Filter device with exhaust chamber

Abstract

The present invention concerns a filter device comprising: - at least one filter chamber (10); - at least one cleaning shaft (32) of the filter chamber (10); - at least one exhaust chamber (40) located at the inlet from the filter chamber through the cleaning shaft (32), and including at the outlet at least one exhaust opening (42); - at least one exhaust enabling valve (90) connected to said exhaust opening (42) to enable and disable said suction, - at least one exhaust pipe (48a, 48b) from said exhaust opening (42) to said exhaust enabling valve (90), characterised by the fact that the ratio RV=L40 / V40 is such that 1,3≤RV≤2,2, where L40 is the length of said exhaust pipe expressed in millimeters (mm) and V40 is the volume of the exhaust chamber (40) expressed in centiliters (cl).

Description

[0001] Inventor: SATI s.r.l. , Via M. Galli, 116 - 47522 San Carlo di Cesena (FC) ITALY.

[0002] VAT Number: 01541770408

[0003] Title: Filter device with exhaust chamber.

[0004] ★ ★ ★ ★ ★

[0005] DESCRIPTION

[0006] The present invention concerns a filter device with exhaust chamber.

[0007] The invention is particularly designed for filtering liquids, preferably water, however, other uses are not excluded.

[0008] PRIOR ART

[0009] In the filter sector, the problem of cleaning has always been an issue, as clogging of the filter elements leads to a loss of efficiency, and even to the breakage of certain components as a result of an abnormal increase in pressure. To solve this problem, it is traditionally known to install inside the filter a rotating cleaning shaft equipped with suction brushes so that during rotation they sweep and suck dirt from the filter element .

[0010] This system is complex and consequently has various disadvantages. For example, it requires high exhaust pressures for cleaning, usually higher than network pressures, due to very poor fluid dynamic. In addition, it is difficult to assemble and disassemble, resulting in maintenance difficulties.

[0011] The purpose of the present invention is to solve all or part of the problems of the prior art.

[0012] In particular, the purpose of the present invention is to provide a filter device with an improved flow during the cleaning phase.

[0013] A further preferable general purpose of the present invention is to provide a highly effective filter device even at normal network pressures.

[0014] Another further preferable purpose of the present invention is to provide a filter device that is easy and inexpensive to implement.

[0015] GENERAL INTRODUCTION

[0016] According to its first aspect, the invention concerns a filter device comprising:

[0017] - at least one filter chamber (10) ;

[0018] - at least one cleaning shaft (32) of the filter chamber (10) ;

[0019] - at least one exhaust chamber (40) located at the inlet from the filter chamber through the cleaning shaft (32) , and including at the outlet at least one exhaust opening (42) ; at least one exhaust enabling valve (90) connected to said exhaust opening (42) to enable and disable said suction,

[0020] - at least one exhaust pipe (48a, 48b) from said exhaust opening (42) to said exhaust enabling valve (90) , characterised by the fact that the ratio RV=L40 / V40 is such that 1,8<RV<2,2, where preferably RV=2 ; where L40 is the length of said exhaust pipe expressed in millimeters (mm) and V40 is the volume of the exhaust chamber (40) expressed in centiliters (cl) .

[0021] Advantageously, after repeated experimental tests, it was found that this ratio is the one that speeds up the emptying of the exhaust chamber the most, giving a quick start to the suction function. Unexpectedly, this ratio is also more advantageous than ratios corresponding to much greater L40 lengths.

[0022] According to some preferred forms of implementation :

[0023] -the exhaust chamber is developed in the longitudinal direction along an X-axis, where the exhaust opening is radial to that axis; the cleaning shaft (30) includes a communication opening (55) arranged at the inlet to the exhaust chamber (40) in said longitudinal direction.

[0024] Preferably said cleaning shaft develops in the longitudinal direction along the same X-axis.

[0025] Preferably said cleaning shaft (32) and said exhaust opening (42) are at least partially offset in said longitudinal direction of the X-axis.

[0026] Preferably said exhaust chamber has two ends (72, 74) in said longitudinal direction, wherein the communication opening (55) is proximal to one, and the exhaust opening (42) is proximal to the other.

[0027] According to some preferred forms of implementation : -said communication opening has a diameter D-IN, -the exhaust chamber (40) comprises a useful height H40 in the longitudinal direction; where the ratio R=D-IN / H40 is 0,30<R<0,40, preferably R=0,35.

[0028] According to some preferred forms of implementation the device comprises a cleaning unit comprising :

[0029] - said cleaning shaft 32, which is rotatable on an axis of longitudinal development X relative to the filter chamber (10) , moved by drive means (60) , and comprising at least one cavity (54) ,

[0030] - at least one suction nozzle 34 supported by the cleaning shaft within the filter chamber (10) and communicating with said cavity (54) ,

[0031] - at least one communication opening (55) of said cavity (54) arranged at the inlet to the exhaust chamber (40) .

[0032] Preferably the exhaust chamber (40) is defined in an exhaust body (38) of a tumbler shape around an X-axis of longitudinal development, the exhaust body (38) comprising a radial guard (70) , a bottom (72) and a coupling opening (74) opposite to the bottom (72) and configured to serve as a seat for the cleaning shaft (32) , where the exhaust opening (42) is on the radial wall, arranged in a longitudinal position closer to the bottom (72) than to the coupling opening (74) .

[0033] DETAILED DESCRIPTION Further features and advantages of the present invention will best be seen from the following detailed description of preferred implementation forms of the invention, made with reference to the accompanying drawings and given by way of example and not limitation . In said drawings :

[0034] - figures 1 to 4 show a sel f-cleaning filter device according to the prior art ;

[0035] - figure 5 shows schematically in longitudinal section a filter device according to an implementation form of the present invention;

[0036] - figure 6 shows the cleaning group of the filter device of figure 5 ;

[0037] - figure 7 shows the exhaust body area of the filter device of figure 5 ; figure 8 shows schematically the exhaust chamber 40 in longitudinal section;

[0038] - figure 9 shows the exhaust body area of the filter device of figure 5 ; figure 10 shows the cleaning shaft of the cleaning unit of figure 6 ; figures 11 and 12 show respectively the pressures and flow speed in the exhaust chamber of the filter device of figure 5 during the exhaust phase ; figure 13 shows a variation of the filter device of figure 5 where the cleaning shaft is provided with reciprocating rectilinear motion in addition to rotary motion .

[0039] - figures 14 and 15 show the extreme positions of the cleaning shaft of figure 12 in relation to the exhaust opening .

[0040] - figures 16 to 19 show the exhaust chamber of two variations of the invention to highlight the recurrence of certain dimensional ratios .

[0041] With reference to figures 1 to 4 , a sel f-cleaning filter device is shown according to the prior art , in particular a device produced by the applicant itsel f , and is shown in order to make more evident the advantages of the present invention, which will be described below .

[0042] Figure 1 shows in detail the exhaust chamber A of the known device , where there is an end B of the cleaning shaft C, visible in its entirety in figure 2 . The cleaning shaft C is hollow and carries the water sucked in by the suction brushes D from the filter chamber (not visible ) . The cleaning shaft C trans fers the suctioned water to the exhaust chamber A via the radial openings E . Exhaust chamber A, in turn, has a radial outlet opening F . The cleaning shaft C rotates around its longitudinal axis in such a way as to drive the brushes . As a result , during rotation, the shaft opening E and the outlet opening F of the chamber cyclically align and misalign in the radial direction, creating a cycle of exhaust pressures that makes the flows very unfavourable .

[0043] Alongside this disadvantage is the need for various centring, sliding blocks and coupling parts for assembly and disassembly . Figures 3 and 4 show, for example , the disassembly of the cleaning shaft C, which leaves in the exhaust chamber A a drive shaft G from which it receives the motion generated by an external motor . The drive shaft G has to be disassembled separately to carry out the internal cleaning of the exhaust chamber .

[0044] As shown in figures 5 onwards , some preferred forms of implementation of the present invention involve the following basic characteristics :

[0045] - improve the fluid dynamics by making an exhaust chamber that optimises the exhaust flow,

[0046] - preferably eliminate the B end portion of the cleaning shaft contained in the exhaust chamber, and feed the flow into the exhaust chamber from a longitudinal direction instead of radial , thus freeing up space and optimising the exhaust flow,

[0047] - preferably make the drive shaft passing through the exhaust chamber and inserted in at least part of the cleaning shaft in a longitudinal direction .

[0048] Below we will describe in more detail some implementation examples of the present invention .

[0049] With reference to figure 5 , a filter device according to the present invention is shown as a whole under reference number 1 .

[0050] Filter device 1 comprises : at least one filtering body 5 comprising a filter chamber 10 ; at least one cleaning unit 30 at least partially inside the filter chamber 10 ;

[0051] - At least one exhaust body 38 comprising an exhaust chamber 40 in communication with the filter chamber via the cleaning unit 30 ; Drive means 60 of the cleaning unit 30 , preferably external to the filter and exhaust chambers .

[0052] The filter chamber 10 has a main development around an X-axis defining a longitudinal direction . The chamber preferably has a geometry of revolution around the X axis , for example comprising at least one bounding wall 12 in a radial direction that is at least partially cylindrical . More preferably, the chamber 10 is substantially cylindrical .

[0053] The filter device 1 comprises a filter element 15 nested in the chamber 10 to divide it into an inlet subchamber 18 and an outlet sub-chamber 20 of the fluid to be filtered . The filter element preferably has a geometry of revolution around the X-axis and more preferably is substantially cylindrical . In general , it is preferable that the filter element 15 extends in the direction of the X-axis along the entire length in said direction of the chamber 10 .

[0054] For example , filter element 15 comprises a mesh, net or filter membrane suitable for filtering fluids , preferably liquids .

[0055] The inlet sub-chamber 18 comprises an inlet 22 for supplying the fluid to be filtered proximal to either end of the chamber 10 in the direction of the X-axis , wherein said inlet is such as to direct the fluid according to a supply flow parallel to the X-axis . Preferably the inlet is coaxial to the X-axis , more preferably it comprises an inlet pipe coaxial to the X- axis . Output sub-chamber 20 includes an output 24 in the radial direction with respect to the X-axis .

[0056] The fluid to be filtered to pass from the inlet 22 to the outlet 24 is forced to pass through the filter element 15 .

[0057] The exhaust chamber 40 in turn includes an exhaust opening 42 , preferably radial to the X-axis .

[0058] The fluid to be filtered is able to pass from the sub-chamber 18 to the exhaust chamber via the cleaning unit 30 , and from there it comes out through the exhaust opening 42 .

[0059] As shown in figure 6 , cleaning unit 30 comprises :

[0060] - a cleaning shaft 32 directed along the X-axis , on which it rotates ;

[0061] - at least one suction noz zle 34 supported by the cleaning shaft, preferably a plurality thereof ; at least one drive shaft 36 coupled to the cleaning shaft and coaxial to it , the drive shaft putting the cleaning shaft into rotation by transmitting motion from drive means 60 , preferably located outside the filter chambers 10 and exhaust chambers 40 .

[0062] The cleaning shaft 32 comprises a proximal end 50 and a distal end 52 in relation to the exhaust chamber 40 .

[0063] The cleaning shaft 30 further comprises at least one internal cavity 54 in communication with the exhaust chamber 40 via a communication opening 55 at the proximal end 50 facing in a longitudinal direction with respect to the X-axis , as shown in figure 7 . The opening 55 is thus a longitudinal outlet of the shaft 32 . The inner cavity 54 is also in communication with the inlet sub-chamber 18 via the at least one inlet noz zle 34 .

[0064] Preferably the cleaning shaft 32 is tubular and includes at least one radial opening 33 for communication with at least one suction noz zle 34 ( figure 10 ) .

[0065] In general , the exhaust opening 42 and the proximal end 50 are located in longitudinal positions along the X-axis at least partially of fset from each other, i . e . distanced or only partially overlapping, including the case where one ends in the longitudinal direction where the other begins .

[0066] Thus , in general , the two openings 42 and 55 are at least partially of fset from each other in the longitudinal X direction .

[0067] Preferably, the exhaust opening 42 and the communication opening 55 of the cleaning shaft are facing the same free area 58 , wherein the former is facing in a radial direction and the latter in a longitudinal direction with respect to the longitudinal axis X .

[0068] Therefore , in front of the radially facing exhaust opening 42 , instead of the distal end of the cleaning shaft as in the described prior art , is the free zone 58 where the communication opening 55 feeds the outflow from the distal end 55 .

[0069] It is clear, in other words , that this input zone is devoid of parts of cleaning shaft 32 .

[0070] The simplest and most ef fective way to achieve such an arrangement is to place the proximal end 50 o f the cleaning shaft outside the exhaust chamber 42 . It is preferable for this position to be fixed, however it is not excluded that it is only one of the positions assumed by the shaft , where , for example , other positions penetrate the exhaust chamber 40 , but always remain with the opening 55 at least partially offset in the longitudinal direction from the exhaust outlet so as to face at least partially a common free zone . An example of a movable shaft is given below in figures 13 to 15 .

[0071] As shown in figure 9 , in order to facilitate such an arrangement between the two openings 42 and 55 , the exhaust body 38 has preferably a tumbler shape around the X-axis , comprising a radial wall 70 , a bottom 72 and a cleaning shaft coupling seat 32 opposite the bottom 72 . The exhaust opening 42 is on the radial wall , arranged in a longitudinal position closer to the bottom 72 than to the coupling seat 75 .

[0072] The coupling seat 74 comprises a coupling opening 75 embracing the cleaning shaft 55 , wherein the shaft may be longitudinally fixed or movable relative thereto ( the latter case being illustrated in figures 13- 15 ) . In the case where the cleaning shaft 32 has a longitudinally fixed potion then preferably the exhaust opening 42 is closer to the bottom 72 than to the communication opening 55 .

[0073] As shown, the only element present in the free zone 58 is the drive shaft 36 ( figure 7 ) . The free zone 58 and the exhaust chamber 40 , in the illustrated case , are intended to coincide , since the coupling opening 74 is the seat of the cleaning shaft 32 .

[0074] As best shown in the schematic figure in figure 8 , in general , zone 58 of the exhaust chamber located radially in front of the exhaust opening 42 develops at least partially around the drive shaft 36 and communicates directly with said exhaust opening 42 . Preferably, as in the example shown, said zone 58 is developed annularly around the drive shaft 36 , preferably concentrically to it .

[0075] In general , it is preferable that both the drive shaft 36 and the discharge opening 42 have substantially circular cross-section, where the diameter DI of the drive shaft 36 is smaller than the diameter D2 of the exhaust opening 42 , e . g . it is D2>=3D1 , more preferably D2>=5D1 .

[0076] The cleaning shaft 30 is rotatable coupled to the exhaust body 38 by bearing means 76 located at the coupling opening 74 .

[0077] The cleaning shaft is restrained from penetrating the free zone 58 by means of longitudinal stop means 78 , preferably comprising said bearing means 76 .

[0078] The cleaning shaft 32 thus coupled to the exhaust body 38 is kept suspended cantilevered within the inlet sub-chamber 18 .

[0079] The communication opening 55 develops at least partially around the drive shaft 36 , preferably forming an annular opening around it .

[0080] The two opposite ends of the drive shaft 36 are respectively connected to the drive means 60 and the cleaning shaft 30 , so that rotary motion around the X- axis is transmitted to the latter .

[0081] In particular, the drive shaft 36 extends into both the free area 58 and the inner cavity 54 of the cleaning shaft 32 .

[0082] The drive shaft is coupled to the cleaning shaft in a coupling zone 80 such that the communication openings 33 with the suction nozzles are interposed, in the longitudinal direction, between the coupling zone 80 and the communication opening 55 .

[0083] Preferably the coupling zone 80 is at the distal end 52 .

[0084] Preferably the drive shaft 36 also acts as a tie rod to keep the cleaning shaft pushing against the exhaust body 38 .

[0085] The drive means 60 comprise at least one motor 62 external to the exhaust body 40 , wherein preferably the coupling to the drive shaft 36 is at or near the bottom 72 of the exhaust body 38 . Preferably, the drive shaft 36 passes at least partially through the bottom 72 to couple to said motor 62 .

[0086] Suction noz zles 34 may also have a function as scrapers of the filter element , commonly referred to as "brushes" although their shape may be di f ferent from that of a brush in the literal sense of the term, e . g . being a spatula .

[0087] The exhaust port 42 in turn communicates with an exhaust enabling valve 90 configured to open when a certain pressure is reached and or at a pre-set time .

[0088] In use , when the filter element 15 is dirty, in the inlet sub-chamber 18 and the exhaust chamber 40 the pressure increases , as they are communicating . When a predetermined pressure is reached, the exhaust enabling valve 90 opens and allows discharge through the exhaust opening 42 . This triggers the suction which from the inlet noz zles 36 carries the flow into the exhaust chamber 40 through the internal cavity 54 of the cleaning shaft and the communication opening 55 .

[0089] Since , although the cleaning shaft is mobile in rotation, the relative position in the longitudinal direction between the exhaust opening 42 and the communication opening 55 always remains of fset , the flow encounters no obstruction, especially variable due to motion . The flow is therefore much improved, as shown in the pressure and speed graphs in figures 11 and 12 , and suction is ef fective even at standard network pressures , such as between 0 , 5 and 4 bar .

[0090] Following various experimental tests , it was possible to identi fy the geometry of the exhaust chamber 40 that optimises the flow . In particular, and with reference to figures 16 to 19 , comparative tests were carried out and this made it possible to fine-tune certain dimensional ratios that could be adopted on various forms of implementation, also made of di f ferent materials .

[0091] One of the dimensional ratios with the greatest influence on the flow is the ratio of the diameter D- IN of the coupling opening 55 to the height H40 of the chamber 40 . The height H40 is calculated between the coupling opening 75 and the bottom 72 . The ratio R=D- IN / H40 is optimal when it is 0 , 25<R<0 , 40 , where preferably R=0,35.

[0092] Figures 16 and 17 show, respectively, an exhaust body made of polymer material 38a and one made of metal 38b, having different D-IN and H40, but with R-ratios falling in the same range.

[0093] Another interesting dimensional ratio is that between the length L40 of an exhaust pipe 48a, 48b at the outlet opening 42 expressed in mm and the volume V40 of the exhaust chamber expressed in centilitres (CL) . Said exhaust pipe runs from the exhaust opening 42 to the exhaust enabling valve 90. The ratio RV=L40 / V40 (mm / CL) is optimal when it is 1,3<RV<2,2, where preferably RV=2.

[0094] Figures 18 and 19 show, respectively, an exhaust body made of polymer material 38a and one made of metal 38b, having different V40 and L40, but with R-ratios falling in the same range.

[0095] With regard to assembly and disassembly, the cleaning unit 30 can be a pre-assembled unit that can be assembled and disassembled directly with respect to the exhaust body 38 and such that it remains positioned with respect to it regardless of the presence or absence of the filter body 5.

[0096] As mentioned preferably, the cleaning unit 30 projects cantilevered into the inlet sub-chamber 18 from the exhaust body 38. It is coupled to the exhaust body via the drive shaft 36 which acts as a tie rod, and via the coupling place 74, where it is centred by the bearing ass e mb 1 y 76.

[0097] It can therefore be without a direct coupling, e.g. centring and stop, on the filter body 5. It is not excluded that the cleaning shaft may also have , in addition to rotary motion, reciprocating rectilinear motion in the longitudinal direction, but even in this case the extreme positions assumed by the proximal end 50 , and in particular by the communication opening 55 , are of fset with respect to the exhaust opening 42 , thus always maintaining a free zone 58 on which both face . It could also be said that the shaft is devoid of positions totally facing the exhaust opening 42 in the radial direction, e . g . it remains longitudinally distanced from it in every possible position .

[0098] Figure 13 shows a variation 101 of device 1 that represents an example equipped with such reciprocating rectilinear motion . The main di f ference with the version in the previous figures is that the drive means include means of reciprocating rectilinear motion 64 , e . g . worm gear means 65 connected to the drive shaft 36 .

[0099] As shown in figures 14 and 15 , in the extreme positions the cleaning shaft 32 remains of fset and not facing the exhaust opening 42 .

[0100] In general , it is not excluded that the exhaust body 38 , in particular the exhaust chamber 40 , is also applicable to other types of filtering devices , with or without a cleaning unit . Indeed, its usefulness in improving the exhaust flow is obvious in any circumstance where it is necessary to exhaust the filter chamber through an outlet other than outlet 24 .

[0101] For example , it is obvious that the exhaust body also improves flow in combination with the cleaning shaft with radial outlet of the prior art of figures 1 to 4 . GENERAL MEANING OF TERMS

[0102] In understanding the purpose of the present invention, the term "comprising" and its derivatives, as used herein, are intended as open-ended terms specifying the presence of the declared characteristics, elements, components, groups, integers and / or phases, but not excluding the presence of other undeclared characteristics, elements, components, groups, integers and / or phases. The above also applies to words with similar meanings such as the terms "including", "having" and their derivatives. In addition, the terms "part", "section", "portion", "member" or "element" when used in the singular may have the dual meaning of a single part or a plurality of parts. As used herein to describe the form(s) of implementation mentioned above, the following directional terms "forward", "backward", "above", "below", "vertical", "horizontal", "underneath" and "transverse", as well as any other similar directional terms refer to the form of implementation described in the operative position. Finally, grade terms such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

[0103] While only selected implementation forms have been chosen to illustrate the present invention, from this description it will be clear to those expert in the field that various modi fications and variations may be made without departing from the purpose of the invention as defined in the attached claims . For example , the si ze , shape , position or orientation of the various components may be modi fied as needed and / or desired . Components shown directly connected or in contact with each other may have intermediate structures interposed between them . The functions of one element can be performed by two and vice versa . The structures and functions of one form o f implementation can be adopted in another one . It is not necessary that all advantages are present in a particular form of implementation at the same time . Each characteristic that is original compared to the prior art , alone or in combination with other characteristics , should also be considered a separate description of further inventions by the applicant , including structural and / or functional concepts incorporated by those characteristics . Therefore , the previous descriptions o f implementation forms according to the present invention are provided for illustrative purposes only and not for the purpose of limiting the invention as defined by the attached claims and their equivalents .

Claims

CLAIMS1. Filter device comprising:- at least one filter chamber (10) ;- at least one cleaning shaft (32) of the filter chamber (10) ;- at least one exhaust chamber (40) located at the inlet from the filter chamber through the cleaning shaft (32) , and including at the outlet at least one exhaust opening (42) ; at least one exhaust enabling valve (90) connected to said exhaust opening (42) to enable and disable said suction,- at least one exhaust pipe (48a, 48b) from said exhaust opening (42) to said exhaust enabling valve (90) , characterised by the fact that the ratio RV=L40 / V40 is such that 1,3<RV<2,2, where L40 is the length of said exhaust pipe expressed in millimeters (mm) and V40 is the volume of the exhaust chamber (40) expressed in centiliters (cl) .

2. Device according to claim 1, characterised by the fact that RV=2.

3. Device according to any of the previous claims characterised by the fact that:-the exhaust chamber is developed in the longitudinal direction along an X-axis, where the exhaust opening is radial to that axis; the cleaning shaft (30) includes a communication opening (55) arranged at the inlet to theexhaust chamber (40) in said longitudinal direction.

4. Device according to claim 3, characterised by the fact that: said cleaning shaft develops in the longitudinal direction along the same X-axis.

5. Device according to claim 4, characterised by the fact that said cleaning shaft (32) and said exhaust opening (42) are at least partially offset in said longitudinal direction of the X-axis.

6. Device according to claim 5, characterised by the fact that said exhaust chamber has two ends (72, 74) in said longitudinal direction, wherein the communication opening (55) is proximal to one, and the exhaust opening (42) is proximal to the other.

7. Device according to any of the previous claims characterised by the fact that:-said communication opening has a diameter D-IN, -the exhaust chamber (40) comprises a useful height H40 in the longitudinal direction; where the ratio R=D-IN / H40 is 0,25<R<0,40.

8. Device according to claim 7, characterised by the fact that R=0,35.

9. Device according to any of the previous claims, characterised by the fact that it comprises acleaning unit comprising:- said cleaning shaft 32, which is rotatable on an axis of longitudinal development X relative to the filter chamber (10) , moved by drive means (60) , and comprising at least one cavity (54) ,- at least one suction nozzle 34 supported by the cleaning shaft within the filter chamber (10) and communicating with said cavity (54) ,- at least one communication opening (55) of said cavity (54) arranged at the inlet to the exhaust chamber (40) .

10. Device according to any of the previous claims, characterized by the fact that the exhaust chamber (40) is defined in an exhaust body (38) of a tumbler shape around an X-axis of longitudinal development, the exhaust body (38) comprising a radial guard (70) , a bottom (72) and a coupling opening (74) opposite to the bottom (72) and configured to serve as a seat for the cleaning shaft (32) , where the exhaust opening (42) is on the radial wall, arranged in a longitudinal position closer to the bottom (72) than to the coupling opening (74) .

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