US4739935A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexible voltage cable for electrostatic spray gun
Assignee: Nordson Corp
•
Filing: 1986-03-12
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Granted: 1988-04-26
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Expires: 2006-03-12
Abstract
Abstract An electrostatic spray system including a spray device having an electrode for electrostatically charging coating particles emitted from the spray device toward an article to be coated, a high voltage electrostatic supply, and a high voltage insulated electrical cable interconnecting the electrostatic supply and the spray device electrode. The high voltage cable includes a fibrous resistive core, preferably fabricated from silicon carbide fibers, a fiber-restraining layer of insulative thread tightly wrapped spirally around the entirety of the core to prevent fiber ends from projecting outwardly from the core, an outer dielectric sheath, and an intermediate sheath sandwiched between the spirally wound inner fiber-restraining layer and the outer dielectric sheath and having a resistivity lying between that of the inner resistive fiber core and the outer dielectric sheath. The intermediate sheath provides uniform voltage stress distribution in the region surrounding the resistive core, thereby avoiding internal corona sites which cause degradation of the outer dielectric sheath, which might otherwise occur due to the very small diameter of the resistive core coupled with the very high operating voltages used in electrostatic spray coating operations. The intermediate sheath also avoids high voltage stresses at the ends of stray resistive fibers projecting through the spirally wound layer, which might otherwise occur due to the extremely small diameter of the projecting fibers.
Inventors
- 👤 Donald R. Hastings
- 👤 John Sharpless
- 👤 George H. Morin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:13
CPC Classifications
B; B05; B05B; B05B5/00; B05B5/08; B05B5/10; H; H01; H01T; H01T19/00; H01T19/04
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
128 words
An electrically insulated high voltage cable comprising: an elongated resistive element of substantially continuous silicon carbide filaments disposed to provide electrical current flow paths primarily in a substantially longitudinal direction therealong, said element being susceptive of having broken filaments which produce filament ends having a tendency to project radially outwardly relative to said longitudinal direction thereof, elongated restraining means spirally-wrapped around and surrounding said resistive element for restraining said filament ends against outward movement to minimize radially outward projection thereof, adjacent convolutions of said restraining means being in close physical proximity with one another and without substantial gaps therebetween whereby to encase substantially the entirety of said resistive element, and a dielectric sheath surrounding said restraining means for insulating said resistive element for safe operation at high voltages.
Claim 2
Dependent Claim
128 words
An electrically insulated high voltage cable comprising: an elongated resistive element of substantially continuous silicon carbide filaments disposed to provide electrical current flow paths primarily in a substantially longitudinal direction therealong, said element being susceptive of having broken filaments which produce filament ends having a tendency to project radially outwardly relative to said longitudinal direction thereof, elongated restraining means spirally-wrapped around and surrounding said resistive element for restraining said filament ends against outward movement to minimize radially outward projection thereof, adjacent convolutions of said restraining means being in close physical proximity with one another and without substantial gaps therebetween whereby to encase substantially the entirety of said resistive element, and a dielectric sheath surrounding said restraining means for insulating said resistive element for safe operation at high voltages.
Claim 3
Dependent Claim
23 words
The cable of claim 1 wherein said restraining means compresses said filament ends radially inwardly relative to said longitudinal direction of said filaments.
Claim 4
Dependent Claim
17 words
The cable of claim 2 wherein said restraining means includes thread spirally wrapped around said resistive element.
Claim 5
Dependent Claim
16 words
The cable of claim 3 wherein said thread encases substantially the entirety of said resistive element.
Claim 6
Dependent Claim
13 words
The cable of claim 4 wherein said thread is fabricated of dielectric material.
Claim 7
Dependent Claim
15 words
The cable of claim 5 wherein said dielectric thread is polyester derived from polyethylene terephthalate.
Claim 8
Dependent Claim
39 words
The cable of claim 1 further comprising an intermediate sheath disposed between said restraining means and said dielectric sheath, said intermediate sheath having a resistivity value intermediate the resistivities of said resistive silicon carbide element and said dielectric sheath.
Claim 9
Dependent Claim
29 words
The cable of claim 7 wherein the resistivity of said silicon carbide filaments is approximately 10 3 ohm-cm., the resistivity of said intermediate sheath is approximately 10 7 ohm-cm.
Claim 10
Dependent Claim
17 words
The combination of claim 8 wherein the resistivity of said dielectric sheath is approximately 10 15 ohm-cm.
Claim 11
Dependent Claim
18 words
The cable of claim 7 wherein said resistive silicon carbide element has a diameter less than approximately 0.05".
Claim 12
Dependent Claim
20 words
The cable of claim 9 wherein said resistive silicon carbide element has a diameter in the approximate range of 0.03"-0.04".
Claim 13
Dependent Claim
16 words
The cable of claim 7 wherein said silicon carbide filaments have a diameter of approximately 0.0005".
Claim 14
Dependent Claim
37 words
The cable of claim 7 wherein the diameter of said silicon carbide element is approximately 0.05", the outside diameter of said intermediate sheath is approximately 0.1", and the outside diameter of said dielectric sheath is approximately 0.2".
Claim 15
Dependent Claim
19 words
The cable of claim 7 wherein said intermediate sheath and said dielectric sheath are bonded at the interface therebetween.
Claim 16
Dependent Claim
19 words
The cable of claim 7 wherein said intermediate sheath and dielectric sheath are chemically cross-linked at the interface therebetween.
Claim 17
Dependent Claim
25 words
The cable of claim 7 wherein said intermediate sheath and dielectric sheath are fabricated of substantially the same polymer, with the intermediate sheath being carbon-loaded.
Claim 18
Dependent Claim
10 words
The cable of claim 16 wherein said polymer is polyethylene.
Claim 19
Dependent Claim
43 words
The cable of claim 7 wherein said intermediate sheath and said dielectric sheath are in intimate physical contact throughout substantially the entirely of the interface therebetween to minimize localized potential corona sites when said silicon carbide fiber element is energized with high voltage.
Claim 20
Dependent Claim
14 words
The cable of claim 18 wherein said intermediate and dielectric sheaths collectively are flexible.
Claim 21
Dependent Claim
24 words
The cable of claim 18 wherein said intermediate and dielectric sheaths are fabricated of substantially the same polymer, with the intermediate sheath being carbon-loaded.
Claim 22
Dependent Claim
185 words
For use in an electrostatic spray coating system having a high voltage electrostatic supply, the combination comprising: A spray coating device for emitting charged coating particles toward an article to be coated; an electrode mounted to said device in charging relationship to coating particles emitted by said spray device; an elongated resistive element of substantially continuous silicon carbide filaments disposed to provide electrical current flow paths primarily in a substantially longitudinal direction therealong, said element being susceptive of having broken filaments which produce filament ends having a tendency to project radially outwardly and relative to said longitudinal direction thereof, said resistive element electrically communicating with said high voltage electrostatic supply and said electrode, elongated restraining means spirally-wrapped around and surrounding said resistive element for restraining said filament ends against outward movement to minimize radially outward projection thereof, adjacent convolutions of said restraining means being in close physical proximity with one another and without substantial gaps therebetween whereby to encase substantially the entirety of said resistive element, and a dielectric sheath surrounding said restraining means for insulating said resistive element for safe operation at high voltages.
Claim 23
Dependent Claim
185 words
For use in an electrostatic spray coating system having a high voltage electrostatic supply, the combination comprising: A spray coating device for emitting charged coating particles toward an article to be coated; an electrode mounted to said device in charging relationship to coating particles emitted by said spray device; an elongated resistive element of substantially continuous silicon carbide filaments disposed to provide electrical current flow paths primarily in a substantially longitudinal direction therealong, said element being susceptive of having broken filaments which produce filament ends having a tendency to project radially outwardly and relative to said longitudinal direction thereof, said resistive element electrically communicating with said high voltage electrostatic supply and said electrode, elongated restraining means spirally-wrapped around and surrounding said resistive element for restraining said filament ends against outward movement to minimize radially outward projection thereof, adjacent convolutions of said restraining means being in close physical proximity with one another and without substantial gaps therebetween whereby to encase substantially the entirety of said resistive element, and a dielectric sheath surrounding said restraining means for insulating said resistive element for safe operation at high voltages.
Claim 24
Dependent Claim
24 words
The combination of claim 21 wherein said restraining means compresses said broken filament ends radially inwardly relative to said longitudinal direction of said filaments.
Claim 25
Dependent Claim
18 words
The combination of claim 22 wherein said restraining means includes thread spirally wrapped around said silicon carbide element.
Claim 26
Dependent Claim
17 words
The combination of claim 23 wherein said thread encases substantially the entirety of said silicon carbide element.
Claim 27
Dependent Claim
13 words
The combination of claim 24 wherein said thread is fabricated of dielectric material.
Claim 28
Dependent Claim
38 words
The combination of claim 21 further comprising an intermediate sheath disposed between said restraining means and said dielectric sheath, said intermediate sheath having a resistivity value intermediate the resistivities of said silicon carbide element and said dielectric sheath.
Claim 29
Dependent Claim
18 words
The combination of claim 26 wherein said intermediate sheath and dielectric sheath are bonded at the interface therebetween.
Claim 30
Dependent Claim
19 words
The combination of claim 26 wherein said intermediate sheath and dielectric sheath are chemically cross-linked at the interface therebetween.
Claim 31
Dependent Claim
25 words
The combination of claim 26 wherein said intermediate sheath and dielectric sheath are fabricated of substantially the same polymer, with the intermediate sheath being carbon-loaded.
Claim 32
Dependent Claim
10 words
The combination of claim 29 wherein said polymer is polyethylene.
Claim 33
Dependent Claim
42 words
The combination of claim 26 wherein said intermediate sheath and said dielectric sheath are in intimate physical contact throughout substantially the entirety of the interface therebetween to minimize localized potential corona sites when said silicon carbide element is energized with high voltage.
Claim 34
Dependent Claim
14 words
The combination of claim 31 wherein said intermediate and dielectric sheaths collectively are flexible.
Claim 35
Dependent Claim
25 words
The combination of claim 31 wherein said intermediate sheath and dielectric sheath are fabricated of substantially the same polymer, with the intermediate sheath being carbon-loaded.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-04-26 | 1991-10-26 | 1992-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-26 | 1995-10-26 | 1996-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-26 | 1999-10-26 | 2000-04-26 | $7700.00 | Window Closed / Lapsed |