US3641971A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for preventing arcing in an electrostatic coating system
Assignee: HG Fischer and Co Inc
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Filing: 1967-09-01
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Granted: 1972-02-15
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Expires: 1987-09-01
Abstract
Abstract A safety device for an electrostatic coating system. This device automatically senses and deenergizes the power to the electrode in the spray gun when it exceeds a predetermined level, as for example, when the operator allows the electrode to approach too close to a grounded object. By properly setting this predetermined level, deenergization occurs prior to the time a disruptive arc or spark would normally be emitted from the gun electrode. In addition, a delay circuit may be provided that is operable by the gun trigger switch. After the operator turns off the coating material at the end of his stroke, this circuit would delay for a short time the deenergization of power to the gun''s electrode. Surges of power are thus avoided in the circuitry which prolongs the life of the power transformer. Example of sharp edged charging nozzle electrodes useful with this system as well as the method of use and setup of the necessary circuitry are also disclosed.
Inventors
- 👤 Arvid C Walberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:23
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: 29
Claim 1
Independent Claim
118 words
An electrostatic coating system comprising: a spray gun, an electrode mounted on said spray gun, a source of high potential connected between said electrode and work to be coated, means for energizing and deenergizing said source of high potential, delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energized for a predetermined period after said energizing control means is operated to deenergize said source of high potential, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and said source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 2
Dependent Claim
118 words
An electrostatic coating system comprising: a spray gun, an electrode mounted on said spray gun, a source of high potential connected between said electrode and work to be coated, means for energizing and deenergizing said source of high potential, delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energized for a predetermined period after said energizing control means is operated to deenergize said source of high potential, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and said source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 3
Dependent Claim
46 words
An electrostatic coating system in accordance with claim 1 having in combination therewith a means to maintain said source of high potential deenergized until said high potential energizing and deenergizing means is recycled after said high potential source has been deenergized by said current determining means.
Claim 4
Dependent Claim
46 words
An electrostatic coating system in accordance with claim 1, wherein said high potential energizing and deenergizing means includes a manually operated switch on said spray gun and switching means connected to said current determining means to be actuated thereby whenever said current exceeds the predetermined value.
Claim 5
Dependent Claim
53 words
An electrostatic coating system in accordance with claim 1, wherein said high potential energizing and deenergizing means includes an airflow actuated switch connected to an air line supplying air to said spray gun and switching means connected to said current determining means to be actuated thereby whenever said current exceeds the predetermined value.
Claim 6
Dependent Claim
39 words
An electrostatic coating system in accordance with claim 1, wherein said delay means includes a resistance-capacitance circuit connected to an electrical switching means which is connected in series with said energizing and deenergizing means and said high potential source.
Claim 7
Dependent Claim
155 words
An electrostatic coating system comprising: a spray gun having a nozzle of electrically conductive material through which coating material is ejected, said nozzle having an internal orifice surface, a forwardly facing surface joining said internal orifice surface to form an obtuse angle therebetween and an outer surface joining said forward facing surface to form a sharp edge, an electrode mounted on said spray gun, a source of high potential connected between said electrode and work to be coated, means for energizing and deenergizing said source of high potential, resistance interposed in series between said electrode and said source of high potential to reduce the maximum length of disruptive arc between said electrode and said work to be coated, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode And source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 8
Dependent Claim
155 words
An electrostatic coating system comprising: a spray gun having a nozzle of electrically conductive material through which coating material is ejected, said nozzle having an internal orifice surface, a forwardly facing surface joining said internal orifice surface to form an obtuse angle therebetween and an outer surface joining said forward facing surface to form a sharp edge, an electrode mounted on said spray gun, a source of high potential connected between said electrode and work to be coated, means for energizing and deenergizing said source of high potential, resistance interposed in series between said electrode and said source of high potential to reduce the maximum length of disruptive arc between said electrode and said work to be coated, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode And source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 9
Dependent Claim
27 words
An electrostatic coating system in accordance with claim 6, wherein said nozzle outer surface is annular to form an annular sharp edge with said forward facing surface.
Claim 10
Dependent Claim
18 words
An electrostatic coating system in accordance with claim 6, wherein sharp edge comprises at least one sharp point.
Claim 11
Dependent Claim
127 words
An electrostatic coating system comprising: a spray gun, an electrode mounted on said spray gun, a source of high potential connected between said electrode and work to be coated, means for energizing and deenergizing said source of high potential, a first resistance interposed in series with said electrode and said source of high potential to reduce the maximum length of disruptive arc between said electrode and said work to be coated, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined values, said determining means including a second resistance interposed in series with said electrode and said source of high potential.
Claim 12
Dependent Claim
127 words
An electrostatic coating system comprising: a spray gun, an electrode mounted on said spray gun, a source of high potential connected between said electrode and work to be coated, means for energizing and deenergizing said source of high potential, a first resistance interposed in series with said electrode and said source of high potential to reduce the maximum length of disruptive arc between said electrode and said work to be coated, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined values, said determining means including a second resistance interposed in series with said electrode and said source of high potential.
Claim 13
Dependent Claim
63 words
In combination with the electrostatic coating system specified in claim 9. delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energized for a predetermined period after said energizing control means is operated to deenergize said source of high potential whenever said current does not exceed said predetermined value of current.
