US3774505A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Swash plate devices
Assignee: Dowty Technical Developments Ltd
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Filing: 1971-03-01
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Granted: 1973-11-27
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Expires: 1991-03-01
Abstract
Abstract This invention concerns a swash plate device having a rotary cylinder block, cylinders in the block arranged parallel to or inclined to the block rotation axis, pistons reciprocable in the cylinders and projecting from one end of the cylinder block, a tiltable swash plate disposed adjacent the one end of the block and having a flat swash surface engaged by the pistons, and a valve surface having a high pressure port and a low pressure port connecting to and disconnecting from cylinder ports during block rotation, the arrangement being such that during cylinder block rotation each piston is urged partly into its cylinder to precompress liquid therein after the cylinder disconnects from the low pressure port before it connects to the high pressure port. Such precompression reduces noise in operation of the swash plate device but causes an alternating tilting moment to be applied to the swash plate depending on the operating pressure of the device. The present invention provides that the tilt axis of the swash plate should lie in between the line of action of the thrust of each piston on the flat swash surface at the extreme end of its stroke in its cylinder as it leaves the low pressure port and a line which passes perpendicularly through the articulation plane of the pistons at the point of intersection with the cylinder block axis.
Inventors
- 👤 D Mcleod
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:08
CPC Classifications
F; F04; F04B; F04B1/00; F04B1/12; F04B1/26; F04B1/30; F04B1/32; F04B1/324; F04B1/20; F04B1/2014; F04B1/2078
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
233 words
A swash plate device comprising a rotary cylinder block, cylinders in the block extending in the direction of the block rotation axis, pistons reciprocable in the cylinders and projecting from one end of the cylinder block, a tiltable swash plate disposed adjacent the one end of the block and having a flat swash surface engaged by the pistons, and a valve surface having a high pressure port and a low pressure port connecting to and disconnecting from cylinder ports during block rotation, the tilt axis of the swash plate, the flat swash surface, the cylinder block axis and the high pressure port being relatively positioned during operation at the maximum swash angle so that each piston during cylinder block rotation is urged partly into its cylinder after the cylinder disconnects from the low pressure port and before it connects to the high pressure port, the tilt axis of the swash plate passing through a triangle formed by the line of action of the thrust of each piston onto the flat swash surface at the extreme end of its stroke in its cylinder as the cylinder disconnects from the low pressure port, the rotation axis of the cylinder block and a Line in the articulation plane between the said rotation axis and the said line of action, said tilt axis being spaced from said rotation axis in the direction of said line of action.
Claim 2
Dependent Claim
233 words
A swash plate device comprising a rotary cylinder block, cylinders in the block extending in the direction of the block rotation axis, pistons reciprocable in the cylinders and projecting from one end of the cylinder block, a tiltable swash plate disposed adjacent the one end of the block and having a flat swash surface engaged by the pistons, and a valve surface having a high pressure port and a low pressure port connecting to and disconnecting from cylinder ports during block rotation, the tilt axis of the swash plate, the flat swash surface, the cylinder block axis and the high pressure port being relatively positioned during operation at the maximum swash angle so that each piston during cylinder block rotation is urged partly into its cylinder after the cylinder disconnects from the low pressure port and before it connects to the high pressure port, the tilt axis of the swash plate passing through a triangle formed by the line of action of the thrust of each piston onto the flat swash surface at the extreme end of its stroke in its cylinder as the cylinder disconnects from the low pressure port, the rotation axis of the cylinder block and a Line in the articulation plane between the said rotation axis and the said line of action, said tilt axis being spaced from said rotation axis in the direction of said line of action.
Claim 3
Dependent Claim
82 words
A swash plate device as claimed in claim 1, wherein the tilt axis of the swash plate passes through and is spaced from the sides of a triangle formed by the line of action of the thrust of each piston onto the flat swash surface at the extreme end of its stroke as the cylinder disconnects from the low pressure port, the rotation axis, and a line in the swash plate surface between the rotation axis and the said line of action.
Claim 4
Dependent Claim
40 words
A swash plate device as claimed in claim 1, including a single-acting hydraulic servo motor connected for adjustment of the swash plate angle, the hydraulic liquid for operating the said servo being the liquid available at said high pressure port.
Claim 5
Dependent Claim
52 words
A swash plate device as claimed in claim 1, wherein the swash plate tilt axis is offset from the flat swash surface on the side thereof remote from the pistons and including a single shaft extending through the swash plate without intersecting the swash surface to determine the swash plate tilt axis.
Claim 6
Dependent Claim
51 words
A swash plate device as claimed in claim 1, wherein the swash plate tilt axis is offset from the flat swash surface on the side threof remote from the pistons and including a single shaft extending through the swash plate without intersecting the swash surface to determine the swash plate axis.
Claim 7
Dependent Claim
25 words
A swash plate device as claimed in claim 1, having five cylinders only in the cylinder block containing pistons which engage the swash plate surface.
Claim 8
Dependent Claim
62 words
A swash plate device as claimed in claim 1, including a restricted flow passage in the valve surface extending from the high pressure port towards the low pressure port such that as each cylinder port passes from the low pressure port to the high pressure port it makes connection to the restricted flow passage before making connection with the high pressure port.
Claim 9
Dependent Claim
67 words
A swash plate device as claimed in claim 1, wherein the pistons engage a flat swash surface through the medium of slippers, there being one slipper universally jointed to each piston, the centre of universal jointing of each piston lying on the said articulation plane, and the tilt axis of the swash plate lying on the side of the flat swash surface, remote from said articulation plane.
References Cited (Backward Citations)
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US3159041A
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US3256782A
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US3512178A
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US3585901A
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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) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |