Piston-housing unit, piston, housing and actuator operated by pressure medium

Abstract

The utility model relates to a piston-housing unit (1) having a piston (2) and a housing (3) which extends along an axis (X) of the piston-housing unit (1), the piston (2) being designed to be movable parallel to the axis (X) and the piston (2) closing a cavity (4) in the housing (3), the piston-housing unit (1) has a cavity (4), the volume of which can be adapted in accordance with a displacement of the piston (2) parallel to the axis (X), and wherein the piston-housing unit (1) has a piston guide (5) arranged in the cavity (4). The utility model further relates to an actuator operated by a pressure medium, to a piston (2) and to a housing (3).

Description

TECHNICAL FIELD

[0001] The present application relates to a piston-housing unit, a piston, a housing and an actuator operated by a pressure medium. BACKGROUND

[0002] Some piston-housing units are known, in which a piston is arranged movably along an axis in a housing of the piston-housing unit. Here, the piston together with the housing forms a cavity, which can be adapted in its volume in accordance with the movement of the piston along the axis. Here, the piston is guided during the movement by the contact between the side of the piston and the inner side of the housing. In addition, usually an additional bearing is provided, which additionally supports the piston by means of a piston rod connected to the piston.

[0003] It is disadvantageous in the case of such a piston-housing unit that, on the one hand, the guidance of the piston can be achieved, but on the other hand the piston cannot be protected against a twisting or turning about the axis along which the piston is displaced. This has a disadvantageous effect on the piston seal arranged between the piston and the inner wall of the housing in order to seal the cavity, since the seal is moved with a rotational movement relative to the inner wall of the housing as a result of the rotational movement of the piston, which additionally loads the seal.

[0004] It is likewise disadvantageous if the piston has an indicator element for detecting the position of the piston, which must be arranged over a large area of the piston, in particular over the entire periphery of the piston, in order to enable a detector device fixed relative to the piston to detect the indicator element and thus the position of the piston, for which the indicator element or a segment of the indicator element must lie within a predetermined detection area of the detector device. This means that an excessive twisting of the piston prevents the detection of the indicator element by the detector device as soon as the indicator element no longer lies within the detection area of the detector device.

[0005] A further disadvantage in such a piston-housing unit is that the piston can here lie against the inner wall of the housing on one side. For example, the piston can lie against the inner wall of the housing on one side as a result of a transverse force exerted on the piston rod, or the seal can at least be loaded on the piston on one side, while the seal is unloaded on the opposite side. SUMMARY

[0006] It is therefore the task of the following application to solve at least one of the above-mentioned problems.

[0007] This task is solved by the subject matter of the independent claims. Advantageous developments are the subject matter of the dependent claims of the following description and the drawings.

[0008] According to a first aspect of the present application, a piston-housing unit is provided, having a piston and a housing. The housing extends along an axis of the piston-housing unit. The piston is configured to be movable parallel to the axis. The piston encloses a cavity in the housing, the volume of which can be adapted to the displacement of the piston parallel to the axis. The piston-housing unit has a piston guide arranged in the cavity.

[0009] Due to the piston guide in the cavity, a corresponding guidance of the piston is possible without the need to provide assembly space for a piston guide outside the cavity.

[0010] The piston-housing unit can have a mechanical transmission element, for example a piston rod, by means of which a movement or a piston force of the piston can be transmitted. Here, the transmission element can be connected to the piston directly or via an intermediate element. The transmission element here forms a mechanical interface by means of which a movement or a piston force of the piston is transmitted to a mechanism which is to be controlled by the piston-housing unit. The piston movement or the piston force can be achieved by supplying or discharging a pressure medium into the cavity. The pressure medium can be gaseous or liquid. In particular, the pressure medium can be compressed air or a hydraulic fluid. The piston-housing unit is therefore particularly suitable for pneumatic or hydraulic applications.

[0011] The housing of the piston-housing unit can in particular be a cylinder in which the piston is guided and in which the cavity delimited by the piston is configured.

[0012] The piston-housing unit can be provided for use in a vehicle, in particular a utility vehicle.

[0013] The piston guide can have a guide element and a counter element which engage into one another. The arrangement of the guide element and the counter element can here be made as desired. In particular, it can be provided that the guide element is arranged in the housing and the counter element is arranged on the piston. Alternatively, the counter element can be arranged in the housing and the guide element can be arranged on the piston.

[0014] The housing can be implemented in multiple components. This allows for easy assembly of the piston-housing unit, especially when assembling the housing and piston. In a multi-component implementation of the housing, the housing can be divided into at least two housing elements. For example, a housing element can be a housing cover that limits the cavity in the axial direction and closes the cavity when the housing cover is correspondingly engaged with a housing element or the remainder of the housing element. In this case, a guide element or mating element can be disposed on the cover and extend completely or partially into the cavity. The advantage of this implementation is that the guide element and mating element can be assembled together with a pre-installed piston. In other words, if the housing cover is assembled in this manner, the guide element and mating element can be configured such that when the guide element and mating element engage with each other accordingly, the housing cover can be assembled only with the remainder of the housing or the remainder of the housing element. In this way, incorrect assembly can be prevented or at least made difficult.

[0015] The guide element and the mating element can be constructed to be axially movable relative to each other. This allows for axial movement of the piston relative to the housing. In particular, the mating element can be configured to extend axially into or through the guide element. Here, the guide element can be constructed, in particular, as a sleeve or track, so that the guide element can accordingly accommodate the mating element. The mating element can be constructed to mate with the guide element and can be constructed, for example, in the form of an axially extending rod. Piston guidance is achieved here by sections of the guide element and the mating element that overlap or engage with each other in the axial direction. That is, the guide element and the mating element can be constructed such that guidance of the piston can be achieved throughout the entire stroke of the piston, i.e., between piston positions corresponding to the minimum and maximum volumes of the cavity. For example, this can be achieved by such that the axial extension dimensions of the mating element and the guide element are coordinated with each other such that even in the piston position corresponding to the maximum volume of the cavity, there is still sufficient overlap between the mating element and the guide element to enable piston guidance. The piston-housing unit, especially the guide element, may have a recess or pocket portion configured such that when the piston moves toward a piston position corresponding to the minimum volume of the cavity, the mating element engages in the corresponding recess or pocket portion, thereby preventing the mating element from colliding with the housing or piston, depending on whether it is mounted on the piston or the housing.

[0016] The guiding element may have an internal structure or a guiding opening, with a mating element engaging with this internal structure or opening. For example, the mating element, constructed to extend axially, may extend into the guiding opening or the internal structure. Here, piston guidance is achieved through the interaction between the guiding element and the mating element, particularly through the contact between the inner surface of the guiding opening or the internal structure and the outer surface of the mating element. In particular, the inner or outer surface is an axially extending surface, thereby enabling axial mobility of the guiding element and the mating element relative to each other. The inner or outer surfaces may be constructed to mate with each other. This means that, on the one hand, the internal structure or guiding opening, and on the other hand, the mating element, have a constant cross-sectional shape in the axial direction. Thus, a sufficient guiding effect on the piston can be achieved along the entire displacement of the piston between the piston positions corresponding to the minimum and maximum volumes of the cavity.

[0017] The piston guide can be configured to limit the piston's movement parallel to its axis. In other words, the piston guide can have a mechanical stop. This stop can be particularly configured between the guide element and the mating element. Here, surfaces that contact each other when the piston reaches a predetermined piston position can be provided. This can particularly be the piston position corresponding to the minimum or maximum volume of the cavity. It is particularly advantageous if the piston-casing unit is used such that the piston is connected to a mechanism, for example, via a transmission element such as a piston rod, which does not have its own limiting mechanism for piston movement but is able to limit the piston movement. This limitation of piston displacement achieved by the piston guide can be configured such that a corresponding protective material can be achieved and the limitation is coordinated with the forces that occur during the operation of the piston-casing unit.

[0018] A piston guide can be configured to guide the piston against rotational motion as it moves parallel to its axis. Rotational motion is understood as rotation about an axis or piston axis. Thus, the piston guide forms an anti-torsion element, by which rotational motion of the piston about its axis is impeded. In particular, rotational motion can be completely prevented or limited to an angular range. This angular range can be less than 2°. By preventing this rotational motion, rotational motion in the sealing section between the piston and the housing is also prevented or at least reduced, thereby protecting one or more seals arranged in the sealing section because no such rotational relative motion occurs between the housing and the piston.

[0019] To achieve anti-torsion, piston guides, particularly mating elements and guide elements, can have corresponding shapes or structures that lock in place to prevent or reduce rotational movement. For example, the internal structure or guide opening of the guide element can be constructed as a non-rotationally symmetrical structure relative to the piston axis, and the mating element is correspondingly constructed such that the outer surface of the mating element contacts the existing or formed surface of the inner surface of the internal structure or guide opening to prevent rotational movement of the piston. For this purpose, the internal structure or guide opening and the mating element can each have a cross-section perpendicular to the axis, which is, for example, axially symmetrical in that plane, or have recesses or protrusions. Different shapes will be conceived by those skilled in the art.

[0020] The piston-housing unit may have an indicator element connected to the piston, wherein the piston-housing unit is configured to determine the position of the piston along the axis by detecting the position of the indicator element along the axis. To detect the indicator element, the piston-housing unit may have a detection device. In particular, the indicator element may be constructed magnetically, for example, permanently magnetically. The detection device may be configured, for example, as a Hall sensor, which can be used to detect the indicator element when it is located within the detection area of ​​the detection device. In particular, multiple such detection devices may be arranged along the axis so that multiple detection areas can be used to cover the possible stroke of the indicator element as completely as possible.

[0021] In particular, if the piston guide is constructed as an anti-torsion element, the indicator element can be arranged only at a specific location on the periphery of the piston, because the implemented anti-torsion element prevents rotational movements that could cause the indicator element to move out of all detection areas of the detection device. In this way, a smaller indicator element is required, thereby ultimately reducing the material requirements for constructing the indicator element.

[0022] If the anti-torsion component is constructed such that the piston can rotate about the axis within a limited angular range (e.g., less than 2°), the indicator element can be coordinated with that angular range, for example, by extending a correspondingly larger portion in the circumferential direction, so that a section of the indicator element always passes through the detection area of ​​the detection device as the piston moves.

[0023] A piston guide can be configured to axially guide the piston during movement parallel to the axis. This axial guidance can replace or supplement the aforementioned anti-torsion element. The axial guidance can be configured such that the piston is centered within the housing or remains centered during movement. This achieves a piston guide that, in its case, avoids or even prevents the piston from abutting on one side, for example, due to introduced lateral forces. In this way, unilateral loading of the seals on the housing wall is prevented in the sealing section between the piston and the housing, resulting in a uniform sealing effect in the circumferential direction. Simultaneously, abutting on one side is prevented, thus preventing one or more seals in the sealing section from being loaded on one side and thus wearing unevenly. This axial guidance of the piston is achieved, for example, through sufficient overlap in the axial direction between the mating element and the guide element. In particular, the tolerance between the guide opening or the internal structure of the guide element on one side and the mating element on the other side should be kept correspondingly low to maintain a low possible clearance when the guide element and the mating element engage. Axial guidance creates a surface contact between the mating element and the guide element, which extends along the axis for a predetermined length that varies with the piston position. The extension of the surface contact is minimal at the piston position corresponding to the maximum volume of the cavity. This means that the extension of the surface contact at this piston position is decisive for axial guidance. With a correspondingly constructed extension of the surface contact, piston tipping can also be prevented, as the axially extended surface contact can support the tipping moment acting on the piston. This also prevents the seals from being loaded on one side in the sealing section between the piston and the housing, thereby reducing seal wear in the sealing section and improving the sealing effect of these seals.

[0024] According to another aspect, a piston is provided for the piston-housing unit as described above. Here, the piston has a guide element and / or a mating element. The guide element is configured to engage with a corresponding mating element of the housing to form a piston guide, allowing the piston to be movably inserted into the housing. The mating element is configured to engage with a corresponding guide element of the housing to form a piston guide, allowing the piston to be movably inserted into the housing. Other features and extended configurations of the piston can be understood from the above description of the piston-housing unit.

[0025] According to another aspect, a housing is provided for the piston-housing unit as described above. The housing is configured such that the piston can be movably inserted into the housing as described above. Here, the housing has guide elements and / or mating elements. The guide elements are configured to engage with corresponding mating elements of the piston to form piston guides. The mating elements are configured to engage with corresponding guide elements of the piston to form piston guides. Other features and other extensions of the housing can be understood from the above description of the piston-housing unit. The housing can be implemented, in particular, as a plurality of components consisting of at least two housing elements connected to each other. For example, one housing element can be implemented as an axially extending housing element, while the other housing element can be implemented as a housing cover that defines a cavity in the axial direction within the axially extending housing element on one side of the axially extending housing element.

[0026] According to another aspect, an actuator operated by a pressure medium is provided, having a mechanism and a piston-housing unit as described above. Here, the mechanism is operatively connected to the piston-housing unit. For example, the operative connection between the mechanism and the piston-housing unit can be established by a mechanical transmission element, such as a piston rod, through which piston movement or piston force can be transmitted to the mechanism. The actuator can be provided for use in vehicles, particularly commercial vehicles. The mechanism can be configured to perform the actuator function by transmitting piston movement or piston force to the mechanism. The actuator can be, for example, a clutch adjuster or a transmission adjuster, such that the actuator function is to perform corresponding adjusting movements for manipulating the clutch or transmission (e.g., gear selection or shift channel selection). The pressure medium can be liquid or gaseous, particularly hydraulic fluid or compressed air, as described above; therefore, the actuator can be a hydraulic brake or a pneumatic actuator. Attached Figure Description

[0027] Other embodiments of this application will now be explained with reference to the accompanying drawings. The drawings show:

[0028] Figure 1 A first embodiment of the piston-housing unit is shown.

[0029] Figure 2 A second embodiment of the piston-housing unit is shown.

[0030] Figure 3 The cross-sectional shape of the mating element is shown, and

[0031] Figure 4 The cross-sectional shape of the guide element is shown. Detailed Implementation

[0032] Figure 1 A first embodiment of the piston-housing unit is shown.

[0033] A piston-housing unit 1 is shown in a schematic cross-sectional view, comprising a piston 2 and a housing 3, wherein the piston 2 is movably arranged within the housing parallel to axis X. The housing 3 extends along axis X of the piston-housing unit 1. The piston 2 encloses a cavity 4 within the housing 3, the volume of which is adapted to the displacement of the piston 2 parallel to axis X. The piston-housing unit 1 has a piston guide 5 arranged within the cavity 4.

[0034] The piston guide 5 has a guide element 5.1 and a mating element 5.2 extending along the axis X. Here, the guide element 5.1 is disposed on the piston 2, more specifically, on the surface of the piston 2 facing the cavity 4. Here, the mating element 5.2 is arranged on the surface of the housing 3 facing the piston 2 and opposite to the piston surface, on which the guide element 5.1 is disposed. In the illustrated figure, the guide element 5.1 and the mating element 5.2 engage with each other. Here, the mating element 5.2 extends to the left in the figure into the guide element 5.1, more specifically, into the internal structure of the guide element 5.1. The guide element 5.1 and the mating element 5.2 are configured such that they can move relative to each other parallel to the axis X, so as not to impede the piston's movement parallel to the axis X. As can be seen from the figure, the guide element 5.1 and the mating element 5.2 overlap in the axial direction. The figure shows the piston position in which the piston 2 is fully moved to the left, and the cavity 4 has its maximum volume. This means that, in the illustration shown, the guide element 5.1 and the mating element 5.2 always overlap to a certain extent, which corresponds to minimal overlap compared to other possible piston positions in which piston 2 is always positioned further to the right than the piston 2 shown. The overlap of the guide element 5.1 and the mating element 5.2 shown here ensures the guidance of piston 2 in the illustrated position. This means that when designing the piston-housing unit 1, the extended dimensions of the guide element 5.1 and the mating element 5.2 should be taken into account, or the overlap caused for each piston position, especially the piston position shown here.

[0035] In the illustrated embodiment of the piston-housing unit 1, the housing 3 is implemented as a plurality of components having a first housing element 3.1 and a second housing element 3.2. Here, the first housing element 3.1 is implemented as a hollow structure that opens to the right on one side as shown in the figure, while the second housing element 3.2 is implemented as a housing cover that closes the first housing element 3.1, thereby limiting the cavity 4 axially to the right. For example, the two housing elements 3.1, 3.2 can be detachably connected to each other, for example, by means of screws (not shown).

[0036] In the illustrated piston-housing unit 1, the mating element 5.2 is arranged on the second housing element 3.2, more specifically, on its inner surface facing the cavity 4 and the piston 2. This is advantageous when assembling the piston-housing unit 1 because the assembly of the housing 3 with the inserted piston 2 can only be achieved when the housing element 3.2 is also placed on the housing element 3.1 such that the mating element 5.2 engages with the guide element 5.1.

[0037] In the illustration shown, the guide element 5.1 can be constructed as a track or sleeve, for example, while the mating element 5.2 is constructed as a rod.

[0038] Due to the axial overlap of the guide element 5.1 and the mating element 5.2, the piston 2 can be guided.

[0039] In a specific application, the piston-housing unit 1 shown is part of an actuator that operates under pressure. This actuator also has a mechanism 10 by which the actuator's function can be realized, and this mechanism can be operated or driven by the piston-housing unit 1. For this purpose, the mechanism 10 and the piston-housing unit 1 are connected to each other via a transmission element 2.2, such as a piston rod extending along axis X. The transmission element 2.2 is connected to the piston 2, so that piston force or piston movement can be transmitted to the mechanism 10 to achieve operation of the mechanism. The actuator shown can be configured, for example, as a clutch adjuster or a transmission adjuster, wherein the mechanism 10 is configured to operate the clutch or the transmission, particularly for gear selection or shift slot selection in the transmission.

[0040] In particular, the piston guide 5 can be configured to prevent rotational movement of the piston 2 about the axis X. Since the guide element 5.1 and the mating element 5.2 extend axially and engage with each other axially, they can be configured to prevent this rotational movement in such a way that the cross-sections of the internal structures of the guide element 5.1 and the mating element 5.2 are shaped in a plane perpendicular to the axis X such that they prevent or lock the rotational movement by form-locking, or more precisely by contact of the two surfaces of the guide element 5.1 and the mating element 5.2. This is particularly advantageous if an indicator element (not shown) is positioned on the piston 2 or the transmission element 2.2, which allows the position of the piston 2 or the transmission element 2.2 along the axis X to be determined by detecting the position of the indicator element by one or more correspondingly attached detection devices (not shown). These detection devices can be fixedly connected, for example, to the housing 3. Furthermore, the anti-torsion component constructed in this manner can protect or unload one or more seals in the sealing section 2.1 between the piston 2 and the inner side of the housing element 3.1, in such a way that the piston 2 is not allowed to rotate about the axis X or only allowed to rotate in a limited manner about the axis X.

[0041] Alternatively or additionally, the piston guide 5 is configured to axially guide the piston 2, particularly to center the piston within the housing element 3.1. This is achieved by precisely forming a fit between the guide element 5.1 and the mating element 5.2, thereby preventing or at least limiting the radial displacement of the piston 2 relative to the axis X. This prevents the sealing section 2.1 and thus one or more piston seals in that section from being loaded on one side, since the piston 2 is guided and centered within the housing element 3.1. Consequently, a better sealing effect is achieved on the cavity 4, because there is therefore no area in the sealing section 2.1 that would be unloaded due to the radial displacement of the piston 2. Since the radial displacement of the piston 2 is avoided or limited, the seals in the sealing section 2.1 are also protected, as they are not excessively pressed against the inner wall of the housing element 3.1 at any one location.

[0042] In designing the extension dimensions of the guide element 5.1 and the mating element 5.2, it is also possible to prevent the tilting motion of the piston 2, for example, tilting motion around an axis perpendicular to the plane of the drawing, by the combination of the guide element 5.1 and the mating element 5.2 forming a sufficiently extended contact surface pairing that can receive the torque acting on the piston 2 and applied to the piston 2 from the mechanism 10, for example, through the transmission element 2.2.

[0043] Figure 2 A second embodiment of the piston-housing unit is shown.

[0044] The piston-housing unit 1 shown here is... Figure 1 The piston-housing unit 1 is constructed in a basically the same way as the housing unit 3.2. The difference lies in that the guide element 5.1 is connected to the housing element 3.2, while the mating element 5.2 is connected to the piston 2. The functional mode of the piston-housing unit 1 corresponds to... Figure 1 The functional methods in [the context].

[0045] The example shown here illustrates only a second embodiment with different positioning of the guide element 5.1 and the mating element 5.2, wherein the function of the piston guide 5 can also be implemented in the same way.

[0046] The design principle applies to both implementations, where the lighter of the two elements, guide element 5.1 and mating element 5.2, is placed on piston 2. This is because it does not significantly increase piston mass compared to placing the heavier of the two elements on piston 2, thus resulting in a lower moving piston mass. Which of the two elements should be placed on piston 2 can depend on the configuration of the two elements. For example, if guide element 5.1 is implemented as a thin-walled sleeve and mating element 5.2 is implemented as a solid rod or pin, then guide element 5.1 can be lighter than mating element 5.2, and in this case, guide element 5.1 should be placed on piston 2. Conversely, if mating element 5.2 is constructed as an axially extending hollow structure, such as a tube, then mating element 5.2 can be the lighter of the two elements, and thus the mating element, as... Figure 2 The figure shown should be arranged on piston 2.

[0047] Figure 3 The cross-sectional shape of the mating element is shown. Figure 4 The cross-sectional shape of the guide element is shown.

[0048] Two cross-sectional shapes are shown in a simplified manner, with the viewing direction extending axially. The mating element 5.2 has a circular cross-section, wherein the protrusion 5.2.1 extends to the right, i.e., in the radial direction.

[0049] The guide element 5.1 shown has a guide opening 5.1.1, the inner surface of which is shaped in a substantially similar manner to the outer surface of the mating element 5.2.

[0050] Therefore, when the mating element 5.2 is introduced into the guide opening 5.1.1 of the guide element 5.1, rotation of the mating element 5.2 within the guide opening 5.1.1 can be prevented because the protrusion 5.2.1 contacts or abuts against the mating inner contour or inner surface of the guide opening 5.1.1. Furthermore, as described above, axial guidance of the piston can be achieved when the outer contour of the mating element 5.2 is correspondingly matched with the inner contour or inner surface of the guide opening 5.1.1. As described above, guidance that resists piston tipping can also be achieved.

[0051] List of reference numerals

[0052] 1 Piston-Housing Unit

[0053] 2 pistons

[0054] 2.1 Sealed Section

[0055] 2.2 Transmission Components

[0056] 3. Shell

[0057] 3.1 Housing Components

[0058] 3.2 Housing Components

[0059] 4. Cavity

[0060] 5 Piston Guide

[0061] 5.1 Guiding element

[0062] 5.1.1 Guide opening

[0063] 5.2 Mating Components

[0064] 5.2.1 Protrusion

[0065] 10 institutions

[0066] X-axis

Claims

1. A piston-housing unit, characterized in that, The piston-housing unit has a piston (2) and a housing (3) extending along the axis (X) of the piston-housing unit (1), wherein the piston (2) is configured to move parallel to the axis (X), and the piston (2) encloses a cavity (4) in the housing (3), the volume of which is adapted to the displacement of the piston (2) parallel to the axis (X), wherein the piston-housing unit (1) has a piston guide (5) arranged in the cavity (4).

2. The piston-housing unit according to claim 1, characterized in that, The piston guide (5) has a guide element (5.1) and a mating element (5.2) that engage with each other.

3. The piston-housing unit according to claim 2, characterized in that, The guide element (5.1) and the mating element (5.2) are configured to move relative to each other in the axial direction.

4. The piston-housing unit according to any one of claims 1 to 3, characterized in that, The piston guide (5) is configured to restrict the movement of the piston (2) parallel to the axis (X).

5. The piston-housing unit according to any one of claims 1 to 3, characterized in that, The piston guide (5) is configured to guide the piston (2) in a manner that resists rotational motion as the piston (2) moves parallel to the axis (X).

6. The piston-housing unit according to claim 5, characterized in that, The piston-housing unit (1) has an indicator element connected to the piston (2), wherein the piston-housing unit (1) is configured to determine the position of the piston (2) along the axis (X) by detecting the position of the indicator element along the axis (X).

7. The piston-housing unit according to any one of claims 1 to 3, 6, characterized in that, The piston guide (5) is configured to guide the piston (2) axially as the piston (2) moves parallel to the axis (X).

8. A piston (2) used in a piston-housing unit (1) according to any one of claims 1 to 7, characterized in that, The piston (2) has a guide element (5.1) and / or a mating element (5.2).

9. A housing (3) for use in a piston-housing unit (1) according to any one of claims 1 to 7, characterized in that, The housing (3) has a guiding element (5.1) and / or a mating element (5.2).

10. An actuator operated by a pressure medium, characterized in that, The actuator has: Institution (10); and The piston-housing unit (1) according to any one of claims 1 to 7, wherein the mechanism (10) is operatively connected to the piston-housing unit (1).

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