EP3770444B1 - Arrangement with a pneumatic or hydraulic piston rod cylinder - Google Patents

Description

The invention is based on an arrangement with a first valve and a pneumatic or hydraulic piston rod cylinder with a cylinder and a first piston therein which can be adjusted in its longitudinal direction, which is coupled to at least one piston rod protruding from the cylinder and converts a volume accommodated in the cylinder into a first pressure chamber, through which the piston rod extends out of the cylinder, and a second pressure chamber, wherein the first and the second pressure chamber are fluidically connected to one another via a bypass and each have a pressure connection which is completely or at least partially in a cylinder wall of the cylinder can be formed, and via which the pressure chambers can be subjected to a fluid pressure by means of the first valve connected to a first pressure connection line, and wherein a first side of the first piston contains the first pressure chamber and a second side arranged opposite the first Side of the first piston, which has a smaller area compared to the first side, depending on the desired direction of movement of the piston, delimits the second pressure chamber, with the piston rod extending from the first piston over the entire length of both the first pressure chamber and the second pressure chamber extends through the respective pressure chamber, the piston rod having a smaller diameter in the first pressure chamber than in the second pressure chamber. Such a piston rod cylinder is from DE 10 2011 009 302 A1 known. Similar piston rod cylinders also describe the DE 2 061 883 A , the DE 19 41 785 A1 , the DE 10 2006 041 707 B4 and the DE 10 2012 007 170 B3 .

The known piston rod cylinders have the disadvantage that the design of the bypass is complex in terms of construction, for example in that the bypass is ensured by a recess in the cylinder. In this case, for example, the bore diameter of the cylinder can be made larger in sections than the diameter of the piston, so that the fluid can flow around the piston in this section. This design also has the disadvantage that it is impossible to install additional functional components, for example the installation of valves in the bypass. Furthermore, solutions are known in which the bypass is formed within the piston rod so that the connection points for the bypass are moved with the piston and interrupted by moving a connection point out of the compressed pressure chamber into another chamber of the bypass becomes. This design is also complex in terms of construction and is therefore correspondingly expensive to provide.

Accordingly, it is the object of the invention to propose an arrangement with a piston rod cylinder of the type described above, in which the bypass is provided with simple technical means and can therefore not only be manufactured inexpensively, but also has a reliable mode of operation.

This object is achieved by an arrangement with the features of claim 1. The dependent claims each relate to advantageous embodiments of the invention.

Accordingly, it is provided that a further pressure connection is arranged one piston adjustment path vertically above the pressure connection of the second pressure chamber, via which a second pressure connection, connected to the further pressure connection valve and a second pressure connection line, pressurization of the second pressure chamber is provided independently of the first valve wherein the piston rod extends from the first piston through a separating element which fluidly separates the second pressure chamber from a third pressure chamber of the cylinder, into the third pressure chamber and has at its end a second piston which separates the third pressure chamber from a fourth pressure chamber of the cylinder is fluidically separated, the fourth pressure chamber being connected via a further pressure connection and an additional pressure connection line to a third valve, via which an excess fluid pressure can be provided in the fourth pressure chamber, so that one on the second Piston acting force the piston together with the piston rod and the first piston can be displaced vertically downwards.

The first piston can thus in particular not be attached to the end of the piston rod, as is the case with the arrangements known from the prior art. Rather, the piston rod can extend in the longitudinal direction of the cylinder on both sides of the piston through both of the pressure chambers, which are fluidically separated from one another by the piston, over their entire length in the longitudinal direction. Due to the different cross-section of the piston rod in relation to the two sides of the piston, the two opposite sides of the piston have a difference in area, which is just the difference in cross-sectional area of the Piston rod in the two pressure chambers corresponds.

The third pressure chamber can have ambient pressure and can be aerated and/or vented to the surroundings of the piston rod cylinder for this purpose via a preferably soundproofed valve.

In order to prevent a leak in the separating element, which would lead to an uncontrolled acceleration of the piston rod, since the third Pressure chamber has ambient pressure, the separating element can be designed as a double seal, with a first and a second seal which are arranged at a distance from one another in the longitudinal direction of the piston and enclose the piston rod.

The bypass of the piston rod cylinder can be designed and guided entirely outside of the cylinder. For this purpose it can be provided that the first and the second pressure chamber are fluidly connected to one another via a bypass line of the bypass connected to pressure connections of the first and the second pressure chamber. The bypass line may be located outside the cylinder over at least part of its length and preferably over its entire length. Alternatively, the bypass line, like the pressure connections it connects, can be completely or essentially completely integrated into a wall of the cylinder.

The bypass line may have a unidirectionally permeable valve, preferably a check valve, which is permeable in the direction of fluid flow from the second pressure chamber to the first pressure chamber and impermeable in the opposite direction.

The bypass line can be connected to the second pressure chamber via the pressure connection of the second pressure chamber. Additionally or alternatively, the bypass line can be connected to the first pressure chamber at its opposite end via the pressure connection of the first pressure chamber.

The first piston can have a stop position in which the piston rod projects into the cylinder by a maximum length and a sealing circumference of the first piston, via which the first piston rests sealingly on the inner circumference of the cylinder, closes or runs over a pressure connection to the second pressure chamber, via which the bypass line is connected to the second pressure chamber.

In the stop position, the fourth pressure chamber can have a minimal volume into which another pressure connection opens. The sealing circumference of the first piston can continuously close or overrun the pressure connection of the bypass line that opens into the second pressure chamber via the piston adjustment path of the first piston ending in the stop position, so that via the piston adjustment path due to the closed bypass line in the first pressure chamber significant overpressure built up compared to the second pressure chamber and accordingly a high force can be exerted on the first piston, so that it can move with corresponding force on the piston adjustment path in the direction of the second pressure chamber, the volume of which is further reduced.

The piston adjustment path can, for example, be up to 10 mm, preferably up to 8 mm and particularly preferably up to or exactly 4 mm and/or be determined by the dimension of the sealing circumference in the longitudinal direction. In particular, the piston adjustment path can be selected precisely thereafter in order to avoid accidentally pinching a finger.

The bypass line can have at least two partial lines connected in parallel, each having a unidirectionally permeable valve, preferably a check valve, which is permeable in the direction from the second pressure chamber to the first pressure chamber and impermeable in the opposite direction.

The difference in area between the two sides of the first piston can, at a given pressure, cause a force acting on the first piston of at most 150 N and more preferably at most 135 N.

In an arrangement according to the invention with the piston rod cylinder, the upward movement of the piston can be controlled in that pressure is applied to a lower and a middle pressure chamber via pressure connection points, for example via valves. This can be vented via a pressure connection point of the uppermost pressure chamber. Since the middle and the lower pressure chamber are connected to each other via a bypass, the same pressure prevails in the lower and the middle pressure chamber. In addition, an unpressurized chamber is separated from the central pressure chamber by a separating element. The unpressurized chamber can be connected to the environment through an opening, a vent valve or a silencer, so that essentially ambient pressure prevails in this chamber. Since the piston rod in the middle chamber has a larger diameter than the piston rod in the lower chamber, a greater force acts on the lower piston from below than from above, causing the piston to move upwards takes place. If the lower piston passes the pressure connection point of the bypass, the Bypass closed and the cylinder can generate a large closing force on the remaining way to the end position.

In order to extend the cylinder again, the uppermost chamber of the cylinder can be pressurized with fluid pressure via its pressure connection point by switching a connected valve, while the valves connected to the lower and middle pressure chambers are switched to the rest position so that they are vented.

Although the principles of the present invention are explained in the above description according to the invention using a piston rod cylinder that executes a retraction movement, into whose cylinder the piston rod retracts when the pressure chambers bridged via the bypass line are subjected to the same fluid pressure, these principles are readily applicable to an extension movement exporting piston rod cylinder transferable, the piston rod of which moves out of the cylinder when pressure is applied to the pressure chambers bridged via the bypass line with the same fluid pressure. All you have to do is swap the piston rod diameters of the two pressure chambers separated by the first piston, assign the other pressure port of the second pressure chamber to the first pressure chamber, and assign the pressure port of the fourth pressure chamber to the third pressure chamber and the vent valve to the fourth pressure chamber. However, such a piston rod cylinder executing an extension movement is not covered by the patent claims.

Figur 1

eine Ausführungsform eines pneumatischen oder hydraulischen Kolbenstangenzylinders in schematischer Darstellung, der nicht zum Gegenstand der Erfindung gehört;

Figur 2

eine Ausführungsform eines erfindungsgemäßen pneumatischen oder hydraulischen Kolbenstangenzylinders in schematischer Darstellung.

Further details of the invention are explained with reference to the figures below. It shows:

figure 1

an embodiment of a pneumatic or hydraulic piston rod cylinder in a schematic representation, which does not belong to the subject of the invention;

figure 2

an embodiment of a pneumatic or hydraulic piston rod cylinder according to the invention in a schematic representation.

the figure 1 shows a schematic representation of an embodiment of a piston rod cylinder 1 that does not belong to the invention a cylinder 2 which has a substantially constant cross-section over its entire height and is therefore simple and inexpensive to provide. A piston 3 is arranged in the cylinder 2 so that it can be adjusted in the longitudinal direction of the cylinder 2, the piston 3 with its sealing circumference 12 being in fluid contact with the inner circumference 13 of the cylinder 2 in a fluid-tight manner, thereby dividing the volume inside the cylinder 2 into two fluidically separate pressure chambers 5 , 6 divided. From one of the opposite sides 8, 9 of the piston 3, namely from the first side 8, the piston rod 4 extends from the piston 3 over the entire length of the first pressure chamber 5 out of the first pressure chamber 5.

Via a first valve 17, a first pressure connection line 19 and a pressure connection 16, the first pressure chamber 5 is subjected to a fluid pressure or optionally vented. Likewise, a pressurization of both the first pressure chamber 5 and the second pressure chamber 6 is provided via a second valve 18 , a second pressure connection line 20 and pressure connections 15 . The lowest pressure connection 16, which is connected via the first valve 17, is arranged below a lower stop position of the piston sealing circumference 12, so that the piston sealing circumference 12 does not close the pressure connection 16 even in this lower stop position and is therefore available for pressurizing the first pressure chamber 5 Available. In contrast, the piston 3 with its sealing circumference 12 in the lower stop position and by an upstream adjustment path x, here 4 mm, closes the lower pressure connection 15 , which is connected to the second valve 18 via the pressure line 20 .

A bypass line 10, which connects the pressure connections 15 to one another and is routed outside of the cylinder 2, ensures that the same pressure always prevails in the first and second pressure chambers 5, 6 when the piston 3 is positioned with its circumferential sealing surface between the two pressure connections 15 is arranged and in particular does not close the lower pressure connection 15 connected to the second valve 18 . The bypass line 10 has two sub-lines 14 running parallel to one another, in each of which a check valve 11 is arranged, so that a redundancy is established with regard to the function of the check valves 11 . The check valves 11 are permeable in the direction from the second pressure chamber 6 to the first pressure chamber 5 and are blocking in the opposite direction. The pressure connection 16, via which the first pressure connection line 19 is connected to the first pressure chamber, is an adjustment path x below that in the first Pressure chamber 5 opening pressure connection 15 of the second pressure connection line 20 is arranged.

In order to move the piston 3 of the piston rod 4 out of the cylinder 2 from a retracted position, as is the case, for example, in figure 1 is shown to be converted into an extended position in which, based on the representation according to figure 1 the piston 3 in the cylinder 2 is shifted further vertically downwards, the two valves 17, 18 provide the same or substantially the same fluid pressure, with which the first and the second pressure chamber 5, 6 via the pressure connection lines 19, 20 and the Pressure connections 15, 16 are applied. Since in the first pressure chamber 5 the cross-sectional area 8 of the piston 3 on which the fluid pressure acts is smaller by the cross-sectional area of the piston rod 4 than the cross-sectional area 9 of the piston 3 in the second pressure chamber 6, a pressure acts in the second pressure chamber 6 compared to the first Pressure chamber 5 higher pressure on the piston 3, so that the piston 3 experiences an effective application of force in the vertical direction downwards, as a result of which the piston 3 together with the piston rod 4 is displaced vertically downwards.

The force that acts on the piston 3 and thus on the piston rod 4 at a given air pressure can thus be adjusted via the diameter of the piston rod 4 . If, for example, the goal is to keep the force acting on the piston 3 so low that fingers are prevented from being trapped, for example, at a given system pressure of 6 bar, which is applied via the pressure connections 15, 16 to the two chambers 5, 6 is given, a maximum piston rod diameter of 16.9 mm can be determined in order to ensure a "tolerable" 135 N clamping force.

Only when the piston 3 has been displaced so far down in the cylinder 2 that it closes the pressure connection 15 with its sealing circumference 12 and thus the pressure equalization via the bypass line 10 is interrupted, can the increased pressurization of the second chamber 6 via the second valve 18 and the second pressure line 20, an increased force can be exerted on the piston 3 and the piston rod 4, as may be required depending on the application.

For this purpose, the pressure connection 15 of the bypass line 10 to the first pressure chamber 5 can be arranged so low and just above a lower stop point of the piston 3 that, for example, it is no longer possible for fingers to be pinched. For example, this last adjustment path x, via which an increased pressure can be built up on the side of the first pressure chamber 5 when the pressure connection line 15 is closed, can amount to only 4 mm or the like.

In order to return the piston 3 from the lower position to the in figure 1 To convert the retracted or partially retracted position shown, a fluid pressure can be provided via the first valve 17 and the first pressure line 19, while the second valve 18, which is connected to the second pressure chamber 6 via the second pressure connection line and the pressure connection 15, is released , so that when the piston 3 is displaced in the vertical direction upwards, with the volume of the second pressure chamber 6 being reduced, pressure equalization can be provided by fluid discharge via the second pressure connection line 20 and the second valve 18 .

An embodiment of the invention is in figure 2 shown. In this case, a second piston 3.2 is arranged along the same piston rod 4 in the cylinder 2 next to a first piston 3.1 at a distance from this. The pistons 3.1, 3.2 are in turn analogous to the embodiment according to FIG figure 1 along their respective outer circumference sealingly on the inner circumference of the cylinder 2, so that they subdivide the volume of fluid accommodated inside the cylinder 2. According to the representation figure 2 Lower piston 3.1 separates a first pressure chamber 5 from a second pressure chamber 6, while the second piston 3.2 separates a third pressure chamber 21 from a fourth pressure chamber 22. The third pressure chamber 21 is separated from the second pressure chamber 6 in a fluid-tight manner by a separating element 23 . The piston rod 4 extends over the entire length of the first pressure chamber 5 through the first pressure chamber 5 and out of the cylinder 2 via this. In the area of the second pressure chamber 6, the piston rod 4 has a diameter that is larger than the diameter of the piston rod 4 in the area of the first pressure chamber. In the area from the second to the fourth pressure chamber 6, 21, 22, the diameter of the piston rod 4 is essentially constant, but it can also have a varying diameter between the second pressure chamber 6 and the fourth pressure chamber 22 in its longitudinal direction. For the embodiment according to figure 2 However, it is essential that the piston rod 4 has a different diameter compared to the first and second pressure chambers 5, 6, the diameter of the piston rod 4 in the second pressure chamber 6 being larger than the diameter of the piston rod 4 in the first pressure chamber 5.

The first pressure connection line 19 is subjected to a fluid pressure by a first valve 17 and opens into the two pressure connections 15 of the first and second pressure chambers 5, 6, which in turn are connected to one another via a bypass line 10 in order to maintain a constant pressure in the two chambers 5 , 6 ensure if the bypass line is not blocked on the outer circumference of the first piston element 3.1. A further pressure connection 25 is arranged by a piston displacement path x of approximately 4 mm vertically above the pressure connection 15 of the second pressure chamber 6, via which pressure is applied to the second pressure chamber 6 independently of the first valve 17 by a second valve 18 and a second pressure connection line 20 can be.

If the same or essentially the same fluid pressure is provided in the pressure chambers 5, 6 via the first and the second valve 17, 18, this results in the embodiment according to FIG figure 2 to the fact that the first piston 3.1 and with it the second piston 3.2 and the piston rod 4 connecting the pistons 3.1, 3.2 to one another are shifted upwards in the vertical direction, since due to the larger diameter of the piston rod 4 in the area of the second pressure chamber 6, the Underside of the first piston 3.1 in the vertical direction upward force is greater than the force acting on the top of the first piston 3.1 in the vertical direction downward. Analogous to the embodiment according to figure 1 is the first piston 3.1. thus in turn shifted upwards with a small force in the vertical direction until the outer circumference of the first piston 3.1 first closes the connection point 15 of the bypass line 10 that opens into the second pressure chamber 6 and then the first piston 3.1 resting on the separating element reaches an upper stop position. If the piston 3.1 closes the bypass line 10, a correspondingly high overpressure can be provided via the first valve 17 and the first pressure connection line in the first pressure chamber 5, which leads to a correspondingly higher force being applied to the first piston 3.1 in the vertical direction upwards, since the pressure equalization to the second pressure chamber 6 via the bypass line 10 is interrupted. The piston 3 . 1 again reaches the upper stop position when it comes to rest on the separating element 23 . Consequently, the increased force on the first piston 3.1 is only provided over the last millimeters of movement, in the present case 4 mm, which can be measured, for example, according to the fact that fingers cannot be pinched analogously to the embodiment according to FIG figure 1 is impossible.

By moving the first piston 3.1 while varying the volumes of the first and second pressure chambers 5, 6, the second piston 3.2 at the upper end of the piston rod 4 is also moved in such a way that the volumes of the third and fourth pressure chambers 21, 22 change. While the fourth pressure chamber 22 is connected via a further pressure connection point 16 and an additional pressure connection line 26 to a third valve 27, via which an overpressure can be reduced by moving the second piston 3.2 upwards, in that the third valve 27 is released, the third pressure chamber 21 an optionally soundproofed ventilation valve 24, so that in the third pressure chamber 21 there is always the ambient pressure. When the second piston 3.2 moves from bottom to top, air from the area around piston rod cylinder 1 is consequently sucked into the third pressure chamber, while when the second piston 3.2 moves in the vertical direction from top to bottom, the air escapes via valve 24 from third pressure chamber 21 can escape.

After the piston rod 4 and the piston 3.1, 3.2 have been displaced from a lower position to an upper position by uniform pressurization of the first and second pressure chambers 5, 6 in the manner described above, as is the case, for example, in figure 2 is shown, by releasing the valves 17, 18 connected to the first and second pressure chambers 5, 6, an excess fluid pressure can finally be provided in the fourth pressure chamber 22 via the third valve 27, the additional pressure connection line 26 and the further pressure connection 16, so that a force acting on the second piston 3.2 moves the piston 3.2 together with the piston rod 4 and the first piston 3.1 vertically downwards.

The valves 17, 18, 27 shown in the embodiments can be designed, for example, as 3-way valves which are connected to a fluid pressure source with a first connection side, for example to a fluid pressure line or to a compressor. With a further connection side they are connected to an unpressurized volume of fluid, for example to the ambient air if the fluid is air. The third valve connection side can then be connected to one of the pressure connection lines 19, 20, 26 in order to provide the fluid pressure at the corresponding pressure connections 15, 16, 25 or to realize pressure equalization as required.

Reference list:

1

piston rod cylinder

2

cylinder

3

Pistons

3.1

first piston

3.2

second piston

4

piston rod

5

first pressure chamber

6

second pressure chamber

7

bypass

8th

first page

9

second page

10

bypass line

11

check valve

12

sealing perimeter

13

inner circumference

14

partial line

15

pressure connection

16

further pressure connection

17

first valve

18

second valve

19

first pressure connection line

20

second pressure connection line

21

third pressure chamber

22

fourth pressure chamber

23

separator

24

silenced valve

25

additional pressure connection

26

third pressure connection line

27

third valve

x

adjustment range

Claims (14)

1. An arrangement with a first valve (17), a second valve (18), a third valve (27) and a pneumatic or hydraulic piston rod cylinder (1) with a cylinder (2) and a first piston (3.1), which is coupled to at least one piston rod (4) projecting from the cylinder (2) and divides a volume accommodated in the cylinder (2) into a first pressure chamber (5), through which the piston rod (4) extends out of the cylinder (2), and a second pressure chamber (6), the first and second pressure chambers (5, 6) are fluidically connected to one another via a bypass (7) as part of a first pressure connection line (19) and each have a pressure connection (15) which can be formed in a cylinder wall of the cylinder (2) and via which the pressure chambers (5, 6) can be acted upon with a fluid pressure by means of the first valve (17) connected to the first pressure connection line (19), and a first side (8) of the first piston (3.1) delimits the first pressure chamber (5) and a second side (9) of the first piston (3.1), which is arranged opposite the first side (8) and has a smaller area compared to the first side (8), delimits the second pressure chamber (6), the piston rod (4) extending from the first piston (3.1) extends over the entire length of both the first pressure chamber (5) and the second pressure chamber (6) through the respective pressure chamber (5, 6), the piston rod (4) having a smaller diameter in the first pressure chamber (5) than in the second pressure chamber (6), wherein a further pressure port (25) is arranged vertically above the pressure port (15) of the second pressure chamber (6) by a piston displacement (x), via which a pressurization of the second pressure chamber (5, 6) can be provided independently of the first valve (17) by the second valve (18) connected to the further pressure port (25) and a second pressure port line (20), wherein the piston rod (4) can be separated from the first piston (3.1) through a separating element (23), which fluidically separates the second pressure chamber (6) from a third pressure chamber (21) of the cylinder (2), into the third pressure chamber (21) and has at its end a second piston (3.2), which fluidically separates the third pressure chamber (21) from a fourth pressure chamber (22) of the cylinder (2), wherein the fourth pressure chamber (22) is connected via a further pressure connection (16) and an additional pressure connection line (26) to the third valve (27), via which a fluid overpressure can be provided in the fourth pressure chamber (22), so that a force acting on the second piston (3.2) can displace the second piston (3.2) together with the piston rod (4) and the first piston (3.1) vertically downwards.
2. The arrangement according to claim 1, wherein the third pressure chamber (21) has ambient pressure and for this purpose is ventilated and/or vented to the environment of the piston rod cylinder (1) via a preferably silenced valve (24).
3. The arrangement according to any one of claims 1 or 2, wherein the first and second pressure chambers (5, 6) are fluidically interconnected via a bypass line (10) of the bypass (7) connected to pressure ports (15) of the first and second pressure chambers (5, 6), which bypass line (10) may be formed in a cylinder wall of the cylinder (2).
4. The arrangement according to claim 3, in which the bypass line (10) is arranged outside the cylinder (2) over at least part of its length and preferably over its entire length.
5. The arrangement according to any one of claims 3 or 4, wherein the bypass line (10) comprises a unidirectional permeable valve (11), preferably a check valve, which is permeable in the fluid flow direction from the second pressure chamber (6) to the first pressure chamber (5).
6. The arrangement of any one of claims 3 to 4, wherein the bypass line (10) is connected to the second pressure chamber (6) via the pressure port (15) of the second pressure chamber (6).
7. The arrangement according to any one of claims 3 to 6, wherein the bypass line (10) is connected to the first pressure chamber (5) via the pressure port (15) of the first pressure chamber (5).
8. The arrangement according to one of the preceding claims, in which the first piston (3.1) has a stop position in which the piston rod (4) projects into the cylinder (2) by a maximum length and a sealing circumference (12) of the first piston (3.1), via which the first piston (3.1) bears in a sealing manner against the inner circumference (13) of the cylinder (2), closes off or passes over a pressure connection (15) of the second pressure chamber (6), via which the bypass line (10) is connected to the second pressure chamber (5).
9. The arrangement of claim 8, wherein in the stop position the fourth pressure chamber (22) has a minimum volume into which the further pressure port (16) opens.
10. The arrangement according to claim 8 or 9, in which the sealing circumference (12) of the first piston (3.1) closes the pressure port (15) of the bypass line (10) opening into the second pressure chamber (6) uninterruptedly over the piston displacement (x) of the first piston (3.1) ending in the stop position, or passes over it.
11. The arrangement according to claim 10, wherein the piston displacement (x) is up to 10 mm, preferably up to 8 mm and particularly preferably up to or exactly 4 mm and/or is determined by the dimension of the seal circumference (12) in the longitudinal direction.
12. The arrangement according to any one of claims 3 to 11, in which the bypass line (10) has at least two partial lines (14) connected in parallel with one another, each of which has a unidirectional permeable valve (11), preferably a check valve, which are permeable in the direction from the second pressure chamber (6) to the first pressure chamber (5).
13. The arrangement according to any one of the preceding claims, in which the difference in area of the two sides (8, 9) of the first piston (3.1) at a given pressure causes a force acting on the first piston (3.1) of at most 150 N and particularly preferably at most 135 N.
14. The arrangement according to one of the preceding claims, wherein the separating element (23) is designed as a double seal, with a first and a second seal which are arranged at a distance from one another in the longitudinal direction of the piston and enclose the piston rod (4).

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