FILTER APPARATUS

Abstract

The invention relates to a filter apparatus having a plurality of filter elements (21) which can be accommodated in a filter housing (1) with a filter inlet (11) for fluid to be filtered and a filter outlet (13) for the filtered fluid, wherein during the operation of the device at least one of the filter elements (21) can be backflushed by means of a backflushing device for cleaning its effective surface, which backflushing device includes a pressure control device (7) to support the backflushing, characterized in that the filter elements (21) are each accommodated in an element housing (30), the element housings (30) with the filter elements (21) performing the filtration process are connected to the fluid outlet (13) by their one open end (33) in a fluid conducting manner, and the element housing (30) of the respective backflushable filter element (21) is exclusively connected with its one open end (33) to the pressure control device (7).

Description

The invention relates to a filter device having a plurality of filter elements which can be accommodated in a filter housing with a filter inlet for fluid to be filtered and a filter outlet for the filtered fluid, wherein during the operation of the device at least one of the filter elements can be backflushed by means of a backflushing device for cleaning its effective filter surface, which backflushing device contains a pressure control device to support the backwashing.

Filter devices of this kind are state of the art and are used in a number of different applications and for the filtration of different flow-capable media, with different device designs being conceivable depending on the field of application. Preferred application fields are the cleaning of fluids, such as hydraulic fluids, lubricants or fuels. Such devices can also be used for water treatment or in conjunction with process fluids or working fluids of other kinds. To ensure an uninterrupted operation of the connected system to be supplied with the filtrate, it is essential to regenerate the filter elements realizing the filtration in a consecutive manner by means of backflushing, wherein during respective backwashing phases a partial flow of the filtrate flows through the filter element to be regenerated in the opposite direction, to remove the dirt from the element and carry it away. In order to also be able to remove stubborn contaminants in the backwashing operation, it is known to realize the backwashing operation not only by employing the operating pressure or system pressure, but to support the backflushing operation with a pressure control device.

As related prior art, document WO 2012/079661 A1 discloses a filter device of the type described above. The pressure control device has a hydropneumatic piston accumulator, the accumulator piston of which forms the mobile separating element between a gas side and a fluid side, which is connected to the filtrate side in the filter housing of the filter device. The filter elements are arranged rotatable in the filter housing in such a way that a filter element to be regenerated can be aligned by means of its raw side with a backflushing cutlet, on which a backflushing valve is located. In order to trigger the backflushing operation for this filter element, the backflushing valve is opened, so that for the backflushing operation the volume of the fluid side with the accumulator pressure of the piston accumulator as pressure gradient is available for removing the contaminants.

Given this prior art, the invention addresses the problem of providing a filter device which is distinguished by particularly advantageous operational behavior.

According to the invention, this problem is solved by means of a filter device having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, a significant feature of the invention is that the filter elements are respectively accommodated in an element housing, that the element housings with the filter elements realizing the filtration operation with their one open end are connected in a fluid-conducting manner to the filter outlet and that the element housing of the respective backflushable filter element with its one open end is connected only to the pressure control device. With this encapsulation of the filter elements formed by the element housings, the pressure of the pressure control device supporting the backflushing operation acts only on the element to be regenerated which is located in the backflushing position. The filter elements realizing the filtration operation thus remain entirely unaffected by the backflushing pressure of the pressure control device, so that these filter elements realize in a normal manner the filtration operation also during backflushing phases under the influence of the system pressure, while the backflushing operation is able to be realized with a relatively higher backflushing pressure permitting a particularly effective dirt removal.

In advantageous exemplary embodiments, the respective element housings are formed from a hollow cylinder with a closed lateral surface, with the other free end of the element housings having an opening delimited by the respective accommodated filter element. In this regard, the arrangement can be such that the filter element adjoins the opening in such a way that said opening forms a fluid connection to the inner cavity of the filter element surrounded by the filter medium.

The respective filter element can particularly advantageously be formed conical and have its smallest diameter in the direction of the pressure control device. Such filter elements, also known as filter candles, are preferably known slotted sieve tube filter elements.

The arrangement can advantageously be such that the flow chamber between the element housing and the accommodated filter element expands conically in the direction of the pressure control device, with the free cross section of the flow chamber at the top end of the respective filter element amounting to 50 to 120%, preferably 100%, of the inlet surface of the element cap of the filter element. This design results in a particularly advantageous flow of the fluid current, so that even stubborn contaminants can be removed in the backflushing operation.

In preferred exemplary embodiments, all filter elements with their element housings are mounted at the end side in rotary receptacles which can be moved from a filtration position into a backflushing position and back to a filtration position by means of a rotary drive, preferably in a consecutive manner. For the individual filter elements a rapid and reliable change of operation type between filtration and backflushing can thus be obtained.

The filter elements realizing the filtration operation can advantageously be flowed through from the inside to the outside and attached at the base to a common-to-all unfiltrate chamber in the filter housing, into which the filter inlet opens, and in the case of a closed head end of the filter element the flow chamber located on the outside thereof opens, via the top open end of the element housing, into a common filtrate chamber, which is connected to the filter outlet.

In this arrangement the respective filter element realizing the backflushing operation is flowed through from the outside to the inside and is connected with its element housing at the head to the pressure control device and is connected in a fluid-conducting manner at the base to a dirt discharge valve via the free element end.

Particularly advantageously, the rotary receptacles which can be pivoted by means of the rotary drive with the filter elements with their element housings can be accommodated concentric and with a definable spacing in the filtrate chamber of the filter housing. With such an arrangement of the filter elements in the manner of an element turret a particularly compact filter device can realize high filter performance.

The pressure control device can particularly advantageously have an accumulator part with a pressure chamber that can be filled with a working gas and a fluid chamber accommodating a backflush volume. This makes it possible to provide, a relatively little constructive expense, a fluid volume which is sufficiently large for an optimal backflushing operation with the desired pressure level.

In particularly advantageous exemplary embodiments, the accumulator part is formed as a piston accumulator, wherein a mobile accumulator piston is arranged for a media separation between the working gas located in the pressure chamber and the fluid.

The arrangement can advantageously be such that, between the pressure control device and the filtrate chamber with the rotary receptacles, a separating wall is drawn in the filter housing, with a throttle point, which in a fluid-conducting manner connects the one bottom piston chamber of the piston accumulator formed with the accumulator piston to the filtrate chamber. The fluid side of the piston accumulator can thus be automatically filled with a filtrate volume during the phases of normal filtration operation via the throttle point, which filtrate volume is available for a subsequent backflushing operation, in which the accumulator piston is driven into the gas side by means of introduction of a pressure medium, such as compressed air, in order to drive out the collected fluid volume from the fluid side of the accumulator.

The invention is explained in detail below with reference to an exemplary embodiment depicted in the drawings, in which:

FIG. 1 shows a depiction, cut open in a perspective oblique view and in the longitudinal direction, of an exemplary embodiment of the filter device according to the invention and

FIG. 2 shows a longitudinal section of the exemplary embodiment, wherein a top housing cover, a dirt release valve and the motor of a rotary drive are omitted.

In the figures, the housing of the depicted exemplary embodiment of the filter device according to the invention is identified as a whole with the reference numeral 1. The housing 1 is formed in three parts and consists of a base part 3, a central part 5 and a top accumulator part 7, which, sealed in a fluid-tight manner, are screwed to each other. The top accumulator part 7 is closed in a fluid-tight manner at the top end by means of a housing cover 9 shown only in FIG. 1. The parts 3, 5 and 7 each comprise a circular cylindrical section of the housing interior. The base part 3 has, in the vicinity of its closed bottom end, a filter inlet 11 for fluid to be filtered and, opposite the filter inlet 11 and offset upwards relative thereto, a filter outlet 13 for the filtered fluid. Diametrically opposite the filter inlet 11 on the base part 3 there is also a dirt outlet 15, by means of which in a backflushing operation the respective backflushing fluid volume can be carried out of the device via a connected dirt release valve 17. The dirt release valve 17 is formed by a motorized valve of standard construction.

In a manner corresponding to the mentioned device (WO 2012/079661 A1) corresponding to the prior art, in the interior, which is comprised of the base part 3 and of the central part 5 together, a rotary drive is provided, with rotary receptacles 19, which with filter elements 21 mounted thereon form an element turret. The filter elements 21 formed from conical filter candles, in particular in the form of so-called slotted sieve tube filter elements, are grouped along a circular arc inside the filter housing 1 about the vertical axis, as in the mentioned, known solution. For a gradual rotational movement of the filter elements 1 about the vertical axis, the rotary receptacles 19 are connected via a drive shaft 23 to a drive motor 25 (hydraulic or electric) which is only depicted in FIG. 1, which generates rotary movements of the shaft 23 in a step by step manner in order to rotate the rotary receptacles 19 into rotary positions in a gradual manner, in which rotary positions the rotary receptacles 19 with the filter elements 21 realizing the filtration are respectively aligned with an unfiltrate chamber 47, into which the fluid inlet 11 opens, and that rotary receptacle 19 with the filter element 21 provided for the backflushing is aligned with a dirt removal channel 29 in the base part 3, which leads to the dirt outlet 15.

Each of the filter elements 21 is accommodated in an element housing 30, the main part of which is formed by a hollow cylinder 31 with a closed lateral surface, which extends between a top open end 33 and a bottom open end 35 of the element housing 30. At the top open end 33 a respective annular body 37 is located on the end of the hollow cylinder 31, which annular bodies are connected via a screw 39 to a support 41 forming a coaxial extension of the drive shaft 23. At the bottom open end 35 of the element housings 30 filter element caps 43 (FIG. 2) are provided, which are each connected in a fluid-tight manner with the assigned rotary receptacle 19.

In this arrangement the inner filter cavity 45 of the filter elements 21 realizing the filtration is connected via the bottom open end 35 to the unfiltrate chamber 47, into which the fluid inlet 11 opens. The filtration thus takes place from the inner cavity 45, which is closed at the top end by means of an end body 46, towards the outside through the filter elements 21, so that the flow chamber 49 between the element housing 30 and the outside of the accommodated filter element 21 forms the respective clean side, with the flow chamber 49 which tapers conically upwards being connected via the top open end of the element housings 30 formed by the annular bodies 37 to a common filtrate chamber 51, to which the fluid outlet 13 is in turn connected.

The housing central part 5 has a separating wall 53 on the top end forming the transition to the accumulator part 7. In this separating wall, at a point which is aligned with the respective filter element 21 provided for a backflushing operation, there is a passage 55. Via this means, the pressure chamber 57 of the accumulator part 7 adjoining the separating wall 53 is connected, via the top open end 33 of the element housing 30 containing the filter element 21 to be backflushed, to the flow chamber 49 on the outside of this filter element 21. This pressure chamber 57 is additionally connected via a throttle point 59 located in the separating wall 53 to the top region 61 of the filtrate chamber 51. As mentioned and as depicted only in FIG. 1, the top end of the accumulator part 7 is closed by means of a cover part 9. With a freely movable accumulator piston 63 which is longitudinally displaceable in the accumulator part 7, the accumulator part 7 thus forms a piston accumulator, in which the pressure chamber 57 located beneath the piston 63 forms the fluid side and the chamber 65 located between the piston 63 and the cover part 9 forms the gas side, which can be filled via a connection 67 located in the cover part 9 with a working gas, such as compressed air. For this purpose, connected to the connection 67 there is a pressure supply device which is not depicted in detail in the drawings and which corresponds to the prior art, as is provided in the mentioned, known filter device (WO 2012/079661 A1) and which comprises a valve device which makes it possible to supply the chamber 65 with compressed air via a compressed air line or to block the compressed air supply, while the chamber 65 is connected to the environment via a filter/throttle device.

In this arrangement the pressure chamber 57 forming the fluid side of the piston accumulator formed in the accumulator part 7 can be filled with filtrate via the throttle point 59, at which the system pressure of the filtrate chamber 51 is applied, with the accumulator piston 63 moving upwards with an aerated gas-side chamber 65. In order to initiate a backflushing operation when the filter element 21 is aligned with the backwashing position, as is the case of the filter element 21 visible on the right in the figures, the gas-side chamber 65 of the piston accumulator is charged with compressed air to a pressure level which corresponds to the desired backflushing pressure. With the now opened dirt release valve 17 the accumulator piston 63 drives the fluid volume collected in the chamber 57 as a backflushing volume through the passage 55 and the top open end 33 of the element housing 30 located in the backflushing position into the flow chamber 49 on the outside of the filter element 21, so that said filter element is flowed through under the backflushing pressure from the outside to the inner cavity 45.

In this backflushing operation, which occurs with backflushing pressure supplied from the piston accumulator, which can be selected significantly higher than the system pressure, even stubborn contaminants are removed to be carried off via the bottom open end 35 of the corresponding element housing 30 and via the removal channel 29. If, after the backflushing is complete, the dirt removal valve 17 is closed and the gas-side chamber 65 above the accumulator piston 63 is again aerated towards the environment via a throttle, another filling of the fluid-side chamber 57 from the filtrate chamber 51 occurs via the throttle point 59 due to the system pressure, while the filter elements 21 not set to the backflushing position realize the filtration. Because these filter elements 21 are completely separated by their element housing 30 from the pressure chamber 57 of the piston accumulator conducting the backflushing pressure, the filtration in the case of the not backflushed filter elements 21 occurs in an entirely undisturbed manner and without any disturbance from the backflushing pressure acting on the backflushed filter element 21.

The support of the backflushing operation by the pressure control could also take place without the media separation formed by the accumulator piston 63 of the accumulator part 7 in such a way that the working gas of the accumulator part 7 acts on the fluid directly. For this purpose the accumulator piston 63 must be removed from the chamber 57 of the accumulator housing and directly connected to an external pressure source, such as a nitrogen source, which, controlled by a valve device which is not depicted in detail, delivers defined pressure volumes into the chamber 57.

Claims

1. A filter device having a plurality of filter elements (21) which can be accommodated in a filter housing (1) with a filter inlet (11) for fluid to be filtered and a filter outlet (13) for the filtered fluid, wherein during the operation of the device at least one of the filter elements (21) can be backflushed by means of a backflushing device for cleaning its effective filter surface, which backflushing device contains a pressure control device (7) to support the backwashing, characterized in that the filter elements (21) are respectively accommodated in an element housing (30), in that the element housings (30) with the filter elements (21) realizing the filtration operation with their one open end (33) are connected in a fluid conducting manner to the filter outlet (13), and in that the element housing (30) of the respective backflushable filter element (21) with its one open end (33) is connected only to the pressure control device (7).

2. The filter device according to claim 1, characterized in that the respective element housings (30) are formed from a hollow cylinder (31) with a closed lateral surface and at their other free end have an opening (43) delimited by the respective accommodated filter element (21).

3. The filter device according to claim 1, characterized in that the respective filter element (21) is formed conical and has its smallest diameter in the direction of the pressure control device (7).

4. The filter device according to claim 1, characterized in that the flow chamber (49) between the element housing (30) and the accommodated filter element (21) expands conically in the direction of the pressure control device (7) and in that the free cross section of the flow chamber (49) at the top end of the respective filter element (21) amounts to 50 to 120%, preferably 100%, of the inlet surface of the element cap (43) of the filter element (21).

5. The filter device according to claim 1, characterized in that all of the filter elements (21) with their element housings (30) are mounted at the end in rotary receptacles (19), which can be moved from a filtration position into a backflushing position and back to a filtration position by means of a rotary drive (25), preferably in a consecutive manner.

6. The filter device according to claim 1, characterized in that the filter elements (21) realizing the filtration operation are respectively flowed through from the inside to the outside and are connected at the base to a common unfiltrate chamber (47) in the filter housing (1), into which the filter inlet (11) opens, and in that in the case of a closed head end (46) of the filter element (21), the flow chamber (49) located on the outside thereof opens, via the top open end (35) of the element housing (1), into a common filtrate chamber (51), which is connected to the filter outlet (13).

7. The filter device according to claim 1, characterized in that the respective filter element (21) realizing the backflushing operation is flowed through from the outside to the inside and is connected with its element housing (30) at the head side to the pressure control device (7) and is connected in a fluid-conducting manner at the base side via the free element end (35) to a dirt release valve (17).

8. The filter device according to claim 1, characterized in that the rotary receptacles (19) which can be pivoted by means of the rotary drive (25) with the filter elements (21) together with their element housings (30) are accommodated concentric and with a definable spacing in the filtrate chamber (51) of the filter housing (1).

9. The filter device according to claim 1, characterized in that the pressure control device has an accumulator part (7) with a pressure chamber (65) which can be filled with working gas and a fluid chamber (57) accommodating a backflushing volume.

10. The filter device according to claim 1, characterized in that the accumulator part (7) as a piston accumulator is formed with an accumulator piston (63) forming a mobile separating element between the pressure chamber (65) and the fluid chamber (57).

11. The filter device according to claim 1, characterized in that, between the pressure control device (7) and the filtrate chamber (51) with the rotary receptacles (19), a separating wall (63) is drawn in the filter housing (1) with a throttle point (59), which connects in a fluid-conducting manner the one bottom piston chamber (57) of the piston accumulator formed with the accumulator piston (63) to the filtrate chamber (51).