Classifications

• • 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
  • F04B45/00—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids
  • F04B45/04—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms
  • F04B45/043—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms two or more plate-like pumping flexible members in parallel
• • 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
  • F04B35/00—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
  • F04B35/04—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric
• • 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
  • F04B41/00—Pumping installations or systems specially adapted for elastic fluids
  • F04B41/06—Combinations of two or more pumps
• • 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
  • F04B45/00—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids
  • F04B45/04—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms
  • F04B45/047—Pumps having electric drive
• • 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
  • F04B49/02—Stopping, starting, unloading or idling control
• • 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
  • F04B49/06—Control using electricity
• • 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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/22—Devices for withdrawing samples in the gaseous state
  • G01N1/24—Suction devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/22—Devices for withdrawing samples in the gaseous state
  • G01N1/2273—Atmospheric sampling

Definitions

• the present invention relates generally to a method for controlling a gas flow of a pump for high flow rates at a low average flow rate. More particularly, the present invention relates to a method as defined in the introductory parts of claim 1 and to a pump assembly for performing such a method as defined as defined in the introductory parts of claim 14.
• the pump that is capable of a high flow rate may be operated to pump with a very small flow rate.
• the pump is operated at a fairly high momentary flow rate, but for a short time period. It is then paused for a while.
• the average flow rate may thus be low while the momentary flow rate is high enough so that the inlet valve and outlet valve for the pump chamber or pump chambers are able to open, since the opening resistance of the inlet valve and outlet valve is overcome.
• the average flow rate may be controlled by the duration of the first, second, and third
• predetermined time period is substantially equal to said second
• the intake and outtake periods for most pumps are operated at equal flow rates, but theoretically, they could be different from each other. It is further preferred that said first predetermined time period and said second predetermined time period correspond to a part of a pump cycle of said pump.
• the first predetermined time period where the pressure inside said pump cavity or pump chamber is decreased, i.e. when the intake valve is forced to open and let gas into the pump cavity, may e.g. be half a pump cycle.
• the second predetermined time period is then preferably the other half of the pump cycle.
• the pump is connected to a control unit, said control unit controlling said gas pressure decrease and said gas pressure increase; and said first predetermined time period and said second predetermined time period.
• the control unit is in digital or electrical communication with a control program or operator control devices so that it may alter said first, second and third time periods and thereby control the average flow rate from the pump.
• control unit controls two or more membrane pumps, said pumps having individual pump cycles that are maximally phase shifted in relation to each other. Since membrane pumps by design will produce a pulsed flow, the use of several membrane pumps that all are connected to the same output flow channel, will reduce the pulsation when they are maximally phase shifted relative each other. Additional gas expansion chambers may also be added to further reduce the pulsation. If, e.g. using three membrane pumps, the pump cycles would be phase shifted 120 degrees to each other so as to reduce pulsation as much as possible (one pump cycle being 360 degrees). A further advantage of using multiple membrane pumps in a pump assembly that are phase shifted is that vibrations are reduced prolonging the lifetime of the pump assembly.
• method further comprises the step of:
• controlling the main gas flow of the pump by repeatedly stopping the active change of gas pressure. This is preferably done by simply stopping the pump motor driving the drive shaft of the pump for the third predetermined time period, the third predetermined time period being set after the desired average flow rate.
• the gas pumped is preferably air and the pump may further be adapted to be used in connection with a sampling device for measuring air quality. It is crucial for pumps used for sampling devices to be able to be controlled accurately and to work for the flow rates that are specified for the sampler used.
• the increase of gas pressure and said decrease of gas pressure are controlled by said control unit based on a voltage provided to a pump motor of said pump or pumps.
• the pump motor may preferably be an electrical motor so that by controlling the voltage of the electrical power driving the motor, the control unit controls the rotational speed of the motor and its drive shaft.
• the voltage provided to said pump motor of said pump or pumps is momentarily substantially higher than the specified input voltage for said pump motor.
• the motor can manage a substantially higher input voltage than specified for the motor.
• the short time duration of the higher voltage means that heat problems do not have time to build up.
• the momentarily higher input voltage than specified for the motor during the start phase of the pump leads to a more rapid start of the motor compared to a normal start when the motor slowly reaches its operational speed for a certain voltage.
• the method further comprises the steps of detecting a rotational speed of said pump motor using a revolution sensor, e.g. a Hall sensor, measuring an output gas flow from said pump or pumps using a flow sensor, e.g. a differential thermal mass flow meter.
• the Hall sensor facilitates the possibility to measure an average flow during an integer number of pump cycles, providing a much more reliable calculated average flow rate, especially if the intervals between running pump cycles are long.
• the method further comprises detecting the angle of the rotor in said pump motor;
• the control unit detects that the rotational speed of the electrical motor and thus the flow rate through the pump chamber/chambers is lower than what is needed for the inlet and outlet valves to operate properly, i.e. open and close as they should, the voltage to the electrical pump motor may be momentarily increased at the angle of the electrical motor corresponding to the most demanding position of a valve operation.
• the method further comprises to monitoring the output gas flow during one revolution or part of one revolution of the pump motor for detecting possible pump failure of any one of said pump or pumps. If, e.g. using a plurality of membrane pumps, a damaged pump may be detected and identified.
• the invention further relates to a pump assembly for high flow rates operated at a low average flow rate comprising: a number of pumps; a pump motor with a number of stator windings adapted to drive said pumps; a control unit adapted to control said pump motor; wherein said number of pumps is equal to said number of stator windings. Since an electrical motor is a lot easier to start at certain angles of the rotor to the stator, it is desired to stop the pump at that position. Using the same number of windings for the pump motor as the number of pumps in the pump assembly, the pump may be pulsed in a manner where one pump finishes a pump cycle, and the motor stops at a position where it is easily started again.
• the position of the pump may be measured by the Hall sensor to ensure stopping at the correct position, i.e. a position where the pump motor has a maximum torque for starting again.
• the membrane pump heads are preferably aligned with the correct stopping position so that at least one pump cycle is at its starting position (0 degrees) at that position, i.e. at least one pump head has a full cycle of intake and outlet ahead that is not begun.
• the stator windings may thus advantageously be positioned relative to said pumps with such an angle that the maximum torque by said rotor and windings is exerted at an angle of said rotor where most force is required to operate said pumps.
• Many stock driver solutions have a start up phase when starting them in order to find motor position, which start up phase may be avoided using the presented method. This saves power, makes the control of the pump assembly more accurate and makes sure that a start of the pump is as rapid as possible for every time period it is used, no matter how short.
• Fig. 1 is a schematic view of a membrane pump with one membrane.
• Fig. 2 is a schematic view of a membrane pump having four pump heads, i.e. four membranes.
• Fig. 3a illustrates the function of the valves for a membrane pump membrane when the pressure in the pump chamber is decreased during inlet of gas.
• Fig. 3b illustrates the function of the valves for a membrane pump membrane when the pressure in the pump chamber is increased during outlet of gas.
• Fig. 4 illustrates malfunction identification of a four membrane pump according to the present invention.
• Fig 5a is a schematic view of a the pump motor windings of a membrane pump.
• Fig 5b is a schematic view of a the pump motor windings of a membrane pump in relation to the three pump heads of the membrane pump.
• Fig. 1 is a schematic view of a membrane pump with one membrane, showing only the drive shaft 1 , the crank shaft 2 and the membrane 1 1 .
• the pump chamber and the inlet and outlet valves are not shown.
• Fig. 2 is a schematic view of a membrane pump of a similar type as in Fig. 1 but having four pump heads, i.e. four membranes 1 1 , 12, 13, 14. The use of four pump heads will reducing the maximum torque required by the pump motor and it will achieve a smother flow since the pump cycles of the four individual pump cycles are phase shifted 90 degrees to each other.
• Fig. 3a illustrates the function of the valves 3, 4 for a membrane pump membrane when the pressure in the pump chamber 5 is decreased during inlet of gas.
• the inlet valve 3 is forced to open while the outlet valve 4 is forced to close due to the decrease in pressure in the pump chamber 5 and a flow of gas indicated by the arrow 17 enter through the inlet valve 3 into the pump chamber 5.
• Fig. 3b illustrates the function of the valves 3, 4 for a membrane pump membrane when the pressure in the pump chamber 5 is increased during outlet of gas.
• the inlet valve 3 is forced to close while the outlet valve 4 is forced to open due to the increase in pressure in the pump chamber 5 and a flow of gas indicated by the arrow 18 exit through the outlet valve 4 exiting the pump chamber 5.
• FIG. 4 illustrates malfunction identification in a four membrane pump according to the present invention.
• a power boost e.g. higher voltage on driver bridges
• the signal to the driver bridges can be reduced while maintaining the same pace. Accurate control of the pump motor may thus be achieved.
• Fig. 5a shows a schematic image of the motor 20 for the pump assembly according to the invention.
• the motor has three windings 21 , 22, 23 and a dipole magnet 24, 25 having a north pole 24 and a south pole 25, said dipole magnet having the drive shaft 1 of the pump assembly arranged in the center of the magnet.
• the rotation of the magnet and the drive shaft is indicated by the arrow 26.
• the motor is positioned for an easy start by having the winding 21 pull the north pole 24 towards it, while the winding 22 is operated in counter phase so that it will push the north pole 24. In that way the rotation is initiated.
• the rotation is then continued in a normal manner for driving an electrical motor, well known for a person skilled in the art.
• Fig. 5b shows the schematic image of the motor 20 as in Fig. 5a, having three pump heads 31 , 32, 33 superposed on the engine 20 attached to the drive shaft 1 of the pump assembly.
• the pump head outlets are

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Molecular Biology (AREA)
• Physics & Mathematics (AREA)
• Biomedical Technology (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Control Of Positive-Displacement Pumps (AREA)
• Reciprocating Pumps (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=56074779

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• 2015
  • 2015-11-27 EP EP15862407.2A patent/EP3224593A4/de not_active Withdrawn
  • 2015-11-27 WO PCT/SE2015/051276 patent/WO2016085400A1/en active Application Filing
  • 2015-11-27 JP JP2017527858A patent/JP2018503764A/ja active Pending
  • 2015-11-27 US US15/528,832 patent/US20170328359A1/en not_active Abandoned

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