Patent US3901031A successfully refreshed from Google Patents.
US3901031A
Expired / Lapsed
US
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Hydrostatic transmission control system
Assignee: Eaton Corp
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Filing: 1974-02-28
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Granted: 1975-08-26
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Expires: 1994-02-28
Abstract
Abstract An improved hydrostatic transmission control system includes electrical control circuitry for effecting operation of a hydraulic motor to vary the effective displacement of a pump unit of a hydrostatic transmission. The control circuitry includes a potentiometer which provides a signal indicative of the actual displacement of the pump unit. A manually operable control lever actuates a second potentiometer to provide a signal indicative of a desired pump unit displacement. These signals are compared and an error signal is provided if the desired displacement is not equal to the actual displacement of the pump unit. If the error signal indicates that there is a relatively large difference between the actual and desired displacements of the pump unit, a hydraulic motor is operated at a relatively high speed to quickly change the displacement of the pump unit toward the desired displacement. As the displacement of the pump unit approaches the desired displacement, the speed of operation of the hydraulic motor is reduced so that the final adjustment of the pump unit displacement is done at a relatively slow speed to promote accuracy in adjusting the actual displacement of the pump unit to the desired displacement. In another embodiment of the invention, the electrical control circuitry is operable to vary the displacements of both the pump and motor units.
Inventors
- 👤 Kenneth K Knapp
- 👤 Charles R Cornell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:34
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/431; F16H61/421
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
383 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, first actuator means for varying the displacement of one of said units, first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing a first electrical output signal which indicates whether the displacement of said one unit differs from the selected displacement and whether the magnitude of this difference is more than a predetermined amount, control means for effecting operation of said first actuator means at a high rate when said first electrical output signal indicates that the displacement of said one unit differs from the selected displacement by at least said predetermined amount and for effecting operation of said first actuator means at a low rate which is slower than said high rate when said first electrical output signal indicates that the displacement of said one unit differs from the selected displacement by an amount which is less than said predetermined amount, second actuator means for varying the displacement of the other of said units, third means for providing a third electrical signal indicative of the displacement of said other unit, said second means including means for providing an electrical signal indicative of a selected displacement of said other unit, and means connected with said second and third means for providing a second electrical output signal which indicates whether the displacement of said other unit differs from the selected displacement and whether the magnitude of this difference is more or less than a second predetermined amount, said control means including means for effecting operation of said second actuator means at a high rate when said second electrical output signal indicates that the displacement of saId other unit differs from the selected displacement by at least said second predetermined amount and for effecting operation of said second actuator means at a low rate which is slower than said high rate of operation of said second actuator means when said second electrical output signal indicates that the displacement of said other unit differs from the selected displacement by an amount which is less than said second predetermined amount.
Claim 2
Independent Claim
383 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, first actuator means for varying the displacement of one of said units, first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing a first electrical output signal which indicates whether the displacement of said one unit differs from the selected displacement and whether the magnitude of this difference is more than a predetermined amount, control means for effecting operation of said first actuator means at a high rate when said first electrical output signal indicates that the displacement of said one unit differs from the selected displacement by at least said predetermined amount and for effecting operation of said first actuator means at a low rate which is slower than said high rate when said first electrical output signal indicates that the displacement of said one unit differs from the selected displacement by an amount which is less than said predetermined amount, second actuator means for varying the displacement of the other of said units, third means for providing a third electrical signal indicative of the displacement of said other unit, said second means including means for providing an electrical signal indicative of a selected displacement of said other unit, and means connected with said second and third means for providing a second electrical output signal which indicates whether the displacement of said other unit differs from the selected displacement and whether the magnitude of this difference is more or less than a second predetermined amount, said control means including means for effecting operation of said second actuator means at a high rate when said second electrical output signal indicates that the displacement of saId other unit differs from the selected displacement by at least said second predetermined amount and for effecting operation of said second actuator means at a low rate which is slower than said high rate of operation of said second actuator means when said second electrical output signal indicates that the displacement of said other unit differs from the selected displacement by an amount which is less than said second predetermined amount.
Claim 3
Dependent Claim
59 words
An apparatus as set forth in claim 1 further including manually actuatable means for effecting operation of said second means to vary said second electrical signal and the indicated selected displacement of said one unit, said manually actuatable means also being operable to effect a variation in the electrical signal indicative of the selected displacement of said other unit.
Claim 4
Dependent Claim
94 words
An apparatus as set forth in claim 1 wherein said first and second actuator means each includes a hydraulic motor, said control means including means for conducting fluid to said hydraulic motors in said first and second actuator means at relatively high flow rate to effect operation of said first and second actuator means at their high rates and for conducting fluid to said hydraulic motor in at least one of said actuator means at a relatively low flow rate to effect operation of said one of said actuator means at its low rate.
Claim 5
Dependent Claim
167 words
An apparatus as set forth in claim 1 wherein said first actuator means includes a first hydraulic motor, said control means including first valve means operable between a closed condition blocking fluid flow to and from said first hydraulic motor and an open condition enabling fluid to flow to said first hydraulic motor, and means for effecting operation of said first valve means from the closed condition to the open condition in response to an electrical output signal from said means for providing a first electrical output signal, said second actuator means including a second hydraulic motor, said control means including second valve means operable between a closed condition blocking fluid flow to and from said second hydraulic motor and an open condition enabling fluid to flow to said second hydraulic motor, and means for effecting operation of said second valve means from the closed condition to the open condition in response to an electrical output signal from said means for providing a second electrical output signal.
Claim 6
Independent Claim
183 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, fluid motor means for varying the displacement of one of said units, first valve means operable between a closed condition and an open condition in which fluid is conducted to said fluid motor means, second valve means operable between a first condition in which fluid is conducted to fluid motor means at a first rate and a second condition in which fluid is conducted to said fluid motor means at a second rate which is less than said first rate, detector means for detecting when the displacement of said one unit is closely approaching a selected displacement during operation of said fluid motor means with said first valve means in said open condition and said second valve means in said first condition, and control means for effecting operation of said second valve means from said first condition to said second condition in response to detection by said detector means that the displacement of said one unit is closely approaching the selected displacement.
Claim 7
Independent Claim
183 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, fluid motor means for varying the displacement of one of said units, first valve means operable between a closed condition and an open condition in which fluid is conducted to said fluid motor means, second valve means operable between a first condition in which fluid is conducted to fluid motor means at a first rate and a second condition in which fluid is conducted to said fluid motor means at a second rate which is less than said first rate, detector means for detecting when the displacement of said one unit is closely approaching a selected displacement during operation of said fluid motor means with said first valve means in said open condition and said second valve means in said first condition, and control means for effecting operation of said second valve means from said first condition to said second condition in response to detection by said detector means that the displacement of said one unit is closely approaching the selected displacement.
Claim 8
Dependent Claim
43 words
An apparatus as set forth in claim 5 wherein said first valve means includes pressure responsive valve means operable between open and closed positions in response to variations in a control fluid pressure and pilot valve means for varying the control fluid pressure.
Claim 9
Dependent Claim
80 words
An apparatus as set forth in claim 5 wherein said detector means includes a first potentiometer, means for varying the output of said first potentiometer in response to variations in the displacement of said one unit, a Second potentiometer, means for varying the output of said second potentiometer in response to variations in the predetermined displacement, and means for detecting when the output of said first potentiometer is closely approaching a predetermined function of the output of said second potentiometer.
Claim 10
Dependent Claim
53 words
An apparatus as set forth in claim 7 wherein said means for detecting when the output of said first potentiometer is closely approaching the output of said second potentiometer includes means for providing an error signal which varies when the output of said first potentiometer closely approaches the output of said second potentiometer.
Claim 11
Dependent Claim
41 words
An apparatus as set forth in claim 5 further including first orifice means for limiting the rate of fluid flow to said first valve means to said second fluid flow rate when said second valve means is in the second condition.
Claim 12
Dependent Claim
35 words
An apparatus as set forth in claim 9 further including second orifice means for conducting fluid to said first valve means at said first rate when said second valve means is in said first condition.
Claim 13
Dependent Claim
24 words
An apparatus as set forth in claim 9 further including means for adjusting said first orifice means to vary said second fluid flow rate.
Claim 14
Dependent Claim
36 words
An apparatus as set forth in claim 5 wherein said fluid motor means including a plurality of relatively movable components around which fluid leaks at a rate which is less than said second fluid flow rate.
Claim 15
Dependent Claim
183 words
An apparatus as set forth in claim 5 further including second fluid motor means for varying the displacement of the other of said units, third valve means operable between a closed condition and an open condition in which fluid is conducted to said second fluid motor means, fourth valve means operable between a first condition in which fluid is conducted to said second fluid motor means at one rate and a second condition in which fluid is conducted to said second fluid motor means at another rate which is less than said one rate, said detector means including means for detecting when the displacement of said other unit is closely approaching a selected displacement during operation of said second fluid motor means with said third valve means in said open condition and said fourth valve means in said first condition, and said control means including means for effecting operation of said fourth valve means from said first condition to said second condition in response to detection by said detector means that the displacement of said other unit is closely approaching the selected displacement.
Claim 16
Independent Claim
237 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, fluid motor means for varying the displacement of one of said units, first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing an electrical output signal which indicates whether the displacement of said one unit differs from the selected displacement, and control means for effecting operation of said fluid motor means when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement, said control means including a valve member movable through a predetermined distance between a closed position blocking fluid flow to said fluid motor means and a fully open position enabling fluid to flow to said fluid motor means, and means for effecting movement of said valve member through said predetermined distance from said closed position to said fully open position when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement and for effecting movement of said valve member through said predetermined distance from said fully open position to said closed position when said electrical output signal indicates that the displacement oF said one unit is at least substantially equal to the selected displacement.
