Patent US3788076A successfully refreshed from Google Patents.
US3788076A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic system with series wound pump drive motor
Assignee: Parker Hannifin Corp
•
Filing: 1972-03-20
•
Granted: 1974-01-29
•
Expires: 1992-03-20
Abstract
Abstract A hydraulic system for apparatus of the type wherein the load resistance during the working stroke of a fluid motor progressively increases from minimum to maximum, characterized in that a fixed displacement pump, driven by a series wound motor, which may be AC OR DC, actuates the fluid motor at high speed under low load resistance conditions (as during the return stroke or during the initial portion of the working stroke), and at progressively decreasing speed and increasing load pressure as the load resistance progressively increases during the remaining portion of the working stroke. The series wound pump drive motor operates at substantially full rated horsepower at all times such that the product of its speed S and torque T, and hence the product of the pump output flow Q and outlet pressure P is approximately equal to a constant K, that is, QP ST K.
Inventors
- 👤 Z Lansky
- 👤 L Claar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:58
CPC Classifications
H; H02; H02K; H02K7/00; H02K7/14; B; B30; B30B; B30B15/00; B30B15/16; B30B15/166; F; F04; F04B; F04B49/00; F04B49/06; Y; Y10; Y10S; Y10S60/00; Y10S60/911
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
97 words
An electric motor driven fixed displacement pump for apparatus of the type wherein load resistance during the working stroke of a fluid motor progressively increases, characterized in the provision of an A.C. power source; a series wound pump drive motor; and rectifying means operatively connected between said A.C. source and said drive motor to energize said motor to drive said pump at a speed and torque such that at any load resistance between minimum and maximum the product of the pump output flow Q and the pump output pressure P is approximately equal to a constant K.
Claim 2
Dependent Claim
97 words
An electric motor driven fixed displacement pump for apparatus of the type wherein load resistance during the working stroke of a fluid motor progressively increases, characterized in the provision of an A.C. power source; a series wound pump drive motor; and rectifying means operatively connected between said A.C. source and said drive motor to energize said motor to drive said pump at a speed and torque such that at any load resistance between minimum and maximum the product of the pump output flow Q and the pump output pressure P is approximately equal to a constant K.
Claim 3
Dependent Claim
145 words
In a hydraulic system for apparatus of the type wherein load resistance during the working stroke of a fluid motor progressively increases, said system including a fluid motor, an electric motor driven fixed displacement pump, a tank, and a control valve operatively interconnected for flow of fluid under pressure delivered by said pump to said fluid motor via said control valve and for flow of fluid displaced by said fluid motor to said tank via said control valve, the improvement which comprises an A.C. power source; a series wound pump drive motor and rectifying means operatively connected between said A.C. source and said drive motor to energize said motor to drive said pump at a speed such that at any load resistance between minimum and maximum, the product of the pump output flow Q and the pressure P is approximately equal to a constant K.
Claim 4
Dependent Claim
145 words
In a hydraulic system for apparatus of the type wherein load resistance during the working stroke of a fluid motor progressively increases, said system including a fluid motor, an electric motor driven fixed displacement pump, a tank, and a control valve operatively interconnected for flow of fluid under pressure delivered by said pump to said fluid motor via said control valve and for flow of fluid displaced by said fluid motor to said tank via said control valve, the improvement which comprises an A.C. power source; a series wound pump drive motor and rectifying means operatively connected between said A.C. source and said drive motor to energize said motor to drive said pump at a speed such that at any load resistance between minimum and maximum, the product of the pump output flow Q and the pressure P is approximately equal to a constant K.
Claim 5
Dependent Claim
13 words
The pump of claim 1 wherein said rectifying means is a bridge rectifier.
Claim 6
Dependent Claim
15 words
The pump of claim 1 wherein said rectifying means is a silicon avalanche bridge rectifier.
Claim 7
Dependent Claim
13 words
The system of claim 2 wherein said rectifying means is a bridge rectifier.
Claim 8
Dependent Claim
15 words
The system of claim 2 wherein said rectifying means is a silicon avalanche bridge rectifier.
References Cited (Backward Citations)
US1911138A
Cited
US2276358A
Cited
US2324727A
Cited
US2663143A
Cited
US3451217A
Cited
US3507868A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |