US3862645A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pilot control valve
Assignee: Caterpillar Inc
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Filing: 1973-06-18
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Granted: 1975-01-28
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Expires: 1993-06-18
Abstract
Abstract There is disclosed a pilot valve for operation of a main control valve wherein the pilot valve is provided with throttling means to modulate the control fluid to effect an accelerated actuation of the main control valve at each end of the modulation range of the main valve and to provide an extended modulation range for effective and precise control of the main control valve by the operator.
Inventors
- 👤 Donald L Bianchetta
- 👤 Kenneth R Lohbauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:01
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/2004; E02F9/22; E02F9/2278; E02F9/2285; F; F15; F15B; F15B13/00; F15B13/02; F15B13/04; F15B13/042; F15B13/0422; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/8667; Y10T137/86694; Y10T137/86702; Y10T137/8671; Y10T137/86718; Y10T137/86734
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
173 words
A pilot control valve, said valve comprising: a housing; a cylindrical bore formed in said housing; inlet and return passages communicating with said bore; a pilot control passage communicating with said bore; a valve spool reciprocally mounted in said bore and operative in a neutral position to block communications between said passages and operative upon movement from said neutral position to provide communications between said passages; and modulating means carried by said spool and operative to provide stepped differential pressure changes in the communication of fluid from the inlet passage to said pilot control passage, said modulating means comprising a first fixed passage and a cross slot formed in said valve spool for providing substantially instantaneous full communication with said fixed passage upon movement of said valve spool from said neutral position, and a variable area slot formed in said spool and operative to provide variable communication in pArallel with said first fixed passage between said inlet and said pilot control passage upon continued movement of said valve spool from said neutral position.
Claim 2
Dependent Claim
173 words
A pilot control valve, said valve comprising: a housing; a cylindrical bore formed in said housing; inlet and return passages communicating with said bore; a pilot control passage communicating with said bore; a valve spool reciprocally mounted in said bore and operative in a neutral position to block communications between said passages and operative upon movement from said neutral position to provide communications between said passages; and modulating means carried by said spool and operative to provide stepped differential pressure changes in the communication of fluid from the inlet passage to said pilot control passage, said modulating means comprising a first fixed passage and a cross slot formed in said valve spool for providing substantially instantaneous full communication with said fixed passage upon movement of said valve spool from said neutral position, and a variable area slot formed in said spool and operative to provide variable communication in pArallel with said first fixed passage between said inlet and said pilot control passage upon continued movement of said valve spool from said neutral position.
Claim 3
Dependent Claim
45 words
The invention of claim 1 comprising a second fixed passage in series with said first fixed passage communicating said pilot control passage with said return passage for reducing the pressure in said pilot control passage to a value below the pressure in said inlet passage.
Claim 4
Dependent Claim
147 words
A pilot control valve, said valve comprising: a housing; a cylindrical bore formed in said housing; inlet and return passages communicating with said bore; a pilot control passage communicating with said bore; a valve spool reciprocally mounted in said bore and operative to control communications between said passages; and modulating means carried by spool and operative to differential pressure changes in said pilot control passage, said modulating means comprising a first fixed passage operative upon initial movememt of said valve spool from a neutral position to communicate said pilot pressure to said pilot control passage; a variable orifice operative in parallel with said first passage to increase the area of communication of said pilot pressure upon further movement of said spool; and a second passage operative in series with said first passage to reduce said pilot pressure below the pressure of the source of said pilot pressure.
Claim 5
Dependent Claim
147 words
A pilot control valve, said valve comprising: a housing; a cylindrical bore formed in said housing; inlet and return passages communicating with said bore; a pilot control passage communicating with said bore; a valve spool reciprocally mounted in said bore and operative to control communications between said passages; and modulating means carried by spool and operative to differential pressure changes in said pilot control passage, said modulating means comprising a first fixed passage operative upon initial movememt of said valve spool from a neutral position to communicate said pilot pressure to said pilot control passage; a variable orifice operative in parallel with said first passage to increase the area of communication of said pilot pressure upon further movement of said spool; and a second passage operative in series with said first passage to reduce said pilot pressure below the pressure of the source of said pilot pressure.
Claim 6
Dependent Claim
74 words
The invention of claim 3 wherein said inlet passage communicates with said bore centrally thereof; a return passage communicates with said bore at either side of said inlet passage; a pilot control line communicates with said bore between said inlet passage and each of said return passages; and, said spool includes a centrally located land and a pair of annular grooves formed on each side of said land for controlling communications between said passages.
Claim 7
Dependent Claim
96 words
The invention of claim 4 wherein: said first fixed passage is operative to provide substantially instantaneous communication between said inlet and one of said pilot control passages upon initial movement of said spool in either direction from said neutral position; said variable area orifice comprising a slot extending from said land to said annular groove operative in parallel with said first passage to provide increased communication between said inlet and said control passage upon further movement of spool; and said second passage is operative to provide communication between said pilot control passage and said return passage.
Claim 8
Dependent Claim
33 words
The invention of claim 5 comprising a cross slot formed in said land to provide said instantaneous communication; and, means to render said second passage ineffective when said annular groove becomes fully effective.
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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) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |