US3958898A
Expired / Lapsed
US
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Pump control systems
Assignee: Waters Associates Inc
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Filing: 1975-02-03
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Granted: 1976-05-25
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Expires: 1995-02-03
Abstract
Abstract A compact pumping system especially useful in liquid chromatography wherein comprising a liquid path which is fully flushed on each stroke of a pump, a pump which provides substantially pulse-free flow, a pressure-sensor integrated into said flow path and operably connected to the control circuit of a bifilar stepping motor. This circuit is so designed that the driving current applied to the motor is only that required to pump the liquid. The avoiding of heat associated with a greater current is particularly important in forming a compact package of motor and pump for use in liquid chromatography.
Inventors
- 👤 Louis Abrahams
- 👤 Burleigh M. Hutchins, Jr.
- 👤 James L. Waters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:33
CPC Classifications
H; H02; H02P; H02P8/00; H02P8/12; F; F04; F04B; F04B1/00; F04B1/02; F04B49/00; F04B49/06; F04B49/08; F04B49/10; F04B49/106; F04B49/20; F04B53/00; F04B53/10; F04B53/1002; F04B53/1005; F04B53/14; F04B53/16; F04B53/162; F04B53/164; F04B9/00; F04B9/02; G; G01; G01N; G01N30/00; G01N30/02; G01N30/26; G01N30/28; G01N30/32; G01N2030/324; G01N2030/326; G01N2030/328
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
198 words
In a liquid delivery system of the type comprising a pump and outlet useful for supplying from said outlet a liquid under pressure the improvement wherein there is interposed between said pump and a discharge port from said delivery means 1) a pressure-sensing means and 2) flow-control means operably communicating between said pressure-sensing means and a motor drive means for said pump, said control means operably interacting with said drive means to control the flow-output of said pump by controlling the speed of said motor; wherein said flow-control means comprises A) Bourdon-type tube, the interior of which forms a flow path for substantially all said liquid B) means for sensing displacement of said tube in response to pressure of the liquid therein, and C) motor control means comprising said sensing means and a motor drive means for said pump; wherein said Bourdon-type tube is enclosed within a housing and mounted between a light source and a light-sensing said light source and sensing means forming said displacement-sensing means, and also forming means to provide an input signal to said motor control means; and wherein said Bourdon tube is bent to form two substantially parallel segments of a single conduit.
Claim 2
Dependent Claim
198 words
In a liquid delivery system of the type comprising a pump and outlet useful for supplying from said outlet a liquid under pressure the improvement wherein there is interposed between said pump and a discharge port from said delivery means 1) a pressure-sensing means and 2) flow-control means operably communicating between said pressure-sensing means and a motor drive means for said pump, said control means operably interacting with said drive means to control the flow-output of said pump by controlling the speed of said motor; wherein said flow-control means comprises A) Bourdon-type tube, the interior of which forms a flow path for substantially all said liquid B) means for sensing displacement of said tube in response to pressure of the liquid therein, and C) motor control means comprising said sensing means and a motor drive means for said pump; wherein said Bourdon-type tube is enclosed within a housing and mounted between a light source and a light-sensing said light source and sensing means forming said displacement-sensing means, and also forming means to provide an input signal to said motor control means; and wherein said Bourdon tube is bent to form two substantially parallel segments of a single conduit.
Claim 3
Dependent Claim
59 words
In a system as defined in claim 1 suitable for handling heat sensitive liquids, and said motor and said pump being mounted adjacent one another, the improvement wherein said motor is a stepping motor system comprising a control means for controlling the volume output of said pump by controlling the driving current applied to the coils of said motor.
Claim 4
Dependent Claim
27 words
Apparatus as defined in claim 2 wherein the liquid's flow path is no more than about 0.2 inches from the mean center line of said flow path.
Claim 5
Dependent Claim
141 words
In a liquid delivery system comprising a pump, a motor drive for said pump and discharge port for supplying a compressible liquid under different pressure, the improvement wherein said liquid delivery system comprises 1. interposed between said pump and said discharge port, a liquid pressure-sensing means, and 2. motor control means operably communicating between said pressure-sensing means and said motor drive means, said motor control means forming means to control the flow-output of said pump by controlling the speed said motor in response to the pressure-sensed by said pressure-sensing means, and 3. wherein said motor control means comprises means to modify motor speed in response to pressure, said control means forming means to continuously compensate for compression of said liquid being pumped, and to maintain a substantially constant output of liquid despite changes in compression of said liquid with varying pressure.
Claim 6
Dependent Claim
141 words
In a liquid delivery system comprising a pump, a motor drive for said pump and discharge port for supplying a compressible liquid under different pressure, the improvement wherein said liquid delivery system comprises 1. interposed between said pump and said discharge port, a liquid pressure-sensing means, and 2. motor control means operably communicating between said pressure-sensing means and said motor drive means, said motor control means forming means to control the flow-output of said pump by controlling the speed said motor in response to the pressure-sensed by said pressure-sensing means, and 3. wherein said motor control means comprises means to modify motor speed in response to pressure, said control means forming means to continuously compensate for compression of said liquid being pumped, and to maintain a substantially constant output of liquid despite changes in compression of said liquid with varying pressure.
Claim 7
Dependent Claim
32 words
A liquid delivery system as defined in claim 5 wherein said means to compensate for compression comprises means to speed up the motor, in response to said pressure-sensing means detecting increased pressure.
Claim 8
Dependent Claim
27 words
A liquid delivery system as defined by claim 5 wherein said motor is a stepping motor and said motor control means controls the frequency to said motor.
Claim 9
Dependent Claim
87 words
Apparatus as defined in claim 5 wherein said pump comprises a plurality of cylinders, a piston in each cylinder, a liquid inlet to each cylinder proximate the end of said piston as positioned at the end of its forward stroke, a liquid outlet to said cylinder proximate the end of said piston as positioned at the backward stroke, and an annular conduit between said piston and said cylinder forming means for said liquid to reach said liquid outlet in response to the forward movement of said piston.
Claim 10
Dependent Claim
87 words
Apparatus as defined in claim 4 wherein said pump comprises a plurality of cylinders, a plunger in each cylinder, a liquid inlet to each cylinder proximate the end of said plunger as positioned at the end of its forward stroke, a liquid outlet to said cylinder proximate the end of said plunger as positioned at the backward stroke, and an annular conduit between said plunger and said cylinder forming means for said liquid to reach said liquid outlet in response to the forward movement of said plunger.
Claim 11
Dependent Claim
18 words
Apparatus as defined in claim 8 wherein said annular conduit is from 0.001 to 0.005 inches in width.
Claim 12
Dependent Claim
24 words
Apparatus as defined in claim 9 wherein said motor is a stepping motor and said control means controls the frequency applied to said motor.
Claim 13
Dependent Claim
26 words
A liquid delivery system as defined in claim 4 wherein said motor is a stepping motor and said control means controls the frequency to said motor.
Claim 14
Dependent Claim
27 words
A system as defined in claim 11 wherein said control means forms means to controllably drive said motor over a speed ratio of about 100:1 or greater.
Claim 15
Dependent Claim
28 words
A liquid delivery system as defined in claim 4 wherein said motor has an operating range which is substantially free of resonance effects and is 100:1 or greater.
Claim 16
Dependent Claim
88 words
A liquid delivery system as defined in claim 4 wherein said pump comprises a two-cylinder piston pump and wherein said pump is operated by a drive forming means to operate the piston in each said cylinder by driving a centrally-located member which in turn, forms means to simultaneously turn two non-circular members 180° out of phase with each other, each said non-circular member forming means to operate a piston in each said cylinder and thereby provide means for achieving a substantially constant discharge of liquid from said pump.
Claim 17
Dependent Claim
27 words
Apparatus as defined in claim 14 wherein the liquid's flow path is no more than about 0.2 inches from the mean center line of said flow path.
Claim 18
Dependent Claim
27 words
A liquid delivery system as defined by claim 14 in said motor is a stepping motor and said motor control means controls the frequency to said motor.
Claim 19
Dependent Claim
33 words
A system as defined in claim 14 wherein substantially all liquid-reactive volume between inlet of a said pump cylinder and discharge port from said cylinder is flushed by each cycle of said piston.
Claim 20
Dependent Claim
88 words
Apparatus as defined in claim 14 wherein said pump comprises a plurality of cylinders, a piston in each cylinder, a liquid inlet to each cylinder proximate the end of said piston as positioned at the end of its forward stroke a liquid outlet to said cylinder proximate at the end of said piston as positioned at the backward stroke, and an annular conduit between said piston and said cylinder forming means for said liquid to reach said liquid outlet in response to the forward movement of said piston.
Claim 21
Dependent Claim
27 words
Apparatus as defined in claim 18 wherein the liquid's flow path is no more than about 0.2 inches from the mean center linq of said flow path.
Claim 22
Dependent Claim
67 words
In a liquid delivery system of the type defined in claim 14, the improvement wherein said flow-control means comprises A) Bourdon type tube, the interior of which forms a flow path for said liquid B) means for sensing displacement of said tube in response to pressure of the liquid therein, and C) motor control means comprising said sensing means and a motor drive means for said pump.
Claim 23
Dependent Claim
27 words
A system as defined in claim 20 wherein said flow path of said Bourdon-type tube has an inside diameter of from about 0.005 inches to 0.10 inches.
Claim 24
Dependent Claim
32 words
A system as defined in claim 20 wherein substantially all liquid-receptive volume between inlet of said pump cylinder and discharge port from said cylinder is flushed by each cycle of said piston.
Claim 25
Dependent Claim
54 words
A liquid delivery system of the type defined in claim 20, wherein said Bourdon-type tube is enclosed within a housing and mounted between a light source and a light-sensing means, said light source and sensing means forming said displacement-sensing means, and also forming means to provide an input signal to said motor control means.
Claim 26
Dependent Claim
33 words
A system as defined in claim 23 wherein substantially all liquid-receptive volume between inlet of a said pump cylinder and discharge port from said cylinder is flushed by each cycle of said piston.
Claim 27
Dependent Claim
25 words
A system of the type defined in claim 20 wherein said Bourdon tube is bent fo form two substantially parallel segments of a single conduit.
Claim 28
Dependent Claim
25 words
A system as defined in claim 25 wherein said motor is a stepping motor and said motor control means controls the frequency to said motor.
Claim 29
Dependent Claim
27 words
Apparatus as defined in claim 25 wherein the liquid's flow path is no more than about 0.2 inches from the mean center line of said flow path.
Claim 30
Dependent Claim
112 words
A pumping process for supplying a compressible liquid under different pressures, said process utilized in conjunction with a pump, a motor drive for said pump, and discharge port, the improvement including the steps of 1. sensing pressure of said liquid at a point between said pump and said discharge port, 2. controlling the speed of said motor in response to the pressure-sensed by said pressure-sensing means, and 3. wherein said controlling step comprises a) modifying motor speed in response to said pressure, and b) continuously compensating for compression of said liquid being pumped, thereby maintaining a substantially constant output of liquid despite changes in compression of said liquid with varying pumping pressures.
Claim 31
Dependent Claim
112 words
A pumping process for supplying a compressible liquid under different pressures, said process utilized in conjunction with a pump, a motor drive for said pump, and discharge port, the improvement including the steps of 1. sensing pressure of said liquid at a point between said pump and said discharge port, 2. controlling the speed of said motor in response to the pressure-sensed by said pressure-sensing means, and 3. wherein said controlling step comprises a) modifying motor speed in response to said pressure, and b) continuously compensating for compression of said liquid being pumped, thereby maintaining a substantially constant output of liquid despite changes in compression of said liquid with varying pumping pressures.
Claim 32
Dependent Claim
46 words
A process as defined in claim 28 suitable for handling heat sensitive liquids, and said motor and said pump being mounted adjacent one another, wherein the volume output of said pump is controlled by varying the driving current applied to the coils of a stepping motor.
Claim 33
Dependent Claim
29 words
A process as defined in claim 28 wherein the liquid's entire flow path is no more than about 0.2 inches from the mean center line of said flow path.
Claim 34
Dependent Claim
27 words
A process as defined in claim 28 wherein said compensating for compression comprises speeding up the motor in response to said pressure-sensing means detecting of increased pressure.
Claim 35
Dependent Claim
30 words
A process as defined in claim 31 wherein said motor is a stepping motor and said speed controlling of said motor is achieved by modifying the frequency to said motor.
Claim 36
Dependent Claim
77 words
A process as defined in claim 28 wherein said pump comprises a two-cylinder piston pump and wherein said pump is operated by a drive forming means to operate the piston in each said cylinder by driving a centrally-located member which, in turn, simultaneously turns two non-circular members 180° out of phase with each other, each said non-circular member operating a piston in each said cylinder and together achieving a substantially constant discharge of liquid from said pump.
Claim 37
Dependent Claim
30 words
A process as defined by claim 33 wherein said motor is a stepping motor and said speed controlling of said motor is achieved by modifying the frequency to said motor.
Claim 38
Dependent Claim
32 words
A process as defined in claim 33 wherein the liquid's entire flow path through the pump is no more than about 0.2 inches from the mean center line of said flow path.
Claim 39
Dependent Claim
30 words
A process as defined in claim 28 wherein said motor is a stepping motor and said speed controlling of said motor is achieved by modifying the frequency to said motor.
Claim 40
Dependent Claim
24 words
A process as defined in claim 29 wherein substantially all liquid-receptive volume between said pump cylinder is flushed on each cycle of said piston.
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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) | 1979-05-25 | 1979-11-24 | 1980-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-25 | 1983-11-24 | 1984-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-25 | 1987-11-24 | 1988-05-25 | $7700.00 | Window Closed / Lapsed |