Plasticizing unit including a plasticizing screw rotationally and linearly movable within an injection cylinder and having a dam element

Abstract

A plasticizing unit includes an injection cylinder having a dispensing opening, via which a plasticized material can be dispensed, and a plasticizing screw arranged to be rotationally and linearly movable in the injection cylinder and having an axis of rotation. A plasticizing zone is formed between the plasticizing screw and the injection cylinder in the radial direction relative to the axis of rotation of the plasticizing screw. The plasticizing screw has a dam element, and in the injection cylinder there is a first opening in the area of the plasticizing zone and/or the dam element and a second opening between the dam element and the dispensing opening.

Claims

1. A plasticizing unit for a molding machine, the plasticizing unit comprising: an injection cylinder having a dispensing opening to dispense a plasticized material; and a plasticizing screw arranged in the injection cylinder, the plasticizing screw being rotationally movable and linearly movable in the injection cylinder by a drive unit configured to linearly move the plasticizing screw over an injection stroke length during an injection movement, the plasticizing screw having an axis of rotation, wherein a plasticizing zone is located between the plasticizing screw and the injection cylinder in the radial direction relative to the axis of rotation of the plasticizing screw, wherein the plasticizing screw has a dam element, and the injection cylinder has a first opening in the area of the plasticizing zone and/or the dam element and has a second opening between the dam element and the dispensing opening, and wherein the first opening and the second opening are spaced apart a distance from each other, the distance corresponding to the injection stroke length.

2. The plasticizing unit according to claim 1, further comprising a molten material line fluidically connecting the first opening to the second opening.

3. The plasticizing unit according to claim 2, further comprising a filter device in the molten material line to filter the plasticized material.

4. The plasticizing unit according to claim 3, wherein the filter device has a filter change device.

5. The plasticizing unit according to claim 4, wherein the filter device is a cassette filter.

6. The plasticizing unit according to claim 2, wherein the molten material line has a valve element.

7. The plasticizing unit according to claim 6, wherein the valve element is arranged in the molten material line between the filter device and the second opening of the injection cylinder.

8. The plasticizing unit according to claim 6, wherein the valve element is a check valve.

9. The plasticizing unit according to claim 2, wherein the molten material line has a discharge opening.

10. The plasticizing unit according to claim 9, wherein the discharge opening is located between the filter device and the first opening of the injection cylinder.

11. The plasticizing unit according to claim 1, wherein the dam element is connected to an injection plunger and/or is formed as an injection plunger.

12. The plasticizing unit according to claim 1, wherein the dam element has a circumferential surface opposing an inner surface of the injection cylinder, the dam element being leakproof with respect to a plasticized material and/or having a converse conveying geometry.

13. The plasticizing unit according to claim 1, wherein a conveying geometry is arranged between the dam element and the dispensing opening.

14. The plasticizing unit according to claim 13, wherein the conveying geometry is fixed to the plasticizing screw so as to move only with the plasticizing screw.

15. The plasticizing unit according to claim 1, wherein a conveying geometry of the plasticizing screw changes into a converse conveying geometry in an area between the first opening and the second opening of the injection cylinder.

16. The plasticizing unit according to claim 1, wherein the first opening and/or the second opening is formed as a recess in the injection cylinder.

17. The plasticizing unit according to claim 16, wherein the recess is a longitudinal groove along the axis of rotation.

18. The plasticizing unit according to claim 17, wherein the longitudinal groove has a varying width along the axis of rotation.

19. A molding machine comprising the plasticizing unit according to claim 1.

20. A method of using the plasticizing unit according to claim 1, comprising using the plasticizing screw with the dam element for retaining the plasticized material, and using an axial drive for axially moving the axially movable plasticizing screw.

21. A plasticizing method using the plasticizing unit according to claim 1, comprising: plasticizing a material with the aid of the plasticizing screw arranged so as to be rotationally and linearly movable in the injection cylinder; conveying the plasticized material out of a plasticizing zone present between the injection cylinder and the plasticizing screw via the first opening, the plasticized material conveyed out of the plasticizing zone being filtered outside the injection cylinder, and returning the filtered plasticized material to the injection cylinder via the second opening.

22. The method according to claim 21, wherein the plasticized material is pushed out of a space in front of the plasticizing screw between the plasticizing screw and the dispensing opening of the injection cylinder and through the dispensing opening by the dam element fixed to the plasticizing screw so as to move only with the plasticizing screw or attached to the plasticizing screw via a linear movement of the plasticizing screw.

23. The method according to claim 21, further comprising exerting a pressure on the plasticized material by a linear movement of the injection screw, whereby the filtered plasticized material is conveyed back into the molten material line arranged at the second opening, and the filter device arranged in the molten material line is backflushed.

24. A control or regulating device for controlling or regulating a drive of a plasticizing screw of a plasticizing unit, the control or regulating device being configured to carry out the method according to claim 21.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and details of the invention are revealed by the figures and the associated description of the figures, in which:

(2) FIGS. 1 and 2 show a first embodiment of a plasticizing unit according to the invention,

(3) FIGS. 3 and 4 show a second embodiment of a plasticizing unit according to the invention,

(4) FIG. 5 shows a third embodiment of a plasticizing unit according to the invention,

(5) FIG. 6 shows a fourth embodiment of a plasticizing unit according to the invention,

(6) FIG. 7 shows a fifth embodiment of a plasticizing unit according to the invention,

(7) FIG. 8 shows a sixth embodiment of a plasticizing unit according to the invention,

(8) FIGS. 9 and 10 show a seventh embodiment of a plasticizing unit according to the invention,

(9) FIGS. 11 and 12 show an eighth embodiment of a plasticizing unit according to the invention,

(10) FIGS. 13 and 14 show a ninth embodiment of a plasticizing unit according to the invention,

(11) FIG. 15 shows a tenth embodiment of a plasticizing unit according to the invention,

(12) FIGS. 16a-16c show a filter device with filter change device, and

(13) FIG. 17 shows a molding machine.

DETAILED DESCRIPTION OF THE INVENTION

(14) FIG. 1 shows a first embodiment of a plasticizing unit 1, comprising an injection cylinder 4 and a plasticizing screw 5 arranged in the injection cylinder 4.

(15) The plasticizing screw 5 is formed to perform, in the injection cylinder 4, a rotational movement about the axis of rotation 6 for plasticizing a material, as well as to perform a linear movement along the axis of rotation 6 for pushing out the plasticized material.

(16) The injection cylinder 4 has a dispensing opening 3, via which dispensing opening 3 plasticized material can be pushed out of the injection cylinder and can for example be injected into a mold 24.

(17) A space in front of the screw 7 is provided along the axis of rotation 6 of the plasticizing screw 5 between the dispensing opening 3 and the end of the plasticizing screw 5 facing the dispensing opening 3.

(18) The plasticizing zone 8 is formed between the plasticizing screw 5 and the injection cylinder 4 in the radial direction relative to the axis of rotation 6 of the plasticizing screw 5.

(19) A molten material line 9 is furthermore provided, which branches off from the injection cylinder 4 out of the plasticizing zone 8 via the first opening 12 of the injection cylinder 4 and opens into the injection cylinder 4 again via the second opening 13 of the injection cylinder 4 with the space in front of the screw 7.

(20) The plasticizing screw furthermore has a dam element 11 at an end facing the dispensing opening 3, wherein in this embodiment the dam element 11 is formed in one piece with the plasticizing screw 5.

(21) The filter device 10 for filtering a plasticized material is furthermore provided in the bypass line 9.

(22) The molten material line 9 can be sealed off with respect to the space in front of the screw 7 by the valve element 16 which here is a check valve.

(23) During a cycle of the plasticizing unit, a material to be plasticized is now moved from a rear area of the plasticizing screw 5 via the conveying geometry 15 of the plasticizing screw 5 in the direction of the plasticizing zone 8, wherein due to the shearing, shear heat and optionally externally introduced heat the material to be plasticized is plasticized in the plasticizing zone 8.

(24) The material and the plasticized material are conveyed by the conveying geometry 15 of the plasticizing screw 5 in the direction of the dispensing opening 3 until the plasticized material emerges from the plasticizing zone 8 via the first opening 12 from the injection cylinder 4 and is channeled into the molten material line 9.

(25) This emerging of the plasticized material from the plasticizing zone 8 and the injection cylinder 4 is facilitated by the dam element 11, and more particularly in this embodiment, the side of the dam element 11 facing away from the space in front of the screw 7.

