US3857541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Servovalve with oscillation filter
Assignee: Moog Inc
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Filing: 1973-06-14
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Granted: 1974-12-31
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Expires: 1993-06-14
Abstract
Abstract The pressure variations in the spool end chambers of a two-stage electrohydraulic servovalve having a second-stage sliding-spool type hydraulic amplifier, resulting from oscillation at a characteristic resonant frequency when the servovalve is operated at relatively high pressures and especially with low viscosity hydraulic fluid, are effectively acoustically filtered out by the provision of a wave tube for each spool end chamber having a length equal to one-quarter the wavelength of such frequency.
Inventors
- 👤 D Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:07
CPC Classifications
F; F15; F15B; F15B13/00; F15B13/02; F15B13/04; F15B13/042; F15B13/043; F15B13/0438; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582; Y10T137/8659; Y10T137/86598; Y10T137/86606; Y10T137/86614
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
96 words
In an electrohydraulic servovalve including a body having a compartment in which a valve spool is slidably arranged leaving chambers at opposite ends of said spool, said servovalve being prone to oscillate at one or more characteristic resonant frequencies resulting in pressure variations in such spool end chambers, the improvement thereof which comprises acoustic filter means for each of said spool end chambers and severally arranged to provide a wave tube having an open end communicating with its corresponding one of said spool end chambers and having a length to provide anti-resonance for one characteristic frequency.
Claim 2
Dependent Claim
96 words
In an electrohydraulic servovalve including a body having a compartment in which a valve spool is slidably arranged leaving chambers at opposite ends of said spool, said servovalve being prone to oscillate at one or more characteristic resonant frequencies resulting in pressure variations in such spool end chambers, the improvement thereof which comprises acoustic filter means for each of said spool end chambers and severally arranged to provide a wave tube having an open end communicating with its corresponding one of said spool end chambers and having a length to provide anti-resonance for one characteristic frequency.
Claim 3
Dependent Claim
28 words
An electrohydraulic servovalve according to claim 1 wherein the end of each of said wave tubes remote from its corresponding one of said spool end chambers is closed.
Claim 4
Dependent Claim
27 words
An electrohydraulic servovalve according to claim 2 wherein said length equals substantially an odd integer multiple of one-quarter wavelength of said characteristic resonant frequency to be attenuated.
Claim 5
Dependent Claim
31 words
An electrohydraulic servovalve according to claim 3 wherein the volume of each of said wave tubes is substantially equal to the volume of its corresponding one of said spool end chambers.
Claim 6
Dependent Claim
32 words
An electrohydraulic servovalve according to claim 3 wherein the volume of each of said wave tubes is at least one-half of the volume of its corresponding one of said spool end chambers.
Claim 7
Dependent Claim
18 words
An electrohydraulic servovalve according to claim 5 wherein said wave tubes are provided by drillings in said body.
Claim 8
Dependent Claim
157 words
An electrohydraulic servovalve according to claim 6 wherein said body comprises a block and first and second end caps at opposite ends of said block, said first and second end caps severally in part defining first and second spool end chambers, one of said wave tubes includes a first intermediate drilling extending through said block, a first connecting drilling in such first end cap connecting one end of said first intermediate drilling with said first spool end chamber and a first dead-ended drilling in said second end cap communicating with the other end of said first intermediate drilling, and the other of said wave tubes includes a second intermediate drilling extending through said block, a second connecting drilling in said second end cap connecting one end of said second intermediate drilling with said second spool end chamber and a second dead-ended drilling in said first end cap communicating with the other end of said second intermediate drilling.
References Cited (Backward Citations)
US3095906A
Cited
US3347252A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-30 | 1978-07-01 | 1978-12-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-30 | 1982-07-01 | 1982-12-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-30 | 1986-07-01 | 1986-12-31 | $7700.00 | Window Closed / Lapsed |