Patent US3775981A successfully refreshed from Google Patents.
US3775981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic drive unit
Assignee: Hydromatik GmbH
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Filing: 1972-02-01
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Granted: 1973-12-04
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Expires: 1992-02-01
Abstract
Abstract A hydrostatic drive unit comprises a pump driven by a prime mover and having constant delivery during normal operation, and at least one variable stroke axial piston-type motor fed by the pump. The intake volume per revolution of the motor is variable by pivoting the cylinder block about an off-center pivot axis through an angle of more than 30* such that the dead space in the cylinders is kept as small as possible. The intake volume per revolution of the motor at maximum pivot position is a multiple of the delivery volume per revolution of the pump. The cylinder block of the motor is carried along by the drive flange through peripherally arranged teeth in mesh in the region of the pivot axis and permitting the pivoting movement of the cylinder block.
Inventors
- 👤 H Molly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:33
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/431; F01; F01B; F01B3/00; F01B3/0032; F01B3/0035; F01B3/0044; F01B3/0064; F01B3/0076; F01B3/10; F01B3/103; F01B3/109; F16H61/427
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
221 words
In a hydrostatic drive unit comPrising a driven shaft, a drive shaft, a rotary hydraulic pump connected to the drive shaft and producing an output of a given volume of hydraulic fluid per revolution, at least one axial piston-type motor communicating with the pump to be supplied with hydraulic fluid from the pump, said motor including a cylinder block, pistons in said cylinder block, a drive flange rotatable about an axis, piston rods connecting the pistons and the drive flange, and means supporting the cylinder block for rotation and for pivotal movement about a pivotal axis whereby the hydraulic fluid intake volume of the motor is varied by changing the pivotal position of the cylinder block, there being a dead space in the cylinders when the pistons are fully seated therein, means connecting the drive flange to the driven shaft, the improvement comprising: in normal operation said pump producing said volume with speed variation being accomplished by pivoting said cylinder block of the motor, said means supporting said cylinder block establishing a maximum angle of pivot of the cylinder block at which the intake volume of the motor is a multiple of said given volume of the pump, said pivotal axis being offset from said rotational axis so that the dead space in the cylinders is kept as small as possible.
Claim 2
Dependent Claim
221 words
In a hydrostatic drive unit comPrising a driven shaft, a drive shaft, a rotary hydraulic pump connected to the drive shaft and producing an output of a given volume of hydraulic fluid per revolution, at least one axial piston-type motor communicating with the pump to be supplied with hydraulic fluid from the pump, said motor including a cylinder block, pistons in said cylinder block, a drive flange rotatable about an axis, piston rods connecting the pistons and the drive flange, and means supporting the cylinder block for rotation and for pivotal movement about a pivotal axis whereby the hydraulic fluid intake volume of the motor is varied by changing the pivotal position of the cylinder block, there being a dead space in the cylinders when the pistons are fully seated therein, means connecting the drive flange to the driven shaft, the improvement comprising: in normal operation said pump producing said volume with speed variation being accomplished by pivoting said cylinder block of the motor, said means supporting said cylinder block establishing a maximum angle of pivot of the cylinder block at which the intake volume of the motor is a multiple of said given volume of the pump, said pivotal axis being offset from said rotational axis so that the dead space in the cylinders is kept as small as possible.
Claim 3
Dependent Claim
31 words
A hydrostatic drive unit according to claim 1, characterized in that the cylinder block of the axial piston-type motor is pivotable up to an angle of pivot of greater than 30*.
Claim 4
Dependent Claim
42 words
A hydrostatic drive unit as set forth in claim 2, wherein the cylinder block and the drive flange have mutually engaging teeth so that they rotate concurrently, said point of engagement of said teeth being in the region of the pivotal axis.
Claim 5
Dependent Claim
82 words
A hydrostatic drive unit as set forth in claim 3 including a housing, wherein the cylinder block and the drive flange have toric surfaces on which said teeth are mounted, said means supporting the cylinder block includes a frame, a bearing trunnion on the side of the housing, a bearing trunnion on the side of the frame and a connecting side bar having bores within which said trunnions are received, and including angle bisecting gearing means interconnecting the housing and the frame.
Claim 6
Dependent Claim
65 words
A hydrostatic drive unit as set forth in claim 4 including a hydraulic fluid conduit between the pump and the motor, characterized by part of said conduit extending through said trunnions and through a channel in the connecting side bar between said bores therein, said trunnions having annular rings thereon at each side of said channel with said rings defining pressure fields about the trunnions.
Claim 7
Dependent Claim
66 words
A hydrostatic drive unit as set forth in claim 5, wherein each trunnion is formed about an axis and the respective rings are in planes inclined in opposite directions with respect to the respective trunnion axis so that the pressure field of a trunnion is larger at one side of the trunnion axis than at the other side, and other side being adjacent the other trunnion.
Claim 8
Dependent Claim
183 words
A hydrostatic drive unit as set forth in claim 6, including a second axial piston type motor communicating with said pump, said second motor including a cylinder block, pistons in said cylinder block, a drive flange rotatable about an axis, piston rods connecting the pistons and the drive flange, and means supporting the cylinder block for rotation and for pivotal movement about a pivotal axis whereby the hydraulic fluid intake volume of the second motor is varied, there being a dead space in the cylinders of the second motor when the pistons are fully seated therein, means connecting the drive flange of the second motor to the driven shaft, said drive flanges being coaxial with respect to each other and rotatable independently of each other, bearing means between the adjacent sides of the flanges, the two cylinder blocks being at the non-adjacent sides of the respective flanges whereby the forces of the piston rods on the flanges act to force the flanges toward each other, said means connecting the drive flanges to the Driven shaft including drive wheels secured to the respective flanges.
Claim 9
Dependent Claim
179 words
A hydrostatic drive unit as set forth in claim 1, including a second axial piston type motor communicating with said pump, said second motor including a cylinder block, pistons in said cylinder block, a drive flange rotatable about an axis, piston rods connecting the pistons and the drive flange, and means rotatably supporting the cylinder block for rotation and for pivotal movement about a pivotal axis whereby the hydraulic fluid intake volume of the motor is varied, there being a dead space in the cylinders when the pistons are fully seated therein, means connecting the drive flange of the second motor to the driven shaft, said drive flanges being coaxial with respect to each other and rotatable independently of each other, bearing means between the adjacent sides of the flanges, the two cylinder blocks being at the non-adjacent sides of the respective flanges whereby the forces of the piston rods on the flanges act to force the flanges toward each other, said means connecting the drive flanges to the driven shaft including drive wheels secured to the respective flanges.
Claim 10
Dependent Claim
163 words
A hydrostatic drive unit as set forth in claim 1, including a housing, said means supporting said cylinder block comprising a frame, a bearing trunnion on the side of the housing, a bearing trunnion on the side of the frame and a connecting side bar having bores within which said trunnions are received, including a hydraulic fluid conduit between the pump and the motor with a part of said conduit extending through said trunnions and through a channel in the connecting side bar between said bores therein, said trunnions having annular rings thereon at each side of said channel with said rings defining pressure fields about the trunnions, each trunnion being formed about an axis and the respective rings being in planes inclined in opposite directions with respect to the respective trunnion axis so that the pressure field of a trunnion is larger at one side of the trunnion axis then at the other side, said other side being adjacent the other trunnion.
References Cited (Backward Citations)
US3175363A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |