Electric cylinder with belt drive

Abstract

Linear motion device (10) with a housing (12) and a boom (60), wherein the boom (60) is movably mounted on the housing (12) with respect to a longitudinal direction (11), wherein it projects out of the housing (12) in a longitudinal direction (11), and wherein it is otherwise preferably received inside the housing (12), wherein a first and a second deflection wheel (31; 41) are provided, which are rotatably mounted at opposite ends of the housing (12) with respect to the longitudinal direction (11), wherein a traction element (90) is provided with a first and a second attachment point (92; 93) different from the first, wherein the traction element (90) wraps around the first and the second deflection wheel (31; 41), wherein the traction element (90) is attached at the first and the second attachment point (92;93) is firmly connected to the boom (60), characterized in that the second deflection wheel (41) is arranged next to the boom (60) with respect to a vertical direction (17) which is oriented perpendicular to the longitudinal direction (11), wherein the first deflection wheel (31) has a larger diameter than the second deflection wheel (41).

Description

[0001] The invention relates to a linear motion device according to the preamble of claim 1.

[0002] A linear motion device, also known as an electric cylinder, is known from DE 10 2007 043 391 A1. The linear motion device has a housing and a boom. The boom is movably mounted on the housing in a longitudinal direction and projects longitudinally out of the housing. The boom is otherwise contained within the housing. The linear motion device has essentially the same external shape as a pneumatic cylinder. However, it is driven by an electric motor. For this purpose, a threaded spindle is provided inside the housing, extending longitudinally and rotatably mounted on the housing. The threaded spindle engages with a nut that is attached to the end of the boom.

[0003] One advantage of the linear motion device according to the invention is that higher movement speeds of the boom are possible. In the known linear motion device, the movement speed of the boom is limited by the critical rotational speed of the threaded spindle. Furthermore, the linear motion device according to the invention is particularly cost-effective. In addition, a complex anti-rotation device between the housing and the boom is unnecessary.

[0004] According to the independent claim, it is proposed that a first and a second deflection pulley are provided, which are rotatably mounted at opposite ends of the housing with respect to the longitudinal direction. A traction element with a first and a second attachment point different from the first is provided, wherein the traction element wraps around the first and the second deflection pulleys and is rigidly connected to the boom at the first and the second attachment points. The traction element is preferably designed as a toothed belt, although the use of a chain is also conceivable. The first and / or the second deflection pulley are preferably designed as toothed belt pulleys. The maximum speed of movement of the boom depends solely on the tensile strength of the traction element and the mass to be accelerated on the boom. A speed-limiting bending critical speed is no longer present.Furthermore, the traction element and deflection pulleys are more cost-effective than the familiar threaded spindle with nut.

[0005] The dependent claims specify advantageous further developments and improvements of the invention.

[0006] It is possible to design the traction element as a finite length, with the first and second attachment points located at opposite ends. Mounting a finite traction element is particularly easy, as it can be readily cut to the required length. This allows for the simple implementation of linear motion devices of varying lengths. Alternatively, an endless toothed belt can be used.

[0007] It can be provided that the second deflection pulley is arranged next to the boom with respect to a vertical direction oriented perpendicular to the longitudinal direction. The traction element preferably runs in a plane parallel to the longitudinal direction to achieve a particularly favorable force flow. This plane preferably intersects the boom so that the linear motion device requires minimal installation space. To prevent the boom from colliding with the second deflection pulley, the latter is arranged next to the boom as proposed above.

[0008] It is possible for the first deflection wheel to have a larger diameter than the second deflection wheel. The diameters of the deflection wheels are preferably selected such that the section of the traction element running between the first and second deflection wheels is aligned parallel to the longitudinal direction. This results in a particularly compact linear motion device.

[0009] It can be provided that the first deflection wheel is equipped with a drive mechanism by which it can be connected to an electric motor for rotary drive. Accordingly, preferably the larger of the two deflection wheels is driven, so that the traction element is subjected to low stress in the area of ​​the driven deflection wheel.

[0010] The cantilever can be arranged, viewed in the vertical direction, between opposite side edges of the traction element. This allows the traction element to be very wide, resulting in high tensile strength and stiffness. At the same time, the linear motion device remains compact. The side edges of the traction element preferably extend parallel to the longitudinal direction and are spaced apart from each other in a transverse direction perpendicular to both the longitudinal and vertical directions.

