TECHNICAL FIELD

The present disclosure relates to devices, for example a gear pump, for pumping fluids. Moreover, the present disclosure concerns methods of using the aforesaid devices to pump fluids. Such fluids are, for example, liquids, gases, gels, emulsions, foam, powders, or any combination or mixture thereof.

BACKGROUND

Gear pumps are used in a wide variety of technical fields, for example when manufacturing automobiles, in food industries, in medicine and so forth. Typically, a known gear pump includes two gear wheels (also referred as “cogwheels”) that are operable to engage with each other, and are rotated when in operation in mutually opposite directions by a drive shaft of a motor. Moreover, the two gear wheels are arranged in a channel of a pump cylinder and are operable to create a suction pressure zone at an inlet of the channel and an ejection pressure zone at an outlet of the channel. Furthermore, the two gear wheels are constructed for allowing a positive displacement of a “substrate” for each cycle (i.e. rotation of the two gear wheels or the drive shaft) of pump operation; such a substrate is, for example a fluid, for example a liquid or a gas. A gear pump can attain a volumetric control in terms of discharge of the substrate therefrom by monitoring and controlling a rotational position of the drive shaft of the motor.

Contemporarily, for achieving such volumetric control, an optical encoder is used in conjunction with a gear pump. For example, the optical encoder is operatively coupled to a drive shaft of a motor of the gear pump for measuring a rotational position of the drive shaft, based upon which a specific volume of the substrate, for example a fluid, for example a liquid or gas, is discharged from the gear pump. Moreover, for the optical encoder to operate efficiently and accurately to measure the rotational position of the drive shaft, the optical encoder must be isolated or separated from the substrate, for example a fluid, for example a liquid or gas. Generally, for isolating the optical encoder from the substrate, for example fluid, for example liquid, a mechanical sealing arrangement is used such that the optical encoder is surrounded with air to function efficiently and accurately. However, the use of such a mechanical sealing arrangement increases an overall complexity and cost of manufacturing for such gear pumps. Moreover, gear pumps which do not incorporate such a sealing arrangement, or where the sealing arrangement is breached, cannot be used for pumping accurate volumes of the substrate, for example a fluid, for example a liquid or a gas, because the rotation of the drive shaft cannot be accurately measured in such a situation using the optical encoder.

Therefore, it will be appreciated from the foregoing that known types of gear pumps, for example when pumping fluids, for example liquids or gases, suffer various problems that can adversely influencing their pumping accuracy.

SUMMARY

The present disclosure seeks to provide an improved device for pumping a fluid, for example a liquid or gas.

The present disclosure also seeks to provide an improved gear pump for pumping a fluid, for example a liquid or a gas, wherein gears of the improved pump are monitored and controlled in operation to sub-tooth angular resolution.

The present disclosure also seeks to provide an improved method of operating a gear pump for pumping fluid, for example a liquid or a gas.

According to a first aspect, there is provided a device for pumping a fluid, wherein the device comprises:

a motor for driving a rotatable drive shaft;

a pump module to be driven in operation by the drive shaft;

a sensor target operatively associated with at least one of: the drive shaft, one or more rotatable pumping components of the pump module;

a sensor for sensing a change in property of the sensor target as the drive shaft rotates in operation, and for generating an output signal corresponding to a rotational position of at least one of: the drive shaft, the one or more rotatable pumping components of the pump module; and

a controller that is operable to calculate the rotational position of at least one of: the drive shaft, the one or more rotatable pumping components of the pump module, based upon the output signal and to control the motor based upon the calculated rotational position to ensure that a controlled volume of fluid is pumped.

The present invention is capable of substantially eliminating the aforementioned problems in the prior art, and is capable of enabling pumping of a controlled volume of fluid, for example a liquid or gas, by a gear motor without being subjected to increased complexity and cost of manufacturing.

Optionally, in operation of the device, the sensor is operable to measure an angular position of the drive shaft for generating the output signal, and the controller is operable to calculate the rotational position of the drive shaft for use in controlling the motor to ensure that a controlled volume of fluid is pumped.

Optionally, in operation of the device, the sensor is operable to measure an angular position of a driven rotating pumping component of the pump module for generating the output signal, and the controller is operable to calculate the calculated rotational position of the driven rotating pump component for use in controlling the motor to ensure that a controlled volume of fluid is pumped. Measuring the angular position of the driven component is capable of improving pump accuracy.

Optionally, in operation of the device, the sensor is operable to measure an angular position of an idling rotating pumping component of the pump module for generating the output signal, and the controller is operable to calculate the calculated rotational position of the idling rotating pumping component for use in controlling the motor to ensure that a controlled volume of fluid is pumped.

Optionally, in operation of the device, the sensor target comprises a disc that has alternate optically transparent and opaque patterns and a light source, and the sensor is a photodetector array that is operable to receive light from the optically transparent and opaque patterns to generate the output signal for use in controlling the motor to ensure that a controlled volume of fluid is pumped.

Optionally, in operation of the device, the sensor target comprises a material whose dielectric and/or conductive properties spatially varies, and the sensor includes a pair of electrodes that are operable to interact capacitively with the sensor target to generate an output signal in response to the rotation of the drive shaft causing a capacitance generated between the pair of electrodes to change.

Optionally, in operation of the device, the sensor target is fabricated from a material whose magnetic properties are spatially varying, and the sensor is operable such that its inductance changes as a function of angular position of the sensor target relative to the sensor, wherein the sensor is operable to generate the output signal in response to the rotation of the drive shaft.

More optionally, in operation of the device, the sensor target comprises a disc having circumferential teeth, and the sensor comprises a magnet and a surrounding coil assembly configured to generate the output signal in a form of magnetic flux as the change in the property in response to the rotation of the drive shaft.

Optionally, in operation of the device, the sensor target and the sensor are included within a pump housing of the device.

Optionally, in operation of the device, the sensor target and the sensor are exterior to a pump housing of the device.

Optionally, in operation of the device, the controller includes a plurality of servo loops coupled to the sensor for controlling the motor, wherein the plurality of servo loops are of mutually different response bandwidth and of mutually different gains.

More optionally, in operation of the device, at least one of the servo loops is operable to monitor an angular position of the drive shaft, and at least one of the servo loops is operable to monitor an angular position of at least one of the one or more rotatable pump components.

Optionally, in operation of the device, the device further comprises a pump housing, having an exterior surface, for accommodating the pump module therein.

More optionally, in the device, the sensor is disposed on or proximal to the exterior surface of the pump housing.

More optionally, in the device, the exterior surface of the pump housing comprises a pump face.

More optionally, in the device, the pump face defines a fluid inlet port and a fluid outlet port.

Optionally, in the device, the pump module is one of a rotary pump or a reciprocating pump.

Optionally, in device, the controller is operable to employ a nested position feedback loop.

According to a second aspect, there is provided a gear pump for pumping fluid, wherein the gear pump comprises:

a motor for driving a rotatable drive shaft;

a drive gear that is operable to be driven by the drive shaft;

an idler gear which meshes with the drive gear;

annular magnet disposed coaxially with the drive shaft (108) and operable to rotate therewith;

a sensor for sensing rotation of the annular magnet and generating an output signal corresponding to a rotational position of the drive shaft; and

a controller that is operable to calculate the rotational position of the drive shaft based upon the output signal and to control the motor based upon the calculated rotational position to ensure that an controlled volume of fluid is pumped.

Optionally, in the gear pump, the sensor comprises a Hall Effect array that is operable to generate the output signal in a form of a Hall Effect voltage in response to the rotation of the annular magnet.

Optionally, in the gear pump, the annular magnet is disposed within the drive gear.

Optionally, in the gear pump, the annular magnet is magnetised diametrically.

Optionally, the gear pump includes a pump housing having an exterior surface.

More optionally, in the gear pump, the sensor is disposed on or proximal to the exterior surface of the pump housing.

More optionally, in the gear pump, the sensor is disposed on or proximal to an inside region within the exterior surface of the pump housing.

More optionally, in the gear pump, the exterior surface of the pump housing comprises a pump face.

More optionally, in the gear pump, the pump face comprises a trench and wherein the sensor is disposed at least partially within the trench.

More optionally, in the gear pump, the trench is positioned in the pump face such that the sensor is disposed coaxially with the annular magnet.

More optionally, in the gear pump, the pump face defines a fluid inlet port and a fluid outlet port.

According to a third aspect, there is provided a method of pumping fluid using a gear pump, wherein the method comprises steps of:

driving a motor to rotate a drive shaft, and arranging for the drive shaft to rotate one or more rotatable components of a pump module for pumping fluid, and for rotating a sensor target associated with the drive shaft and/or the one or more rotatable components of the pump module;

using a sensor to sense rotation of sensor target and to generate an output signal corresponding to an annular position of the sensor target;

calculating the rotational position of the drive shaft and/or the one or more the one or more rotatable components of the pump module based upon the output signal; and

controlling the motor based upon the calculated rotational position to controllably pump a volume of fluid.

Optionally, the method includes arranging for the sensor target to include an annular magnet.

Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative preferred embodiments construed in conjunction with the appended claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the detailed description of the disclosure, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

FIG. 1 is a schematic view of a device for pumping fluid, in accordance with an embodiment of the present disclosure;

FIG. 2 is an exploded plan view of a gear pump, in accordance with an embodiment of the present disclosure;

FIG. 3 is an exploded isometric view of the gear pump of FIG. 2, in accordance with an embodiment of the present disclosure;

FIG. 4 is an assembled elevation view of the gear pump of FIG. 2, in accordance with an embodiment of the present disclosure;

FIG. 5 is an assembled plan view of the gear pump of FIG. 2, in accordance with an embodiment of the present disclosure;

FIGS. 6A-C are the assembled plan view of the gear pump, a cross-sectional view of the assembled plan view about an axis A-A′, and an enlarged view of a portion A″ of the cross-sectional view, respectively, in accordance with an embodiment of the present disclosure;

FIGS. 7A-C are the assembled elevation view of the gear pump, a cross-sectional view of the assembled elevation view about an axis B-B′, and an enlarged view of a portion B″ of the cross-sectional view, respectively, in accordance with an embodiment of the present disclosure;

FIGS. 8A-B are the assembled elevation view of the gear pump and a cross-sectional view of the assembled elevation view about an axis C-C′, respectively, in accordance with an embodiment of the present disclosure;

FIGS. 9A-B are the assembled elevation view of the gear pump and a cross-sectional view of the assembled elevation view about an axis D-D′, respectively, in accordance with an embodiment of the present disclosure; and

FIG. 10 illustrates a flow chart depicting steps of operation of the gear pump, in accordance with an embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

The present disclosure will now be described in more detail by reference to preferred particular embodiments.

DETAILED DESCRIPTION OF THE DISCLOSURE

Embodiments of the disclosure will now be described in more detail with reference to component parts of a device for pumping a fluid, for example a liquid. The embodiments concern a gear pump, and a method of operating such a gear pump.