Field of the Invention

[0001] The invention relates to a cleaning arrangement for a filter vessel. The invention also relates to a filter vessel with a cleaning arrangement.

Background

[0002] Filter vessels have filter elements for filtering water and cleaning elements for cleaning the filter elements when the filter elements become clogged with debris and contaminants. The cleaning elements include a cleaning shaft to which suction nozzles are mounted. The cleaning shaft is driven by an external electric motor or by an internal hydraulic rotor operated by flush water. During a cleaning operation, the electric motor or hydraulic rotor will rotate the cleaning shaft as the suction nozzles remove debris and contaminants from the filter elements.

[0003] Existing filter vessels that use an internal hydraulic rotor for rotating the cleaning shaft has a piston arrangement to move the cleaning shaft linearly relative to the filter elements. During a cleaning operation, a flush valve is opened which causes water to escape via the hydraulic rotor thereby causing the hydraulic rotor to rotate the shaft. At the same time as the rotation, the piston arrangement operates to move the shaft linearly relative to the filter elements. Thereby, the suction nozzles would move rotationally as well as linearly relative to the filter elements to provide a broader cleaning coverage of the filter elements.

[0004] A disadvantage with the existing filter vessels that use an internal hydraulic rotor is that they do not provide efficient, or any, cleaning at low internal pressures in the chamber. In low pressures, the hydraulic rotor would rotate slowly or not at all. As a result, in low internal pressures, cleaning can take more time or does not take place at all.

[0005] Filter vessels that use an external electric motor for rotating the cleaning shaft have limit switches for controlling the linear motion for the cleaning shaft. During a cleaning operation, the electric motor rotates the shaft clockwise and moves the shaft in a forward direction. When the shaft reaches the end of the path in the first direction, the shaft triggers one of the limit switches that causes the electric motor to operate in reverse to rotate the shaft counterclockwise and to move the shaft in a second (reverse) direction. When the shaft reaches the end of the path in the second direction, another one of the limit switches is triggered by the shaft that causes the electric motor to rotate the shaft clockwise and the move the shaft in the forward direction. Thereby, the suction nozzles would move rotationally as well as linearly relative to the filter elements to provide an increased cleaning coverage of the filter elements.

[0006] A disadvantage with the existing filter vessels that use an external electric motor is that the componentry involved for the cleaning operation make these existing vessels complex and expensive. The control system for controlling the cleaning operation is also complex and expensive because it needs to monitor the states of the limit switches and operate the electric motor in a clockwise and counterclockwise direction.

[0007] In this context, there is a need for a cleaning arrangement with reduced complexity. In addition, in the same context, there is a need for a cleaning arrangement that can operate independently of the internal pressures of the filter vessel chamber.

Summary of the Invention

[0008] According to an aspect of the present invention, there is provided a cleaning arrangement for a filter vessel, the cleaning arrangement including: a shaft adapted to be coupled to a cleaning element for cleaning the filter vessel, the shaft being rotatable about a central axis; an engagement feature for engaging the shaft to, upon rotation of the shaft in one direction about the central axis, guide the shaft to move reciprocatingly along the central axis; and a motor arrangement externally locatable to the filter vessel, the motor arrangement coupled to the shaft for rotating the shaft about the central axis.

[0009] The shaft can preferably move reciprocatingly along the central axis in one of a forward direction and a reverse direction. The shaft may have a shaft portion that is engageable by the engagement portion, the shaft portion having a rear point and a forward point with a range of linear motion for the shaft being defined between the rear point and the forward point. For example, upon rotating the shaft in the one direction, the shaft moves in a forward direction until the engagement portion reaches the rear point of the shaft portion. At that point, continued rotation of the shaft in the same one direction causes the shaft to move in the reverse direction until the engagement portion reaches the forward point of the shaft portion. At that point, further continued rotation of the shaft in the same one direction causes the shaft to move in the forward direction until the engagement portion reaches the rear point. The reciprocating movement of the shaft between the first direction and the second direction continues while the shaft rotates.

[0010] The cleaning element preferably has a plurality of cleaning arms distributed along the central axis, wherein a length of the shaft portion may correspond to a distance between adjacent cleaning arms. The length of the shaft portion is preferably a distance between the rear point and the forward point. The length of the shaft portion is preferably the equal to or greater than the distance between adjacent cleaning arms.

[0011] The one direction may be a clockwise direction. Alternatively, the one direction may be a counter-clockwise direction.

[0012] In one embodiment, the shaft includes a bi-directional thread and the engagement feature includes a follower for engaging the bi-directional thread. When the motor rotates the shaft, the bi-directional thread preferably rotates relative to the follower to cause the shaft to move reciprocatingly along the central axis.