[0011] It may be provided that a separate drive element is rigidly connected to one end of the boom, with the traction element being rigidly connected to the drive element at the first and second attachment points. The boom preferably extends longitudinally with a constant cross-sectional shape, most preferably being designed as a circular tube. The drive element is preferably located inside the housing. Preferably, the traction element is clamped to the drive element at the first and / or second attachment point. This results in a particularly cost-effective linear motion device that is easy to assemble.

[0012] It can be provided that the first and second attachment points of the traction element are arranged at opposite ends of the driver with respect to the longitudinal direction. The traction element preferably has a straight course in the area of ​​these attachment points, most preferably running parallel to the longitudinal direction. This avoids kinks in the traction element, thereby reducing the risk of breakage.

[0013] It can be provided that the first and second attachment points of the traction element are arranged on opposite sides of a central axis of the boom with respect to the vertical direction. This allows the diameter of the first deflection pulley to be particularly large, so that any drive forces that may occur there on the toothed belt are low. The traction element preferably has a straight course in the area of ​​the aforementioned attachment points, most preferably running parallel to the longitudinal direction. The boom is preferably designed in the form of a circular cylindrical tube. The central axis of the boom preferably runs parallel to the longitudinal direction.

[0014] The second deflection pulley may be equipped with a tensioning device designed to tension the traction element. Accordingly, the tensioning device is preferably located on the smaller of the two deflection pulleys. It can therefore be designed to be particularly compact.

[0015] It can be provided that a pivot axis of the first deflection wheel is arranged next to the central axis of the boom with respect to the vertical direction. This pivot axis of the first deflection wheel is preferably arranged in a median plane of the housing, so that the latter is designed to be particularly compact. Preferably, the median plane runs along the geometric center of the housing with respect to the vertical direction.

[0016] A displacement measuring system can be provided which comprises an elongated measuring rod and a permanent magnet, wherein the arm is tubular in design, the measuring rod being attached to the housing at a first end, and extending into the interior of the tubular arm at a second end opposite the first, wherein the permanent magnet is attached to the arm, at least indirectly. The permanent magnet is preferably attached to the drive element. With such a displacement measuring system, the position of the arm relative to the housing can be measured in a simple manner. A displacement measuring system with a measuring rod and a permanent magnet is known, for example, from the datasheet that was available on February 19, 2015, at the internet address http: / / www.megatron.de / kategorie / potentiometrische-positionssensoren / download / 128.html.In conjunction with the proposed displacement measuring system, the traction element is preferably designed to be finite so that it does not cross or collide with the measuring rod.

[0017] The second end of the measuring rod can be designed to slide against the inside of the boom. This prevents lateral movement of the second end of the measuring rod. A separate support element is preferably attached to the second end of the measuring rod, which slides against the inside of the boom. The support element is preferably made of plastic.

[0018] It can be provided that the housing is internally supplied with a sliding surface against which the driver and / or the boom rests in a sliding manner, the sliding surface having a cross-sectional shape that deviates from a circular one. This results in an anti-rotation device between the boom and the housing, which is designed to be particularly simple and cost-effective. It should be noted that the traction drive according to the invention does not exert any forces on the anti-rotation device. The anti-rotation device serves solely to fix the rotational position of the boom relative to the housing. The cross-sectional shape of the sliding surface is, for example, elliptical. The sliding surface may have at least one interruption along its circumference.

[0019] It can be provided that the axis of rotation of the first and / or the second deflection wheel runs parallel to a transverse direction, with the transverse direction being perpendicular to the longitudinal and vertical directions. This results in a particularly compact linear motion device.

[0020] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0021] The invention is explained in more detail below with reference to the accompanying drawings. They show:

[0022] Fig. 1 a perspective view of a linear motion device according to the invention;

[0023] Fig. 2 a longitudinal section of the linear motion device according to Fig. 1;

[0024] Fig. 3 a cross-section of the linear motion device according to Fig. 1, wherein the cutting plane passes through the first axis of rotation of the first deflection wheel;

[0025] Fig. 4 a partial exploded view of the linear motion device according to Fig. 1 in the area of ​​the second end block;

[0026] Fig. 5 a cross-section of the main body of the housing; and

[0027] Fig. 6 a perspective view of the carrier.

[0028] Fig. Figure 1 shows a perspective view of a linear motion device according to the invention. 10 The linear motion device 10 includes a housing 12 and a boom 60 The boom 60 is with respect to a longitudinal direction 11 movable relative to the housing 12 , in the longitudinal direction 11 from the case 12 stands out. The casing 12 is made up of a main body20 and a first and a second end block 30 ; 40 composed. The main body 20 extends with the in Fig. 5 shown, constant cross-sectional shape in longitudinal direction 11 , which is made of aluminum using an extrusion process. The end blocks 30 ; 40 are preferably manufactured as castings. At the first end block 30 are a clutch housing 16 ; a gearbox 14 and an electric motor 13 attached.

[0029] The boom 60 is designed in the form of a circular cylindrical tube, the central axis of which 62 parallel to the longitudinal direction 11 runs. At the free end of the boom. 60 is a fastening device 61 arranged, which can be designed, for example, as a thread or as a ball joint head.

[0030] Fig. Figure 2 shows a longitudinal section of the linear motion device 10 after Fig. 1. Inside the case 12 located end of the boom 60 is a separate carrier 70 attached, which in Fig. 6 is shown in more detail. The driver 70 is equipped with two separate sliding surfaces 71 provided which are located inside the main body 20 The boom is designed to slide smoothly. 60 in a sliding bushing 44 guided linearly in plastic, with the sliding bushing 44 in the second end block 40 is attached. Next is the second end block. 40 with a ring-shaped shape around the boom 60 circumferential seal 45 provided with a sealing lip that slides on the boom 60 is pending.

[0031] Between the main body 20 and the first end block 30 is a separate adapter plate 86Permanently installed. Into the adapter plate 86 is a first end 84 a separate measuring rod 81 screwed in, secured with a lock nut 87 is secured. The measuring rod 81 together with a permanent magnet 83 a distance measuring system 80 , with which the position of the boom 60 relative to the case 12 can be measured. The permanent magnet 83 is on the inside of the drive pin 70 attached, thereby securing the measuring rod 81 surrounds in a ring shape. At the first opposite second end 85 The measuring rod has a separate support part. 82 made of plastic, which slides against the inside of the boom, so that the second end 85 of the measuring rod 81 perpendicular to the longitudinal direction 11 is supported.

[0032] In the first end block 30 is a first deflection wheel 31with respect to a first axis of rotation 34 rotatable mounting. The first axis of rotation 34 is in the upward direction 17 offset with respect to the central axis 62 of the boom 60 arranged, wherein the upward direction 17 perpendicular to the longitudinal direction 11 is aligned. The transverse direction 18 is perpendicular to the longitudinal direction 11 and towards the uphill direction 17 aligned.

[0033] In the second end block 40 is a second deflection wheel 41 with regard to a second axis of rotation 46 rotatably mounted, equipped with a clamping device 50 is provided which in Fig. 4 is shown in more detail. The second deflection wheel 41 is in the upward direction 17 completely next to the boom 60 arranged so that the boom 60 and the second deflection wheel 41 in no position of the linear motion device 10touch. Furthermore, a finite traction element is required. 90 The system is designed to wrap around the first and second deflection pulleys by 180° each. The traction element 90 is in the present form of a toothed belt, wherein the first and the second deflection pulley 31 ; 41 are designed as toothed belt pulleys. The diameter of the second deflection pulley 41 is smaller than the diameter of the first deflection wheel 31 The aforementioned diameters and the position of the first and second axes of rotation 34 ; 46 are coordinated in such a way that the section 96 the traction means 90 , which is between the first and the second deflection pulley 31 ; 41 is arranged parallel to the longitudinal direction 11 proceeds.

[0034] The first deflection wheel 31 associated end of the finite traction element 90 forms a first attachment point 92, which with the driver 70 is jammed. The corresponding first clamping device 72 is in Fig. 6 shown in more detail. Between the first attachment point 92 and the first deflection wheel 31 the traction element runs 90 straight and parallel to the longitudinal direction 11 . The second deflection wheel 41 assigned end of the traction element 90 forms a second attachment point 93 , which with the driver 70 via a second clamping device 73 It's jammed. The first and second mounting points. 92 ; 93 are with respect to the longitudinal direction 11 at opposite ends of the drive 70 arranged. Furthermore, the first and second attachment points are 92 ; 93 on opposite sides of the central axis 62 of the boom 60 arranged. Between the second fastening point93 and the second deflection wheel 41 the traction element runs 90 straight and parallel to the longitudinal direction 11 .

[0035] Fig. Figure 3 shows a cross-section of the linear motion device 10 after Fig. 1, where the cutting plane passes through the first axis of rotation 34 of the first deflection wheel 31 The circular outline of the boom 60 is indicated by a dashed line. The width of the traction element. 90 is larger than the diameter of the boom 60 Upwards 17 The boom is considered 60 between the two side edges 91 of the traction element 90 arranged. The traction element designed as a toothed belt 90 extends in a transverse direction 18 parallel to the first axis of rotation 34 .

[0036] The first deflection wheel 31 is a single piece with a first deflection axis32 formed, which is approximately cylindrical. The first deflection axis 32 is by means of two first pivot bearings 33 regarding the first axis of rotation 34 rotatable at the first end block 30 mounted. The first pivot bearings 33 are on opposite sides of the first deflection pulley 31 arranged as radial groove ball bearings. The outer ring of each first rotary bearing is 33 in an assigned, separate warehouse keeper 36 It is attached to the first end block. This is achieved through the separate bearing holders. 36 The assembly of the first rotary bearings will begin. 33 simplified. The first deflection axis 32 is a single piece with a drive mechanism 35It is equipped with a drive shaft designed in the form of a circular cylindrical shaft. The drive shaft may be fitted with a key for torque transmission. Furthermore, the four fastening screws are... 26 to point out that in the four corner areas of the first end block 30 are arranged. Via the fastening screws 26 will be the first end block 30 with the main body (No. 20 in Fig. 2) screwed together.

[0037] The propulsion system 35 is equipped with a coupling 15 The two parts are connected in a rotationally fixed manner and are designed as bellows couplings. The coupling is located on the opposite side. 15 with a drive pin of the gearbox 14 The coupling is connected in a rotationally fixed manner. 15 is inside a separate coupling housing 16 recorded, which is between the first end block 30 and the gearbox 14 is permanently installed.

[0038] Fig. Figure 4 shows a partial exploded view of the linear motion device according to Fig. 1 in the area of ​​the second end block 40 The second end block 40 is just like the first end block (No. 30 in Fig. 1) via four fastening screws 26 firmly attached to the main body (No. 20 in Fig. 1) screwed together. Furthermore, the second end block is attached. 40 the ring-shaped sliding bushing 44 and the ring-shaped seal 45 attached to which the boom (No. 60 in Fig. 1) each slides into place.

[0039] The second deflection wheel 41 , which is designed as a toothed belt pulley, is connected via two second rotary bearings 43 rotatable on a separate second deflection axis 42 The second pivot bearings 43 are designed as needle bearings, with the respective assigned running surfaces on the inside of the second deflection wheel 41and on the outside of the second deflection axis 42 are circularly cylindrical in shape. The second deflection axis is located at both opposite ends. 42 each of a connecting screw 53 perpendicular to the second axis of rotation 46 permeated. The connecting screws 53 are each inserted into an associated U-shaped leg at the front. 54 a U-shaped clamping bracket 51 screwed in, which is the second deflection wheel 41 encompasses in such a way that the second deflection wheel 41 inside the clamping bracket 51 can rotate freely. The clamping bracket 51 and the second deflection axis 42 are firmly and securely connected to each other.

[0040] The tensioning bracket 51 is part of a clamping device 50 for the traction device (No. 90 in Fig. 2) The clamping device 50 includes two clamping screws 52 , which forms the second end block 40penetrate in such a way that their screw heads are accessible from the outside for a screwdriver. At the opposite end are the clamping screws. 52 into an assigned thread 56 at the base of the clamping bracket 51 screwed in. By tightening the clamping screws 52 The tensioning bracket is connected to the second deflection wheel. 41 to the second end block 40 pulled, thereby the traction element (No. 90 in Fig. 2) is tensioned. By loosening the tensioning screws 52 The tension of the traction element can be reduced.

[0041] Fig. Figure 5 shows a cross-section of the main body 20 of the casing. The main body 20 is made of aluminum using an extrusion process, whereby it has the in Fig. The cross-sectional shape shown in section 5 is present. The outer cross-sectional shape is rectangular with rounded corners. Fastening threads are located in the corner areas. 52 for the fastening screws (No. 26 in Fig. 4) arranged. The extruded profile is only equipped with the corresponding core holes, into which an internal thread is cut at both longitudinal ends.

[0042] Inside is the main body 20 with a first, a second and a third free space 21 ; 22 ; 23 equipped with which the traction element (No. 90 in Fig. 1) is conducted. The open spaces 21 ; 22 ; 23 They are each rectangular in shape. The first and second open spaces 21 ; 22 are from the sliding surface 24 for the drive unit (No. 70 in Fig. 2) cut, with the third free space 23has an undisturbed rectangular shape. In the third open space 23 The section (No.) runs 96 in Fig. 1) of the traction element, which is arranged between the first and second deflection pulleys. In the second free space 22 The section of the traction element runs between the second deflection wheel and the second attachment point (No. 93 in Fig. 2) of the traction element is arranged. In the first free space 21 The section of the traction element runs between the first deflection wheel and the first attachment point (No. 92 in Fig. 2) of the traction element.

[0043] The sliding surface 24 The drive element has a cross-sectional shape that deviates from a circular shape, in this case being elliptical. The sliding linings (No. 71 in Fig. 6) The drive lugs are essentially free of play on the sliding surface 24so that the driver cannot be rotated with the boom about its central axis. It should be noted that the driver is connected to the boom in a rotationally and longitudinally fixed manner. Viewed along its circumference, the sliding surface has 24 There are a total of three interruptions, which are separated by the first and second free space. 21 ; 22 be formed.

[0044] Furthermore, attention should be paid to the cavities. 27 in Fig. 5. which primarily serve to save material.

[0045] Fig. Figure 6 shows a perspective view of the driver. 70 The outer and inner perimeter surfaces 76 ; 77 of the driver 70 are circular cylindrical with respect to the central axis (No. 62 in Fig. 2) of the boom. On the outer circumferential surface 76 are two separate sliding surfaces 71 arranged in the longitudinal direction and made of plastic11 are spaced apart from each other. The sliding pads 71 are each designed as a slotted ring, which has a rectangular cross-sectional shape around the driver 70 circumferentially, over the remaining outer circumferential surface 76 of the driver 70 survive.

[0046] In the longitudinal direction 11 between the sliding linings 71 is a first clamping device 72 on the outer perimeter surface 76 of the driver 70 arranged. The first clamping device 72 runs in the first free space (No. 21 in Fig. 5) of the main body, without touching the main body. The first clamping device 72 includes two clamping plates 74 , between which the first attachment point of the traction element is clamped, the traction element being designed as a toothed belt. A clamping plate 74It is equipped with a tooth profile that engages with the teeth of the timing belt. The two clamping plates 74 and the traction element is held by a clamping screw 75 permeates which are in the carrier 70 It is screwed in. With the clamping screw 75 The aforementioned parts will be protected against flattening on the outer circumferential surface. 76 of the driver 70 clamped.

[0047] The second clamping device 73 The second attachment point of the traction element is integrally attached to the drive lug. 70 The drive mechanism is designed with a slot in the drive element that is adapted to the timing belt. The slot may be penetrated by a clamping screw.

[0048] The disengagement 78 The drive pin serves to mount the boom. It is located in the notch. 78 In particular, a (not shown) clamping jaw can be accommodated, over which the driver 70can be clamped to the boom. Reference symbol list 10 Linear motion device 11 Longitudinal direction 12 cases 13 Electric motor 14 gearboxes 15 Clutch 16 clutch housings 17 Upward direction 18 Transverse direction 20 main bodies 21 first free space 22 second free space 23 third free space 24 Sliding surface for drive pin 25 mounting threads 26 fastening screw 27 Cavity 30 first end block 31 first deflection wheel 32 first deflection axle 33 first pivot bearing 34 first axis of rotation of the first deflection wheel 35 Propulsion devices 36 bearing holders 40 second end block 41 second deflection wheel 42 second deflection axis 43 second pivot bearing 44 Sliding bushing 45 Seal 46 second axis of rotation of the second deflection wheel 50 clamping device 51 clamping brackets 52 Tensioning screw 53 Connecting screw 54 U-shaped leg of the clamping bracket 55 Base of the clamping bracket 56 threads for clamping screw 60 booms 61 Fasteners 62 Central axis of the boom 70 drivers 71 Sliding lining on the drive pin 72 first clamping device 73 second clamping device 74 clamping plate 75 clamping screw 76 Outer circumference of the drive lug 77 Inner circumferential surface of the drive pin 78 Disconnection 80 Distance measuring system 81 Measuring stick 82 Support part 83 Permanent magnet 84 first end of the measuring rod 85 second end of the measuring rod 86 Adapter plate 87 Locknut 90 traction elements 91 Side edge of the traction element 92 first attachment point 93 second attachment point 96 Section of the traction element between the first and the second deflection wheel goes QUOTES INCLUDED IN THE DESCRIPTION

[0049] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0050] DE 102007043391 A1

[0002] Cited non-patent literature

[0051] http: / / www.megatron.de / kategorie / potentiometrische-positionssensoren / download / 128.html

[0016]

Claims

[1] Linear motion device ( 10 ) with a housing ( 12 ) and a boom ( 60 ), wherein the boom ( 60 ) with respect to a longitudinal direction ( 11 ) movable on the housing ( 12 ) is stored, with it being in the longitudinal direction ( 11 ) from the housing ( 12 ) protrudes, preferably being located inside the housing ( 12 ) is recorded, characterized by that a first and a second deflection wheel ( 31 ; 41 ) are provided which, with respect to the longitudinal direction ( 11 ) at opposite ends of the housing ( 12 ) are rotatably mounted, wherein a traction element ( 90 ) with a first and a second attachment point different from it ( 92 ; 93 ) is provided, wherein the traction element ( 90 ) the first and the second deflection pulley ( 31 ; 41 ) encircles, whereby the traction element ( 90) at the first and second attachment points ( 92 ; 93 ) firmly attached to the boom ( 60 ) is connected. [2] Linear motion device according to claim 1, wherein the traction element ( 90 ) is finally formed, with the first and second attachment points ( 92 ; 93 ) at opposite ends of the traction element ( 90 are arranged. [3] Linear motion device according to one of the preceding claims, wherein the second deflection wheel ( 41 ) regarding a vertical direction ( 17 ), perpendicular to the longitudinal direction ( 11 ) is aligned next to the boom ( 60 ) is arranged. [4] Linear motion device according to claim 3, wherein the first deflection wheel ( 31 ) a larger diameter than the second deflection wheel ( 41 ) has. [5] Linear motion device according to claim 3 or 4, wherein the first deflection wheel ( 31) with a propulsion means ( 35 ) is equipped with which it is connected to an electric motor via a rotary drive ( 13 ) is bringable. [6] Linear motion device according to one of claims 3 to 5, wherein the boom ( 60 ) in an upward direction ( 17 ) viewed between opposite side edges ( 91 ) of the traction element ( 90 ) is arranged. [7] Linear motion device according to one of the preceding claims, wherein a separate driver ( 70 ) is provided, which is connected to one end of the boom ( 60 ) is firmly connected, with the traction element ( 90 ) at the first and second attachment points ( 92 ; 93 ) firmly attached to the drive pin ( 70 ) is connected. [8] Linear motion device according to claim 7, wherein the first and the second mounting point ( 92 ; 93 ) of the traction element ( 90) with respect to the longitudinal direction ( 11 ) at opposite ends of the driver ( 70 are arranged. [9] Linear motion device according to any one of claims 3 to 8, wherein the first and the second mounting point ( 92 ; 93 ) of the traction element ( 90 ) regarding the upward direction ( 17 ) on opposite sides of a central axis ( 62 ) of the boom ( 60 are arranged. [10] Linear motion device according to one of claims 3 to 9, wherein the second deflection wheel ( 41 ) with a clamping device ( 50 ) is equipped with a device designed to pull the traction element ( 90 ) to tension. [11] Linear motion device according to one of claims 3 to 10, wherein a rotary axis ( 34 ) of the first deflection wheel ( 31 ) regarding the upward direction ( 17 ) next to the central axis ( 62 ) of the boom ( 60 ) is arranged. [12] Linear motion device according to one of the preceding claims, wherein a displacement measuring system ( 80 ) is provided, which includes an elongated measuring rod ( 81 ) and a permanent magnet ( 83 ) has, wherein the boom ( 60 ) is tubular in shape, wherein the measuring rod ( 81 ) at a first end ( 84 ) on the casing ( 12 ) is attached, with its second end opposite the first ( 85 ) into the interior of the crude boom ( 60 ) extends into it, with the permanent magnet ( 83 ) at least indirectly on the boom ( 60 ) is attached. [13] Linear motion device according to claim 12, wherein the second end ( 85 ) of the measuring rod ( 80 ) inside the boom ( 60 ) lies in a gliding position. [14] Linear motion device according to one of claims 7 to 13, wherein the housing ( 12) inside with a sliding surface ( 24 ) is provided, on which the driver ( 70 ) and / or the boom ( 60 ) is glidingly positioned, whereby the sliding surface ( 24 ) has a cross-sectional shape that deviates from a circular shape. [15] Linear motion device according to one of claims 3 to 14, wherein the axis of rotation ( 34 ; 46 ) of the first and / or the second deflection pulley ( 31 ; 41 ) parallel to a transverse direction ( 18 ) run, with the transverse direction ( 18 ) perpendicular to the longitudinal direction ( 11 ) and towards the upward direction ( 17 ) is aligned.

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