SERVO DRIVEN PUMP

Abstract

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.

Description

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. See FIG. 1 showing 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 pump 1 of FIG. 2 utilizes an air valve 2 which has an internal spool allowing compressed air to be alternatively directed between air chambers 3 and 4 which drive the thrust tube 5 back and forth thereby directing diaphragms 8,9 to move in the direction of the thrust tube 5 along axis 10 to then direct fluid from inlet 11 through fluid chambers 6,7 which selectively increase and decrease in volume to direct fluid out outlet 12 as 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 of FIG. 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.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a schematic view of a prior art electrically operated double diaphragm pump;

FIG. 2 is a cutaway view of a prior art pneumatically operated double diaphragm pump; and

FIG. 3 is a cutaway view of a presently preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 3 shows a pump 20 of a presently preferred embodiment of the present invention.

The pump 20 is a double diaphragm pump which advantageously employs a linear actuator 22 which converts rotational drive normally provided by a motor, preferably a servo motor, 24 possibly through a gear box 26 into liner motion to drive a thrust tube 28 along a reciprocating axis 30 so as to move first and second diaphragms 32,34 to pump fluid content selectively from fluid cavities 36,38 as they are filled from inlet 40 and then the contents alternatingly directed out outlet 42.

Servo motor 24 provides a drive impetus through a rotating shaft 44 which may be received by gear box 26. Rotational motion from the servo motor 34 may have torque increased by gear box 26. The linear actuator 22 may have threads 46 which selectively drive piston 48 linearly and selectively along reciprocation axis 30 as the linear actuator 22 receives potential input. The piston 48 is preferably connected to the thrust tube 28 and is preferably secured thereto to impart the desired linear motion to the thrust tube 28.

One advantage of many embodiments of the pump 20 is that it can replace air driven technology with modern servo control. Another advantage of many embodiments is that it replaces a tie rod 13 and thrust tube bearings 14 shown in FIG. 2 with a precision lead screw 46 which drives piston 48 as shown in FIG. 3.

The air valve 2 can be replaced with an electric servo motor 24 or other motor and possibly a gear box 26 in many embodiments. Some embodiments may connect the motor like a servo motor 24 directly to the linear actuator 22 without a gear box 26.

Increase in efficiency of the pump 20 may be achieved by utilizing the electric motor 24 rather than compressed air as required by the prior art motor 1. 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 motor 24 instead of compressed air, potentially a savings of roughly being six times more efficient.

Additionally, by switching to the motor 24/actuator 22 combination to drive the thrust tube 28, operational noise is believed to be significantly reduced. Operational noise may be reduced to a recirculating ball bearing inside a nut and/or actuator 22 inside a nut which could be housed within the pump 20 and/or linear actuator 22. There certainly would not be air exhausting from the pump 20 or air compressor noise as a result of needing to provide compressed air to the pump 20.

Automatic control could be provided to the pump 20 such as through controller 50 such as a programmable logic controller (PLC), a human machine interface (HMI), or other controller. Control of the pump 20 may then become virtually limitless. The stroke, speed and cycles may be controlled independently with a controller 50. Different profiles for pumping different products may be saved and reused with the controller 50.

Many users of pump 20 may have process and packaging manufacturing facilities. Electric data acquisition systems for production, quality and quality assurance may be in place. The servo motor 24 having the pump 20 may provide performance feedback to such a system possibly from the controller 50. The servo driven pump 20 could also be integrated to existing process machinery. Additionally, the existing systems can provide an on/off signal to control the pump 20 possibly directly or through the controller 50 for various embodiments.

The controller 50 such as a PLC or others may enable sensor feedback to control the pump 20. This may assist in identifying a component failure or system fault.

Servo motors 24 may be available such as 3-A and EHDG or others possibly from Kollmorgen or other manufacturers.

Current design flaws of the pneumatic pump 1 can be overcome with the pump 20 such 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 pump 20 to the prior art pump of FIG. 1 one 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 tube 28 is connected to piston 48 of liner actuator 22 and is restricted only to the amount of linear travel. The shaft or piston 48 passes through the outer housing 52 and reciprocates along axis 54 through the housing 52. The linear actuator 22 preferably has an axis 54 which is parallel to the reciprocating axis 30 if not colinearly disposed there along. The rotation axis 56 is preferably parallel to the liner actuator axis 54.

For some embodiments the motor may have shaft 44 extend from motor 24 oppositely oriented relative to the piston 48 extending from linear actuator 22. The gear box 26 is helpful to minimize the footprint of the motor 24 and pump 20 combination.

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.

Claims

1. A double diaphragm pump characterized by opposing first and second fluid chambers which selectively receive input from an inlet and discharge output from an outlet, with the fluid chambers respectively acted upon by respective diaphragms in an alternating manner whereby when the first chamber is filling with input, the second chamber is discharging output, and when the first chamber is discharging output, the second chamber is filling with input, the improvement comprising: a linear actuator connected to a thrust tube, whereby the thrust tube is connected to the diaphragms of the first and second fluid chambers and the linear actuator is restricted to linear motion along an axis thereby driving the thrust tube in reciprocating linear motion.

2. The pump of claim 1 further comprising a motor having a rotating shaft operably coupled to the linear actuator instigating the reciprocating linear motion of the linear actuator.

3. The pump of claim 2 further comprising a gear box intermediate the motor and the linear actuator.

4. The pump of claim 3 whereby the gear box increases torque from the motor as applied to the linear actuator.

5. The pump of claim 4 wherein the motor is a servo motor.

6. The pump of claim 3 wherein a drive shaft of the motor extends in a direction oppositely oriented relative to a piston extending from the linear actuator.

7. The pump of claim 1 wherein the linear actuator has threads which selectively drive a piston linearly along the axis.

8. The pump of claim 7 wherein the piston is connected to the thrust tube.

9. The pump of claim 7 wherein the threads are a portion of a precision lead screw.

10. The pump of claim 9 wherein the precision lead screw has a rotation axis and the rotation axis is parallel to a reciprocation axis of the thrust tube.

11. The pump of claim 1 driven by a controller.

12. The pump of claim 11 wherein the controller is one of a programmable logic controller (PLC) and a human machine interface (HMI).

13. The pump of claim 11 wherein the controller directs at least one of stroke, speed and cycles.

14. The pump of claim 11 wherein the controller permits adjustment of at least one of stroke, speed and cycles by an operator.

15. The pump of claim 11 wherein the controller provides feedback to an electric data acquisition system.

16. The pump of claim 1 wherein the axis is parallel to a reciprocation axis of the thrust tube.

17. The pump of claim 16 wherein the axis is colinear with the reciprocation axis.