Patent US4158290A successfully refreshed from Google Patents.
US4158290A
Expired / Lapsed
US
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Electro-hydraulic controller
Assignee: Eaton Corp
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Filing: 1978-05-24
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Granted: 1979-06-19
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Expires: 1998-05-24
Abstract
Abstract An electro-hydraulic control for a hydrostatic transmission including a variable displacement hydraulic pump, a fixed displacement hydraulic motor, and fluid operable strokers to vary the displacement of the pump. The electro-hydraulic control is in series between the charge pump and the standard manual controller and determines the pressure of the charge fluid ported to the standard controller. The electro-hydraulic control includes a spool biased toward a first position to port fluid from the charge pump to the standard controller, and biased toward a second position to relieve to tank the pressure of fluid ported to the manual controller. The biasing toward the second direction is accomplished, in part, by pressure in a fluid chamber exerting a biasing force on the spool, the fluid chamber being in communication with drain through a variable orifice which is variable in response to a pressure command signal. This signal is generated by control logic including a horsepower command signal generator which is variable to correspond to a maximum desired input horsepower, and circuitry providing a horsepower approximation signal representing the product of motor output speed and the instantaneous pressure command signal. The circuitry compares the horsepower command and horsepower approximation signals and generates a new pressure command signal tending to minimize the difference between the horsepower command and approximation signals. As a result, the commanded maximum system pressure varies, such that the product of maximum system pressure and motor output speed (proportional to pump flow) is constant, for a given input horsepower setting.
Inventors
- 👤 Charles R. Cornell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:08
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/475; F04; F04B; F04B49/00; F04B49/06; F04B2201/00; F04B2201/12; F04B2201/1204; F04B2205/00; F04B2205/08; F16H61/42; F16H61/433; Y; Y10; Y10S; Y10S60/00; Y10S60/911
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
342 words
A control system for a hydrostatic transmission including a fluid pump and a fluid motor, said fluid pump having fluid operable means for varying the displacement thereof, and a source of pressurized fluid for operating the fluid operable means, said control system comprising: (a) a housing defining a valve bore, an inlet fluid port adapted for series fluid communication with the source of pressurized fluid, a control fluid port adapted for series fluid communication with the fluid operable means, and a drain fluid port adapted for communication with a fluid drian, said ports being in fluid communication with said valve bore; (b) valve means disposed in said valve bore and movable between a first position permitting fluid communication between said inlet fluid port and said control fluid port and a second position; (c) first means for biasing said valve means toward said first position; (d) second means for biasing said valve means toward said second position; (e) one of said first and second biasing means including: (1) means for generating a variable electrical command signal P; and (2) means responsive to said variable electrical command signal P to provide a variable biasing force, biasing said valve means toward said respective position, said variable biasing force being related to said variable electrical command signal P in a known manner; (f) said means for generating said command signal P including: (1) input command signal generator means which is variable to correspond to a maximum desired input to the transmission; (2) means providing an electrical signal N m representative of the output speed of the fluid motor, said maximum desired input being proportional to the product of P and N m ; (3) means providing an electrical input approximation signal representative of the product of the speed N m of the fluid motor and the instantaneous command signal P; and (4) means for comparing said input command signal and said input approximation signal and generating a new command signal P tending to minimize the difference between said input command signal and said input approximation signal.
Claim 2
Dependent Claim
342 words
A control system for a hydrostatic transmission including a fluid pump and a fluid motor, said fluid pump having fluid operable means for varying the displacement thereof, and a source of pressurized fluid for operating the fluid operable means, said control system comprising: (a) a housing defining a valve bore, an inlet fluid port adapted for series fluid communication with the source of pressurized fluid, a control fluid port adapted for series fluid communication with the fluid operable means, and a drain fluid port adapted for communication with a fluid drian, said ports being in fluid communication with said valve bore; (b) valve means disposed in said valve bore and movable between a first position permitting fluid communication between said inlet fluid port and said control fluid port and a second position; (c) first means for biasing said valve means toward said first position; (d) second means for biasing said valve means toward said second position; (e) one of said first and second biasing means including: (1) means for generating a variable electrical command signal P; and (2) means responsive to said variable electrical command signal P to provide a variable biasing force, biasing said valve means toward said respective position, said variable biasing force being related to said variable electrical command signal P in a known manner; (f) said means for generating said command signal P including: (1) input command signal generator means which is variable to correspond to a maximum desired input to the transmission; (2) means providing an electrical signal N m representative of the output speed of the fluid motor, said maximum desired input being proportional to the product of P and N m ; (3) means providing an electrical input approximation signal representative of the product of the speed N m of the fluid motor and the instantaneous command signal P; and (4) means for comparing said input command signal and said input approximation signal and generating a new command signal P tending to minimize the difference between said input command signal and said input approximation signal.
Claim 3
Dependent Claim
347 words
A control system for a hydrostatic transmission including a fluid pump and a fluid motor, said fluid pump having fluid operable means for varying the displacement thereof, and a source of pressurized fluid for operating the fluid operable means, said control system comprising: (a) a fluid housing defining a valve bore, an inlet fluid port adapted for series fluid communication with the source of pressurized fluid, a control fluid port adapted for series fluid communication with the fluid operable means, and a drain fluid port adapted for communication with a fluid drain, said ports being in fluid communication with said valve bore; (b) valve means disposed in said valve bore and movable between a first position permitting fluid communication between said inlet fluid port and said control fluid port, and a second position restricting fluid communication between said control fluid port and said inlet fluid port; (c) first means for biasing said valve means toward said first position; (d) second means for biasing said valve means toward said second position; (e) one of said first and second biasing means including: (1) means for generating a variable electrical pressure command signal P; and (2) means responsive to said variable electrical pressure command signal P to provide a variable biasing force, biasing said valve means toward said respective position, said variable force being related to said variable electrical pressure command signal P in a known manner; (f) said means for generating said pressure command signal P including: (1) horsepower command signal generator means which is variable to correspond to a maximum desired input horsepower to the transmission; (2) means providing an electrical signal N m representative of the ouput speed of the fluid motor; (3) means providing an electrical horsepower approximation signal representative of the product of the speed N m of the fluid motor and the instantaneous pressure command signal P; and (4) means for comparing said horsepower command signal and said horsepower approximation signal and generating a new pressure command signal P tending to minimize the difference between said horsepower command signal and said horsepower approximation signal.
Claim 4
Dependent Claim
347 words
A control system for a hydrostatic transmission including a fluid pump and a fluid motor, said fluid pump having fluid operable means for varying the displacement thereof, and a source of pressurized fluid for operating the fluid operable means, said control system comprising: (a) a fluid housing defining a valve bore, an inlet fluid port adapted for series fluid communication with the source of pressurized fluid, a control fluid port adapted for series fluid communication with the fluid operable means, and a drain fluid port adapted for communication with a fluid drain, said ports being in fluid communication with said valve bore; (b) valve means disposed in said valve bore and movable between a first position permitting fluid communication between said inlet fluid port and said control fluid port, and a second position restricting fluid communication between said control fluid port and said inlet fluid port; (c) first means for biasing said valve means toward said first position; (d) second means for biasing said valve means toward said second position; (e) one of said first and second biasing means including: (1) means for generating a variable electrical pressure command signal P; and (2) means responsive to said variable electrical pressure command signal P to provide a variable biasing force, biasing said valve means toward said respective position, said variable force being related to said variable electrical pressure command signal P in a known manner; (f) said means for generating said pressure command signal P including: (1) horsepower command signal generator means which is variable to correspond to a maximum desired input horsepower to the transmission; (2) means providing an electrical signal N m representative of the ouput speed of the fluid motor; (3) means providing an electrical horsepower approximation signal representative of the product of the speed N m of the fluid motor and the instantaneous pressure command signal P; and (4) means for comparing said horsepower command signal and said horsepower approximation signal and generating a new pressure command signal P tending to minimize the difference between said horsepower command signal and said horsepower approximation signal.
Claim 5
Dependent Claim
39 words
A control system as claimed in claim 1 or 2 wherein said means providing a variable biasing force comprises a fluid chamber and means responsive to the pressure of fluid in said fluid chamber to bias said valve means.
Claim 6
Dependent Claim
36 words
A control system as claimed in claim 3 including a source of pressurized fluid in communication with said fluid chamber and restriction means adapted for series fluid communication between said fluid chamber and a fluid drain.
Claim 7
Dependent Claim
42 words
A control system as claimed in claim 4 wherein said restriction means includes means defining a variable orifice and said means providing a variable biasing force includes means responsive to changes in said pressure command signal P to vary said variable orifice.
Claim 8
Dependent Claim
36 words
A control system as claimed in claim 5 wherein said variable orifice varies between a maximum orifice area and a minimum orifice area as said pressure command signal P varies between a maximum and a minimum.
Claim 9
Dependent Claim
33 words
A control system as claimed in claim 2 wherein said variable biasing force varies between a maximum and a minimum as said pressure command signal P varies between a maximum and a minimum.
Claim 10
Dependent Claim
30 words
A control system as claimed in claim 7 wherein said means generating said pressure command signal P includes logic utilizing the relationship P=K(HP-HP'), wherein K is a constant gain factor.
Claim 11
Dependent Claim
34 words
A control system as claimed in claim 1 or 2 wherein said comparing and generating means includes integrator circuit means to maintain said setting approximation signal HP' substantially equal to said input setting HP.
Claim 12
Dependent Claim
31 words
A control system as claimed in claim 1 or 2 including a main flow control valve disposed in series fluid communication between said control fluid port and said fluid operable means.
Claim 13
Dependent Claim
50 words
A control system as claimed in claim 10 wherein said means for generating, and said means responsive to, said variable electrical command signal P comprise said second biasing means, and said second biasing means further includes means responsive to system pressure to bias said valve means toward said second position.
Claim 14
Dependent Claim
37 words
A control system as claimed in claim 11 wherein said means providing a variable biasing force comprises a fluid chamber and means responsive to the pressure of fluid in said fluid chamber to bias said valve means.
Claim 15
Dependent Claim
36 words
A control system as claimed in claim 12 including a source of pressurized fluid in communication with said fluid chamber and restriction means adapted for series fluid communication between said fluid chamber and a fluid drain.
Claim 16
Dependent Claim
43 words
A control system as claimed in claim 13 wherein said restriction means includes means defining a variable orifice and said means providing a variable biasing force includes means responsive to changes in said variable electrical command signal P to vary said variable orifice.
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) | 1982-06-18 | 1982-12-18 | 1983-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-06-18 | 1986-12-18 | 1987-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-06-18 | 1990-12-18 | 1991-06-19 | $7700.00 | Window Closed / Lapsed |