US4920748A
Expired / Lapsed
US
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Hydraulic drive system
Assignee: Bosch Rexroth AG
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Filing: 1984-08-10
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Granted: 1990-05-01
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Expires: 2004-08-10
Abstract
Abstract The torque of a hydraulic machine is dependent of the fluid pressure delivered to the machine and is further dependent of the adjustment of its volume of through-put. In response to a load coupled to the machine, a speed results which is controlled by a speed control system acting on the adjusting system of the hydraulic machine. According to the invention, an electro hydraulic speed control comprises a pair of control circuits which are connected to, but operate independent of each other. Thus the electrical control circuit produces a control signal y e1 from the difference of the actual value and the desired value of the speed for adjusting a hydraulic restricting means which produces a hydraulic pressure signal p st in the hydraulic control circuit which pressure signal is compared with a hydraulic reference signal p o to produce a differential pressure signal p o -p st which is applied to the adjusting cylinder of the hydraulic machine. The control system thus comprises two circuits, i.e. an electrical speed control circuit and a hydraulic pressure control circuit resulting in optimizing the control operation.
Inventors
- 👤 Rolf Kordak
- 👤 Heinrich Nikolaus
- 👤 Frank Metzner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:23
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/423; F04; F04B; F04B49/00; F04B49/08; F16H61/46; F16H61/47; B; B60; B60K; B60K6/00; B60K6/08; B60K6/12; F16H61/4043; F16H61/4052; Y; Y02; Y02T; Y02T10/00; Y02T10/60; Y02T10/62
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
236 words
A hydraulic drive system, comprising a first hydraulic machine having an adjustable volume of through-put and operable as a pump or motor, a line of load-independent pressure to which said first machine is connected, a second hydraulic machine coupled for rotation with said first machine for functioning as a signal transmitter for providing a hydraulic signal indicative of speed of said first machine, said second machine being operable as a motor or pump in response to the direction of rotation of said first machine to produce a control flow speed signal proportional to the actual speed of the first machine, and means for adjusting the through-put of said first machine comprising a flow restricting system for providing a pressure signal including a pump and an adjustable throttle cooperable with the control flow of said signal transmitter for delivering a pressure signal P st which is compared with a predetermined pressure P O for setting the volume of through-put of said first machine in response to the differential pressure p st -p O , characterized by a tacho generator driven by said first machine for providing an electrical signal indicative of actual speed of operation of said first machine, n ist , said adjustable throttle being set by an output signal of an electrical control means receiving a differential signal which is defined by a desired speed signal n soll and an actual speed n ist .
Claim 2
Dependent Claim
236 words
A hydraulic drive system, comprising a first hydraulic machine having an adjustable volume of through-put and operable as a pump or motor, a line of load-independent pressure to which said first machine is connected, a second hydraulic machine coupled for rotation with said first machine for functioning as a signal transmitter for providing a hydraulic signal indicative of speed of said first machine, said second machine being operable as a motor or pump in response to the direction of rotation of said first machine to produce a control flow speed signal proportional to the actual speed of the first machine, and means for adjusting the through-put of said first machine comprising a flow restricting system for providing a pressure signal including a pump and an adjustable throttle cooperable with the control flow of said signal transmitter for delivering a pressure signal P st which is compared with a predetermined pressure P O for setting the volume of through-put of said first machine in response to the differential pressure p st -p O , characterized by a tacho generator driven by said first machine for providing an electrical signal indicative of actual speed of operation of said first machine, n ist , said adjustable throttle being set by an output signal of an electrical control means receiving a differential signal which is defined by a desired speed signal n soll and an actual speed n ist .
Claim 3
Dependent Claim
16 words
The hydraulic drive system of claim 1, wherein said adjustable throttle comprises a flow control valve.
Claim 4
Dependent Claim
14 words
The drive system of claim 1, wherein said adjustable throttle comprises a proportional valve.
Claim 5
Dependent Claim
31 words
The drive system of claim 1, wherein a fixed throttle is provided in parallel to said adjustable throttle and wherein said fixed throttle is set independent of the electrical control signal.
Claim 6
Dependent Claim
47 words
The drive system of claim 1, wherein the differential pressure is fed to a directional servo valve comprising a pilot valve for the volume control device of said first machine and wherein said directional servo valve is mechanically connected to said control device via a feed back.
Claim 7
Dependent Claim
15 words
The drive system of claim 1, wherein the adjustable throttle comprises a pressure control valve.
Claim 8
Dependent Claim
14 words
The drive system of claim 1, wherein the adjustable throttle comprises a servo valve.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-30 | 1993-10-30 | 1994-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-30 | 1997-10-30 | 1998-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-30 | 2001-10-30 | 2002-05-01 | $7700.00 | Window Closed / Lapsed |