US3736753A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic drive
Assignee: Deere and Co
•
Filing: 1971-09-22
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Granted: 1973-06-05
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Expires: 1991-09-22
Abstract
Abstract A hydraulic drive includes a hydraulic pump and a variable displacement axial piston type hydraulic motor. The swash plate of the motor is adjusted by a hydraulic cylinder having an accumulator connected to the pressurized end of the cylinder so that the motor displacement is at a maximum value when the pressure in the accumulator and the cylinder is below a predetermined value and decreases as the pressure in the accumulator builds up. A pilot-operated valve controls the flow of pressurized fluid from the pump to the motor, the pressure to open the pilot valve being supplied through a manually shiftable valve which also directs fluid pressure to the accumulator through an orifice, which retards the pressure buildup in the accumulator to gradually decrease the motor displacement after the control valves are shifted to their open positions.
Inventors
- 👤 W Roth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:42
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/472; F16H61/42; F16H61/423
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
188 words
A hydraulic drive comprising: a hydraulic pump means; a variable displacement hydraulic motor hydraulically connected to and driven by the pump means through a first conduit means and having a hydraulically actuated control means responsive to fluid pressure in a second conduit means to maintain the motor at maximem displacement when the pressure in said second conduit means is below a predetermined value and to decrease the displacement in response to increasing pressure in said conduit means above said predetermined value; a valve means operative to selectively control the flow of pressured fluid from the pump means to the motor and the second conduit means; an orifice means in the second conduit means for restricting the flow of pressured fluid to the control means; and an accumulator in the second conduit means downstream of the control valve means and orifice means and operative to gradually build up the pressure in the second conduit means after the valve means is actuated to supply fluid pressure thereto and thereby cause a gradual decrease in the displacement of the motor after the valve means is actuated to supply fluid pressure thereto.
Claim 2
Dependent Claim
188 words
A hydraulic drive comprising: a hydraulic pump means; a variable displacement hydraulic motor hydraulically connected to and driven by the pump means through a first conduit means and having a hydraulically actuated control means responsive to fluid pressure in a second conduit means to maintain the motor at maximem displacement when the pressure in said second conduit means is below a predetermined value and to decrease the displacement in response to increasing pressure in said conduit means above said predetermined value; a valve means operative to selectively control the flow of pressured fluid from the pump means to the motor and the second conduit means; an orifice means in the second conduit means for restricting the flow of pressured fluid to the control means; and an accumulator in the second conduit means downstream of the control valve means and orifice means and operative to gradually build up the pressure in the second conduit means after the valve means is actuated to supply fluid pressure thereto and thereby cause a gradual decrease in the displacement of the motor after the valve means is actuated to supply fluid pressure thereto.
Claim 3
Dependent Claim
44 words
The invention defined in claim 1 wherein the orifice means is a variable orifice operative to selectively vary the flow rate in the second conduit means and thereby vary the rate of pressure increase therein and the rate of change of the motor displacement.
Claim 4
Dependent Claim
56 words
The invention defined in claim 1 wherein the control means includes a hydraulic cylinder actuatable in response to fluid pressure in the second conduit means to shift the control means in one direction and thereby decrease the motor displacement and a spring means biasing the control means in the opposite direction toward its maximum displacement condition.
Claim 5
Dependent Claim
61 words
The invention defined in claim 3 wherein the control means includes a housing having a cylindrical boRe with a piston mounted in the bore to form said hydraulic cylinder and the accumulator includes a shiftable member mounted in said bore opposite the piston, the second conduit means being in fluid communication with the bore between said shiftable member and said piston.
Claim 6
Dependent Claim
61 words
The invention defined in claim 4 wherein the end of the bore opposite the shiftable member is closed to trap a compressible gas between said end and the shiftable member, the shiftable member shifting to compress the trapped gas in response to fluid pressure in the second conduit means, so that the pressure of the trapped gas establishes the accumulator pressure.
Claim 7
Dependent Claim
25 words
The invention defined in claim 5 and including means for varying the quantity of the trapped gas and thereby the initial pressure in the accumulator.
Claim 8
Dependent Claim
19 words
The invention defined in claim 5 wherein the shiftable member comprises a second piston slidably mounted in said bore.
Claim 9
Dependent Claim
17 words
The invention defined in claim 5 wherein the shiftable member comprises a flexible membrane spanning said bore.
Claim 10
Dependent Claim
56 words
The invention defined in claim 8 and including a generally annular member mounted in the bore between the flexible membrane and the piston with its central aperture communicating with the second conduit means, the end of the annular member opposite the membrane having an axial projection which mates with an axially extending recess in the membrane.
Claim 11
Dependent Claim
17 words
The invention defined in claim 4 wherein the housing is an integral part of the motor housing.
Claim 12
Dependent Claim
39 words
The invention defined in claim 1 wherein the pump means includes a first pump operative to supply fluid pressure to the first conduit means and a second pump operative to supply fluid under pressure to the second conduit means.
Claim 13
Dependent Claim
55 words
The invention defined in claim 1 wherein the valve means includes a first valve operative to selectively supply fluid pressure to the second conduit means and a hydraulically actuated valve in the first conduit means responsive to fluid pressure in the second conduit means to direct fluid pressure from the pump means to the motor.
Claim 14
Dependent Claim
67 words
The invention defined in claim 1 wherein the control means includes a hydraulic cylinder having a piston shiftable in response to fluid pressure to shift the control means and a servo valve responsive to the fluid pressure in the accumulator and operative to direct fluid to or exhaust fluid from the cylinder so that the position of the piston varies according to the pressure in the accumulator.
Claim 15
Dependent Claim
83 words
The invention defined in claim 13 wherein the piston has an axial bore and the servo valve includes a spool-type valve member coaxially slidable in said bore and acted on in one direction by the fluid pressure in the accumulator and in the opposite direction by a spring means, the valve member shifting in said bore to control the flow of pressurized fluid to and from the cylinder so that the position of the cylinder corresponds to the position of the valve member.
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) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |