SERVO DRIVEN PUMP

A double diaphragm pump having opposing diaphragms acted upon by a thrust rod are driven by a linear actuator preferably connected to a motor, such as a servo motor. The linear actuator is restricted to linear only motion and may have a piston oppositely oriented relative to a direction of a shaft extending from the motor.

FIELD OF THE INVENTION

The present invention relates to a motor driven double diaphragm pump and more particularly to an electric servo motor driven, double diaphragm pump employing a linear actuator.

BACKGROUND OF THE INVENTION

Companies such as Tapflo have utilized electric motors to operate double diaphragm pumps. Graco also sells an electronic operated double diaphragm (EODD) pump. The prior art EODD electric operated double diaphragm pumps of Tapflo and Graco rely on the rotation of a motor shaft which drives an eccentric cam to move a piston left and right relative to diaphragms to affect the pumping through the pump. SeeFIG.1showing a schematic of how prior art electrically operated double diaphragm pumps operate.

While this certainly is one way of electrically operating a double diaphragm pump, there are believed to be improved ways of employing electrically operated motors to drive double diaphragm pumps in the marketplace.

The applicant's prior art pneumatic double diaphragm pump1ofFIG.2utilizes an air valve2which has an internal spool allowing compressed air to be alternatively directed between air chambers3and4which drive the thrust tube5back and forth thereby directing diaphragms8,9to move in the direction of the thrust tube5along axis10to then direct fluid from inlet11through fluid chambers6,7which selectively increase and decrease in volume to direct fluid out outlet12as is well known in the art.

Instead of using compressed air to pneumatically operate a double diaphragm pump as is shown with the Applicant's prior art design ofFIG.2, improved efficiency and other advantages are believed to be possible utilizing a new design.

SUMMARY OF THE INVENTION

It is an object of many embodiments of the present invention to provide an improved electrically operated double diaphragm pump.

It is another object of many embodiments of the present invention to provide an improved double diaphragm pump operated with a linear actuator.

It is another object of many embodiments of the present invention to provide an improved servo motor operated double diaphragm pump.

It is another object of many embodiments of the present invention to provide an improved servo motor electrically operated double diaphragm pump providing a linear actuator which linearly reciprocates diaphragms to pump fluid from an inlet to an outlet.

Accordingly, for many preferred embodiments, a servo motor may be provided, possibly in combination with a gear box, along with a linear actuator which converts rotary drive from a motor into linear motion to drive a thrust tube of a double diaphragm pump back and forth to direct fluid from an inlet to an outlet selectively through fluid chambers in the pump.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG.3shows a pump20of a presently preferred embodiment of the present invention.

The pump20is a double diaphragm pump which advantageously employs a linear actuator22which converts rotational drive normally provided by a motor, preferably a servo motor,24possibly through a gear box26into liner motion to drive a thrust tube28along a reciprocating axis30so as to move first and second diaphragms32,34to pump fluid content selectively from fluid cavities36,38as they are filled from inlet40and then the contents alternatingly directed out outlet42.

Servo motor24provides a drive impetus through a rotating shaft44which may be received by gear box26. Rotational motion from the servo motor34may have torque increased by gear box26. The linear actuator22may have threads46which selectively drive piston48linearly and selectively along reciprocation axis30as the linear actuator22receives potential input. The piston48is preferably connected to the thrust tube28and is preferably secured thereto to impart the desired linear motion to the thrust tube28.

One advantage of many embodiments of the pump20is that it can replace air driven technology with modern servo control. Another advantage of many embodiments is that it replaces a tie rod13and thrust tube bearings14shown inFIG.2with a precision lead screw46which drives piston48as shown inFIG.3.

The air valve2can be replaced with an electric servo motor24or other motor and possibly a gear box26in many embodiments. Some embodiments may connect the motor like a servo motor24directly to the linear actuator22without a gear box26.

Increase in efficiency of the pump20may be achieved by utilizing the electric motor24rather than compressed air as required by the prior art motor1. Operating air compressor to store potential energy normally only converts 10-15% of the energy required into usable compressed air as reported by www.cagi.org. On the other hand, depending on the application and torque required, servo motors may be up to 85% efficient or possibly even more. This results in an energy savings to be able to utilize the servo motor24instead of compressed air, potentially a savings of roughly being six times more efficient.

Additionally, by switching to the motor24/actuator22combination to drive the thrust tube28, operational noise is believed to be significantly reduced. Operational noise may be reduced to a recirculating ball bearing inside a nut and/or actuator22inside a nut which could be housed within the pump20and/or linear actuator22. There certainly would not be air exhausting from the pump20or air compressor noise as a result of needing to provide compressed air to the pump20.

Automatic control could be provided to the pump20such as through controller50such as a programmable logic controller (PLC), a human machine interface (HMI), or other controller. Control of the pump20may then become virtually limitless. The stroke, speed and cycles may be controlled independently with a controller50. Different profiles for pumping different products may be saved and reused with the controller50.

Many users of pump20may have process and packaging manufacturing facilities. Electric data acquisition systems for production, quality and quality assurance may be in place. The servo motor24having the pump20may provide performance feedback to such a system possibly from the controller50. The servo driven pump20could also be integrated to existing process machinery. Additionally, the existing systems can provide an on/off signal to control the pump20possibly directly or through the controller50for various embodiments.

The controller50such as a PLC or others may enable sensor feedback to control the pump20. This may assist in identifying a component failure or system fault.

Servo motors24may be available such as3-A and EHDG or others possibly from Kollmorgen or other manufacturers.

Current design flaws of the pneumatic pump1can be overcome with the pump20such as by preventing stalling or slipping bearings for at least some embodiments. Other advantages may be an ability to run dry without damage, an ability to self-prime from a dry suction pipe, a long design life, and/or other advantages.

When comparing the pump20to the prior art pump ofFIG.1one will see that there is no eccentric cam utilized to drive the internal mechanism in accordance with the eccentricy of the eccentric cam. Instead of rotating within an internal mechanism as is done in the prior art, the thrust tube28is connected to piston48of liner actuator22and is restricted only to the amount of linear travel. The shaft or piston48passes through the outer housing52and reciprocates along axis54through the housing52. The linear actuator22preferably has an axis54which is parallel to the reciprocating axis30if not colinearly disposed there along. The rotation axis56is preferably parallel to the liner actuator axis54.

For some embodiments the motor may have shaft44extend from motor24oppositely oriented relative to the piston48extending from linear actuator22. The gear box26is helpful to minimize the footprint of the motor24and pump20combination.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to an example embodiment of the presently disclosed technology which is for purposes of illustration only and not to be construed as a limitation of the presently disclosed technology. All such modifications which do not depart from the spirit of the presently disclosed technology are intended to be included within the scope of the appended claims.