Abstract: A pump control system and method employs a variable drive for controlling the speed of an AC electric motor driving a cyclic load. A real-time tuning of the frequency and voltage of the AC input to the motor allows a controlled variation of a cycle speed of the cyclic load. The control system and method adjusts motor speed according to a desired motor speed characteristic for different portions of a complete cycle and over multiple cycles of the cyclic load. The variable drive rectifies a poly-phase AC power input to provide a source of DC power on a DC bus and periodically samples the DC bus current and DC bus voltage across the DC bus to optimize the motor operation.

Abstract: A filling machine with a rotary peristaltic dispenser that compensates for the nonlinear flow rate characteristic of the dispenser to increase product fill accuracy is disclosed. A computer processor including associated electronic circuitry and programs is provided for defining, digitizing and storing the real pulsating flow rate characteristic of the dispenser. In order to ensure a precise delivery of the filled product, the computer calculates the angular rotation of the rotor needed to deliver the desired fill weight for each filling cycle. The angular rotation needed to maintain a uniform fill weight is generally different for each filling cycle. The current position of the rotor is first established prior to each filling cycle and then located on a stored look-up table containing the flow rate characteristic as a starting point for digital integration of the characteristic over the angular distance of the driver.

Abstract: A system that includes a pump driven by a variable speed electric motor, the pump being directly connected to a hydraulic actuator by an open hydraulic circuit. This setup allows using one motor pump combination to drive any number of axes sequentially. The main advantages are significant energy savings but also higher control quality achieved by the substitution of control valves. Power control is dedicated to electronic power transistors while hydraulics are used for power transmission. For two and four quadrant operation, a hydraulic accumulator is proposed exerting a spring load on the hydraulic actuator. This allows for driving and braking the actuator and the associated machine axis in both directions of motion while the hydraulic pressure is always applied to the same port of the pump. The other pump port can be connected to tank.

Abstract: There is disclosed a pump and pumping system for pumping dense phase gases, specifically for injecting carbon dioxide into an oil or gas reservoir that includes a pump, a motor, and a casing in which the pump and motor reside. There is also disclosed a pump and pumping system for injecting dense phase greenhouse gases into a reservoir or underwater. The pump may include a downhole electric submersible pump. A method of controlling the pump and pumping system is also described involving the use of a variable speed drive in conjunction with an on-line gas chromatograph to maintain a constant carbon dioxide injection rate.

Abstract: An interface apparatus for fan monitoring and control includes a current source amplifier that generates a programmable current in response to its input voltages. Associated with an output capacitor, which is able to reduce noise, the programmable current drives the fan at a desired speed. The rotating fan induces a ripple signal in the output capacitor, which is fed to a band-pass amplifier to produce a tachometer pulse. Through a buffer amplifier, an input control signal combined with a thermal sensor signal has direct control over the current source amplifier. Alternatively, a PWM circuit having a comparator, a ramp oscillator and the output of the buffer amplifier drives the current source amplifier in switching mode. Since the ramp oscillator can be synchronized by the input, both analog and pulse signals can function as the input control signals.

Abstract: A rotation control for a device to be rotated includes a variable speed DC motor having a constant rotational speed upon receiving a selected fixed voltage electrical input power from an adjustable electrical input power supply connected to the motor for supplying the selected fixed voltage. A switch circuit is connected between the motor and the power supply activatable in response to a first electrical signal to turn the motor "on" and activatable in response to a second electrical signal to turn the motor "off". A selectable frequency, regular interval electrical signal device is connected to the switch circuit to provide electrical signals to activate the switch circuit to turn the motor "on" at regular intervals. An encoder wheel is coupled to the device to be rotated and to the motor for rotation of the timing disk at a speed proportional to the constant rotational speed of the motor. The timing disk has a plurality of openings around the disk with predetermined spacing there between.

Abstract: A motor speed controller for a shaded pole ceiling fan motor having low audible noise, includes a burst period generator for generating gating signals of a duration varying between a preselected minimum equal to at least one wavelength of an AC drive signal to the motor, and a maximum equal to a large number of wavelengths, and a controlled switch such as a triac, connected between the power source and fan motor, and having a gate terminal connected to the burst period generator.

Abstract: A controller, for a variable capacity pump, prevents engine stalls due to rapid changes in operating load by increasing the pump absorption torque when the engine speed is high so as to increase the work amount and by reducing the pump absorption torque when the engine speed is low. The controller receives a signal from an engine speed sensor for detecting engine speed. A pump absorption torque curve is pre-set so as to be consecutively stepped with respect to engine speed so as to intersect at an engine rated point. The pump absorption torque is then calculated in accordance with increases or decreases in engine speed. The pump absorption torque is then set to prescribe values based on the results of these calculations and an instruction is outputted to a control valve in such a manner as to regulate a regulator of the variable capacity pump.

Abstract: A device for dosing medicinal fluids, in particular a feeding solution for enteral alimentation, has a pump unit (2) with a displacement element (15) and a drive unit (3) for the displacement element. The pump unit (2) can be separated from the drive unit (3) and is realized in the form of a non-reusable, disposable item. After the device has been used, the pump unit is simply replaced with a new pump unit, so that it is unnecessary to clean the parts of the dosing device that carry the fluid.

Abstract: A method and system for controlling a refrigeration system is operative to reduce a system pressure of the refrigeration system. The system pressure is reduced to reduce a start-up current associated with a compressor motor of the refrigeration system. Another method and system for controlling a refrigeration system includes steps of performing an operation of the refrigeration system in accordance with at least one parameter, sensing an amount of energy utilized in at least a portion of the refrigeration system to perform the operation, and modifying the at least one parameter to reduce the amount of energy required to subsequently perform the operation.

Abstract: An apparatus for controlling an electrohydraulic system of a work machine having an engine that drives a variable displacement pump is disclosed. The apparatus includes a pump displacement setting device that produces a pump command signal, a pressure sensor that detects the fluid pressure associated with the variable displacement pump and produces a pressure signal, and an engine speed sensor that detects the speed of the engine and produce an engine speed signal. A microprocessor computes the torque demand on the engine in response to the desired pump displacement, determines a torque limit associated with the engine in response to the engine speed, and responsively modifies the pump command signal to limit the engine torque.

Abstract: A method and apparatus for detecting the presence of a ground leakage path in an electric motor system including an alternating current (ac) electric motor coupled for receiving electric power from a switching inverter of the type having, for each phase of the motor, a pair of serially connected electronic switching devices connected between relatively positive and negative direct current (dc) voltage buses with the switching devices being alternately gated into and out of conduction for providing switched electric power to the motor. The inverter includes a current detector for detecting current in the relatively negative voltage bus. The method comprises initially applying a gating pulse each time the motor is energized to the switching device of each phase connected to the negative voltage bus and identifying a ground leakage path when such gating pulse produces current at the current detector.

Abstract: A power control system in combination with a three-phase AC motor coupled to a water pump enables the operation of the motor at speeds up to 10,800 RPM so as to provide improved pumping capacity with a smaller motor and smaller pump. The control system supplies AC power to the motor with a frequency of the power being increased at a first high rate up to a frequency at which pump pressure is about equal to a value at which water is being pumped from the outlet pipe of the pump. Thereafter, AC power frequency is increased to the second, slower rate up to a maximum operating frequency of the motor. During the time that frequency of the AC power is being increased, motor current is continuously monitored and compared to a maximum allowable current. If monitored current exceeds allowable current, the frequency of operation is decreased until monitored current is less than the allowable current. Thereafter, frequency is again increased so long as monitored current is less than allowable current.

Abstract: A method and an apparatus are provided for stopping a motor-driven pressure generating pump of a system for coating workpieces with atomized liquid coating material in case of an empty material reservoir or a leakage in a material supply from a material reservoir to the pump or from the pump to an atomizer. The pressure and/or the volume flow at the pump outlet and/or the speed of the pump piston or a value dependent thereon are continually measured. The measured values are then converted to electric signals to be input to an electronic analyzer and analyzed therein. If, during operation, the pressure and/or the volume flow drops below a predetermined value and/or the speed of the piston exceeds a predetermined value, the electrically controlled driving connection between motor and pump or the power supply to the pump motor will be cut-off by output signals from the electronic analyzer.

Abstract: In a piston pump for pumping liquid carbon dioxide at a temperature below 30 degrees Fahrenheit and pressures at least as high as 7500 psi, the volume leaving the pump is determined by measuring only pressure or other parameter related to flow and movement of the plunger. The position of the piston is measured and the resulting displacement is integrated to determine volume of fluid pumped.

Abstract: Balancing the load between compressors is not trivial. An approach is disclosed to balance loads for compression systems which have the characteristic that the surge parameters, S, change in the same direction with rotational speed during the balancing process. Load balancing control involves equalizing the pressure ratio, rotational speed, or power (or functions of these) when the compressors are operating far from surge. Then, as surge is approached, all compressors are controlled, such that they arrive at their surge control lines simultaneously.

Abstract: The invention is based on the premise that, for a given air blower, the current I consumed by the electric motor, the rotational speed N and the air flow rate Q are interconnected, regardless of the dynamic pressure, by a law Q=f(I, N) which can be experimentally determined on a ventilation bench. In order to perform any adjustment, I and N are measured, from which a calculator derives Q by means of the above-mentioned law. The comparison of the calculated value with the desired flow rate Qd provides an error signal which is applied to a control device which determines the supply voltage (U) of the motor of the blower. The invention is applicable to heating or air-conditioning installations for the passenger space of vehicles.

Abstract: In a pump in which dual plunger is reciprocated with cams attached to the rotating shaft of a motor, the delivery pressure of liquid is measured during a certain period in each cycle of the pump. By setting the pressure during the certain period as a standard pressure value, the motor is controlled so that the delivery pressure during the remaining period in each cycle approaches to the standard pressure value. In this pump, rotating-speed-priority control and pressure-priority control are alternatingly performed to decrease pulsation during delivering liquid.

Abstract: The present invention relates to a downhole hydraulic pump monitoring system and more specifically relates to a system which detects and/or anticipates pump malfunctions by processing readings taken by a pressure transmitter on the operating pressure and the stroke rate of the downhole hydraulic pump where decisions are reached regarding positive pump operation or inefficient pump malfunction based upon comparisons between the instantaneous pressure readings of the pressure transmitter and a time-averaged operating pressure of the power fluid taken over a multitude of pump strokes.

Abstract: A system for controlling the operation of a turbo-type fluid machine driven by a variable speed prime mover, which enables the characteristics of the fluid machine to be improved so as to become favorable for actual use while allowing the prime mover to exhibit its capacity to the maximum even at an operating point other than the rated point. The operation control system includes a turbo-type fluid machine driven by a driving machine, and a device for detecting an operating head or operating pressure of the fluid machine.

Abstract: Devices and methods for perfusing organs by controlling either the perfusion pressure or the perfusate flow rate. The operator may select either method of perfusion control. Also provided are devices and methods for perfusing multiple organs simultaneously on the same device.

Abstract: A method of operating liquid chromatography apparatus. The method includes the steps of determining a given rate of liquid flow desired from a piston pump to the column; establishing for the piston a predetermined stroke length and rate of reciprocation for providing the given rate of liquid flow; determining for each cycle of the pump a desired liquid volume that would be delivered to the column by the pump if producing the given rate of liquid flow; ascertaining for each cycle of the pump the actual liquid volume delivered thereby to the column; determining for a predetermined operating period of the pump the total desired liquid volume that would have been delivered to the column by the pump if producing the given rate of liquid flow during each cycle of the predetermined operating period; and determining the total actual liquid volume delivered to said column by said pump during all cycles of said predetermined operating period.

Abstract: A fan speed controller and a method which allows to maintain a constant level of thermal sensation felt by a human body when air temperature, relative humidity, thermal radiation and distance between the fan and the human body are changing. Desired thermal comfort index can be preset and fan speed is varied in response to air temperature, relative humidity, thermal radiation and distance between the fan and the human body to provide a constant level of thermal sensation.

