FLEXIBLE LANCE DRIVE APPARATUS WITH AUTOSTROKE FUNCTION

Abstract

An apparatus for sensing an obstruction within a tube being cleaned and repetitively advancing and retracting a flexible high pressure fluid cleaning lance within the tube is disclosed. The method includes sensing a pneumatic supply pressure to a pneumatic lance drive motor at the motor during forward operation, sensing a pneumatic discharge pressure at the drive motor during forward operation, determining a difference between the pressures, comparing the difference to a predetermined difference threshold; reversing the drive motor direction for a predetermined time interval if the difference exceeds the threshold, and restoring forward operation after the predetermined time interval; and repeating the reversing and restoring operations until the difference no longer exceeds the predetermined difference threshold.

Claims

1. A flexible lance drive apparatus comprising: a generally rectangular housing having an array of upper and lower drive rollers in an outer section each rotatably supported by an axle shaft passing laterally through spaced outer and inner walls defining a mid section of the housing; a drive motor within the mid section of the housing connected to each of the upper and lower drive rollers; wherein each lower drive roller shaft is rotatably supported in a fixed position and the upper rollers may be lowered against the lower rollers via a pneumatic cylinder to sandwich a flexible lance therebetween; a control console connected to the drive motor via forward and reverse pneumatic pressure supply lines, the console having forward and reverse manual controls for directing pneumatic pressure to forward and reverse ports of the drive motor; and a solenoid valve connected across the forward and reverse pressure lines operable to reverse pneumatic pressure connections to the drive motor when energized; and an automatic blockage sensor circuit having pneumatic sensing lines connected directly at the forward and reverse ports on the drive motor, wherein the circuit is operable to sense a drive motor pressure differential between the ports above a predetermined threshold and energize the solenoid valve to reverse the pneumatic pressure supply lines to the drive motor.

2. The apparatus according to claim 1 wherein the solenoid valve is operable only when the forward manual control is supplying pneumatic pressure to the drive motor.

3. The apparatus according to claim 1 wherein the automatic blockage sensor circuit comprises a first pressure transducer connected to a forward side of the drive motor and a second pressure transducer connected to a reverse side of the drive motor and a microcontroller configured to monitor a differential pressure between the transducers to determine the predetermined threshold.

4. A flexible lance hose drive apparatus for propelling at least one high pressure flexible lance hose into and out of at least one heat exchanger tube to be cleaned, the apparatus comprising: a generally rectangular housing having an array of drive rollers therein; a pneumatic drive motor within the housing connected to each of the drive rollers; a control console remote from the housing connected to the drive motor via forward and reverse pneumatic pressure supply lines, the console having forward and reverse manual controls for directing pneumatic pressure to forward and reverse ports of the drive motor; and a solenoid valve connected across the forward and reverse pressure lines operable to reverse pneumatic pressure connections to the hose drive motor when energized; and an automatic blockage sensor circuit having pneumatic sensing lines connected directly to the forward and reverse ports on the hose drive motor, wherein the circuit is operable to sense a drive motor pressure differential between the ports above a predetermined threshold and energize the solenoid valve to reverse the connection of pneumatic pressure supply lines to the drive motor to reverse movement of the flexible lance for a predetermined period of time.

5. The apparatus according to claim 4 wherein the automatic blockage sensor circuit performs operations of: sensing a pneumatic supply pressure to the pneumatic lance drive motor at the drive motor during forward operation; sensing a pneumatic pressure at an opposite side of the drive motor at the drive motor during forward operation; determining a difference between the pressures; comparing the difference to a predetermined difference threshold; reversing the supply line connections to the drive motor so as to reverse drive motor direction for the predetermined period of time if the difference exceeds the threshold; restoring the supply line connections after the predetermined period of time; and repeating the sensing, determining, comparing, reversing and restoring operations until the difference no longer exceeds the predetermined difference threshold.

6. The apparatus according to claim 5 wherein the predetermined time interval is adjustable.

7. The apparatus according to claim 5 wherein the predetermined threshold is adjustable.

8. The apparatus according to claim 4 wherein reversing and restoring is controlled by a microcontroller operated switch.

9. The apparatus according to claim 8 wherein the switch actuates a solenoid valve connecting the pneumatic supply connections to the drive motor.

10. An automatic blockage sensor apparatus for use with a flexible high pressure cleaning lance drive motor comprising: a first pressure sensor connected to a first directional side of a bidirectional lance drive motor operable to produce a first electrical pressure signal; a second pressure sensor connected to a second directional side of the bidirectional lance drive motor operable to produce a second electrical signal; and a control circuit operable to compare the first and second electrical signals, generate an output if the difference between the first and second signals exceeds a predetermined threshold, causing pneumatic pressure to the bidirectional lance drive motor to reverse direction.

11. The apparatus according to claim 10 wherein the first directional side is a forward direction of the lance drive motor.

12. The apparatus according to claim 11 wherein the control circuit includes a microcontroller generating the output and the output closes a switch in a solenoid valve power circuit.

13. The apparatus according to claim 10 further comprising a sensitivity adjustment control for setting the threshold pressure differential.

14. The apparatus according to claim 13 further comprising a reversal duration control connected to the microcontroller for setting a duration for the reverse direction.

15. An automatic blockage sensor apparatus for use with a flexible high pressure cleaning lance drive motor comprising: a first pressure sensor connected via a sensing line directly to a forward port of a bidirectional lance drive motor operable to produce a first electrical pressure signal; a second pressure sensor connected via a sensing line directly to a reverse port of the bidirectional lance drive motor operable to produce a second electrical signal; and a control circuit operable to compare the first and second electrical signals, generate an output if the difference between the first and second signals exceeds a predetermined threshold, and cause the bidirectional lance drive motor to reverse direction.

16. The apparatus according to claim 15 wherein the control circuit includes a switch operated by the output to actuate solenoid valve directing pneumatic supply pressure to the lance drive motor.

17. The apparatus according to claim 15 wherein the control circuit includes a microcontroller for generating the output.

18. A flexible lance drive apparatus comprising: a pneumatic drive motor operating a plurality of drive rollers to move one or more flexible lances into and out of a conduit to be cleaned; a control console located remotely from the drive motor, the control console being connected to the drive motor via forward and reverse pneumatic pressure supply lines, the console having forward and reverse manual controls for directing pneumatic pressure to forward and reverse ports of the drive motor; a solenoid valve connected across the forward and reverse pressure lines operable to reverse pneumatic pressure connections to the drive motor when energized; and an automatic blockage sensor circuit having pneumatic sensing lines connected directly to forward and reverse ports on the drive motor, wherein the circuit is operable to sense a drive motor pressure differential between the ports above a predetermined threshold and energize the solenoid valve to reverse the pneumatic pressure supply lines to the drive motor.

19. The apparatus according to claim 18 wherein the solenoid valve is energizable only when the forward manual control is supplying pneumatic pressure to the drive motor.

20. The apparatus according to claim 18 wherein the automatic blockage sensor circuit comprises a first pressure transducer connected to a forward port on the drive motor and a second pressure transducer connected to a reverse port on the drive motor and a microcontroller configured to monitor a differential pressure between the transducers to determine the predetermined threshold.

Description

DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a perspective view of a flexible lance drive apparatus in accordance with the present disclosure.

[0012] FIG. 2 is a diagram of the pneumatic connections between a remote operator's control console and the drive apparatus shown in FIG. 1.

[0013] FIG. 3 is a schematic electrical and pneumatic control diagram of the apparatus shown in FIG. 2.

DETAILED DESCRIPTION

[0014] An exemplary drive apparatus 100 incorporating an automatic blockage sensor in accordance with the present disclosure is shown in FIG. 1 with a side cover open showing the set of 3 pairs of drive rollers 102 arranged for driving two flexible lances 104 in accordance with one embodiment of the present disclosure. The apparatus 100 includes a housing 106 in which a drive motor 108 drives each of the six drive rollers 102. FIG. 1 shows a drive apparatus 100 supported for guiding one or more flexible lance hoses 104 into and out of a tube in a tube sheet 110. The drive apparatus 100 is typically mounted on a flexible lance guide 117 which is fastened to a frame 119 that places the drive apparatus 100 in alignment with the tubes penetrating the tube sheet 110.

[0015] The drive apparatus 100 is pneumatically remotely controlled via a control console 200, as shown in FIG. 2, carried by or positioned adjacent to an operator (not shown) standing a safe distance from the apparatus 100. Attached to the control console 200 is an automatic blockage sensing control circuit box 220. This automatic blockage sensing control circuit box 220 houses an electronic monitoring circuit that monitors air motor pressure at the air motor 108 in the drive apparatus 100 shown in FIG. 1 and controls a solenoid valve also located in or adjacent to the box 220 as will be described more fully below.

[0016] The operator preferably can stand about 20-40 feet from the drive apparatus 100. The operator pneumatic control console 200, shown in FIG. 2, in accordance with the present disclosure connects to an air pressure supply source line (not shown) and includes a forward line 202 connected to the air motor 108 in the drive apparatus 100, a retract, or reverse, line 204 connected to the air motor 108, and a clamp air line (not shown) that connects to an air cylinder in the housing 106 in the apparatus 100 for adjusting clamp pressure of the row of upper rollers 102 on the lance(s) 104.

