US3633359A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic apparatus
Assignee: Dowty Hydraulic Units Ltd
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Filing: 1970-01-28
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Granted: 1972-01-11
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Expires: 1990-01-28
Abstract
Abstract A hydraulic power transfer system, for use for example in the propulsion of a vehicle, comprising an engine, a fixed positive displacement pump driven by the engine, a fixed positive displacement pump driven by the engine, a variable positive displacement motor, a control valve controlling flow of liquid from the pump to the motor and a pressure responsive means responding to increase in hydraulic pressure at the motor to increase motor displacement and increase engine speed. The variable positive displacement motor may be the propulsion motor for the vehicle. The control valve may include a variable flowselecting device adapted to feed the motor some of the pressure liquid delivered by the pump and including a bypass to carry the remainder of the liquid carried by the pump back to reservoir. The pressure-responsive means may operate to limit hydraulic pressure to a value which having regard to the volumetric displacement of the pump will demand a driving torque from the engine less than the maximum torque of which the engine is capable.
Inventors
- 👤 Calude Leslie Gordon Worn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:04
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/4157; F16H61/42; F16H61/423; F16H61/465
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
53 words
A hydraulic power transfer system comprising an engine, a fixed positive-displacement pump driven by the engine, a variable positive-displacement motor, a connection to carry liquid from the pump to the motor, and a pressure-responsive means responding to increase in hydraulic pressure at the motor to increase motor displacement and to increase engine speed.
Claim 2
Dependent Claim
53 words
A hydraulic power transfer system comprising an engine, a fixed positive-displacement pump driven by the engine, a variable positive-displacement motor, a connection to carry liquid from the pump to the motor, and a pressure-responsive means responding to increase in hydraulic pressure at the motor to increase motor displacement and to increase engine speed.
Claim 3
Dependent Claim
61 words
A hydraulic power transfer system as claimed in claim 1 wherein the pressure responsive means operates over the displacement adjustment range of the motor to limit hydraulic motor pressure to a value which having regard to the volumetric displacement of the pump will demand a driving torque from the engine less than the maximum torque of which the engine is capable.
Claim 4
Dependent Claim
40 words
A hydraulic power transfer system as claimed in claim 1 wherein at the speed of the engine at which maximum power can be developed the power required by the pump is equal to the maximum power available from the engine.
Claim 5
Dependent Claim
49 words
A hydraulic power transfer system as claimed in claim 1 wherein the connection includes a variable flow-selecting device adapted to feed the motor some of the pressure liquid delivered by the pump, and a bypass to carry the remainder of the liquid delivered by the pump back to reservoir.
Claim 6
Dependent Claim
36 words
A hydraulic power transfer system as claimed in claim 4 wherein the variable flow-selecting device includes a reversing means capable of feeding the selected liquid flow either in one direction or the other through the motor.
Claim 7
Dependent Claim
44 words
A hydraulic power transfer system as claimed in claim 4 wherein the variable flow-selecting device includes a manual control which is also arranged to adjust engine speed in the sense to increase engine speed with increase in selected flow of liquid from the pump.
Claim 8
Dependent Claim
21 words
A hydraulic power transfer system as claimed in claim 6 wherein the manual control is also arranged to adjust motor displacement.
Claim 9
Dependent Claim
40 words
A hydraulic power transfer system as claimed in claim 1 including an overrun valve connected in the return line from the motor to throttle return flow from the motor in the event that the motor is driven as a pump.
Claim 10
Dependent Claim
58 words
A hydraulic power transfer system as claimed in claim 4 wherein the variable flow-selecting device includes a manually adjustable throttle valve and a flow valve acting to adjust the selected flow from the pump through the throttle valve to the motor in the sense to maintain or tend to maintain a constant pressure drop at the throttle valve.
Claim 11
Dependent Claim
30 words
A hydraulic power transfer system as claimed in claim 4 wherein the bypass passage includes an open-center service vAlve adapted to connect the bypass liquid to operate a second motor.
Claim 12
Dependent Claim
37 words
A hydraulic power transfer system as claimed in claim 10 including a pressure relief valve for the pump to limit pump delivery pressure to a value corresponding to the maximum torque of which the engine is capable.
Claim 13
Dependent Claim
39 words
A hydraulic power transfer system as claimed in claim 10 wherein the open-center service valve is mechanically connected to the engine speed control so as to increase engine speed when the bypass is connected to operate the second motor.
Claim 14
Dependent Claim
86 words
A hydraulic power transfer system comprising an engine, a fixed positive-displacement pump driven by the engine, a variable positive-displacement motor, a connection to carry liquid at pressure from the pump to the motor, a service control valve, a service motor selectively fed with liquid at pressure from said service valve, a bypass valve connected to carry liquid at pressure from said connection to said service control valve, and means responsive to flow demand from said service control valve to said bypass valve to increase engine speed.
Claim 15
Dependent Claim
86 words
A hydraulic power transfer system comprising an engine, a fixed positive-displacement pump driven by the engine, a variable positive-displacement motor, a connection to carry liquid at pressure from the pump to the motor, a service control valve, a service motor selectively fed with liquid at pressure from said service valve, a bypass valve connected to carry liquid at pressure from said connection to said service control valve, and means responsive to flow demand from said service control valve to said bypass valve to increase engine speed.
Claim 16
Dependent Claim
45 words
A hydraulic power transfer system as claimed in claim 13, including a variable flow-selecting device located in said connection between the bypass valve and the variable-displacement motor to selectively adjust flow to the variable-displacement motor by adjustment of the bypass valve to control bypass flow.
Claim 17
Dependent Claim
51 words
A hydraulic power transfer system as claimed in claim 14, wherein the service control valve is of the open-center type which permits the bypass to flow therethrough to a low-pressure zone when the service motor is inoperative and diverts such bypass flow to the service motor when operation thereof is selected.
Claim 18
Dependent Claim
54 words
A hydraulic power transfer system as claimed in claim 14, wherein the flow-selecting device is a manually variable throttle and the bypass valve includes spring loading and hydraulic working spaces connected to the flow-selecting device and arranged to adjust bypass flow in the sense to maintain a constant pressure drop at the flow-selecting device.
Claim 19
Dependent Claim
54 words
A hydraulic power transfer system as claimed in claim 15, wherein the flow-selecting device is a manually variable throttle and the bypass valve includes spring loading and hydraulic working spaces connected to the flow-selecting device and arranged to adjust bypass flow in the sense to maintain a constant pressure drop at the flow-selecting device.
Claim 20
Dependent Claim
34 words
A hydraulic power transfer system as claimed in claim 14, wherein the variable flow-selecting device includes porting to enable the connection to the variable displacement motor to be in the forward and reverse senses.
Claim 21
Dependent Claim
34 words
A hydraulic power transfer system as claimed in claim 15, wherein the variable flow-selecting device includes porting to enable the connection to the variable displacement motor to be in the forward and reverse senses.
Claim 22
Dependent Claim
34 words
A hydraulic power transfer system as claimed in claim 16, wherein the variable flow-selecting device includes porting to enable the connection to the variable displacement motor to be in the forward and reverse senses.
Claim 23
Dependent Claim
33 words
A hydraulic power transfer system as claimed in claim 17, wherein the variable flow-selecting device includes porting to enable the connection to the variable-displacement motor to be in the forward and reverse senses.
Claim 24
Dependent Claim
113 words
A hydraulic power transmission comprising a pump, a first hydraulic motor, a second hydraulic motor, a main variable throttle connecting the pump delivery to the first motor, a bypass variable throttle controlling flow from the pump delivery to the second motor, means for adjusting said bypass throttle comprising a cylinder, a piston in the cylinder to define two working spaces connected one to either side of the main throttle, spring loading acting to urge the piston and the bypass throttle oppositely to the resultant hydraulic force generated in the working spaces such that the bypass throttle is adjusted in the sense to tend to maintain a constant pressure drop across the main throtTle.
Claim 25
Dependent Claim
113 words
A hydraulic power transmission comprising a pump, a first hydraulic motor, a second hydraulic motor, a main variable throttle connecting the pump delivery to the first motor, a bypass variable throttle controlling flow from the pump delivery to the second motor, means for adjusting said bypass throttle comprising a cylinder, a piston in the cylinder to define two working spaces connected one to either side of the main throttle, spring loading acting to urge the piston and the bypass throttle oppositely to the resultant hydraulic force generated in the working spaces such that the bypass throttle is adjusted in the sense to tend to maintain a constant pressure drop across the main throtTle.
Claim 26
Dependent Claim
35 words
A hydraulic power transmission as claimed in claim 22, wherein the bypass throttle is connected in series with the main throttle and the second motor is connected to pump delivery upstream of the bypass throttle.
Claim 27
Dependent Claim
99 words
A hydraulic power transmission as claimed in claim 22, including a slide valve device having forward and reverse main variable throttles selectable by movement into forward and reverse positions, forward and reverse first motor connections connected to said forward and reverse variable throttles, a pair of auxiliary ports opened and closed during slide valve movement and connected both to one working space of the bypass throttle such that the one working space is connected alternatively to the forward and reverse first motor connections in dependence on adjustment of the slide valve to open the forward or reverse main throttles.
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) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |