US3793875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for sensing the presence of threads on a surface
Assignee: Robertshaw Controls Co
•
Filing: 1972-02-18
•
Granted: 1974-02-26
•
Expires: 1992-02-18
Abstract
Abstract The method of determining the presence or absence of threads on a surface relies upon the difference in back pressure sensed by the probe of a fluidic system. Back pressure will be greater when the probe is inserted into an unthreaded bore or encompasses an unthreaded stud and will trigger an output indicating that no threads are present. The apparatus for determining the presence or absence of threads on an object has no moving parts and includes a probe, a proportional center dump fluidic element connected to the probe and to a source of pressure, and a fluidic Schmitt trigger connected to amplify the output of the proportional element when the predetermined condition is sensed. Since the system operates on the difference in back pressure fed by the probe to the porportional element, it can be calibrated to generate an output signal indicating higher back pressure due to the absence of threads in a bore or on a stud.
Inventors
- 👤 W Jurkiewicz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:15
CPC Classifications
F; F15; F15C; F15C1/00; F15C1/005; G; G01; G01B; G01B13/00; G01B13/16; G01B13/22; Y; Y10; Y10T; Y10T137/00; Y10T137/206; Y10T137/218; Y10T137/2202; Y10T137/2213
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
65 words
A method for determining the presence or absence of screw threads on a surface comprising the steps of directing a fluid toward the surface such that the only substantial passage for the fluid is through the grooves of the screw threads; and sensing the back pressure of the fluid directed toward the surface to determine the presence or absence of screw threads on the surface.
Claim 2
Independent Claim
65 words
A method for determining the presence or absence of screw threads on a surface comprising the steps of directing a fluid toward the surface such that the only substantial passage for the fluid is through the grooves of the screw threads; and sensing the back pressure of the fluid directed toward the surface to determine the presence or absence of screw threads on the surface.
Claim 3
Dependent Claim
54 words
A method according to claim 1 wherein said sensing step includes balancing a fluidic system for a back pressure existing when screw threads are present on the surface and unbalancing the fluidic system when the back pressure increases above the balanced back pressure in response to the absence of screw threads on the surface.
Claim 4
Dependent Claim
46 words
A method according to claim 1 wherein the surface is an internal cylindrical surface and said fluid directing step includes positioning an outer cylindrical surface of a probe having a radially directed opening in wiping contact with the internal surface and supplying fluid to the probe.
Claim 5
Dependent Claim
41 words
A method according to claim 1 wherein the surface is an external cylindrical surface and said fluid directing step includes positioning a cylindrical internal surface of a probe in wiping contact with the external surface and supplying fluid to the probe.
Claim 6
Dependent Claim
81 words
A fluidic device for determining the presence or absence of screw threads on a surface, comprising fluidic probe means having surface means for contacting the surface to be examined such that grooves of the screw threads provide the only substantial passage for fluid and means for directing a flow of pressurized fluid toward the surface to be examined; and means for sensing back pressure developed at said probe means whereby an increase in back pressure indicates the absence of screw threads
Claim 7
Dependent Claim
81 words
A fluidic device for determining the presence or absence of screw threads on a surface, comprising fluidic probe means having surface means for contacting the surface to be examined such that grooves of the screw threads provide the only substantial passage for fluid and means for directing a flow of pressurized fluid toward the surface to be examined; and means for sensing back pressure developed at said probe means whereby an increase in back pressure indicates the absence of screw threads
Claim 8
Dependent Claim
18 words
A fluidic device according to claim 5 wherein said sensing means includes a proportional center dump fluidic element.
Claim 9
Dependent Claim
25 words
A fluidic device according to claim 6 wherein said sensing means includes a fluidic Schmitt trigger connected to amplify an output of said fluidic element.
Claim 10
Dependent Claim
34 words
A fluidic device according to claim 7 wherein said surface means of said probe means is an external cylindrical surface and said fluid directing means includes a radially directed opening in said external surface.
Claim 11
Dependent Claim
34 words
A fluidic device according to claim 7 wherein said surface means of said probe means is an internal cylindrical surface and said fluid directing means includes an axially directed opening in said probe means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |