US20190353147A1 - Injection pump - Google Patents
Injection pump Download PDFInfo
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- US20190353147A1 US20190353147A1 US16/415,420 US201916415420A US2019353147A1 US 20190353147 A1 US20190353147 A1 US 20190353147A1 US 201916415420 A US201916415420 A US 201916415420A US 2019353147 A1 US2019353147 A1 US 2019353147A1
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- Prior art keywords
- pump
- motor
- rotor
- suction
- stroke
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
- F04B17/03—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/02—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having two cylinders
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/20—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by changing the driving speed
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/22—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by means of valves
- F04B49/24—Bypassing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
- F04B9/02—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical
- F04B9/04—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms
- F04B9/042—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms the means being cams
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B2203/00—Motor parameters
- F04B2203/02—Motor parameters of rotating electric motors
- F04B2203/0209—Rotational speed
Definitions
- the invention relates to chemical injection pumps and methods of controlling pump output.
- Rotary motors typically electric or hydraulic motors, are used to power injection pumps which inject chemicals into a process.
- the motors are connected by a gearbox or transmission to a camshaft which reciprocates a plunger within a cylinder to pump fluid through an injection valve.
- Control of the injection rate of such chemical pumps is conventionally controlled by varying the speed or duty cycle of the motor, or the stroke length and diameter of the piston, however, this does not always allow for precise control over injection rates and may be unduly complicated when dealing with multiple chemicals requiring different injection rates at different times.
- the present invention relates to a positive displacement pump driven by an indexable, reversible electric motor.
- the motor comprises an outrunner brushless DC (BLDC) electric motor.
- the pump does not comprise a gearbox.
- the invention may comprise a pump system comprising:
- the cam profile is created by a non-circular profile of the rotor.
- the rotor has a circular profile but with an axis of rotation which is offset from the centre of the circle.
- the cam profile may be defined by a cam wheel, separate from the motor rotor.
- the pump system comprises at least two pump heads, radially arrayed around the rotor, wherein each pump head comprises a housing and a reciprocating plunger.
- the pump system further comprises a motor controller for controlling the speed and, optionally, direction of the motor.
- the motor controller may be configured to stroke one or more pump heads by cycling the cam profile or cam wheel backwards and forwards, over the entire pressure ramp, or a portion of the pressure ramp.
- the invention may comprise a pump system comprising:
- the reversible and controllable motor comprises an outrunner BLDC, a stepper motor or a servo motor.
- the motor is preferably an outrunner BLDC having a rotor with an outer surface which defines the cam wheel.
- the reversible and controllable motor comprises an outrunner BLDC, a stepper motor or a servo motor.
- the motor is preferably an outrunner BLDC having a rotor with an outer surface which defines the cam wheel.
- the method is implemented to actuate two or more reciprocating pumps, arrayed radially around the circumference of the rotor. In one embodiment, the method comprises the further step of cycling the rotor backwards and forwards to stroke at least one pump on the pressure ramp.
- the invention may comprise a control system for controlling a chemical injection rate for an injection pump comprising a suction valve and an output valve, comprising a mechanism for disabling operation of the suction valve or output valve, to maintain the suction valve in an open bypass position during the pressure stroke, or to maintain the output valve in an open bypass position during the suction stroke.
- control system may be used in connection with any electrical motor and pump configuration, such as those conventionally used in chemical injection pumps or in connection with a BLDC motor as described herein.
- the invention comprises a method of disabling a pump having a suction valve at its inlet and output valve at its outlet, comprising the step of opening the suction valve during a pressure stroke of the pump while keeping the output valve closed, or by opening the output valve during a suction stroke while keeping the suction valve closed.
- the present invention comprises a control system comprising: a circuit control device for operative connection to an electric circuit comprising an electric motor for actuating a chemical injection pump; a processor operatively connected to the circuit control device; and a memory comprising a non-transitory tangible medium storing instructions readable by the processor to implement one or a combination of the methods as described herein.
- FIG. 1A is a top plan view of one embodiment of the invention.
- FIG. 1B is a schematic representation of a motor controller.
- FIG. 2 is a cross-sectional view along line II of FIG. 1 .
- FIG. 3 is a cross-sectional view along line III of FIG. 1 .
- FIG. 4 is another view of FIG. 2 , showing offset axes.
- FIG. 5 is another view of FIG. 2 , showing indexed rotation over a portion of the rotor cam profile.
- FIG. 6 is an exploded view of an alternative embodiment of the invention.
- FIG. 7 is a vertical cross-section of the embodiment shown in FIG. 6 .
- FIG. 8 is another vertical cross-section along line VIII in FIG. 7 .
- FIG. 9 is a schematic view of an alternative embodiment having two pump heads arrayed at a 90 degree angle, with an offset circular cam wheel.
- FIG. 10 is a graph showing sinusoidal pattern of a pump piston stroke compared to the rotation of the cam wheel of FIG. 9 .
- FIG. 11 is an exploded view of the embodiment of FIG. 6 , having a suction valve deactivation system.
- FIG. 12 is a top plan view of the embodiment of FIG. 11 .
- FIG. 13 is a vertical cross-section along line XIII of FIG. 12 .
- FIGS. 14A and 14B show details of a portion of FIG. 13 , showing the actuator in an active and bypass position, respectively.
- the invention may comprise a positive displacement pump comprising an outrunner brushless DC (BLDC) motor comprising a stator and a rotor, wherein the rotor defines an external cam profile. Rotation of the rotor/cam actuates at least one plunger which reciprocates to pump fluid in a conventional manner.
- BLDC outrunner brushless DC
- This configuration may take advantage of the low RPM, high torque capability of an outrunner BLDC motor. No gearbox or transmission is required, and is specifically excluded in one embodiment of the invention.
- FIG. 1 is a top plan view
- FIGS. 2 and 3 are cross-sectional views of one embodiment along a vertical plane.
- FIG. 2 is taken in a transverse direction while FIG. 3 is taken in a longitudinal direction.
- the longitudinal horizontal axis is defined by the axis of rotation of the motor.
- BLDC motors also known as electronically commutated motors (ECMs or EC motors), or synchronous DC motors
- ECMs electronically commutated motors
- synchronous DC motors are synchronous motors powered by DC electricity through an inverter or switching power supply which produces an AC electric current to drive each phase of the motor with a closed loop controller.
- the controller provides pulses of current to the motor windings that control the speed and torque of the motor.
- the structural elements of a brushless motor system are well known in the art, and are conventionally similar to a permanent magnet synchronous motor, but can also be a switched reluctance motor, or an induction (asynchronous) motor.
- the controller ( 300 ) may be configured to allow control injection rates for at least one injection pump, and preferably for two or more injection pumps, independently of each other.
- the controller may comprise a processor ( 302 ); a memory ( 304 ); an input device ( 306 ); and a circuit control device ( 308 ).
- the memory ( 304 ) stores a set of instructions that are readable by the processor ( 302 ) to implement a method of pump operation as is further described below.
- the memory ( 304 ) may be a read-write memory allowing the stored set of instructions to be modified or selected by the user.
- the input device ( 306 ) may be any computer hardware device that allows a user to input data to the processor ( 302 ).
- Non-limiting examples of an input device ( 306 ) include a keypad, a touch screen, or a pointing device such as a computer mouse used in conjunction with a display device.
- the circuit control device ( 308 ) modifies the voltage and/or current applied to the electric motor, in accordance with a method of the present invention.
- outrunner refers to a type of BLDC electric motor which spins its outer shell (rotor) around stationary windings (stator). Usually, outrunner motors have more poles, so they spin slower than their inrunner counterparts, while producing more torque.
- the system comprises a chemical injection pump comprising an outrunner BLDC motor ( 12 ), contained within a housing ( 10 ).
- the motor stator ( 13 ) is supported within the housing ( 10 ) by a spindle ( 8 ) which allows passage of electrical power and control wires.
- the rotor ( 14 ) is supported by bearings within the housing.
- One preferred feature of this system is that the rotor ( 14 ) is supported by only two bearings, at the front ( 15 ) and at the rear ( 17 ), which reduces friction and maintenance needs.
- the rotor ( 14 ) has an outer surface defining a cam profile with a non-uniform radius, as measured from the axis of rotation.
- the outer cam profile comprises at least one lobe ( 16 ) which rotates about the central axis of the motor.
- the rotor ( 14 ) may define a cam profile with a non-uniform radius as a result of having an oval or other non-circular shape, or the rotor may be circular but with an offset axis of rotation.
- the rotor may have any configuration with a pressure ramp so long as rotation of the rotor is able to cause linear reciprocation of a plunger.
- the rotor may drive a separate cam wheel which defines an external cam profile or rotates eccentrically as required.
- each pump comprises a roller ( 22 ), a return spring ( 24 ), and a plunger ( 26 ). Rotation of the rotor ( 14 ) causes reciprocation of the plunger ( 26 ) by means of the roller ( 22 ).
- the motor ( 12 ) may operate a plurality of pumps, which may be operated by the same rotor (and therefore be aligned in a vertical plane).
- a plurality of rotor cams or cam wheels having the same axis of rotation i.e. mounted on the same shaft
- Each rotor/cam or cam wheel may have one or more lobes or pressure ramps, which may operate in phase with other cam lobes or pressure ramps, or out of phase in varying degrees.
- the pump system may be configured with a wide range of output options.
- a single cam lobe ( 16 ) on the motor rotor drives two horizontally opposed pumps ( 18 , 20 ).
- a substantially continuous single rate injection may be achieved because the pressure ramp of the earn profile extends 180 degrees and increases linearly.
- the 180 degree arc of the rotor opposite the cam lobe is the base circle, and the plunger ( 26 ) of pump ( 20 ) does not reciprocate when on this portion of the cam.
- the plunger of pump ( 18 ) moves to the top of its stroke, culminating at the peak of the pressure ramp ( 16 A), followed by a shorter suction ramp ( 16 B) to the base circle ( 16 C).
- the pressure ramp and the suction ramp may have different lengths and slopes.
- the pressure ramp and suction ramp may be of equal length.
- the pressure stroke may be lengthened in duration by lengthening the pressure ramp, for example to 320 degrees.
- Such a cam profile would reduce motor torque requirement, maximize the flow time and create longer periods of constant flow.
- the effective slope of the pressure ramp and/or the suction ramp may be non-linear.
- the rollers and the axis of the pump are offset from the centreline (C) of the drive axis, which reduces or eliminates side loading on the plunger drive mechanism.
- the pump axes (P 1 and P 2 ) are both slightly offset from the drive axis centreline (C), minimizing off-axis forces on the roller and pump components.
- BLDC motors are reversible and highly controllable with conventional motor controllers.
- the motor may be indexable with rotational index or position information provided by a shaft encoder or the like, or by using a load profile.
- a pump may be stroked by cycling the rotor back and forth, as opposed to continuous rotation in one direction.
- the cycle may comprise the 180 degree phase of the pressure ramp, or some portion of it, for example, a 90 degree portion illustrated in FIG. 5 as arc “A”.
- the pump heads may be independently controlled to vary flow rate. This may be particularly useful if the two pump heads pump different chemicals, and the injection rates of each are desired to be different, or different at different times.
- the other pump head may be positioned differently or with a differently configured rotor cam profile, to be actuated at a lower injection rate.
- stroking a pump by cycling a rotor back and forth may be also realized by using a motor other than a BLDC motor.
- stepper motors or servo motors are also reversible and conveniently controllable and may be used to drive a cam wheel with the desired cam profile.
- FIGS. 6-8 An alternative embodiment is shown in FIGS. 6-8 .
- the motor ( 112 ) has the same outrunner configuration with a stator ( 113 ) and rotor ( 114 ).
- the rotor ( 114 ) does not have a cam profile, but rotates a spindle ( 116 ) which extends into a pump drive housing ( 118 ) and an eccentric cam wheel ( 120 ).
- the pump drive housing bolts to the motor housing ( 110 ) as shown.
- the cam wheel ( 120 ) is circular, but is mounted to the spindle ( 116 ) in a offset manner, resulting in eccentric rotation of the cam wheel ( 120 ) within the housing ( 118 ).
- Opposing pump heads ( 101 ) and ( 102 ) comprise plungers ( 122 , 124 ) which extend outwards and operate in conjunction with suction and output valves ( 126 , 128 ), which may be ball valves, to open and close the injection fluid path, in a conventional manner.
- suction and output valves 126 , 128
- suction and output valves 126 , 128
- Single or multiple pump variations are of course possible.
- Rotation of the eccentric cam wheel ( 120 ) results in separate actuation of the pump heads ( 101 , 102 ), each being stroked in a sinusoidal pattern. Because the two pump heads are 180 degrees opposed, the two sinusoidal patterns will be 180 degrees out-of-phase.
- the two pump heads ( 101 , 102 ) may be spaced at 90 degrees apart, resulting in sinusoidal patterns that are 90 degrees out-of-phase, as is illustrated in FIG. 10 .
- this configuration or a similar configuration, to independently vary the injection rate of two or more pump heads with one electric motor.
- a range of rotation angle exists where there is maximum differential between the pump strokes and the rotation angle of the cam wheel (cam). If the motor is cycled back and forth in this range of rotation angle, a large difference in injection rates between the two pump heads can be realized.
- two or more cam wheels having non-aligned eccentricities, may be mounted to the same spindle, and actuate different pump heads.
- the rotor/spindle assembly is supported by two bearings only, a front bearing ( 115 ) positioned adjacent the cam wheel ( 120 ) in the pump drive housing ( 118 ), while a rear bearing ( 117 ) is positioned at the rear of the spindle ( 116 ), adjacent the stator ( 113 ).
- the invention comprise a method and system for controlling a pump, for example, to vary its injection rate. In one embodiment, this may permit independent operation of one pump head, from another pump head driven by the same motor.
- the motor and pump configuration may as described herein, or may be a conventional chemical injection pump configuration using any known motor and pump, provided the pump comprises a suction valve on its intake and an output valve on its output.
- a rotor ( 114 ) actuates two opposing pump heads ( 101 , 102 ), as described above.
- one or both of the pump heads ( 101 ) may be adapted with a control system ( 200 ) which is configured to modulate one or both of the suction valve or the output valve, in order to disable fluid injection by that pump head. This may be implemented by the motor controller as part of its control options.
- the plunger ( 124 ) will draw fluid into the pump chamber ( 202 ) during its suction stroke.
- the suction side has a check valve ball ( 204 ) which is unseated off its valve seat ( 206 ) by the pressure differential, allowing fluid to flow into the pump chamber ( 202 ) while the output valve ( 210 ) remains closed.
- a suction valve return spring ( 208 ) biases the suction valve in a closed position:
- the output valve ( 210 ) may also comprise check valve ball ( 212 ) which is also biased in a closed position with spring ( 214 ), and which opens with the pressure generated by the pressure stroke.
- the fluid drawn into the pump chamber ( 202 ) is discharged through the output valve, while the suction ball check valve remains seated and closed.
- This normal operation of the pump may be disabled or modulated by force opening or force closing either valve during either the pressure stroke or the suction stroke.
- force opening the suction valve during the pressure stroke or force closing the suction valve during the suction stroke will impair fluid pumping.
- force opening the output valve during the suction stroke, or force closing the output valve during the pressure stroke will also impair fluid pumping.
- control system ( 200 ) is used to disable the suction valve by keeping it open during the pressure stroke of the pump. As a result, the volume of fluid within the pump chamber simply flows back into the suction line ( 220 ) as the output valve ( 210 ) remains closed.
- the suction valve is kept open by physically blocking it from seating in its valve seat ( 206 ).
- a pin ( 230 ) protrudes upward through the valve seat opening, and may be extended or retracted by a pin actuating mechanism comprising a ferromagnetic armature ( 232 ) and an solenoid coil ( 234 ).
- the pin is biased in an upward position within the armature ( 232 ) by a coil spring ( 236 )
- FIG. 12A the pin is shown in its retracted position (valve active), which allows the valve ball ( 204 ) to seat normally.
- the pin is biased into a normally retracted position, allowing normal operation of the suction valve (valve active).
- the pin may be biased into a normally extended position, in which case the suction valve is disabled (valve bypass).
- the output valve may be disabled, for example by keeping it in an open position during suction stroke.
- a switchable magnet (not shown) may hold the check valve ball ( 212 ) open. As a result, fluid in the output line will be drawn back into the pump, while the suction valve will fail to open because of a lack of pressure differential.
- references in the specification to “one embodiment”, “an embodiment”, etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may he combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.
Abstract
Description
- The invention relates to chemical injection pumps and methods of controlling pump output.
- During the production of oil and gas, it is often necessary to inject a treatment chemical into a well, particularly into the annular space between the well casing and production tubing. These chemicals might include demulsifiers, corrosion inhibitors, scale inhibitors, or paraffin inhibitors. The various chemicals and their intended effects are well known in the industry.
- Rotary motors, typically electric or hydraulic motors, are used to power injection pumps which inject chemicals into a process. The motors are connected by a gearbox or transmission to a camshaft which reciprocates a plunger within a cylinder to pump fluid through an injection valve.
- Control of the injection rate of such chemical pumps is conventionally controlled by varying the speed or duty cycle of the motor, or the stroke length and diameter of the piston, however, this does not always allow for precise control over injection rates and may be unduly complicated when dealing with multiple chemicals requiring different injection rates at different times.
- In one aspect, the present invention relates to a positive displacement pump driven by an indexable, reversible electric motor. In preferred embodiments, the motor comprises an outrunner brushless DC (BLDC) electric motor. In preferred embodiments, the pump does not comprise a gearbox.
- Thus, the invention may comprise a pump system comprising:
-
- (a) an outrunner BLDC motor comprising a stator having a central axis and a rotor, wherein the rotor defines a cam profile having a pressure ramp and a suction ramp, which rotates about the stator axis; and
- (b) at least one pump head comprising an injection pump having a reciprocating plunger which is actuated by rotation of the cam profile.