Abstract: An eddy current coupling with an electrically controllable field current is used to rotatably connect a drive motor to an oil well pumping mechanism where the eddy current drive speed is controlled to a reference speed using a speed feedback control system and operation can be limited in torque output by a torque feedback control system. In a first alternative embodiment, the eddy current coupling output speed is controlled by a stroke modulation unit using a first selected speed for the upward pumping stroke and a second selected speed for the downward pumping stroke. In a second alternative embodiment a controller is used to select torque or speed control for the upward or downward .pumping stroke.

Abstract: Transfer by pumping of effluents containing at least one gas phase and at least one liquid phase in a transfer line connecting a source of effluents is optimized by interposing on the line, between the source and the point of designation, a multiphase pump. The rotating speed of the pump is regulated so as to adapt the pump flow rate to at least one of the following parameters: flow rate variation well, variation of the volumetric ratio GLR or pressure drop variations occurring in the line during transfer. The values of the parameters are controlled and adjusted to values comparable with the operation of the pump.

Abstract: A slit disk having a hole at a specified portion of its flat surface and a plurality of slits at regular intervals at a peripheral portion thereof is mounted to a shaft of an infusion pump. A controller clears a live band determination counter based on a light detection signal from a sensor when the hole is detected, and increments the count value of a live band determination counter when an side edge of one of the plurality of slit is detected. When the count value of the live band determination counter falls within "10" to "24" or "0" to "2", it is determined that the infusion pump is in a live band, and the count value of the live band counter is incremented. Thus an operation amount of the infusion pump in the live band is detected to measure a fluid delivery rate taking a dead band into account.

Abstract: Drive system for a water pump unit (7, 8) driven by the shaft of a reversible motor (4) through a partition wall, about said shaft (5) being mounted a first sealing ring (14) fixed to said wall (13), and a second sealing ring (15) rotatably driven by the shaft and forming a rotatable water-tight sealing arrangement (6) with the first ring (14). The system includes control device (19, 22) capable of normally actuating the motor according to a preset program, and devices (19, 20, 26) to make the motor temporarily oscillate at a predetermined frequency (f), with a sequence of rotations in alternate directions, in case the two sealing rings (14, 15) are sticked together. The oscillation of the rotatable unit associated with the rotor (5) causes the two sealing rings to mutually separate.

Abstract: Disclosed herein is an apparatus and method for controlling electrically powered liquid-moving pumps, particularly bilge and sump pumps. The apparatus is characterized by the fact that no portion thereof need be located in the hostile environment of the bilge or sump served by the pump controlled thereby.

Abstract: A well pumping system includes a pivotally mounted walking beam and "horsehead" connected to a downhole pump by a pump rod in the conventional manner. A hydraulic lift piston and cylinder and a pneumatic balance piston and cylinder are connected to the walking beam. A process control computer controls input signals to a hydraulic control valve for controlling the hydraulic cylinder rate and direction of travel to provide corresponding control over the motion of the walking beam. The computer receives input information from a position sensor indicating the displacement of the beam in its range of travel. The computer program also is responsive to a timer for determining actual stroke rate and acceleration of the beam. The computer monitors and controls operation of the hydraulics and pneumatics as the pumping unit produces the lift necessary to extract fluid from the well.

Abstract: A multichannel pump system for HPLC and other uses has a plurality of fluid pumps whose input is fed separately to at least one high pressure mixing unit downstream of the pumps and any associated items such as pulse dampeners and pressure transducers. A pump controller is connected to control each of the pumps separately in a coordinated manner to provide a plurality of operational modes. The operational modes include an isocratic mode, in which optionally the output of solvent of like composition from two or more pumps is pooled to provide increased output capacity, as well as binary, ternary, etc., gradient modes in which different solvents are selectively mixed before being applied to an analytical unit such as an HPLC column. The pump system further includes a novel linear drive pump having interchangeable piston modules providing different ranges of flow rates. The linear drive pump is capable of providing precise solvent delivery at high pressure for flow rates from 20 ml/minute down to 0.

Abstract: A compressor, used for compressing a working fluid to be discharged into a reservoir, includes at least one compressor element. A prime driver, capable of operating at varying angular velocities, applies motive force to the compressor. A ratio maintaining device, disposed between each compressor element and the prime driver, ensures that a ratio defined as an angular velocity of the compressor element divided by the angular velocity of the prime driver remains constant. The prime driver is typically internal combustion engine powered. A controllable fuel valve is in communication with the prime driver and is positionable for controlling a fuel flow to the prime driver. A controller positions the fuel valve based upon a combination of parameters including a variable setpoint reservoir pressure, ambient pressure and ambient temperature, wherein the prime driver is operated at an angular velocity at which the actual pressure at the reservoir can be maintained at the setpoint reservoir pressure.

Abstract: The current invention detects malfunctions in a variable flow delivery pump. These malfunctions prevent the pump from sustaining inherently high accuracy and/or cause damages to the pump. The invention detects the malfunctions without comparing sampled values to a preset absolute value. A malfunction is determined by a pattern of force exerted on a displacement pump in relation to the displacement positions. The pattern is compared to an empirically established range of pattern values. Once a malfunction is determined, the invention responds in a preselected manner.

Abstract: An electric motor driven inline hydraulic apparatus comprising a housing having end plates closing said housing, an electric motor stator mounted in said housing, an electric motor rotor, a shaft on which the rotor is mounted is journalled in the housing and a vane type pump mounted on one of the end plates. The shaft extends through an opening in the end plate and is connected to the vane rotor of the pump. Hydraulic fluid is supplied to the interior of the electric motor housing and flows through passages in the housing to the intake of the vane pump on the end plate. In one form, the vane pump delivers fluid through an outlet in the end plate on which it is mounted. In another form, the vane pump delivers fluid through an outlet in the pump housing.

Abstract: An air sampling device comprises a pump assembly including a pump and a motor operably associated with the pump, the air flow rate of the assembly being substantially characterized by a function having a plurality of measurable variables; sensors for periodically automatically monitoring the variables; a programmable computer operably associated with the sensors for periodically estimating the instantaneous air flow rate of the pump from the function and the monitored variables and for camparing the calculated instantaneous air flow rate with a previously programmed desired air flow rate; and a DC-DC converter responsive to the computer and operably associated with the motor for modulating the motor speed in response to the computer to thereby cause the instantaneous air flow rate of the pump to approach the desired air flow rate.

Abstract: A variable-speed pump system comprising: a hydraulic machine having a flow adjusting means and including at least a pumping function; a rotary machine operatively connected to the hydraulic machine and including at least a motor function for rotating the hydraulic machine; a frequency converter for driving the rotary machine; and a control system for controlling variable-speed operation of the rotary machine according to a command signal from an external unit. The pump system also includes an electric power control system, a flow adjustment control system, and a rotational speed control system. The power control system has a negligibly small time constant, compared to the time constant of the rotational speed control system.

Abstract: An electric-motor hydraulic pump includes a housing having a stationary internal shaft. A pair of cylinder blocks are rotatably carried by the shaft within the housing, and an array of pistons are slidably disposed with each cylinder block. A yoke plate is mounted within the housing and engages the pistons for determining displacement of the pistons within the cylinder blocks. Fluid inlet and outlet ports are provided in the housing and are coupled to the cylinder blocks. An induction motor includes a rotor carried by the cylinder block for corotation therewith, and a stator mounted within the housing surrounding the rotor. An electronic controller for controlling outlet fluid pressure and flow from the pump includes a plurality of sensors mounted on the housing for sensing operating characteristics of the pump and motor to provide electronic sensor signals as functions thereof.

Abstract: A three-phase transformer includes six windings, disposed in three pairs, all of which six windings are serially interconnected. A desired turns ratio between the two windings of each pair establishes a desired phase shift between one three-phase output of the connected windings and a second three-phase output of the windings. These two windings can be used in combination to drive a load, such as an induction motor, such as through a twelve pulse rectifier requiring two three-phase outputs out of phase by 30.degree.. Alternately, one of the three-phase outputs can be used to supply the full load of the motor directly. This is particularly useful in a electric submersible pumping system having a three-phase induction motor which is normally operated by a maintenance intensive twelve-pulse rectifier, which motor needs to be directly driven through a by-pass motor controller when the rectifier is in maintenance.

Abstract: An apparatus for the generation of compressed air is disclosed, where the supply of air from the compressor (1) to the user (6) is interrupted in case of preset user-side pressure. This apparatus prevents a freezing in case of low ambient temperatures in the pressure lines in which condensed water has formed. A temperature sensitive switching device (14, 29) responds to the actual ambient temperature. The switching device (14) does not stop the compressor (1) in case of a preset user-side pressure and in case of a falling below of a preset ambient temperature. The compressor (1) carries then the warmed-up air through a region of the device before discharging it into the surrounding atmosphere. The device is particularly suited for compressed-air generation plants in motor vehicles which are adapted to be used in cases of low ambient temperatures.

Abstract: The invention is a method and apparatus for significantly improving the performance of a reciprocating pump by delivering the pumping fluid at a desired pressure and flow rate with minimal flow fluctuations. The compressibility of the pumping fluid directly effects volumetric flow rate and mass flow rate. The method includes the step of sensing various pump parameters related to said compressibility and adjusting the pumping speed to make appropriate accommodations. In particular, the compressibility of the pumping fluid is effected by the adiabatic heating of the pumping fluid during compression, variations in pumping fluid density, leaks in the check valves of cylinder/piston seals and the primary and secondary switching losses in the fluid flow occurring when the primary and secondary pistons reverse direction.

Abstract: A method of detecting a counterflow in a pump comprises providing with detecting means for detecting variations in the discharge pressure of the pump and signal analyzing means for analyzing oscillation components contained in an output signal from the pressure detecting means, and detecting the pump's operating point to have entered a counterflow characteristic operation region when a waveform of the detection signal generated in association with the variations in the discharge pressure of the pump exhibits a predetermined spectrum distribution. Further, when it is detected that the operating point enters a counterflow characteristic operation region, the escape from that region is performed by temporally throttling the guide vane and temporally increasing the rotating speed.

Abstract: Precise gradient control is accomplished using a high flow three-way valve, appropriate mixing, and precise metering control. Gradient elution profiles are generated for flow rates above 100 ml/min. Control involves precise selection of two solvents, and correction factors for valve lag times and pump/valve synchronizations. The gradient is controlled simultaneously with other non-timed operations through a single microprocessor controller.

Abstract: A variable speed pump control system and method which senses operational parameters during the first one half of the down stroke to control pump speed to maximize production. The method and equipment maintains ths fluid level of a well as low as possible while avoiding the pump-off condition. A variable speed motor drives a pump jack and a control means varies the pump speed. Means are provided for simultaneously sensing the pump speed, load on the rod, and the position of the rod in the pump stroke. These measurements are utilized to calculate the power transferred between the rod string and the beam during a portion of the downstroke. Before the pump is continuously operated, a series of measurements are made in the full barrel pumping condition to determine the power transferred between the rod and beam at various speeds. These are utilized to establish a relationship between pump speed and power during a portion of the downstroke.

Abstract: A torque control unit rotates a motor machine having a motor element and a load element. The load element is coupled to the motor element via a rotational main shaft and driven to rotate by the motor element. Rotational acceleration at each rotation angle during one revolution of the rotational main shaft is detected and fed back. An electromagnetic torque of the motor element is controlled so that a difference between the electromagnetic torque of the motor element and a load torque of the load element may become zero at each rotation angle of the rotational main shaft.

