CN112688530A

CN112688530A - Linear driving device

Info

Publication number: CN112688530A
Application number: CN202011109702.5A
Authority: CN
Inventors: S·潘塔齐斯; D·黑尔贝尔; D·克斯滕; P·泰莱特; T-Y·比尔迈尔
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 2019-10-18
Filing date: 2020-10-16
Publication date: 2021-04-20
Also published as: DE102019216117A1

Abstract

The invention relates to a linear drive for providing a linear movement, having a cylinder sleeve in which a piston is accommodated in a linearly movable manner, having a first magnet arrangement and the piston delimits a variable-size working space in the cylinder sleeve, and having a rotor which is mounted on the cylinder sleeve in a linearly movable manner along a central axis and which forms a working gap with the cylinder sleeve and which has a second magnet arrangement which is formed in the working gap for a contactless magnetic coupling with the first magnet arrangement. According to the invention, it is provided that the first magnet arrangement and/or the second magnet arrangement comprise radially magnetized permanent magnets and axially magnetized permanent magnets, respectively, alternately in rows along the center axis, in order to achieve a maximum magnetic flux in the working gap.

Description

Linear driving device

Technical Field

The invention relates to a linear drive for providing a linear movement, having a cylinder sleeve in which a piston is accommodated in a linearly movable manner, which piston has a first magnet arrangement and which piston delimits a variable-size working space in the cylinder sleeve, and having a rotor which is mounted on the cylinder sleeve in a linearly movable manner along a central axis and which forms a working gap with the cylinder sleeve and which has a second magnet arrangement which is formed in the working gap for contactless magnetic coupling with the first magnet arrangement, and having a fluid connection which passes through the cylinder sleeve and which opens out into the fluid working space.

Background

A fluid-actuated linear drive is known from WO 2007/121808 Al, in which a driven slide is mounted displaceably on the outer circumference of a housing sleeve. For this purpose, two guide surface pairs which extend along the housing sleeve and have guide surfaces which lie opposite one another in the axial direction of a first transverse axis of the housing sleeve are arranged in each case at the outer circumference of the housing sleeve, said guide surface pairs being spaced apart from one another in the axial direction of a second transverse axis of the housing sleeve which is at right angles to the first transverse axis. The guide surfaces are correspondingly inclined with respect to the first and second transverse axes, as seen in a cross section of the housing sleeve, wherein a first bearing element arranged on the output slide, which can be pivoted independently of one another with respect to a pivot axis running in the longitudinal direction of the housing sleeve, is in contact with one of the first guide-surface-facing guide surfaces, and wherein a second bearing element arranged on the output slide, whose transverse position in the axial direction of the first transverse axis relative to the output slide can be variably preset, is in contact with the other second guide-surface-facing guide surface.

Disclosure of Invention

The object of the present invention is to provide a linear drive having a compact and simple design.

This object is achieved for a linear drive of the type mentioned at the outset by the features of claim 1. It is provided that the first magnet arrangement and/or the second magnet arrangement comprise radially magnetized permanent magnets and axially magnetized permanent magnets, respectively, alternately in rows along the center axis, in order to achieve a maximum magnetic flux in the working gap. In the case of such an arrangement of permanent magnets having differently oriented magnetizations, it is based on the consideration that an optimization of the density of the magnetic flux, which can be provided by the respective magnet arrangement, can be achieved if the radially and axially magnetized permanent magnets are suitably arranged alternately at the surface of the first magnet arrangement and/or at the surface of the second magnet arrangement. It is particularly preferably provided that such a flux density is provided for the first magnet arrangement at a surface facing the second magnet arrangement. In addition or alternatively, it can be provided that the maximum flux density of the second magnet arrangement is formed at the surface of the second magnet arrangement facing the first magnet arrangement. Overall, the contactless magnetic coupling between the first and the second magnet arrangement should be achieved by the measures described with the least possible use of permanent magnetic material and the resulting cost and weight advantages.

In the case of axially magnetized permanent magnets, the magnetic flux within the axially magnetized permanent magnets is oriented at least substantially parallel to the center axis, in particular parallel to the center axis. In the radially magnetized permanent magnets, it is provided that the magnetic flux within the permanent magnets is oriented in the radial direction inwards or outwards, respectively, with respect to the center axis of the cylinder sleeve.

It is particularly advantageous if both the first and the second magnet arrangement have radially magnetized permanent magnets and axially magnetized permanent magnets, respectively, alternately in rows along the center axis. It is preferably provided that the radially magnetized permanent magnets of the first and second magnet arrangements, which are arranged at the same position along the central axis, have the same radial magnetization direction. In addition or alternatively, it is provided that the axially magnetized permanent magnets of the first and second magnet arrangements, which are arranged at the same position along the central axis, are magnetized in mutually opposite directions. This results in a particularly high flux density in the working gap between the first magnet arrangement assigned to the piston arranged in the cylinder sleeve and the second magnet arrangement assigned to the rotor mounted on the cylinder sleeve.

Advantageous developments of the invention are the subject matter of the dependent claims.

Suitably, the first magnet arrangement and/or the second magnet arrangement comprises at least one magnet group configured as a row arrangement of radially outwardly magnetized permanent magnets, axially magnetized permanent magnets in the positive axial direction and radially inwardly magnetized permanent magnets. In this case, radially outwardly oriented magnetization is understood to mean magnetization in which the magnetic flux points in permanent magnets arranged at a distance from the center axis in a direction away from the center axis, wherein the direction is oriented transversely to the center axis. Correspondingly, in the case of a radially inwardly magnetized permanent magnet, there are flux directions which are oriented exactly opposite. The permanent magnets magnetized in the positive axial direction have a magnetic flux direction which runs in an arbitrarily selected direction parallel to the spatial direction in which the center axis is oriented. Instead of a permanent magnet magnetized in the positive axial direction, a permanent magnet magnetized in the negative axial direction can be used, which is magnetized in the exactly opposite direction compared to the permanent magnet magnetized in the positive axial direction. The arrangement of such oriented permanent magnets with corresponding magnetic fluxes in a magnet group is also referred to as a halbach arrangement. Due to the orientation of the magnetic flux of the respective permanent magnet within the magnet assembly, an increased magnetic flux is provided at a first surface of the magnet assembly, while a reduced magnetic flux is provided at a second, oppositely oriented surface of the magnet assembly. It is particularly advantageously provided that the first magnet arrangement has a maximum magnetic flux at the radially outer surface, while the second magnet arrangement has a maximum magnetic flux at the radially inwardly directed surface. This ensures that the first and second magnet arrangements, which are arranged opposite one another and spaced apart by the working gap designed as a recess, face one another with their maximum magnetic flux, as a result of which the desired optimum utilization of the magnetic flux density provided by the respective permanent magnet is ensured. In this arrangement of the permanent magnets for the first and second magnet arrangements, both the first and second magnet arrangements thus form a halbach arrangement, respectively.

Preferably, it is provided that the permanent magnets of the first magnet arrangement and/or the permanent magnets of the second magnet arrangement are designed as ring magnets and are arranged coaxially to the center axis. In this embodiment of the permanent magnet, it is possible to design the cylinder jacket to have a circular cross section in a cross-sectional plane oriented transversely to the center axis. Correspondingly, the piston can likewise have a circular cross section in the same cross section plane. The seal between the outer surface of the piston and the inner surface of the cylinder sleeve, as is provided when the linear drive is used as a pneumatic or hydraulic drive, is thus achieved in a simple manner by means of suitable sealing rings. In the design of the permanent magnets of the first magnet arrangement as ring magnets, a total of three differently magnetized permanent magnets are necessary. In addition to permanent magnets magnetized outward in the radial direction, permanent magnets magnetized inward in the radial direction and permanent magnets magnetized in the axial direction are necessary. When assembling the magnet assembly, the axially magnetized permanent magnets can be arranged between two permanent magnets having a radial magnetization corresponding to the respectively necessary orientation of the magnetic flux in the positive axial direction or in the negative axial direction. This applies in the same way in the corresponding design of the permanent magnets of the second magnet arrangement.

In a development of the invention, it is provided that the permanent magnets of the first magnet arrangement, which are designed as ring magnets, are penetrated by a rod section of the piston, which extends along the center axis, in particular a rod section having a circular cross section. A compact arrangement of the permanent magnets of the first magnet arrangement at the piston is thereby achieved. It is preferably provided that at least the rod section of the piston and/or the entire piston is made of a material which guides the magnetic flux, in order to take into account the smallest possible influence of stray magnetic fields next to the first magnet arrangement.

In an alternative refinement of the invention, it is provided that the permanent magnets of the first magnet arrangement and/or the permanent magnets of the second magnet arrangement are designed as bar magnets, the longest edges of which are oriented transversely to the center axis. In this embodiment of the first magnet arrangement and/or the second magnet arrangement, it can be provided that the cylinder jacket has an elliptical or rectangular cross section in a cross-sectional plane oriented transversely to the center axis. This enables a collapsing design of the cylinder sleeve and of the rotor mounted linearly movably on the cylinder sleeve to be achieved. The permanent magnets of the first magnet arrangement and/or of the second magnet arrangement are in this case, for example, designed as bar magnets, in particular bar magnets having a square or rectangular cross section in a cross-sectional plane which includes the center axis. This results in a particularly compact arrangement of the permanent magnets for both the first and the second magnet arrangement. In addition, a particularly favorable packing density for the respective permanent magnet is thereby achieved. In addition, in such a configuration of the permanent magnets for the first and/or second magnet arrangement, it is advantageous if only a single embodiment of the permanent magnets is necessary, which has the desired orientation of the flux direction only by the arrangement of its space within the respective magnet assembly.

Preferably, the permanent magnets of the first magnet arrangement comprise pairs of correspondingly mirror-inverted pairs of permanent magnets. This ensures that the first magnet arrangement has its maximum flux density at the mutually opposite outer surfaces. This measure prevents high normal forces of the moving parts relative to the cylinder jacket tube, which would lead to high frictional forces.

In a further embodiment of the invention, it is provided that the magnet pairs formed from permanent magnets are respectively arranged on the largest surfaces of the piston that are oriented opposite one another of the rod sections that are rectangularly shaped along the center axis, the longest edges of said rod sections extending along the center axis. It is provided, for example, that the rod section is made of a material which guides the magnetic flux and can thus serve as a flux guide for the respectively mirror-inverted magnet pair. Thereby, the magnetic coupling between the permanent magnets of the first magnet mechanism is improved. Next to the rod section (which can have a rectangular profile along the center axis), the piston is formed with a profile which at least substantially corresponds to the cross section of the combination of the rod section and the magnet pair arranged there and which is formed in a cross-sectional plane oriented transversely to the center axis, for example rectangularly or elliptically or as a rounded rectangle.

Preferably, the permanent magnets of the first and/or second magnet arrangement are directly adjacent to each other in a row direction oriented along the central axis. A simple design for the first magnet arrangement and/or the second magnet arrangement can be achieved by dispensing with flux-guiding elements, such as, for example, pole rings made of ferromagnetic material. It is particularly advantageous if the permanent magnets are in direct physical contact or at least without intermediate connections of a magnetic flux-guiding or magnetic flux-damping material between the permanent magnets.

In a further embodiment of the invention, it is provided that the axially magnetized permanent magnets have a smaller extension along the center axis than the radially magnetized permanent magnets. This arrangement of the axially magnetized permanent magnets in the form of ring magnets can lead to a particularly compact design of the first and/or second magnet arrangement. The task of axially magnetized permanent magnets can be seen primarily in that the magnetic flux of radially magnetized permanent magnets is redirected as efficiently as possible in order to ensure a favorable magnetic coupling between adjacently arranged, radially magnetized permanent magnets.

In an alternative refinement of the invention, it is provided that the radially magnetized permanent magnets have a smaller extent along the center axis than the axially magnetized permanent magnets. This arrangement of the permanent magnets is advantageous when the permanent magnets are configured as bar magnets.

Drawings

In the drawings, there is shown advantageous embodiments of the invention. Here:

fig. 1 shows a perspective illustration of a first embodiment of a linear drive having a cylinder jacket, which is designed in a cylindrical manner, and a rotor, which is designed in a square manner, which surrounds the cylinder jacket,

figure 2 shows a longitudinal sectional illustration of the linear drive according to figure 1,

figure 3 shows a detailed illustration of the first and second magnet mechanism of the linear drive device according to figure 2,

fig. 4 shows a perspective illustration of a second embodiment of a linear drive, which has a substantially rectangular profile of the cylinder sleeve and of the rotor along the center axis,

fig. 5 shows a partially cut-away front view of the linear drive according to fig. 4, an

Fig. 6 shows a strictly schematic illustration of the first and second magnet mechanisms of the second embodiment of the linear drive device according to fig. 4 and 5.

Detailed Description

The first embodiment of a linear drive 1 (which can also be referred to as a piston-rod-free pneumatic drive) shown in fig. 1 to 3 comprises a stator 2 and a rotor 3 mounted in a linearly movable manner on the stator 2. Purely by way of example, the stator 2 comprises a cylinder sleeve 5, which extends along the center axis 4 and is formed with a cylindrical profile. On the end side, the cylinder jacket 5 is provided with a sealing plug 6, 7, respectively, which is arranged in a sealing manner, wherein each sealing plug has a fluid connection symbolically designated as a bore hole 8, 9.

The rotor 3 has purely exemplarily a square-shaped outer geometry and is penetrated by the stator 2. It is provided by way of example that the stator 2 is fastened to a machine support, which is not shown in greater detail, and that the rotor 3 can perform a linear movement along the center axis 4 relative to the stator 2, if a pressure application, for example by means of compressed air, is carried out at one of the boreholes 8, 9.

In order to facilitate the movement of the rotor 3 relative to the stator 2, provision is made according to fig. 2 in a working recess 10 which is delimited by an inner surface 11 of the cylinder sleeve 5, an end face 12 of the closing plugs 6, 7 and a recess 15 of the closing plugs 6, 7 and a piston 16 which is arranged in the cylinder sleeve 5 so as to be linearly movable. The supply and removal of the pressure-loaded fluid into the working recess 10 can take place via the bore 8 in the closing plug 6. The piston 16 can be moved along the center axis 4 as a function of the pressure difference of the pressures prevailing between the working recess 10 according to fig. 2 and a working recess, not shown, which is arranged symmetrically in the cut-out part of the linear drive 1 shown in fig. 2. In an exemplary embodiment, the piston 16 has, at least in some regions, in a cross-sectional plane 17 drawn purely by way of example, a circular cross-section which is not shown in greater detail and which corresponds approximately to a cross-section of the cylinder sleeve 5 in the cross-sectional plane 17 which is likewise not drawn in greater detail. For the seal between the piston 16 and the inner surface 11 of the cylinder sleeve 5, a shaft sealing ring 18 is provided, which is accommodated in a groove 19 of the piston 16. Adjacent to the groove 19, a further groove 20 is furthermore provided, in which groove 20 a sliding ring 21 is accommodated for the movable guidance of the piston 16 in the cylinder sleeve 5.

Purely by way of example, it is provided that the piston 16 is formed by two end sections 23 arranged in a mirror image with respect to the piston center plane 22, which are preferably formed identically, and a connecting rod 24, which connects the two end sections 23 to one another. It is provided by way of example that the coupling rod 24 is received in a cylindrical recess 25 of the end section 23 and is fastened at the end face in a threaded bore 27 of the end section 23 by means of a threaded section 26. The cylindrical recess 25 and the extension of the connecting rod 24 are selected in such a way that a receiving region 28 is formed between the end sections 23 arranged symmetrically with respect to the piston center plane 22, said receiving region having a geometry which is rotationally symmetrical with respect to the center axis 4 and which has a rectangular profile which can be recognized in fig. 2.

In the receiving region 28, a plurality of

permanent magnets

29, 30, 31 and 32, which are arranged along the center axis 4, in particular in direct contact with one another, are arranged by way of example and are designed as ring magnets, which form a first magnet arrangement 36. Within the first magnet mechanism 36,

permanent magnets

29, 30, 31 and 32, which are arranged, for example, in line directly one another, form a first magnet group 38. It is provided by way of example that the outer diameter of the permanent magnets 29 to 32 corresponds to the outer diameter 33 of the end section 23, while the inner diameter of the permanent magnets 29 to 32 corresponds to the outer diameter 34 of the connecting rod 24. A more detailed description of the design of the permanent magnets 29 to 32 is given in connection with the description of fig. 3.

The rotor 3 comprises a basic body 40, which is designed purely exemplarily with a square outer geometry and is penetrated by a borehole 41, which is designed exemplarily cylindrically. In the bore 41, two guide sleeves 42, which are designed with a circular outer geometry and are provided with a first annular groove 44 and a second annular groove 45 on an inner surface 43, are arranged in a mirror image in relation to the piston center plane 22. In the first annular groove 44, a shaft sealing ring 46 is arranged, the flexible, circumferential sealing lip of which bears against the outer surface 14 of the cylinder sleeve 5. A sliding ring 47, which can be produced, for example, from a plastic material and is formed on the outer surface 14 of the cylinder sleeve 5 for the slidable mounting of the rotor 3, is accommodated in the second annular groove 45. The outwardly pointing end face 48 of the guide sleeve 42 bears against a securing ring 49, which is secured in an annular groove 50, which is introduced at the inner surface 43 of the bore 41. The purpose of the securing ring 49 is to axially secure the guide sleeve 42 in a form-fitting manner.

Between the mutually opposite end sides 51 of the guide sleeve 42, an annular receiving space 52 is formed, in which

permanent magnets

55, 56, 57 and 58, which are formed as ring magnets, are arranged. It is provided by way of example that the permanent magnets 55 to 58 form the second magnet arrangement 37 and, with regard to their magnetization, two magnet groups 39 are formed by way of example, which are described in more detail later in connection with fig. 3.

Between the cylindrically formed inner surface 59 of the permanent magnets 55 to 58, which are formed as ring magnets, and the outer surface 14 of the cylinder jacket 5, a working gap 60, which is formed as a recess and in which there is a magnetic interaction between the permanent magnets 29 to 31 of the piston 16 and the permanent magnets 55 to 58 of the rotor 3. The magnetic interaction effects a force transmission between the piston 16 and the rotor 3 in the direction of the center axis 4. Correspondingly, the rotor 3 follows the linear movement of the piston 16 as long as the movement of the piston 16 along the central axis 4 is carried out by the pressure difference between the two working recesses 10 in the stator 2.

As can be recognized from the illustration in fig. 3, which shows the permanent magnets 29 to 32 of the first magnet mechanism 36 and the permanent magnets 55 to 58 of the second magnet mechanism 37 in more detail, both the first magnet mechanism 36 and the second magnet mechanism 37 respectively comprise permanent magnets 29 to 32 and 55 to 58, which are designed as ring magnets. The arrows drawn in fig. 3 should symbolically represent the respective magnetization of the individual permanent magnets 29 to 32 and 55 to 58. Purely exemplarily, the assembly of four permanent magnets 29 to 32 in the first magnet arrangement 36 forms a first magnet group 38, which is arranged in correspondence with the halbach. The

permanent magnets

29, 30, 31 and 32 are arranged, for example, directly adjacent to one another along the center axis 4, so that no material is provided between the individual permanent magnets 29 to 32, which material would have a negative influence on the magnetic flux between the permanent magnets 29 to 32 of the first magnet arrangement 36.

It is provided, for example, that the permanent magnets 29 are arranged radially inward, i.e. with a magnetization pointing toward the center axis 4. It is also provided that the permanent magnet 30 is provided with a magnetization in the axial direction, which magnetization points in a positive direction parallel to the center axis 4. The permanent magnets 31 are provided with magnetization directed radially outwards. The permanent magnet 32 is provided with an axially oriented magnetization whose magnetization direction is opposite to the magnetization direction of the permanent magnet 30 and can therefore also be referred to as negative magnetization direction.

Furthermore, it is provided as an example that the permanent magnets 32, which are arranged purely as an example in the region of the piston center plane 22, are used as a component of the two magnet groups 38, since they are also in magnetic interaction with the

permanent magnets

29, 30 and 31 arranged on the right. By means of this arrangement of the permanent magnets 29 to 32, a maximum magnetic flux is provided at the outer surface 35 of the first magnet arrangement 36, whereas a significantly lower magnetic flux is present at the unmarked axial end faces of the first magnet arrangement 36 and also at the unmarked inner surface.

The permanent magnets 55 to 58 of the second magnet arrangement 37 are in principle arranged in the same way as the permanent magnets 29 to 33 of the first magnet arrangement 36, however, the orientation of the axially magnetized

permanent magnets

56 and 58 within the respective magnet groups 39 is selected opposite to the orientation of the

permanent magnets

30 and 32 of the first magnet arrangement 36. This makes it possible to provide a maximum magnetic flux at the inner surface 59 of the second magnet arrangement 37, while a relatively low magnetic flux is present at the end faces of the second magnet arrangement 37, which are not labeled in greater detail, and at the outer surfaces, which are likewise not labeled in greater detail.

In order to prevent damage to the second magnet arrangement 37 during operation of the linear drive 1, elastic O-rings 61 are arranged between the respectively outer

permanent magnets

55 and 57 and the opposite end sides 51 and 52 of the guide sleeve, which O-rings provide an elastic coupling between the second magnet arrangement 37 and the guide sleeve 42. This and thus the reduction of force peaks which can occur in the case of highly dynamic operation of the piston 16.

The second embodiment of the linear drive 71, which is shown in more detail in fig. 4 to 6, has basically the same design as the linear drive 1, so that only the differences between the two linear drives 1 and 71 should be discussed later. In contrast to the linear drive 1, a flat design is provided for the linear drive 71, in which the stator 72 and the rotor 73 can each be embodied with a substantially rectangular profile along the center axis 74. However, the flat design requires a different design from that of the linear drive 1 with regard to the design of the first magnet arrangement 116 formed from the

permanent magnets

99, 100, 101, 102 and with regard to the second magnet arrangement 117 formed from the

permanent magnets

125, 126, 127 and 128. The use of permanent magnets 29 to 31 and 55 to 58 embodied as ring magnets from the first linear drive 1 is not provided here. More precisely, the permanent magnets 99 to 102 and 125 to 128 are each designed as rod-shaped magnets, the

longest edges

106 and 129 of which, as can be seen in fig. 5, respectively extend parallel to one another and transversely to the center axis 74. As can be seen from the illustration in fig. 6, the bar magnets 99 to 102 and 125 to 128 each have a rectangular profile. Purely exemplarily, it is provided that the permanent magnets 99 to 102 and 125 to 128 have the same length extension in the direction of their

longest edge

106 or 129.

Furthermore, purely exemplarily, the permanent magnets 99 to 102 and 124 to 128 have the same thickness 107 or 130, respectively, corresponding to the illustration of fig. 6. The

width

108 or 131 of the radially magnetized

permanent magnets

99 and 101 of the first magnet arrangement 116 or the

permanent magnets

125 and 127 of the second magnet arrangement 117 is purely exemplarily selected to be larger than the width 109 or 132 of the axially magnetized

permanent magnets

100 and 102 or 126 and 128 with respect to the extension along the central axis 74. This ensures a particularly suitable use of the respective magnetic effect with respect to the volume of the respective permanent magnet 99 to 102 or 125 to 128. Furthermore, the action of the permanent magnets 125 to 128 of the second magnet arrangement 117 is optimized by the flux guide plates 122, which respectively bear against the surfaces of the permanent magnets 125 to 128 of the second magnet arrangement 117 that face away from the first magnet arrangement 116.

Furthermore, the function of the linear drive 71 is equivalent to the function of the linear drive 1, in particular when there is a pressure difference in the working recess, which is not shown in greater detail, which leads to a movement of the piston, which is also not shown in greater detail, in the linear drive 71 there is likewise provided a movement of the rotor 73 relative to the stator 72. Here, the piston moves the rotor 73 together due to the magnetic coupling between the first magnet mechanism 116 and the second magnet mechanism 117. Purely exemplarily, it is provided that in the linear drive 71 the coupling rod 24 known from the linear drive 1 is replaced by a coupling web 94, which is produced purely exemplarily as a parallel planar plate made of a material which guides the magnetic flux. In this case, the associated permanent magnets 99 to 102 of the first magnet arrangement 116 respectively lie in a planar manner against the largest mutually

opposite surfaces

95 and 96 of the coupling section 94.

Furthermore, it is provided that the permanent magnets 99 to 102 of the first magnet arrangement 116 are arranged in mirror image with respect to a plane of symmetry 97 which is oriented symmetrically with respect to the connecting web 94 and which includes the center axis 74, as a result of which a correspondingly maximum magnetic flux occurs at the outer surface 103 of the first magnet assembly 118 formed by the bar magnets 99 to 102.

Claims

1. Linear drive (1; 71) for providing a linear movement, having a cylinder sleeve (5), in which a piston (16) is accommodated in a linearly movable manner, said piston having a first magnet arrangement (36; 116) and said piston bounding a variable-size working space (10) in the cylinder sleeve (5), and having a rotor (3; 73) which is mounted in a linearly movable manner along a central axis (4; 74) on the cylinder sleeve (5), said rotor forming a working gap (60) with the cylinder sleeve (5) and having a second magnet arrangement (37; 117) which is formed in the working gap (60) for a contactless magnetic coupling with the first magnet arrangement (36; 116), and having a fluid coupling (8, 8, 9) Which passes through the cylinder casing (5) and which opens out into the working space (10), characterized in that the first magnet mechanism (36; 116) and/or the second magnet mechanism (37; 117) comprises a longitudinal axis (4; 74) respectively alternately in rows of radially magnetized permanent magnets (29, 31, 55, 57; 99. 101, 125, 127) and axially magnetized permanent magnets (30, 32, 56, 58; 100. 102, 126, 128) in order to achieve a maximum magnetic flux in the working gap (60).

2. Linear drive according to claim 1, characterized in that the first magnet mechanism (36; 116) and/or the second magnet mechanism (37; 117) comprises at least one magnet group (38, 39; 118, 119) configured as a row of permanent magnets (31, 57; 101, 127) magnetized radially outwards, permanent magnets (30, 58; 100, 128) magnetized axially in the positive axial direction, permanent magnets (29, 55; 99, 125) magnetized radially inwards.

3. Linear drive according to claim 1 or 2, characterized in that the permanent magnets (29, 30, 31, 32) of the first magnet mechanism (36) and/or the permanent magnets (55, 56, 57, 58) of the second magnet mechanism (37) are configured as ring magnets and are arranged coaxially to the central axis.

4. Linear drive according to claim 3, characterized in that the permanent magnets (29, 30, 31, 32) of the first magnet mechanism (36) which are configured as ring magnets are passed through by a rod section (24) of the piston (16), which extends along the central axis (4), in particular with a circular cross section.

5. Linear drive according to claim 1 or 2, characterized in that the permanent magnets (99, 100, 101, 102) of the first magnet mechanism (116) and/or the permanent magnets (125, 126, 127, 128) of the second magnet mechanism (117) are configured as bar magnets, the longest edges (106) of which are oriented transversely to the central axis (74).

6. Linear drive according to claim 5 in combination with claim 2, characterized in that the permanent magnets (99, 100, 101, 102) of the first magnet mechanism (116) comprise pairs of magnets of permanent magnets (99, 100, 101, 102) which are respectively mirror-image opposed in pairs.

7. Linear drive according to claim 6, characterized in that the magnet pairs formed by permanent magnets (99, 100, 101, 102) are respectively arranged on mutually oppositely oriented largest surfaces (95, 96) of a rod section (94) of the piston which is rectangularly shaped along the central axis (74), the longest edge of the rod section extending along the central axis (74).

8. Linear drive device according to one of the preceding claims, characterized in that the permanent magnets (29, 30, 31, 32; 99, 100, 101, 102) of the first magnet mechanism (36; 116) and/or the permanent magnets (55, 56, 57, 58; 125, 126, 127, 128) of the second magnet mechanism (37; 117) are directly adjacent to each other in a row direction oriented along the centre axis (4; 74).

9. Linear drive device according to claim 3 or 4, characterized in that the axially magnetized permanent magnets have a smaller extension along the central axis than the radially magnetized permanent magnets.

10. Linear drive device according to claim 5, 6 or 7, characterized in that the radially magnetized permanent magnets (99, 101, 125, 127) have a smaller extension along the central axis (74) than the axially magnetized permanent magnets (100, 102, 126, 128).