(26) The dam element 11 has an external geometry that corresponds to the internal geometry of the injection cylinder 4, with the result that between dam element 11 and injection cylinder 4 only a small gap remains, which is chosen so that it is formed leakproof with respect to a plasticized material.

(27) This means that the gap between dam element 11 and injection cylinder 4 is formed so small that plasticized material cannot penetrate through it.

(28) The material plasticized by the plasticizing screw 5 is thus driven through the molten material line 9 and the filter device 10 arranged therein.

(29) The filter device 10 is formed to filter contaminants out of the plasticized material, wherein these contaminants remain in the filter device and the filtered plasticized material is channeled through the molten material line 9 via the valve element 16 and the second opening 13 of the injection cylinder 4 back into the injection cylinder 4, and more particularly in this embodiment, back into the space in front of the screw 7.

(30) The filtered plasticized material now accumulates in the space in front of the screw 7.

(31) As the dispensing opening 3 is closed during the plasticizing (for example via a hotrunner closure system), a melt cushion consisting of plasticized material builds up in the space in front of the screw 7, which pushes the plasticizing screw 5 away backwards, whereby the space in front of the screw 7 increases in size.

(32) This plasticizing process (often also referred to as metering) is performed until a desired quantity of plasticized material is present in the space in front of the screw 7 (as can be seen in FIG. 2).

(33) If this desired plasticized material for the further processing is achieved in the space in front of the screw 7, the valve element 16 is closed, the dispensing opening 3 is opened and then the dam element 11 is moved in the direction of the dispensing opening 3 via a linear movement of the plasticizing screw 5, wherein, via the dam element 11, the plasticized material is pushed out of the space in front of the screw 7 via the dispensing opening 3 and is for example supplied to a mold 24, and more particularly in this embodiment, a cavity of the mold 24.

(34) FIGS. 3 and 4 show a further embodiment of a plasticizing unit 1, wherein the plasticizing unit is again represented during a plasticizing in FIG. 3, and FIG. 4 shows the plasticizing unit 1 just before the injection process.

(35) In comparison with FIGS. 1 and 2, the embodiment of the plasticizing unit 1 of FIGS. 3 and 4 has a plasticizing screw 5 which is again formed in one piece with a dam element 11, but wherein between dam element 11 and dispensing opening 3 a further conveying geometry 14 is provided, which is formed by a screw extension.

(36) After the filtration of the plasticized material by the filter device 10, the plasticized material returned to the space in front of the screw 7 via the second opening 13 can be conveyed, via this further conveying geometry 14, further in the direction of the dispensing opening 3 and heated/plasticized once again via shearing and shear heat.

(37) A nonreturn valve 30, which serves to prevent the plasticized material from flowing back out of the space in front of the screw 7 to the further screw geometry 14 during the injection, is arranged at the end of the further conveying geometry 14 facing the dispensing opening 3.

(38) Through the provision of the nonreturn valve 30 and the further screw geometry 14, a valve element 16 is not necessary in the embodiment of FIGS. 3 and 4.

(39) It can also be provided that the plasticizing screw 5, as represented in FIGS. 4 and 5, only has a cylindrical extension instead of the further screw geometry 14, wherein a nonreturn valve 30 can be arranged at an end of the cylindrical extension facing the dispensing opening, wherein a valve element 16 can likewise be dispensed with by means of such an embodiment.

(40) FIG. 5 shows a third embodiment of a plasticizing unit 1 which, in comparison with the embodiment of FIG. 1, has a converse conveying geometry 35 on the plasticizing screw 5.

(41) This converse conveying geometry 35 is formed in an area between the first opening 12 and the second opening 13 of the injection cylinder 4, more precisely in an area between the first opening 13 and the dam element 11.

(42) The converse conveying geometry 35 of the plasticizing screw 5 changes from the conveying geometry 15 of the plasticizing screw 5 into the converse conveying geometry 35.

(43) Through the provision of the converse conveying geometry 35, the plasticized material can additionally be retained in the area of the transition from the conveying geometry 15 into the converse conveying geometry 35 and an emerging of the plasticized material from the injection cylinder 4 through the first opening 12 can be promoted.

(44) FIG. 6 shows a fourth embodiment of a plasticizing unit 1 which, in comparison with the embodiment of FIG. 1, has a dummy 36 instead of the filter device 10.

(45) Such a dummy 36 or also placeholder can for example be inserted into the molten material line 9 for delivery and/or transport of the plasticizing unit 1, in order to prevent damage.

(46) When the plasticizing unit is put into operation, this dummy 36 can be removed from the molten material line 9 and replaced with a filter device 10 for the filtration of the plasticized material.

(47) However, it can also be provided that the dummy 36 and/or the filter device 10 are replaced with a connecting pipe or a continuous molten material line 9, wherein a clean material to be plasticized, which requires no further filtration (as can be seen in the fifth embodiment of FIG. 7), can for example be processed.

(48) Through the provision of a connecting pipe or a continuous molten material line 9, the processing of an already clean plasticized material can thus be optimized in that, for example, an unnecessary flow obstruction, as represented by a filter device 10, can be avoided.

(49) FIG. 8 shows a sixth embodiment of a plasticizing unit 1, which has a control or regulating device 37.

(50) This control or regulating device 37 of the plasticizing unit 1 is connected by signal-carrying connections (represented dashed here) to a drive unit 26 of the plasticizing screw 5, a filter change device 17 of the filter device 10, the valve element 16 and a shutoff nozzle 38 of the dispensing opening 3, wherein the control or regulating device 37, with the aid of the signal-carrying connections, is formed to control or regulate these elements and optionally receive characteristic signals from sensors which are arranged on these elements.

(51) Thus, the control or regulating unit 37 can be formed, for example for the measurement of a coating or blocking of the filter device 10, to measure a pressure before and after the filter device 10 with the aid of correspondingly arranged pressure sensors and via the pressure difference between these two pressureswhen the pressure difference becomes too greatto indirectly refer to the coating or blocking of the filter device 10.

(52) When this coating or blocking of the filter device 10 reaches or exceeds a stored or predefinable limit value, the control or regulating unit 37 can be formed to carry out a filter change and/or a filter cleaning.

(53) A filter change can be performed by the control or regulating unit 37 through a corresponding control or regulation of actuators of the plasticizing screw 5 and the filter change device 17. Reference may be made at this point to the following FIGS. 16a to 16c, wherein a filter change will be expanded on.

(54) In the case of a filter cleaning by the control or regulating unit 37, a backflushing can for example be performed, wherein a cleaning of the filter device by backflushing the plasticized material through the filter device 10 can be performed by the control or regulating device 37 (as already described previously) through a corresponding control or regulation of the plasticizing screw 5, the valve element 16, a shutoff nozzle 38 of the dispensing opening 3 and optionally an actuator or valve element 16 of a discharge opening.

(55) FIGS. 9 and 10 show a further embodiment of a plasticizing unit 1, wherein the plasticizing screw 5 has an injection plunger 39.

(56) Through the provision of a plasticizing screw 5 with an injection plunger 39, the possibility can be created that a conveying geometry 15 of the plasticizing screw 5 is kept axially fixed during the entire plasticizing process, wherein, through the prevention of axial movements of the dam geometry 11, a better sealing of the dam geometry 11 with respect to the inner wall of the injection cylinder 4 as well as lower wear between dam geometry 11 and injection cylinder 4 are implemented.

(57) During a cycle of the plasticizing unit 1, a material to be plasticized is now moved from a rear area of the plasticizing screw 5 via the conveying geometry 15 of the plasticizing screw 5 in the direction of the plasticizing zone 8, wherein due to the shearing, shear heat and optionally externally introduced heat the material to be plasticized is plasticized in the plasticizing zone 8.

(58) The material and the plasticized material are conveyed by the conveying geometry 15 of the plasticizing screw 5 in the direction of the dispensing opening 3 until the plasticized material emerges from the plasticizing zone 8 via the first opening 12 from the injection cylinder 4 and is channeled into the molten material line 9.

(59) This emerging of the plasticized material from the plasticizing zone 8 and the injection cylinder 4 is facilitated by the dam element 11.

(60) The material plasticized by the plasticizing screw 5 is thus driven through the molten material line 9 and the filter device 10 arranged therein.

(61) The filter device 10 is formed to filter contaminants out of the plasticized material. These contaminants remain in the filter device, and the filtered plasticized material is channeled through the molten material line 9 via the valve element 16 and the second opening 13 of the injection cylinder 4 back into the injection cylinder 4, in this embodiment, back into the space in front of the screw 7.

(62) The filtered plasticized material now accumulates in the space in front of the screw 7.

(63) As the dispensing opening 3 is closed during the plasticizing (for example via a hotrunner closure system), a melt cushion consisting of plasticized material builds up in the space in front of the screw 7, which pushes the injection plunger 39 away backwards, whereby the space in front of the screw 7 increases in size.

(64) This plasticizing process (often also referred to as metering) is performed until a desired quantity of plasticized material is present in the space in front of the screw 7 (as can be seen in FIG. 9).

(65) If this desired plasticized material for the further processing is achieved in the space in front of the screw 7, the valve element 16 is closed, the dispensing opening 3 is opened, and then dam element 11 is moved in the direction of the dispensing opening 3 via a linear movement of the injection plunger 39 of the plasticizing screw 5. Via the injection plunger 39, the plasticized material is pushed out of the space in front of the screw 7 through the dispensing opening 3 and is, for example, supplied to a mold 24, in this embodiment, a cavity of the mold 24 (as can be seen in FIG. 10).

(66) The remaining features of FIGS. 9 and 10 substantially correspond to those of FIGS. 1 and 2.

(67) FIG. 11 and FIG. 12 show an embodiment which, in comparison with the embodiment of FIG. 5 and FIG. 6, has a nonreturn valve instead of a valve element 16 formed as a 2-way valve.

(68) FIG. 13 and FIG. 14 show an embodiment which, in comparison with the embodiment of FIG. 3 and FIG. 4, has a converse conveying geometry 35 on the plasticizing screw 5.

(69) This converse conveying geometry 35 is formed in an area between the first opening 12 and the second opening 13 of the injection cylinder 4, more precisely in an area between the first opening 13 and the dam element 11.

(70) The converse conveying geometry 35 of the plasticizing screw 5 changes from the conveying geometry 15 of the plasticizing screw 5 into the converse conveying geometry 35.

(71) Through the provision of the converse conveying geometry 35, the plasticized material can additionally be retained in the area of the transition from the conveying geometry 15 into the converse conveying geometry 35 and an emerging of the plasticized material from the injection cylinder 4 through the first opening 12 can be promoted.

(72) It can for example be provided that the first opening 12 is formed as a recess in the injection cylinder 4, which recess is formed by a longitudinal groove with a varying width along the axis of rotation 6, as can be seen in the embodiment of FIG. 15.

(73) FIG. 15 shows a top view of an injection cylinder 4, wherein the inside of the injection cylinder 4 and thus the plasticizing screw 5 arranged in the injection cylinder 4 can be recognized through the first opening 12.

(74) A flow direction of the plasticized material is illustrated by the arrow represented, wherein the material plasticized by the plasticizing screw 5 is conveyed in the direction of the first opening 12, before the plasticized material leaves the injection cylinder 4 via the first opening 12.

(75) If the dam element (such as for example in the case of an embodiment of FIGS. 1-8 or 13-14), together with the plasticizing screw 5, now makes an axial movement in the injection cylinder 4, it may be the case that, in certain operating states, areas of the first opening 12 are at least partially covered (see in particular FIG. 2).

(76) In order nevertheless to be able to implement a sufficient volume flow of plasticized material out of the injection cylinder 4, it can be provided to implement the first opening 12 with a varying width along the axis of rotation 6 of the plasticizing screw 5.

(77) Through a corresponding design, the feeding of the molten material line 9 and thus of the filter device 10 can be controlled or regulated, depending on what proportion of the first opening 12 is cleared by the dam element 11.

(78) Due to the varying width of the first opening 12, it can be achieved that for example a relatively large melt stream gets through the first opening 12, even if a relatively small part of the first opening 12 is cleared by the dam element.

(79) Moreover, it can for example be achieved that the melt stream can be relatively finely regulated in the area of the maximum melt stream (if the first opening 12 is completely or almost completely cleared) in that the first opening 12 at the end that is on the left in FIG. 15 is relatively narrow.

(80) FIGS. 16a to 16c show, purely schematically, a filter device 10 which has a filter change device 17.

(81) This filter change device 17 has a first filter element 33 and a (further) second filter element 34, which can be alternately added to a fluid stream 31 consisting of plasticized material in order to filter the plasticized material and/or to remove contaminants from it.

(82) Correspondingly (see FIG. 16a), first of all a first filter element 33 is located in the molten material line 9 in order to filter the fluid stream 31 of plasticized material.

(83) If the first filter element 33 now has too great a coating (contamination), a filter change can be carried out.

(84) For the measurement of a coating, a pressure can for example be measured before and after the filter element 33, 34 and via the pressure difference between these two pressureswhen the pressure difference becomes too greatthe coating of the filter element 33, 34 can be referred to indirectly.

(85) The cyclic filter change represents an alternative solution, wherein, according to empirical values, the filter elements 33, 34 are exchanged after a certain number of plasticizing cycles have been carried out.

(86) During a filter change (such as is represented by FIG. 16b), the fluid stream 31 of plasticized material is briefly interrupted and, via a change system 32, the first filter element 33 is taken out of the molten material line 9 and replaced with the second filter element 34.

(87) After the change has been effected, the fluid stream 31 of plasticized material can be started again and supplied to the second filter element 34 (see FIG. 16c).

(88) The filter element 33 can then be cleaned while the second filter element 34 is being used and exchanged again once a coating of the second filter element 34 in the fluid stream 31 of plasticized material becomes too great.

(89) It can be provided that the molten material line 9 is formed as a hotrunner system, with the result that during the filter change the plasticized material in the molten material line 9 does not cool too much and possibly solidify.

(90) The molding machine 2 represented by way of example in FIG. 17 is an injection-molding machine and has an injection unit 18 and a clamping unit 19, which are arranged together on a machine frame 20. The machine frame 20 could alternatively also be formed multi-part.

(91) The clamping unit 19 has a fixed platen 21, a movable platen 22 and an end plate 23.

(92) The movable platen 22 is movable relative to the machine frame 23 via a symbolically represented knuckle joint mechanism 29.

(93) Mold halves of a mold 24 can be clamped or fitted (represented dashed) on the fixed platen 21 and the movable platen 22.

(94) The fixed platen 21, the movable platen 22 and the end plate 23 are mounted and guided relative to each other by the rails 25.

(95) The mold 24 represented closed in FIG. 17 has at least one cavity. An injection channel, via which a plasticized material can be supplied to the plasticizing unit 2, leads to the cavity.

(96) FIG. 17 shows a molding machine 2 with an injection unit 18, wherein the injection unit 18 shown in this embodiment has a plasticizing screw 5 formed as an injection screw, which is also used for plasticizing a material to be plasticized.

(97) The injection unit 18 of this embodiment has an injection cylinder 4 and a plasticizing screw 5 arranged in the injection cylinder 4. This plasticizing screw 5 is rotatable about an axis of rotation 6 as well as movable axially along the axis of rotation 6 in the conveying direction.

(98) These movements are driven via a schematically represented drive unit 26. This drive unit 26 preferably comprises a rotary drive for the rotational movement and a linear drive for the axial injection movement.

(99) The plasticizing unit 1 (and thus the injection unit 18) is in signaling connection with a control or regulating unit 27. Control commands are for example output to the plasticizing unit 1 and/or the drive unit 27 by the control or regulating unit 27.

(100) The control or regulating unit 27 can be connected to an operating unit and/or a display device 28 or can be an integral constituent of such an operating unit.

(101) It can be provided that the control or regulating unit 27 of the molding machine 2 at least partly undertakes the function of the control or regulating device 37 of the plasticizing unit 1, is formed as the latter or alternatively even is implemented independently and/or separately from the latter.

LIST OF REFERENCE NUMBERS

(102) 1 plasticizing unit 2 molding machine 3 dispensing opening 4 injection cylinder 5 plasticizing screw 6 axis of rotation 7 space in front of the screw 8 plasticizing zone 9 molten material line 10 filter device 11 dam geometry 12 first opening of the injection cylinder 13 second opening of the injection cylinder 14 further conveying geometry 15 conveying geometry 16 valve element 17 filter change device 18 injection unit 19 clamping unit 20 machine frame 21 fixed platen 22 movable platen 23 end plate 24 mold 25 rail 26 drive unit 27 control or regulating unit 28 display device 29 knuckle joint mechanism 30 nonreturn valve 31 fluid stream 32 change system 33 first filter element 34 second filter element 35 converse conveying geometry 36 dummy 37 control or regulating device 38 shutoff nozzle 39 injection plunger