Claim 17
Independent Claim
237 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, fluid motor means for varying the displacement of one of said units, first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing an electrical output signal which indicates whether the displacement of said one unit differs from the selected displacement, and control means for effecting operation of said fluid motor means when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement, said control means including a valve member movable through a predetermined distance between a closed position blocking fluid flow to said fluid motor means and a fully open position enabling fluid to flow to said fluid motor means, and means for effecting movement of said valve member through said predetermined distance from said closed position to said fully open position when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement and for effecting movement of said valve member through said predetermined distance from said fully open position to said closed position when said electrical output signal indicates that the displacement oF said one unit is at least substantially equal to the selected displacement.
Claim 18
Dependent Claim
48 words
An apparatus as set forth in claim 14 wherein said means for effecting movement of said valve member includes coil means energizable to provide a magnetic field and means movable under the influence of a magnetic field eminating from said coil means upon energization of said coil means.
Claim 19
Dependent Claim
87 words
An apparatus as set forth in claim 14 further including means for effecting operation of said second means to vary the second electrical signal through a range in which the displacement of the one unit differs from the selected displacement by varying amounts, said means for effecting movement of said valve member being operable to effect movement of said valve member between the open and closed positions at substantially the same rate regardless of the difference between the displacement of said one unit and the selected displacement.
Claim 20
Dependent Claim
96 words
An apparatus as set forth in claim 14 wherein said means for providing an electrical output signal includes means for providing an electrical output signal which has a first characteristic when the displacement of said one unit is equal to the selected displacement and a second characteristic when said one unit has a displacement which is different than the selected displacement, said means for effecting movement of said valve member including means for moving said valve member through said predetermined distance in response to a change in the output signal between said first and second characteristics.
Claim 21
Independent Claim
327 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, said actuator means including a reversible hydraulic motor, first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing an electrical output signal which indicates whether the displacement of said one unit differs from the selected displacement, and control means for effecting operation of said actuator means when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement, said control means including a directional control valve connected in fluid communication with said hydraulic motor, said directional control valve being operable under the influence of fluid pressure from an unactuated condition to a first actuated condition to effect operation of said hydraulic motor in a first direction to decrease the displacement of said one unit, said directional control valve being operable under the influence of fluid pressure from the unactuated condition to a second actuated condition to effect operation of said hydraulic motor in a second direction to increase the displacement of said one unit, first pilot valve means connected in fluid communication with said directional control valve, said first pilot valve means being operable from an unactuated condition to an actuated condition to port fluid pressure to said directional control valve and effect operation of said directional control valve from the unactuated condition to the first actuated condition, and second pilot valve means connected in fluid communication with said directional control valve, said second pilot valve means being operable from an unactuated condition to an actuated condition to port fluid pressure to said directional control valve and effect operation of said directional control valve from the unactuated condition to the second actuated condition.
Claim 22
Independent Claim
327 words
An apparatus comprising a hydrostatic transmission, said hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, said actuator means including a reversible hydraulic motor, first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing an electrical output signal which indicates whether the displacement of said one unit differs from the selected displacement, and control means for effecting operation of said actuator means when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement, said control means including a directional control valve connected in fluid communication with said hydraulic motor, said directional control valve being operable under the influence of fluid pressure from an unactuated condition to a first actuated condition to effect operation of said hydraulic motor in a first direction to decrease the displacement of said one unit, said directional control valve being operable under the influence of fluid pressure from the unactuated condition to a second actuated condition to effect operation of said hydraulic motor in a second direction to increase the displacement of said one unit, first pilot valve means connected in fluid communication with said directional control valve, said first pilot valve means being operable from an unactuated condition to an actuated condition to port fluid pressure to said directional control valve and effect operation of said directional control valve from the unactuated condition to the first actuated condition, and second pilot valve means connected in fluid communication with said directional control valve, said second pilot valve means being operable from an unactuated condition to an actuated condition to port fluid pressure to said directional control valve and effect operation of said directional control valve from the unactuated condition to the second actuated condition.
Claim 23
Dependent Claim
160 words
An apparatus as set forth in claim 18 wherein said control means includes a rate control valve connected in fluid communication with said directional control valve, said rate control valve being operable from a first condition to a second condition to increase the rate of flow of fluid frOm said directional control valve to said hydraulic motor when said directional control valve is in one of its actuated conditions, said control means further including means for effecting operation of said rate control valve from the first condition to the second condition when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement by at least a predetermined amount and for effecting operation of said rate control valve from the second condition to the first condition when said electrical output signal indicates that the displacement of said one unit differs from the selected displacement by an amount which is less than the predetermined amount.
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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |