HK1249877A1 - Flexible lance drive apparatus with autostroke function - Google Patents

Description

Flexible spray gun driving device with automatic stroke function

Technical Field

The present disclosure is directed to a high pressure fluid rotary nozzle operating system. In particular, embodiments of the present disclosure are directed to such an apparatus for advancing and retracting one or more flexible tube cleaning lances from a position adjacent to a heat exchanger tube sheet relative to tubes arranged in an array, for example, in a heat exchanger, and automatically and repeatedly reversing the forward (forward) feed motion of the lances upon encountering an obstruction within the tubes or other piping system being cleaned.

Background

One conventional tube blowing system consists of a rotating reel flexible lance hose reel and hose dispensing device that carries a predetermined length of flexible lance hose wound around a drum. A spool in the drum is rotated by a pneumatic motor to push a flexible lance out of the drum and into one or both heat exchanger tubes. The pneumatic motor drive may be automatically reversed upon pneumatically sensing a large increase in air pressure supplied to the forward side of the motor that would occur if the flexible lance being propelled due to rotation of the spool encountered an obstruction within the pipe being cleaned. In this case, when such a pressure increase is sensed, a pneumatically operated valve connected to the pneumatic motor drive shuts off air to the forward side of the pneumatic motor and supplies air to the opposite side of the pneumatic motor. The pneumatic motor is reversed to retract the lance a predetermined time/distance. This automatic reversal of the pneumatic motor drive can then be repeated until the obstruction in the tube is cleared. In this way, the flexible lance "pecks" at a restriction or obstruction within the tube until the undesirable pressure increase is no longer sensed (indicating that the obstruction has been cleared). Such drum and reel arrangements must necessarily be located somewhat remote from the heat exchanger tube sheet in order to accommodate the size of the drum and the air motor drive.

One problem with this approach is that: the air pressure increases significantly (almost causing the flexible lance within the tube to stall) so that the air pressure increases sufficiently to trigger the reversal. Furthermore, if the flexible lance is far inside the tube being cleaned, the length of the hose inside the tube creates a resistance against the positive pneumatic motor supplying pressure that propels the hose and through the tube, which itself may increase the air supply pressure without actually stalling the lance. Thus, a sufficient pressure change may occur to trigger the reversal without the lance actually encountering an obstacle. Furthermore, the forward air pressure supplied to the air motor in the forward direction in typical industrial cleaning operations often varies greatly, so that conventional systems are prone to fraudulent pneumatic pressure spikes and, therefore, frequent reversals. This is undesirable. There is therefore a need for an apparatus and method for reliably and accurately detecting a restriction within a conduit of a heat exchanger tube or other piping system being cleaned.

Disclosure of Invention

The flexible lance drive apparatus and automatic blockage sensor according to the present disclosure directly address these needs. One exemplary embodiment of the flexible lance drive apparatus according to the present disclosure includes a generally rectangular housing having an array of upper and lower drive rollers in an outer portion, each drive roller rotatably supported by a drive shaft passing laterally through both separate outer and inner walls defining a middle portion of the housing. A pneumatic drive motor is housed within the middle portion of the housing and is connected to each of the upper and lower drive rollers. Each lower drive roller shaft is rotatably supported at a fixed position and the upper drive roller is capable of being lowered relative to the lower drive roller by an air cylinder to nip the flexible spray gun between the upper and lower drive rollers. Such a drive means may be positioned near the inlet to the piping system to be cleaned, for example mounted to a frame fixed to the tube sheet of the heat exchanger tube bundle.

The console is connected to the drive motor and cylinder in the drive means by positive and negative pneumatic pressure supply lines so that the operator can stand at the console remote from the drive means, thus avoiding high pressure water jets from the device during operation. The console has forward and reverse manual controls for directing pneumatic pressure through pneumatic lines to the forward and reverse sides of the drive motor. In this embodiment, a four-way solenoid valve is connected across the positive and negative pressure lines adjacent the console. The four-way solenoid valve is operable to reverse the pneumatic pressure connection to the drive motor when energized.

In an exemplary embodiment, an automatic jam sensing circuit is mounted within or attached to the console remote from the lance drive. In other embodiments, the automatic occlusion sensing circuit may be housed within the drive device itself. Such circuitry is operable to sense an increase in drive motor pressure differential above a predetermined threshold at the pneumatic drive motor and energize the four-way solenoid valve to reverse the pneumatic pressure line connection to the drive motor when this occurs. This function of the automatic jam sensing circuit and the four-way solenoid valve can only be operated when the forward manual control at the console is supplying pneumatic pressure to the drive motor.