[0017] A pair of pressure sensing lines 208 and 210 is connected directly to the forward and reverse ports on the motor 108 in the apparatus 100. These sensing lines 208 and 210 connect to a pair of pressure transducers 212 and 214 mounted in the control box 220 shown in the schematic diagram shown in FIG. 3. Each pressure transducer 212 and 214 produces an electrical signal, either current or voltage, proportional to the pressure sensed at its particular side of the air motor 108.

[0018] The automatic blockage sensing control box 220 includes a microcontroller 222 that utilizes the forward pressure signal from transducer 212 to determine when to institute an autostroke cycle or event. More precisely, the microcontroller 222 utilizes the signals from both transducer 212 and 214 to compute a pressure differential. When the pressure differential exceeds a threshold value the autostroke event is triggered. When the pressure difference between the applied air pressure in the forward direction through line 202 sensed at the air motor 108 and the pressure sensed at the reverse port at the air motor 108 increases to a predetermined value indicative of high torque caused by the nozzles encountering a restriction or blockage in the tube(s) being cleaned, the microcontroller 222 produces an output on lines A1-A2 which closes a switch 224 to apply 12 volts DC to a solenoid valve 226 through which the forward and reverse lines 202 and 204 are connected. This switch 224 is preferably a solid state transistor switch. When the solenoid valve 226 is energized, the ports within the valve 226 redirect the forward air motor pressure to the opposite (reverse) side of the air motor 108. After a predetermined period of motor reversal, the solenoid valve 226 is de-energized and the forward air pressure restored to the forward port of the motor 108, at which time forward lance movement resumes if the operator is still pressing the forward control button. If the obstruction is again met, motor pressure again increases as the motor bogs down, and the process repeats.

[0019] The automatic blockage sensor control box 220 has two potentiometers 228 and 230. Potentiometer 228 is used to adjust the threshold pressure differential at which the microcontroller 222 will close the switch 224 to energize the solenoid 226, and thereby direct forward drive pneumatic pressure to the reverse port of the air motor 108. The potentiometer 230 is used to adjust the length of time that pneumatic pressure is diverted to the reverse direction of air motor 108, and hence the lance retraction distance before air pressure is restored to the forward direction of the air motor 108.

[0020] The microcontroller 222 continually monitors and compares this threshold to the sensed forward pressure via transducer 212. If the pressure difference rises above the threshold, an autostroke event is triggered. When this occurs while the operator is holding the Hose Feed control in the forward direction, the microcontroller 222 actuates the solenoid valve 226 which reverses the pneumatic pressure connection from the forward feed line 202 to the reverse line 204. This solenoid valve 226 is a 5-way two position valve that is internally piloted. The forward air hose 202 is connected to the pressure port of the valve 226 and the reverse air hose 204 is teed to both of the exhaust ports on the valve which effectively makes valve 226 a 4 way valve. Because the solenoid valve 226 is internally piloted, it will only shift when the operator is driving the drive apparatus 100 forward.

[0021] FIG. 3 is a composite schematic of the pneumatic system between the separate control console 200 and the drive apparatus 100, and incorporates, in the dashed portion, the electronic circuitry within the automatic blockage sensor control box 220. The solenoid valve 226 may be mounted within the control box 220 or it may be mounted separately between the control box 220 and the drive apparatus 100. Alternatively the control box 220 and the solenoid valve 226 could be integrated completely into the housing of the drive apparatus 200.

[0022] In FIG. 3, the power source 232 is shown as being 12 volts DC. Other supply voltages may be utilized depending on the requirements of the microcontroller 222 and the solenoid valve 226. Furthermore, the power source 232 may be a battery, a series of batteries, or, for example, a pneumatic/electric generator appropriately selected according to the power requirements of the solenoid valve 226 and the microcontroller 222. An on-off switch 234 is also provided in series with the power source 232 to remove the autostroke functionality when not desired.

[0023] Many variations are envisioned as within the scope of the present disclosure. For example, all components of the control box 220 may be physically housed within the control console 200. Alternatively, the components within the control box 220 could be integrated into the drive apparatus 100. In alternative embodiments, electrical or hydraulic actuators and motors may be used in place of the pneumatic motors shown and described. Therefore, all such changes, alternatives and equivalents in accordance with the features and benefits described herein, are within the scope of the present disclosure. Such changes and alternatives may be introduced without departing from the spirit and broad scope of this disclosure as defined by the claims below and their equivalents.