[0013] The cleaning arrangement may further include a coupling body having a passage through which the shaft can pass. The coupling body preferably includes a port for containing the follower such that the follower, when contained by the port, engages the shaft that passes through the passage of the coupling body. The cleaning arrangement may further include a cover securable to the coupling body, the follower being located between the cover and the shaft.

[0014] In another embodiment, the engagement feature includes a bi-directional thread and the shaft includes a follower for engaging the bi-directional thread. When the motor rotates the shaft, the follower preferably moves along the bi-directional thread to cause the shaft to move reciprocatingly along the central axis. For example, the bi-directional thread is provided on an internal wall of a housing of the cleaning arrangement through which the shaft passes.

[0015] The cleaning arrangement may further include a housing, the shaft being located in the housing and being linearly moveable along the central axis in a first direction towards the filter vessel and in a second direction away from the filter vessel. The engagement feature may be located at a fixed location relative to the housing. Preferably, the housing has one end coupled to the filter vessel and an opposite end coupled to the motor. [0016] The motor arrangement may include an electric motor.

[0017] The motor arrangement may further include a drive head coupled to the housing, the drive head for receiving and, upon operation of the motor arrangement, rotating the shaft. The shaft is preferably moveable reciprocatingly along the central axis through the drive head.

[0018] According to another aspect of the present invention, there is provided a filter vessel including: a chamber having one or more filter elements; a cleaning element located in the chamber for cleaning the filter elements; and a cleaning arrangement including: a shaft coupled to the cleaning element, the shaft being rotatable in the chamber about a central axis; an engagement feature for engaging the shaft to, upon rotation of the shaft in one direction about the central axis, guide the shaft to move reciprocatingly along the central axis; and a motor arrangement externally located to the chamber, the motor coupled to the shaft for rotating the shaft about the central axis to thereby cause the shaft to move reciprocatingly along the central axis.

[0019] The cleaning arrangement may include the cleaning arrangement of the aspect previously described above or any of the features of that aspect.

[0020] According to another aspect of the present invention, there is provided a control system for controlling a cleaning operation of filter vessel, the filter vessel including a chamber having one or more filter elements; a cleaning element located in the chamber for cleaning the filter elements; and a cleaning arrangement including: a shaft coupled to the cleaning element, the shaft being rotatable in the chamber about a central axis; an engagement feature for engaging the shaft to, upon rotation of the shaft in one direction about the central axis, guide the shaft to move reciprocatingly along the central axis; and a motor arrangement externally located to the chamber, the motor arrangement coupled to the shaft for rotating the shaft about the central axis; the control system including: a processor configured to operate the motor arrangement to rotate the shaft in one direction which causes the shaft to move reciprocatingly along the central axis.

Brief Description of the Drawings

[0021] The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figures 1A and 1B show sectional views of the filter vessel and the cleaning arrangement according to an embodiment of the present invention in different configurations; and

Figures 2A and 2B show detailed sectional views of the cleaning arrangement of Figures 1 A and 1B respectively.

Detailed Description

[0022] Figures 1A and 1B illustrate a cleaning arrangement 100 for a filter vessel 200. The filter vessel 200 includes a chamber 220 in which cylindrical filter elements 240 are provided. Water to be filtered enters the filter vessel 200 through an inlet 202 of the chamber 220 and is filtered by passing radially through the cylindrical filter elements 240. Once filtered, the filtered water passes through an outlet 204 of the chamber 220. Over time, the filter elements 240 will become clogged with debris and contaminants, and will need to be cleaned.

[0023] The filter vessel 200 has a pressure sensing apparatus for sensing the pressure differential across the filter element 240. If the filter element 240 is not clogged, there would be no (or a minimal) pressure differential across the filter element 240. If the filter element 240 becomes clogged, there will be pressure drop across the filter element 240. Once the pressure differential reaches a predefined threshold, a control system of the filter vessel 200 triggers a cleaning operation of the filter elements 240 using a cleaning element 260. For example, the cleaning operation may be triggered when the pressure drop across the filter reaches about 40kPa to 50kPa. Other sensors, systems, or arrangements may be employed to trigger the cleaning operation.

[0024] The cleaning element 260 has a plurality of cleaning arms 262 distributed about a central axis C through the filter vessel 200. Each cleaning arm 262 includes a suction nozzle. The cleaning element 260 includes an elongate member 264 located on and along the central axis C on which the plurality of cleaning arms 262 are distributed. The cleaning arrangement 100 is coupled to the cleaning element 240 and drives the cleaning element 260 to rotate about the central axis C as well to move reciprocatingly along the central axis C to clean the filter elements 240 (as will be discussed in further detail below). When the cleaning operation is triggered, a flush valve 280 opens and causes, due to pressure differences, the suction nozzles of the cleaning arms 262 to remove or suck the debris and contaminants from the filter elements 240 as the cleaning arms 262 move rotationally and linearly relative to the filter elements 240 to thereby clean the filter elements 240.

[0025] The cleaning arrangement 100, which drives the cleaning element 260, includes a housing arrangement 120, a shaft 140 that is housed in the housing arrangement 100 and that is movable relative the housing arrangement 100 rotationally about a central axis C and reciprocatingly along the central axis C, an engagement feature 160 for engaging the shaft 140 and for guiding the shaft 140 to move reciprocatingly along the central axis C, and a motor arrangement 180 to rotate the shaft 140.

[0026] The housing arrangement 120 houses the shaft 140. A first end 121 of the housing arrangement is coupled to the filter vessel 200, while a second end 122 of the housing is coupled to the motor arrangement 180. The housing arrangement 120 includes two separable compartments - a first housing compartment 123 and a second housing compartment 124, and a coupling body 125 intermediate to the first and second housing compartments 123, 124. The first and second housing compartments 123, 124 are made from stainless steel or carbon steel.

[0027] The coupling body 125 is for housing the engagement feature 160. The coupling body 125 includes a passage l25a (shown in Figures 2A and 2B) through which the shaft 140 can pass. In particular, when the shaft 140 is in the passage l25a, the shaft 140 can rotate about the central axis C and move reciprocatingly linearly about the central axis C. The coupling body 125 further includes a port l25b (shown in Figures 2A and 2B) for containing the follower 180. The port l25b is transverse to the passage l25a. The follower 180, when contained by the port l25b, engages the portion of the shaft 140 that passes through the passage l25a. The coupling body 125 is made from stainless steel, brass, carbon steel, or plastic.

[0028] The cleaning arrangement 100 further includes a cover 126 or plate that can be fastened to the coupling body 125. The engagement feature 160 is located between the cover 126 and the shaft 140. In particular, the follower 160 is sandwiched between the cover 126 and the shaft 140. The cover 126 is secured to the coupling body 125 using fasteners such as bolts for example. The engagement feature 160 in the port is urged against the shaft 140 and is allowed to toggle between thread portions of the shaft having a first direction and thread portions of the shaft having a second direction opposite to the first direction. [0029] The shaft 140 is coupled, via a coupling, to the elongate member 264 of the cleaning element 260 for cleaning the filter vessel 200. When cleaning of the filter elements 240 is desired, the motor arrangement 180 is operated to rotate the shaft 140 such that the shaft 140 will move reciprocatingly along the central axis (i.e. alternating between a forward direction and a rearward direction) in the housing arrangement 120 to cause the cleaning element 260 to move, in unison with the shaft 140, rotationally and reciprocatingly in a forward and reverse direction in the filter vessel 200. When the motor arrangement 180 is operated, the shaft 140 rotates about a central axis C and move reciprocatingly along the central axis C in the housing arrangement 120 between a first position (shown in Figures 1 A & 2A) and a second position (shown in Figures 1B & 2B).

[0030] The shaft 140 has bi-directional (or helical) threads 142 along a shaft portion. Bi directional threads 142 have two thread portions that interconnect with, but run in opposite directions to, each other. The bi-directional threads allow the shaft to move reciprocatingly in the housing upon rotation of the shaft 140 relative to the follower 180 in one direction (e.g. in a clockwise direction or in a counter-clockwise direction). A length of the shaft portion (with the bi-directional threads) corresponds to a distance between adjacent cleaning arms 262 of the cleaning element 260. In particular, the length of the shaft portion is equal to the distance between adjacent cleaning arms 262. In other examples, the length of the shaft portion is greater than the distance between adjacent cleaning arms.

[0031] The engagement feature 160 is at a fixed location on the housing arrangement 120. The engagement feature 160 is in the form of a follower (or guide or nut) for engaging the bi-directional threads of the shaft 140. The engagement feature 160 is retained in place in the coupling body 125 as previously described above. The engagement feature 160 is urged against the shaft portion to maintain the engagement therebetween. Upon rotation of the shaft 140, the engagement feature 160 is guided along the thread portions of the shaft 140. The engagement between the engagement feature 160 and the bi-directional threads 142 of the shaft 140 allows the shaft 140 to move reciprocatingly along the central axis C upon rotation of the shaft in one direction (e.g. in either a clockwise direction or in a counter clockwise direction). The cleaning arrangement 100 includes a greaser or lubricator for lubricating the engagement feature 160 as it toggles between the different thread portions 142 of the shaft 140. [0032] During a rotation of the shaft 140 by the motor arrangement 180 in one direction, the engagement feature 160 will be guided along a first one of the thread portions of the bi- directional threads 142 and the shaft 140 will move linearly in a first direction along the central axis C until the engagement feature 160 reaches the end A of the first thread portion (shown in Figure 2 A). At that point, with continued rotation of the shaft 140 in the one direction, the engagement feature 160 switches to the second one of the thread portions of the bi-directional threads and the engagement feature 160 will be guided along the second thread portion and the shaft 140 will move linearly in a second direction (opposite to the first direction) along the central axis C until the engagement feature 160 reaches the end B of the second thread portion (shown in Figure 2B). At that point, with further continued rotation of the shaft 140 in the one direction, the engagement feature 160 switches back to the first thread portion and the engagement feature 160 will be guided along the first thread portion to cause the shaft 140 to move in the first direction once again. The shaft 140 will move reciprocatingly between the first and second directions while the motor arrangement 180 rotates the shaft 140.

[0033] The bi-directional threads 142 on the shaft 140 allow the motor arrangement 180 to be operated only in a single mode of operation to either provide clockwise rotation or counter clockwise rotation. The motor arrangement does not need to be operated to provide clockwise rotation and counter-clockwise rotation in order to move the shaft back and forth.

[0034] Further having a suitable length for the shaft portion with the bi-directional threads 142 eliminates the need to have limit switches (or other sensors) to detect when the shaft 140 reaches the limit in its forward/rearward movement. Rather, the shaft 140 can move reciprocatingly in a seamless and continuous manner simply by rotating the shaft 140 about the central axis C relative to the engagement feature 160 in one direction.

[0035] The motor arrangement 180 includes an electric motor 182. The motor arrangement 180, including the motor 182, is externally located to the filter vessel 200. By having the motor arrangement 180 externally located to the chamber 220 of the filter vessel 200, the motor arrangement can operate independently of the internal pressures in the chamber. The motor 182 is coupled to the shaft 140 for rotating the shaft 140 about the central axis C to thereby cause the shaft 140 to move reciprocatingly along the central axis C. The electric motor is preferably driven at about 35rpm. The electric motor may be driven at other speeds depending on the filter vessel or on the cleaning elements, for example between lOrpm and 50rpm.

[0036] The motor arrangement 180 further includes a drive head 184 coupled to the housing arrangement 120. The drive head 184 receives the shaft and, upon operation of the motor 182, rotates the shaft 140. The shaft 140 is can move reciprocatingly along the central axis C through the drive head 184.

[0037] The cleaning arrangement 100 further includes a control system for controlling a cleaning operation of filter vessel 200. The control system has a processor that is configured to operate the motor arrangement 180 to rotate the shaft 140 in one direction which causes the shaft 140 to move reciprocatingly along the central axis C. The processor is triggered to operate the motor arrangement 180 to rotate a shaft based on a sensed pressure differential in the filter vessel 100. For example, the processor operates the motor arrangement 180 when the sensed pressure differential exceeds a predetermined threshold. In addition or alternatively, the processor is triggered to operate the motor arrangement 180 to rotate the shaft 140 periodically. For example, the processor operates the motor arrangement 180 on a flexible basis, for example, every few minutes, hourly, daily, weekly, or monthly.

[0038] The processor of the control system stops the operation of the motor arrangement 180 at least after one movement of the shaft 140 along the central axis C (i.e. one forward movement or one rearward movement of the shaft 140 along the central axis C). The processor may stop the operation of the motor arrangement 180 after one reciprocating movement (i.e. after one forward movement and one rearward movement of the shaft), or after two or more reciprocating movements of the shaft 140. The processor may also be triggered to operate the motor arrangement constantly until there is no, or a minimal, pressure drop across the filter elements. In the case of a heavy dirt load as an example, the processor constantly operates the cleaning arrangement until no, or a minimal, pressure drop is sensed across the filter elements.

[0039] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

[0040] By way of example, the engagement feature includes a bi-directional thread and the shaft includes a follower for engaging the bi-directional thread. The threads are located on an internal wall of the housing arrangement. In this embodiment, when the motor arrangement rotates the shaft, the follower moves along the bi-directional thread to cause the shaft to move reciprocatingly along the central axis.

[0041] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavor to which this specification relates.

[0042] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.