Abstract: To provide smooth constant flow from a pump, a chromatographic system comprises: a chromatographic column having an inlet; a pump for supplying fluid to the inlet of the chromatographic column; a power means for the pump motor; positive and negative feedback loop means for controlling said power means; means for energizing and de-energizing said positive and negative feedback control means; said negative feedback control means receiving a signal from said means for measuring flow rate and including means for comparing said signal with said corrected flow rate reference signal while said second feedback loop is energized to generate an error signal controlling said power means; and said positive feedback control means applying an acceleration voltage to said motor from a time a preset period after the initiation of a return stroke of said piston until after a timed duration.

Abstract: A liquid chromatograph includes a multi piston reciprocating pump for delivering liquid at a desired flow rate to a separating column. The pistons in the pump have overlapping delivery strokes and when the pump is provided with two pistons their rate of advance is halved during the overlapping delivery periods. The instant when both pistons start delivery is dependent on solvent compressibility and the delivery pressure of the pump and thus will vary according to the operating conditions. The delivery pressure of the pump is monitored and if a pressure increase (or decrease) is found during one pump cycle between the start of stroke of one piston (SST1) and the end of delivery of the other piston (EOD2) the instant when the speed of advance of the pistons is halved (HS1) is advanced (or retarded) in the next pump cycle.

Abstract: An output control system for an internal combustion engine for an automotive vehicle having a variable capacity type compressor installed therein and driven by the engine, in which the output torque of the engine is increased by means of an engine output incremental value in response to operation of the compressor. Load torque produced by the compressor is detected through the piston stroke and discharge pressure of the compressor, and the engine output incremental value is set depending on the detected load torque. The engine output incremental value is also set depending on the engine rotation speed.

Abstract: Method and apparatus for compensating for the deficiency in fluid flow occurring during the refill and piston chamber pump-up cycle of a single piston fluid pump are disclosed. The period of time during which the outlet valve is closed and no fluid is being delivered to the system is determined and the pump is driven at a speed greater than the normal delivery speed for a period of time such that the quantity of excess fluid delivered approximates the quantity of fluid that would have been delivered during the refill and pump-up period had the pump been delivering fluid at its normal delivery rate.

Abstract: A portable infusion pump assembly utilizing continuous drive propulsion means (8) to effect automatic and incremental displacement of a plunger (5) within a disposable syringe (3) so as to deliver accurately repeatable volumes of fluid from the syringe (3) over a predetermined period of time.Intermittent drive of the continuous drive propulsion means (8) is effected. Comparison of desired delivery rate with actual delivery rate is made by use of angular displacement signals received from a shaft encoder (10) attached to the shaft of the continuous propulsion means (8).This method of control also allows indirect measurement of fluid pressure in the syringe (3) without the need for a pressure sensor to be located in direct contact with the fluid being delivered.

Abstract: A peristaltic pump controller provides control of a positive displacement pump as either an uncalibrated or calibrated flowmeter, or a calibrated dispenser. A calibration constant is calculated, after the pump is primed, to determine the amount of volume output produced by an increment of angular rotation of the pump. The constant is determined during a calibration operation where an arbitrary calibration volume is metered. The controller has a low flow and high flow mode where the low flow mode provides a higher resolution for dispensing. The flow mode of operation is determined by the value of the calibration constant and is automatically set when the constant is calculated. DUring a dispensing operation, the controller will meter fluid to within a predetermined amount of the final volume dependent upon the speed of the pump motor and then dribble in the remaining amount of a batch for precision.

Abstract: An apparatus for controlling a variable displacement type hydraulic pump including an engine as a driving power source is disclosed. The subject invention detects the number of revolutions of the engine and the pressure of hydraulic oil delivered from the hydraulic pump, and sets a pump absorption torque characteristic which decreases in relation to the number of revolutions of the engine. The inclination angle of a swash plate in the pump is detected with reference to the pump absorption torque characteristic and the pressure of hydraulic oil delivered from the pump, and the swash plate in the pump can be controlled so as to assure its inclination angle; the number of revolutions of the engine can be reduced without the absorption torque of the hydraulic pump exceeding the allowable torque of the engine. When the controlled apparatus is utilized, the number of revolutions of the engine can be optimally reduced and fuel consumption cost reduced correspondingly.