The automatic occlusion sensing circuit includes a first pressure sensor connected to a forward air port of the drive motor and a second pressure sensor connected to a reverse air port of the drive motor by a sense line directly connected to the drive motor, and a microcontroller configured to monitor a pressure differential between the sensors, the microcontroller comparing the pressure differential to a predetermined threshold and generating a current output when the threshold is exceeded.

The present disclosure also describes a method of automatically clearing an obstruction encountered when cleaning one or more tubes in a tube sheet of a heat exchanger with a flexible lance drive apparatus having a linear array of drive rollers that push one or more flexible lances into the one or more tubes. The method comprises the following steps: sensing a pneumatic supply pressure applied to the pneumatic lance drive motor at the pneumatic lance drive motor during forward operation; sensing pneumatic pressure on an opposite side of the drive motor during forward operation; determining a pressure difference between the pressures; comparing the pressure difference to a predetermined difference threshold; when the pressure difference exceeds a threshold value, the supply line connection to the drive motor is reversed so as to reverse the direction of the drive motor for a predetermined time interval. The method may include restoring the supply line connection after a predetermined time interval; and repeating the sensing, reversing, and restoring operations until the pressure differential no longer exceeds the predetermined differential threshold.

Further features, advantages, and characteristics of embodiments of the present disclosure will become apparent by reading the following detailed description with reference to the drawings.

Drawings

Fig. 1 is a perspective view of a flexible lance drive according to the present disclosure.

FIG. 2 is a schematic view of the pneumatic connection between the remote operator console and the drive arrangement shown in FIG. 1.

Fig. 3 is a schematic diagram of the electrical and pneumatic control of the apparatus shown in fig. 2.

Detailed Description

An exemplary drive arrangement 100 including an automatic jam sensor according to the present disclosure is shown in fig. 1 with a side cover open, showing a set of three pairs of drive rollers 102 arranged to drive two flexible spray guns 104 according to an exemplary embodiment of the present disclosure. The drive device 100 includes a housing 106 in which a drive motor 108 drives each of the six drive rollers 102. FIG. 1 shows a drive arrangement 100 supported to introduce and withdraw one or more flexible lance hoses 104 into and out of tubes in a tube sheet 110. The drive 100 is typically mounted to a flexible lance guide 117, the flexible lance guide 117 being secured to a frame 119 that places the drive 100 in alignment with the tubes penetrating the tube sheet 110.

As shown in fig. 2, the drive device 100 is pneumatically remotely controlled through a console 200 carried by or located adjacent to an operator (not shown) standing at a safe distance from the device 100. An automatic jam sensing control circuit box 220 is attached to the console 200. This automatic jam sensing control circuit box 220 houses an electronic monitoring circuit that monitors the pneumatic motor pressure at the pneumatic motor 108 in the drive device 100 shown in fig. 1 and controls a solenoid valve also located in or near the circuit box 220, as will be described in more detail below.

The operator may preferably stand approximately twenty to forty feet from the drive 100. As shown in fig. 2, an operator pneumatic console 200 according to the present disclosure is connected to an air pressure supply line (not shown) and includes a forward line 202 connected to the pneumatic motor 108 in the drive device 100, a retract or reverse line 204 connected to the pneumatic motor 108, a clamping air line (not shown) connected to an air cylinder in the housing 106 in the drive device 100 for adjusting the clamping pressure of the upper row of rollers 102 on the spray gun 104.

A pair of pressure sensing lines 208 and 210 are connected directly to the forward and reverse ports on the motor 108 in the device 100. These sense lines 208 and 210 are connected to pressure sensors 212 and 214 mounted in a control box 220, as shown in the schematic diagram shown in fig. 3. Each pressure sensor 212 and 214 generates an electrical signal (current or voltage) that is proportional to the pressure sensed at a particular side of the air motor 108.

The automatic occlusion sensing control box 220 includes a microcontroller 222 that utilizes a positive pressure signal from the sensor 212 to determine when to initiate an automatic stroke cycle or event. More precisely, the microcontroller 222 uses the signals from the sensors 212 and 214 to calculate the pressure difference. When the pressure differential exceeds a threshold, an auto-stroke event is triggered. When the pressure differential between the pressure sensed at the air motor 108 applied in the forward direction through line 202 and the pressure sensed at the reverse port at the air motor 108 increases to a predetermined value indicative of high torque due to the nozzle encountering a restriction or blockage in the tube or tubes being cleaned, the microcontroller 222 generates an output on line a 1-a 2 that closes switch 224 to apply 12V of dc voltage to solenoid valve 226, connecting the forward line 202 and the reverse line 204 through solenoid valve 226. This switch 224 is preferably a solid state transistor switch. When the solenoid valve 226 is energized, a port within the solenoid valve 226 redirects the forward air motor pressure to the opposite side (reverse side) of the air motor 108. After the motor is reversed for a predetermined period of time, the solenoid valve 226 is de-energized and the forward pneumatic pressure is restored to the forward port of the motor 108, at which point forward (forward) movement of the spray gun resumes if the operator is still pressing the forward control button. If the obstruction is encountered again, the motor pressure increases again as the motor stalls, and the process described above is repeated.

The automatic occlusion sensing control box 220 has two potentiometers 228 and 230. The potentiometer 228 is used to adjust the pressure differential threshold, upon which the microcontroller 222 will close the switch 224 to energize the solenoid valve 226 and thereby direct the forward driving pneumatic pressure to the reverse port of the pneumatic motor 108. The potentiometer 230 is used to adjust the length of time that pneumatic pressure is diverted to the reverse direction of the pneumatic motor 108 and, thus, the distance the lance is retracted before pneumatic pressure is restored to the forward direction of the pneumatic motor 108.

The microcontroller 222 continuously monitors this threshold and compares it to the forward pressure sensed by the sensor 212. If the pressure differential rises above a threshold, an auto-stroke event is triggered. When this occurs while the operator is maintaining the "hose feed" control in the forward direction, the microcontroller 222 actuates the solenoid valve 226, which solenoid valve 226 reverses the pneumatic pressure connection from the forward supply line 202 to the reverse line 204. The solenoid valve 226 is an internally controlled five-way two-position valve. The forward air hose 202 is connected to the pressure port of the valve 226 and the reverse air hose 204 is placed in two exhaust ports on the valve 226, which in effect makes the valve 226 a four-way valve. Since the solenoid valve 226 is internally controlled, it will only be indexed when the operator is driving the drive 100 forward.

Fig. 3 is a combined schematic of the pneumatic system between the separate console 200 and the drive device 100, and includes the electronic circuitry within the automatic jam sensing control box 220 in phantom. The solenoid valve 226 may be installed in the control box 220 or it may be separately installed between the control box 220 and the driving device 100. Alternatively, the control box 220 and the solenoid valve 226 may be completely integrated into the housing of the drive device 100.

In fig. 3, power supply 232 is shown as 12V dc. Other supply voltages may be used as required by microcontroller 222 and solenoid valve 226. Further, the power source 232 may be a battery, a set of batteries, or a pneumatic/motor generator suitably selected, for example, based on 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 supply 232 to shut off the automatic stroke function when not needed.

Many variations are envisioned within the scope of the disclosure. For example, all of the components of the control box 220 may be physically housed within the console 200. Alternatively, the components within the control box 220 may be integrated into the drive device 100. In alternative embodiments, electric or hydraulic actuators and motors may be used in place of the pneumatic motors shown and described. Accordingly, all such modifications, alterations and equivalents as may be in accordance with the features and advantages described herein are intended to be within the scope of this disclosure. Such changes and substitutions may be introduced without departing from the spirit and broad scope of the disclosure as defined by the following claims and their equivalents.

Claims (19)

1. A flexible lance drive apparatus comprising:

a generally rectangular housing having in an outer portion an array of upper and lower drive rollers, each drive roller rotatably supported by a drive shaft passing laterally through both a spaced outer wall and an inner wall defining a middle portion of the housing;

a drive motor within a middle portion of the housing and connected to each of the upper and lower drive rollers;

wherein the drive shaft of each lower drive roller is rotatably supported at a fixed position and the upper drive roller is capable of being lowered relative to the lower drive roller by an air cylinder to sandwich the flexible spray gun between the upper and lower drive rollers;

a console connected to the drive motor by a forward pneumatic pressure supply line and a reverse pneumatic pressure supply line, the console having a forward manual controller and a reverse manual controller for directing pneumatic pressure to the forward port and the reverse port of the drive motor; and

a solenoid valve connected across the forward pneumatic pressure supply line and the reverse pneumatic pressure supply line, the solenoid valve operable to reverse the pneumatic pressure connection to the drive motor when energized; and

an automatic occlusion sensing circuit having pneumatic sensing lines directly connected to a forward port and a reverse port on a drive motor, wherein the circuit is operable to sense that a drive motor pressure differential between the forward port and the reverse port is above a predetermined threshold and energize the solenoid valve to reverse a pneumatic pressure supply line to the pneumatic motor.

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

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

4. A method of automatically clearing an obstruction encountered in cleaning one or more tubes in a tube sheet of a heat exchanger with a flexible lance drive apparatus having an array of driven rollers that push one or more flexible lances into the one or more tubes, the method comprising:

sensing a pneumatic supply pressure applied to a pneumatic lance drive motor at the drive motor during forward operation;

sensing pneumatic pressure at the drive motor on an opposite side of the drive motor during forward operation;

determining a pressure difference between the pressures;

comparing the pressure difference to a predetermined difference threshold;

reversing the supply line connection to the drive motor when the pressure difference exceeds a threshold value, so as to reverse the direction of the drive motor for a predetermined time interval;

restoring the supply line connection after a predetermined time interval;

the sensing, determining, comparing, reversing, and restoring operations described above are repeated until the pressure differential no longer exceeds the predetermined differential threshold.

5. The method of claim 4, wherein the predetermined time interval is adjustable.

6. The method of claim 4, wherein the predetermined difference threshold is adjustable.

7. The method of claim 4, wherein the reversing and restoring operations are controlled by a microcontroller operated switch.

8. The method of claim 7, wherein the switch actuates a solenoid valve that connects a plurality of pneumatic supply connections to a drive motor.

9. An automatic blockage sensing device for a flexible high pressure cleaning spray gun drive motor comprising:

a first pressure sensor connected to a first directional side of the bidirectional lance drive motor and operable to generate a first electrical pressure signal;

a second pressure sensor connected to a second directional side of the bidirectional lance drive motor and operable to generate a second electrical pressure signal; and

a control circuit operable to compare the first and second electrical pressure signals and to generate an output when a difference between the first and second electrical pressure signals exceeds a predetermined threshold, thereby reversing the pneumatic pressure to the bidirectional lance drive motor.

10. The apparatus of claim 9, wherein the first directional side is a forward direction of the lance drive motor.

11. The apparatus of claim 10, wherein the control circuit comprises a microcontroller that generates the output and the output closes a switch in a solenoid power circuit.

12. The apparatus of claim 9, further comprising a sensitivity adjustment control for setting a threshold pressure differential.

13. The apparatus of claim 12, further comprising a reversal duration controller connected to the microcontroller for setting a duration of the reversal.

14. An automatic blockage sensing device for a flexible high pressure cleaning spray gun drive motor comprising:

a first pressure sensor directly connected to a forward port of the bidirectional lance drive motor by a sense line and operable to generate a first pressure electrical signal;

a second pressure sensor directly connected to a reverse port of the bidirectional lance drive motor by a sense line and operable to generate a second pressure electrical signal; and

a control circuit operable to compare the first and second electrical pressure signals and to generate an output when a difference between the first and second electrical pressure signals exceeds a predetermined threshold and to reverse the bidirectional lance drive motor.

15. The apparatus of claim 14, wherein the control circuit comprises a switch operated by the output to actuate a solenoid valve to direct pneumatic supply pressure to a lance drive motor.

16. The apparatus of claim 14, wherein the control circuit comprises a microcontroller for generating the output.

17. A flexible lance drive apparatus comprising:

a pneumatic drive motor operating a plurality of drive rollers to move one or more flexible spray guns into and out of a conduit to be cleaned;

a console located remotely from the drive motor, the console connected to the drive motor by a forward pneumatic pressure supply line and a reverse pneumatic pressure supply line, the console having a forward manual control and a reverse manual control for directing pneumatic pressure to a forward port and a reverse port of the drive motor;

a solenoid valve connected across the forward and reverse pneumatic pressure supply lines, the solenoid valve operable to reverse the pneumatic pressure connection to the drive motor when energized;

an automatic occlusion sensing circuit having a pneumatic sense line directly connected to a forward port and a reverse port on a drive motor, wherein the circuit is operable to sense that a drive motor pressure differential between the forward and reverse ports is above a predetermined threshold and energize the solenoid valve to reverse a pneumatic pressure supply line to the drive motor.

18. The apparatus of claim 17, wherein the solenoid valve can only be energized when the forward manual controller is supplying pneumatic pressure to the drive motor.

19. The device of claim 17, wherein the automatic occlusion sensing circuit comprises a first pressure sensor connected to a forward port on the drive motor, a second pressure sensor connected to a reverse port on the drive motor, and a microcontroller configured to monitor a pressure differential between the first pressure sensor and the second pressure sensor to determine the predetermined threshold.