- In some embodiments, the cam profile is created by a non-circular profile of the rotor. In alternative embodiments, the rotor has a circular profile but with an axis of rotation which is offset from the centre of the circle. Alternatively, the cam profile may be defined by a cam wheel, separate from the motor rotor.
- In some embodiments, the pump system comprises at least two pump heads, radially arrayed around the rotor, wherein each pump head comprises a housing and a reciprocating plunger.
- In some embodiments, the pump system further comprises a motor controller for controlling the speed and, optionally, direction of the motor. The motor controller may be configured to stroke one or more pump heads by cycling the cam profile or cam wheel backwards and forwards, over the entire pressure ramp, or a portion of the pressure ramp.
- In another aspect, the invention may comprise a pump system comprising:
-
- (a) a reversible and controllable electric motor driving a cam wheel having a pressure ramp and a suction ramp, which rotates about an axis; and
- (b) at least one pump head comprising an injection pump having a reciprocating plunger which is actuated by rotation of the cam wheel.
- In some embodiments, the reversible and controllable motor comprises an outrunner BLDC, a stepper motor or a servo motor. The motor is preferably an outrunner BLDC having a rotor with an outer surface which defines the cam wheel.
- In another aspect, the invention comprises a method of actuating a reciprocating pump having a plunger, comprising the steps of
-
- (a) providing a reversible and controllable electric motor driving a cam wheel having a pressure ramp and a suction ramp, which rotates about an axis;
- (b) rotating the cam wheel to actuate the plunger.
- In some embodiments, the reversible and controllable motor comprises an outrunner BLDC, a stepper motor or a servo motor. The motor is preferably an outrunner BLDC having a rotor with an outer surface which defines the cam wheel.
- In one embodiment, the method is implemented to actuate two or more reciprocating pumps, arrayed radially around the circumference of the rotor. In one embodiment, the method comprises the further step of cycling the rotor backwards and forwards to stroke at least one pump on the pressure ramp.
- In another aspect, the invention may comprise a control system for controlling a chemical injection rate for an injection pump comprising a suction valve and an output valve, comprising a mechanism for disabling operation of the suction valve or output valve, to maintain the suction valve in an open bypass position during the pressure stroke, or to maintain the output valve in an open bypass position during the suction stroke.
- In one embodiment, the control system may be used in connection with any electrical motor and pump configuration, such as those conventionally used in chemical injection pumps or in connection with a BLDC motor as described herein.
- In another aspect, the invention comprises a method of disabling a pump having a suction valve at its inlet and output valve at its outlet, comprising the step of opening the suction valve during a pressure stroke of the pump while keeping the output valve closed, or by opening the output valve during a suction stroke while keeping the suction valve closed.
- In another aspect, the present invention comprises a control system comprising: a circuit control device for operative connection to an electric circuit comprising an electric motor for actuating a chemical injection pump; a processor operatively connected to the circuit control device; and a memory comprising a non-transitory tangible medium storing instructions readable by the processor to implement one or a combination of the methods as described herein.
- In the drawings shown in the specification, like elements may be assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention.
-
FIG. 1A is a top plan view of one embodiment of the invention.FIG. 1B is a schematic representation of a motor controller. -
FIG. 2 is a cross-sectional view along line II ofFIG. 1 . -
FIG. 3 is a cross-sectional view along line III ofFIG. 1 . -
FIG. 4 is another view ofFIG. 2 , showing offset axes. -
FIG. 5 is another view ofFIG. 2 , showing indexed rotation over a portion of the rotor cam profile. -
FIG. 6 is an exploded view of an alternative embodiment of the invention. -
FIG. 7 is a vertical cross-section of the embodiment shown inFIG. 6 . -
FIG. 8 is another vertical cross-section along line VIII inFIG. 7 . -
FIG. 9 is a schematic view of an alternative embodiment having two pump heads arrayed at a 90 degree angle, with an offset circular cam wheel. -
FIG. 10 is a graph showing sinusoidal pattern of a pump piston stroke compared to the rotation of the cam wheel ofFIG. 9 . -
FIG. 11 is an exploded view of the embodiment ofFIG. 6 , having a suction valve deactivation system. -
FIG. 12 is a top plan view of the embodiment ofFIG. 11 . -
FIG. 13 is a vertical cross-section along line XIII ofFIG. 12 . -
FIGS. 14A and 14B show details of a portion ofFIG. 13 , showing the actuator in an active and bypass position, respectively. - In one aspect, the invention may comprise a positive displacement pump comprising an outrunner brushless DC (BLDC) motor comprising a stator and a rotor, wherein the rotor defines an external cam profile. Rotation of the rotor/cam actuates at least one plunger which reciprocates to pump fluid in a conventional manner. This configuration may take advantage of the low RPM, high torque capability of an outrunner BLDC motor. No gearbox or transmission is required, and is specifically excluded in one embodiment of the invention.
- In the following description, the terms “horizontal” and “vertical” are used to describe the relative orientation of elements of the invention in reference to the drawings, where
FIG. 1 is a top plan view andFIGS. 2 and 3 are cross-sectional views of one embodiment along a vertical plane.FIG. 2 is taken in a transverse direction whileFIG. 3 is taken in a longitudinal direction. The longitudinal horizontal axis is defined by the axis of rotation of the motor. When installed and in operation, the actual orientation of the motor and the pump may of course be different. - BLDC motors, also known as electronically commutated motors (ECMs or EC motors), or synchronous DC motors, are synchronous motors powered by DC electricity through an inverter or switching power supply which produces an AC electric current to drive each phase of the motor with a closed loop controller. The controller provides pulses of current to the motor windings that control the speed and torque of the motor. The structural elements of a brushless motor system are well known in the art, and are conventionally similar to a permanent magnet synchronous motor, but can also be a switched reluctance motor, or an induction (asynchronous) motor.
- In some embodiments, the controller (300) may be configured to allow control injection rates for at least one injection pump, and preferably for two or more injection pumps, independently of each other. The controller may comprise a processor (302); a memory (304); an input device (306); and a circuit control device (308). The memory (304) stores a set of instructions that are readable by the processor (302) to implement a method of pump operation as is further described below. The memory (304) may be a read-write memory allowing the stored set of instructions to be modified or selected by the user. The input device (306) may be any computer hardware device that allows a user to input data to the processor (302). Non-limiting examples of an input device (306) include a keypad, a touch screen, or a pointing device such as a computer mouse used in conjunction with a display device. In one embodiment, under the control of the processor (302), the circuit control device (308) modifies the voltage and/or current applied to the electric motor, in accordance with a method of the present invention.
- The term “outrunner” refers to a type of BLDC electric motor which spins its outer shell (rotor) around stationary windings (stator). Usually, outrunner motors have more poles, so they spin slower than their inrunner counterparts, while producing more torque.
- In one embodiment, the system comprises a chemical injection pump comprising an outrunner BLDC motor (12), contained within a housing (10). The motor stator (13) is supported within the housing (10) by a spindle (8) which allows passage of electrical power and control wires. The rotor (14) is supported by bearings within the housing. One preferred feature of this system is that the rotor (14) is supported by only two bearings, at the front (15) and at the rear (17), which reduces friction and maintenance needs.
- In one embodiment, the rotor (14) has an outer surface defining a cam profile with a non-uniform radius, as measured from the axis of rotation. In one embodiment, the outer cam profile comprises at least one lobe (16) which rotates about the central axis of the motor. In an alternative embodiment, the rotor (14) may define a cam profile with a non-uniform radius as a result of having an oval or other non-circular shape, or the rotor may be circular but with an offset axis of rotation. The rotor may have any configuration with a pressure ramp so long as rotation of the rotor is able to cause linear reciprocation of a plunger.
- In alternative embodiments, the rotor may drive a separate cam wheel which defines an external cam profile or rotates eccentrically as required.
- In the example shown in
FIG. 2 , two opposing pumps (18, 20) which are aligned in the vertical plane are actuated by the motor rotor (14). Each pump comprises a roller (22), a return spring (24), and a plunger (26). Rotation of the rotor (14) causes reciprocation of the plunger (26) by means of the roller (22). - As one skilled in the art may appreciate, the motor (12) may operate a plurality of pumps, which may be operated by the same rotor (and therefore be aligned in a vertical plane). Alternatively, or additionally, a plurality of rotor cams or cam wheels having the same axis of rotation (i.e. mounted on the same shaft) may be provided to operate pumps which are disposed horizontally adjacent to each other. Each rotor/cam or cam wheel may have one or more lobes or pressure ramps, which may operate in phase with other cam lobes or pressure ramps, or out of phase in varying degrees. As a result, the pump system may be configured with a wide range of output options.
- In the example shown in
FIGS. 1-3 , a single cam lobe (16) on the motor rotor drives two horizontally opposed pumps (18, 20). By combining the output of the two pumps, a substantially continuous single rate injection may be achieved because the pressure ramp of the earn profile extends 180 degrees and increases linearly. The 180 degree arc of the rotor opposite the cam lobe is the base circle, and the plunger (26) of pump (20) does not reciprocate when on this portion of the cam. Through the 180 degree pressure ramp profile, the plunger of pump (18) moves to the top of its stroke, culminating at the peak of the pressure ramp (16A), followed by a shorter suction ramp (16B) to the base circle (16C). In alternative embodiments, the pressure ramp and the suction ramp may have different lengths and slopes. For example, in one embodiment, the pressure ramp and suction ramp may be of equal length. - In one alternative embodiment, the pressure stroke may be lengthened in duration by lengthening the pressure ramp, for example to 320 degrees. Such a cam profile would reduce motor torque requirement, maximize the flow time and create longer periods of constant flow.
- In other embodiments, the effective slope of the pressure ramp and/or the suction ramp may be non-linear.
- In one embodiment, as shown in
FIG. 4 , the rollers and the axis of the pump are offset from the centreline (C) of the drive axis, which reduces or eliminates side loading on the plunger drive mechanism. As may be seen inFIG. 3 , the pump axes (P1 and P2) are both slightly offset from the drive axis centreline (C), minimizing off-axis forces on the roller and pump components. - BLDC motors are reversible and highly controllable with conventional motor controllers. The motor may be indexable with rotational index or position information provided by a shaft encoder or the like, or by using a load profile. As a result, a pump may be stroked by cycling the rotor back and forth, as opposed to continuous rotation in one direction. In the embodiment shown in
FIG. 5 , if the rotor (14) is cycled back and forth from the position shown, the left hand pump (18) will be actuated, while the right hand pump (20) will not be actuated. The cycle may comprise the 180 degree phase of the pressure ramp, or some portion of it, for example, a 90 degree portion illustrated inFIG. 5 as arc “A”. In this manner, the pump heads may be independently controlled to vary flow rate. This may be particularly useful if the two pump heads pump different chemicals, and the injection rates of each are desired to be different, or different at different times. In other embodiments, the other pump head may be positioned differently or with a differently configured rotor cam profile, to be actuated at a lower injection rate. - The advantages of stroking a pump by cycling a rotor back and forth may be also realized by using a motor other than a BLDC motor. For example, stepper motors or servo motors are also reversible and conveniently controllable and may be used to drive a cam wheel with the desired cam profile.
- An alternative embodiment is shown in
FIGS. 6-8 . In this example, the motor (112) has the same outrunner configuration with a stator (113) and rotor (114). In this example, the rotor (114) does not have a cam profile, but rotates a spindle (116) which extends into a pump drive housing (118) and an eccentric cam wheel (120). The pump drive housing bolts to the motor housing (110) as shown. In this example, the cam wheel (120) is circular, but is mounted to the spindle (116) in a offset manner, resulting in eccentric rotation of the cam wheel (120) within the housing (118). - Opposing pump heads (101) and (102) comprise plungers (122, 124) which extend outwards and operate in conjunction with suction and output valves (126, 128), which may be ball valves, to open and close the injection fluid path, in a conventional manner. During the suction stroke, fluid is drawn into the pump through the suction valve, and expelled during the pressure stroke through the output valve. Single or multiple pump variations are of course possible. Rotation of the eccentric cam wheel (120) results in separate actuation of the pump heads (101, 102), each being stroked in a sinusoidal pattern. Because the two pump heads are 180 degrees opposed, the two sinusoidal patterns will be 180 degrees out-of-phase.
- In a further alternative embodiment, as illustrated in
FIG. 9 , the two pump heads (101, 102) may be spaced at 90 degrees apart, resulting in sinusoidal patterns that are 90 degrees out-of-phase, as is illustrated inFIG. 10 . Of course, it is possible to use this configuration, or a similar configuration, to independently vary the injection rate of two or more pump heads with one electric motor. In this case, as shown inFIG. 10 , a range of rotation angle exists where there is maximum differential between the pump strokes and the rotation angle of the cam wheel (cam). If the motor is cycled back and forth in this range of rotation angle, a large difference in injection rates between the two pump heads can be realized. - In some embodiments, two or more cam wheels, having non-aligned eccentricities, may be mounted to the same spindle, and actuate different pump heads.
- In a preferred embodiment, the rotor/spindle assembly is supported by two bearings only, a front bearing (115) positioned adjacent the cam wheel (120) in the pump drive housing (118), while a rear bearing (117) is positioned at the rear of the spindle (116), adjacent the stator (113).
- In another aspect, the invention comprise a method and system for controlling a pump, for example, to vary its injection rate. In one embodiment, this may permit independent operation of one pump head, from another pump head driven by the same motor. In this case, the motor and pump configuration may as described herein, or may be a conventional chemical injection pump configuration using any known motor and pump, provided the pump comprises a suction valve on its intake and an output valve on its output.
