrode and the work to be coated to a predetermined value, determining the amount of electrical current flowing between said electrode and said work to be coated, and promptly deenergizing said source of high potential whenever said electrical current exceeds a predetermined value resulting from the electrode approaching a distance from the work to be coated that is less than said predetermined value of maximum disruptive arc length.
Claim 7
Independent Claim
110 words
A method of reducing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated comprising: reducing the maximum length of a disruptive arc between the electrode and the work to be coated to a predetermined value, determining the amount of electrical current flowing between said electrode and said work to be coated, and promptly deenergizing said source of high potential whenever said electrical current exceeds a predetermined value resulting from the electrode approaching a distance from the work to be coated that is less than said predetermined value of maximum disruptive arc length.
Claim 8
Dependent Claim
53 words
A method of reducing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated in accordance with claim 5, wherein the predetermined value of the maximum length of a disruptive arc is less than one inch.
Claim 9
Dependent Claim
53 words
A method of reducing disruptive arcs is an electrostatic coating system have a source of high potential connected across an electrode associated with a spray gun and work to be coated in accordance with claim 5, wherein the predetermined value of the maximum length of a disruptive arc is less than 2 inches.
Claim 10
Dependent Claim
68 words
A method of reducing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated in accordance with claim 5, including normally delaying the de-energizing of said source of high potential after control are operated to de-energize it and de-energizing it whenever said current exceeds a predetermined value without delaying such de-energization.
Claim 11
Dependent Claim
62 words
A method of reducing disruptive arcs in an electrostatic coating system having a source of high potential connected across an electrode associated with a spray gun and work to be coated in accordance with claim 8, which includes a step of preventing the reenergization of said source of high potential unit said controls are recycled to energize said source of high potential.
References Cited (Backward Citations)
US2650329A
Cited
US3273015A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |