Reciprocating pump with electronically monitored air valve and piston

Abstract

An air operated pump 10 uses a magnet 14 mounted in the valve cup 16 of the air motor 18 and two reed sensors 20 mounted in the valve cover 22 to monitor the speed and position of the valve 16. A solenoid 24 is mounted on the valve cover 22 and can be commanded to extend a plunger 26 into the valve cup 16 to stop valve movement and therefore the pump from running away A magnetoresistive sensor 34 is located in the center of the air motor 18 to precisely monitor the piston 36 position and with air valve sensors 20 provides the input necessary for precise control and diagnostics of the pump 10 and makes it suitable for metering and plural component application.

Description

BACKGROUND

Air-operated reciprocating piston pumps are well known for the pumping of various fluids. Such pumps typically have mechanically or pneumatically operated air valves to control the flow of air to the two sides of the piston. Control of such pumps has traditionally been by monitoring and controlling the resulting fluid flow rather than the pump itself. Prior art devices such as Graco's EXTREME-MIX™ proportioner have monitored the position of the piston for purposes of control.

SUMMARY

It is therefore an object of this invention to provide a system which allows enhanced monitoring and control of a reciprocating air motor so as to allow monitoring of piston position, cycle and flow rates, total cycles, runaway control and the ability to diagnose failing air motor and pump lower components.

The control uses a magnet mounted in the valve cup of the air motor and two reed sensors mounted in the valve cover to monitor the speed and position of the valve. A solenoid is mounted on the valve cover and can be commanded to extend a plunger into the valve cup to stop valve movement and therefore the pump from running away (typically caused by the fluid supply being empty.) The user interface comprises an LCD and buttons to set up and control the pump. The display can be toggled to display cycle rate, flow rate (in various units), total cycles and diagnostic errors. Setup parameters can include fluid units (quarts, liters, etc.) and the runaway set point.

The reed switches and magnets are located so as to detect when the air valve is at the extreme position of each stroke or in transition or both. The controller calculates the rate at which the motor is running by counting the opening and closing of the reed switches activated by the varying positions of the air valve. The controller then compares that rate to a pre-programmed value to determine if the air motor is in a runaway condition. When that condition is present, the controller activates the solenoid preventing changeover which stops the motor. This acts to prevent spilled fluid and/or pump damage.

A magnetoresistive sensor is located in the center of the air motor to precisely monitor the piston position. The data from this sensor in conjunction with that from the air valve sensors provides the input necessary for precise control and diagnostics of the pump and makes it suitable for metering and plural component application.

The controller of the instant invention can use information from the linear transducer for feedback to the air pressure (or fluid pressure if hydraulic) to control the flow volume and rate by controlling shaft displacement and velocity. This feedback may be used in either a simple meter dispense system with one fluid or a two (or more) component system where the feedback is used to maintain flow, pressure and ratio.

These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section of the air valve as part of the instant invention showing the magnets and reed switches.

FIG. 2 shows a detail of the FIG. 1 cross-section of the air valve as part of the instant invention.

FIG. 3 shows a cross-section (opposite that of FIG. 1) of the air valve as part of the instant invention showing the solenoid.

FIG. 4 shows a view of a pump incorporating the instant invention.

FIG. 5 shows a detail of the user interface of the instant invention.

FIG. 6 shows the diagnostic codes which may be obtained by sensing the air valve.

FIG. 7 shows the piston and magnetoresistive sensor.

FIG. 8 shows a black diagram including a piston pump, controller, air motor, pressure regulator, and supply.

DETAILED DESCRIPTION

In an air-operated reciprocating piston pump 10, the controller 12 uses a magnet 14 mounted in the valve cup 16 of the air motor 18 and two reed sensors 20 mounted in the valve cover 22 to monitor the speed and position of the valve 16. A solenoid 24 is mounted on the valve cover 22 and can be commanded to extend a plunger 26 into the valve cup 16 to stop valve movement and therefore the pump 10 from running away (typically caused by the fluid supply being empty or the hose of other supply conduit having a leak/rupture.) The user interface 28 comprises an LCD display 30 and buttons 32 to set up and control the pump 10. The display 30 can be toggled to display cycle rate, flow rate (in various units), total cycles and diagnostic errors. Setup parameters can include fluid units (quarts, liters, etc.) and the runaway set point.

The reed switches 20 and magnets 14 are located so as to detect when the air valve 16 is at the extreme position of each stroke or in transition or both. The controller 12 calculates the rate at which the motor 18 is running by counting the opening and closing of the reed switches 20 activated by the varying positions of the air valve 16. The controller 12 then compares that rate to a pre-programmed value to determine if the air motor 18 is in a runaway condition. If that condition is present, the controller 12 activates the solenoid 24 preventing changeover which stops the motor 18. This acts to prevent spilled fluid and/or pump damage.

A magnetoresistive sensor 34 is located in the center of the air motor 18 to precisely monitor the piston 36 position. The data from this sensor 34 in conjunction with that from the air valve sensors 20 provides the input necessary for precise control and diagnostics of the pump 10 and makes it suitable for metering and plural component application.

The controller 12 of the instant invention seen in FIG. 8 can use information from the linear transducer for feedback to the air pressure (or fluid pressure if hydraulic) to control the flow volume and rate by controlling shaft displacement and velocity. Such can be done via an air pressure regulator 40 which modulates a supply 42 of pressurized air (or hydraulic fluid). This feedback may be used in either a simple meter dispense system with one fluid or a two (or more) component system where the feedback is used to maintain flow, pressure and ratio.

It is contemplated that various changes and modifications may be made to the pump control without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1. A pump system comprising: a fluid pump;a reciprocating air motor that is connected to the fluid pump for driving the fluid pump, the reciprocating air motor including a piston and an air valve;a plurality of sensors that produce signals indicative of air valve operation and piston position;a user interface having inputs for receiving setup parameters and having a display that displays monitored operating parameters; anda controller that controls operation of the reciprocating air motor based upon the setup parameters from the inputs of the user interface and the signals from the plurality of sensors and controls the display to display at least one of: a diagnostic message indicating a runaway condition based upon the signals from the plurality of sensors and the runaway set point when the speed of the pump exceeds the runaway set point for a predetermined number of cycles;a diagnostic message indicating that the piston is travelling twice as fast on an upstroke as it is on a downstroke when signals from the plurality of sensors indicate that the speed of the piston is twice as fast on an upstroke as it is on a downstroke; ora diagnostic message indicating that the piston is travelling twice as fast on a downstroke as it is on a upstroke when the signals from the plurality of sensors indicate that the speed of the piston is twice as fast on a downstroke as it is on a upstroke.

2. The pump system of claim 1, wherein the setup parameters include a runaway set point.

3. The pump system of claim 1, and further comprising: a solenoid actuated by the controller to extend a plunger into the air valve when a runaway condition has occurred, to stop movement of the air valve.

4. The pump system of claim 3, wherein the controller causes the display to display a diagnostic message if the solenoid fails to operate properly.

5. The pump system of claim 1, wherein the diagnostic message includes at least one of a diagnostic code and a picture depicting a condition indicated by the diagnostic code.

6. The pump system of claim 1 wherein the operating parameters include at least one of cycle rate, flow rate, total cycles and diagnostic errors.

7. The pump system of claim 1 wherein the plurality of sensors includes a linear transducer for sensing position of the piston.

8. The pump system of claim 7 wherein the linear transducer comprises a magnetoresistive sensor.

9. The pump system of claim 1, wherein the controller utilizes information from the linear transducer to control air pressure input to the air motor.

10. The pump system of claim 1, wherein the controller utilizes information from the linear transducer to control air pressure input to the air motor.

11. A pump system comprising: a fluid pump;a reciprocating air motor that is connected to the fluid pump for driving the fluid pump, the reciprocating air motor including a piston and an air valve that moves between extreme positions;a plurality of sensors that produce signals indicative of air valve operation and piston position;a solenoid configured to extend a plunger into the air valve upon receiving an actuation command and to retract the plunger upon receiving a retract command;a user interface having inputs for receiving setup parameters including a runaway set point and a display that displays monitored operating parameters; anda controller that issues an actuation command and a retract command to the solenoid, controls operation of the reciprocating air motor based upon the setup parameters from the inputs of the user interface and the signals from the plurality of sensors, and controls the display to display at least one of: a diagnostic message indicating that the air motor continues to reciprocate when the solenoid has been commanded to extend the plunger into the air valve and the controller determines, based on signals indicative of air valve operation and piston position, that the air motor continues to reciprocate;a diagnostic message indicating that the plunger has failed to extend when the controller has commanded the solenoid to extend the plunger and the controller determines, based on signals indicative of air valve operation and piston position, that no extension of the plunger has occurred; ora diagnostic message indicating that the plunger has failed to retract when the controller has commanded the solenoid to retract the plunger and the controller determines, based on signals indicative of air valve operation and piston position, that the plunger has not retracted.

12. The pump system of claim 11, wherein the diagnostic message includes at least one of a diagnostic code and a picture depicting a condition indicated by the diagnostic code.

13. The pump system of claim 11, wherein the operating parameters include at least one of cycle rate, flow rate, total cycles and diagnostic errors.

14. The pump system of claim 11, wherein the plurality of sensors includes a linear transducer for sensing position of the piston.

15. The pump system of claim 14, wherein the linear transducer comprises a magnetoresistive sensor.