- In one embodiment, shown schematically in
FIGS. 11-14 , a rotor (114) actuates two opposing pump heads (101, 102), as described above. However, one or both of the pump heads (101) may be adapted with a control system (200) which is configured to modulate one or both of the suction valve or the output valve, in order to disable fluid injection by that pump head. This may be implemented by the motor controller as part of its control options. - In normal operation, the plunger (124) will draw fluid into the pump chamber (202) during its suction stroke. The suction side has a check valve ball (204) which is unseated off its valve seat (206) by the pressure differential, allowing fluid to flow into the pump chamber (202) while the output valve (210) remains closed. A suction valve return spring (208) biases the suction valve in a closed position: The output valve (210) may also comprise check valve ball (212) which is also biased in a closed position with spring (214), and which opens with the pressure generated by the pressure stroke. During the pressure stroke, the fluid drawn into the pump chamber (202) is discharged through the output valve, while the suction ball check valve remains seated and closed.
- This normal operation of the pump may be disabled or modulated by force opening or force closing either valve during either the pressure stroke or the suction stroke. For example, force opening the suction valve during the pressure stroke or force closing the suction valve during the suction stroke will impair fluid pumping. Alternatively, force opening the output valve during the suction stroke, or force closing the output valve during the pressure stroke will also impair fluid pumping.
- In general terms, in one embodiment, the control system (200) is used to disable the suction valve by keeping it open during the pressure stroke of the pump. As a result, the volume of fluid within the pump chamber simply flows back into the suction line (220) as the output valve (210) remains closed.
- In one embodiment, the suction valve is kept open by physically blocking it from seating in its valve seat (206). In a preferred embodiment, a pin (230) protrudes upward through the valve seat opening, and may be extended or retracted by a pin actuating mechanism comprising a ferromagnetic armature (232) and an solenoid coil (234). Optionally, the pin is biased in an upward position within the armature (232) by a coil spring (236) In
FIG. 12A , the pin is shown in its retracted position (valve active), which allows the valve ball (204) to seat normally. Upward movement of the armature (232) allows spring (236) to push the pin (230) upwards and off its valve seat (206), thereby disabling the suction valve. The armature is moved upwards by energizing the solenoid coil (234). - In one embodiment, the pin is biased into a normally retracted position, allowing normal operation of the suction valve (valve active). Alternatively, the pin may be biased into a normally extended position, in which case the suction valve is disabled (valve bypass).
- In an alternative embodiment, the output valve may be disabled, for example by keeping it in an open position during suction stroke. In one embodiment, a switchable magnet (not shown) may hold the check valve ball (212) open. As a result, fluid in the output line will be drawn back into the pump, while the suction valve will fail to open because of a lack of pressure differential.
- References in the specification to “one embodiment”, “an embodiment”, etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may he combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.
- It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as “solely,” “only,” and the like, in connection with the recitation of claim elements or use of a “negative” limitation. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.
- The singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. The WI “and/or” means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase “one or more” is readily understood by one of skill in the art, particularly when read in context of its usage.
Claims (25)
Priority Applications (1)
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US16/415,420 US20190353147A1 (en) | 2018-05-18 | 2019-05-17 | Injection pump |
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US201862673635P | 2018-05-18 | 2018-05-18 | |
US16/415,420 US20190353147A1 (en) | 2018-05-18 | 2019-05-17 | Injection pump |
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US20190353147A1 true US20190353147A1 (en) | 2019-11-21 |
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US16/415,420 Abandoned US20190353147A1 (en) | 2018-05-18 | 2019-05-17 | Injection pump |
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US (1) | US20190353147A1 (en) |
CA (1) | CA3043820A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
USD938998S1 (en) * | 2019-01-24 | 2021-12-21 | Sirius Instrumentation And Controls Inc. | Stacking injection pump manifold |
US20220145875A1 (en) * | 2020-11-09 | 2022-05-12 | Hydrocision, Inc. | System, apparatus, and method for motor speed control |
-
2019
- 2019-05-17 CA CA3043820A patent/CA3043820A1/en active Pending
- 2019-05-17 US US16/415,420 patent/US20190353147A1/en not_active Abandoned
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
USD938998S1 (en) * | 2019-01-24 | 2021-12-21 | Sirius Instrumentation And Controls Inc. | Stacking injection pump manifold |
USD962296S1 (en) * | 2019-01-24 | 2022-08-30 | Sirius Instrumentation And Controls Inc. | Stacking injection pump manifold |
US20220145875A1 (en) * | 2020-11-09 | 2022-05-12 | Hydrocision, Inc. | System, apparatus, and method for motor speed control |
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