Claim 14
Dependent Claim
43 words
An electrostatic coating system in accordance with claim 10, wherein said current determining means is connected to said means for energizing and deenergizing said source of high potential to deenergize said source of high potential whenever the said current exceeds the predetermined value.
Claim 15
Dependent Claim
46 words
An electrostatic coating system in accordance with claim 9, wherein said high potential energizing and deenergizing means includes a manually operated switch on said spray gun and switching means connected to said current determining means to be actuated thereby whenever said current exceeds the predetermined value.
Claim 16
Dependent Claim
53 words
An electrostatic coating system in accordance with claim 9, wherein said high potential energizing and deenergizing means includes an airflow actuated switch connected to an air line supplying air to said spray gun and switching means connected to said current determining means to be actuated thereby whenever said current exceeds the predetermined value.
Claim 17
Dependent Claim
39 words
An electrostatic coating system in accordance with claim 9, wherein said delay means includes a resistance-capacitance circuit connected to an electrical switching means which is connected in series with said energizing and deenergizing means and said high potential source.
Claim 18
Dependent Claim
43 words
An electrostatic coating system in accordance with claim 1, wherein said current determining means includes a voltage sensing circuit connected across a resistance, said resistance being connected in series with said source of high potential, said electrode and said work to be coated.
Claim 19
Dependent Claim
24 words
An electrostatic coating system in accordance with claim 15, wherein said sensing circuit includes a silicone-controlled rectifier connected through amplification stages to said resistance.
Claim 20
Dependent Claim
39 words
An electrostatic coating system in accordance with claim 10, wherein said delay means includes a resistance-capacitance circuit connected to an electrical switching means which is connected in series with said energizing and deenergizing means and said high potential source.
Claim 21
Dependent Claim
108 words
An electrostatic coating system in accordance with claim 9, wherein said spray gun comprises: a body having a forward end provided with a passage therein having an intake connection to a source of coating material and an outlet through which coating material is ejected inTo the atmosphere from the forward end of the body, means comprising a nozzle for atomizing said coating material on ejection from said outlet, a shield of electrical nonconductor material surrounding all conducting portions on the forward end of said body, and means applying an electrostatic field to the material passing from the nozzle including said electrode extending through said shield at said body.
Claim 22
Dependent Claim
34 words
An electrostatic coating system in accordance with claim 9, wherein the electrode has an electrical capacitance to the work to be coated which exceeds that of a metal sphere having a 3 centimeter radius.
Claim 23
Dependent Claim
19 words
An electrostatic coating system in accordance with claim 9, wherein the predetermined current value exceeds the effective arcing current.
Claim 24
Dependent Claim
21 words
An electrostatic coating system in accordance with claim 9, wherein the predetermined current value exceeds the electrode grounded steady-state current value.
Claim 25
Dependent Claim
25 words
A nozzle in accordance with claim 1, wherein said nozzle outer surface is annular to form an annular sharp edge with said forward facing surface.
Claim 26
Dependent Claim
158 words
An electrostatic coating system comprising: a spray gun having a nozzle of electrically conductive material through which coating material is ejected, said nozzle having an internal orifice surface, a forward facing surface joining said internal orifice surface to form an obtuse angle therebetween and an outer surface joining said forward facing surface to form a sharp edge, a source of high potential connected between said nozzle and work to be coated, means for energizing and deenergizing said source of high potential, delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energized for a predetermined period after said energizing control means is operated to deenergize said source of high potential, means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 27
Dependent Claim
158 words
An electrostatic coating system comprising: a spray gun having a nozzle of electrically conductive material through which coating material is ejected, said nozzle having an internal orifice surface, a forward facing surface joining said internal orifice surface to form an obtuse angle therebetween and an outer surface joining said forward facing surface to form a sharp edge, a source of high potential connected between said nozzle and work to be coated, means for energizing and deenergizing said source of high potential, delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energized for a predetermined period after said energizing control means is operated to deenergize said source of high potential, means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 28
Dependent Claim
127 words
An electrostatic coating system comprising: a spray gun having an orifice through which coating material is ejected, an electrode adjacent and spaced from said orifice having an annular sharp edge facing forwardly of said orifice, said source of high potential connected between said electrode and work to be coated, delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energizer for a predetermined period after said energizing control means is operated to deenergize said source of high potential, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
Claim 29
Dependent Claim
127 words
An electrostatic coating system comprising: a spray gun having an orifice through which coating material is ejected, an electrode adjacent and spaced from said orifice having an annular sharp edge facing forwardly of said orifice, said source of high potential connected between said electrode and work to be coated, delay means connected to said source of high potential and to said energizing control means to maintain said source of high potential energizer for a predetermined period after said energizing control means is operated to deenergize said source of high potential, and means for determining that the current through said electrode exceeds a predetermined value connected to said electrode and source of high potential to deenergize said source of high potential whenever said current exceeds the predetermined value.
References Cited (Backward Citations)
US2509277A
Cited
US2658009A
Cited
US2894175A
Cited
US2764712A
Cited
US3048498A
Cited
US3072341A
Cited
US3263127A
Cited
US3248606A
Cited
US3317138A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |