Actuator with sensors and evaluation module

Abstract

The invention relates to an actuator (10) with a housing (20) in which a threaded spindle is accommodated so as to be rotatable with respect to a rotational axis (11), wherein a boom (50) protrudes from the housing (20), wherein the housing (20) comprises a main body (30). According to the invention, the main body (30) has an opening extending radially to the axis of rotation (11), which connects the second cavity (32) to the environment (12), wherein the opening is closed by an evaluation module (60), wherein the opening (34) delimits a first and a second section of the second cavity from one another, wherein the first section is arranged in the region of the first end (41) of the threaded spindle (50), wherein the second section is arranged in the region of the second end of the threaded spindle (40), wherein a first sensor is fastened to the housing (20) in such a way that it can detect the interior of the housing (20), wherein it is electrically connected to the evaluation module (60) via a first cable, wherein the first cable is inserted at the end into the first section of the second cavity of the main body (30), wherein a second sensor is arranged within the second section of the second cavity,wherein the second sensor is electrically connected to the evaluation module (60) via a second cable, the second cable being arranged entirely in the second cavity.,

Description

The invention relates to an actuator according to the preamble of claim 1.An actuator is known from DE 10 2020 212 703 B4. The actuator has a housing in which a threaded spindle is rotatably mounted with respect to a rotational axis. A cantilever protrudes from the housing movably in the direction of the axis of rotation, wherein it is in screw engagement with the threaded spindle. The actuator has a similar external shape to a hydraulic cylinder, wherein the threaded spindle can be driven by an electric motor. This is therefore referred to as an electric cylinder. The actuator is equipped with a planetary screw drive, which can generate considerable waste heat during operation. Therefore, the interior of the housing is filled with oil to cool and / or lubricate the planetary screw.From DE 10 2020 212 705 A1 a similar actuator is known, which however is provided with a grease lubrication. This is used when only small forces act on the boom, so that little waste heat arises.Further comparable actuators are known from DE 10 2020 212 704 B4 and DE 10 2020 212 706 A1.Within the scope of the invention, the actuator is to be provided with an electronic display which indicates how far the performance of the actuator is exhausted. In the case of oil lubrication, the current temperature of the actuator is primarily decisive. In the case of grease lubrication, the distance covered by the boom, which determines the wear state of the actuator, is primarily decisive. The corresponding electronic components should be designed such that they can be used equally for both cases, so that they can be produced in large numbers and thus cost-effectively. The electronic components are to be arranged within the actuator in a protected manner. In this case, it should be ensured, in particular, that they cannot come into contact with the oil filling explained above. The corresponding sealing measures should be able to be carried out cost-effectively.According to the independent claim, it is proposed that the main body has an aperture running radially to the axis of rotation, which connects the second cavity to the environment, wherein the aperture is closed off with an evaluation module, wherein the aperture delimits a first and a second section of the second cavity from one another, wherein the first section is arranged in the region of the first end of the threaded spindle, wherein the second section is arranged in the region of the second end of the threaded spindle, wherein a first sensor is fastened to the housing in such a way that it can sense the interior of the housing, wherein it is electrically connected to the evaluation module via a first cable, wherein the first cable is introduced at the end side into the first section of the second cavity of the main body, wherein a second sensor is arranged within the second section of the second cavity, wherein the second sensor is electrically connected to the evaluation module via a second cable, wherein the second cable is arranged completely in the second cavity. The main body is preferably made of aluminium, most preferably it is made by extrusion. The evaluation module preferably comprises a display, the display of which is dependent on the measured value of the first and / or of the second sensor.The dependent claims specify advantageous refinements and improvements of the invention.It can be provided that the first sensor is an inductive proximity switch, with which a rotational speed of the threaded spindle can be measured. As a result, the distance covered by the boom can be determined, which significantly influences the wear state of the actuator. A proximity switch operates substantially wear-free.It can be provided that the first sensor is arranged on the side of the pivot bearing facing away from the main body. As a result, a longer first cable is indeed required. The corresponding cable path and the first sensor itself can, however, be protected in a simple manner against penetrating fluids.It can be provided that in the detection region of the first sensor an adjusting nut is arranged, with which the pivot bearing is fastened to the threaded spindle, wherein the adjusting nut has at least one recess, which can be detected with the first sensor. The threaded spindle typically consists of hardenable rolling bearing steel and is accordingly difficult to machine. On the adjusting nut, the mentioned recesses can be produced in contrast easily, for example by means of drilling. The adjusting nut preferably sets the prestress of the rotary bearing, which most preferably comprises a plurality of angular ball bearings. The adjusting nut preferably comprises a clamping device, with which the rotational position of the adjusting nut relative to the threaded spindle can be fixed. The adjusting nut can be designed, for example, according to EP 3 105 462 B1. Preferably, the adjusting nut has a plurality of recesses which are arranged uniformly distributed over the circumference of the adjusting nut. The at least one recess is preferably each formed as a circular cylindrical blind hole.It can be provided that a sealing ring is arranged in the direction of the axis of rotation between the pivot bearing and the first cavity, which sealing ring is installed in such a way that no fluid can pass from the first cavity to the pivot bearing. In the case of oil lubrication of the threaded drive, it would be expedient in principle for the oil filling also to lubricate the rotary bearing. However, it is preferred that no use be made of this possibility. Rather, the pivot bearing is sealed with respect to the oil filling. As a result, the first sensor is also protected from the oil filling. The pivot bearing is preferably lubricated by means of grease. The sealing ring is preferably designed as a radial shaft sealing ring. It preferably surrounds the threaded spindle.It can be provided that the housing comprises a first and a second end block which are fastened to opposite ends of the main body in the direction of the axis of rotation, wherein the first end block is arranged in the region of the first end of the threaded spindle, wherein the pivot bearing is accommodated in the first end block, wherein it is fastened there by a clamping nut. The boom preferably passes through the second end block.It can be provided that the sealing ring is accommodated in the clamping nut.It can be provided that the clamping nut comprises a flange which is arranged opposite an end face of the first end block, wherein at least one fixing screw is screwed into the flange, which is in each case oriented parallel to the axis of rotation, wherein it is supported on the said end face. The at least one fixing screw prevents the clamping nut from loosening during operation. The otherwise customary adhesion of the clamping nut, which is difficult to release in the event of repair, can be dispensed with. The fixing screw is preferably each designed in the form of a threaded pin with a tip. The fixing screw is preferably tightened so firmly that the tip plastically deforms the said end face, so that the rotational position of the clamping nut is secured in a positive-locking manner. Preferably, a plurality of fixing screws are provided which are arranged uniformly distributed over the circumference of the clamping nut.It can be provided that the second sensor is designed as a temperature sensor. The temperature of the oil filling in the first cavity can thus be measured approximately at any rate. Overheating of the actuator can subsequently be indicated on the evaluation module.It can be provided that the second sensor is thermally coupled to a circumferential wall of the second cavity toward the first cavity. The measurement value of the second sensor thus approximates the temperature in the first cavity well. The mentioned thermal coupling can be effected, for example, using a heat-conducting paste or a heat-conducting pad.It can be provided that the evaluation module has a first and a second operating mode, wherein the first operating mode can be set when the first cavity is filled with oil to an extent of at least 30%, wherein otherwise the second operating mode can be set, wherein in the first operating mode a display on a display of the evaluation module depends on a temperature measured with the second sensor. The aforementioned setting of the operating mode preferably takes place once during the production of the actuator. The software of the evaluation module thus implements both operating modes, wherein the desired operating mode is selected by adjusting a parameter, namely depending on whether the actuator is to be lubricated with oil or with grease. The display mentioned is preferably designed as a color bar. The color bar is preferably green if the measured temperature is not critical. The color bar is preferably red if the measured temperature is so high that the operation of the actuator must be stopped promptly. Incidentally, the color bar is preferably yellow or orange. If the socket described below allows data transmission, the actuator can be stopped automatically if necessary.It can be provided that in the second operating mode of the evaluation module a travel path of the boom can be determined using the first sensor, wherein a display on a display of the evaluation module depends on the travel path mentioned. The same color bar is preferably used as the display, which is also used in the first operating mode. The red color then preferably indicates a worn actuator.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.The invention is explained in more detail below with reference to the attached drawings. It shows: FIG. 1 is a perspective view of an actuator according to the invention; FIG. 2 is a longitudinal section of the actuator of FIG. 1; FIG. 3 is a partial longitudinal section of the actuator according to FIG. 1, the sectional plane being rotated with respect to FIG. 2 ; FIG. 4 shows a perspective partial view of the threaded spindle with the pivot bearing and the first sensor; FIG. 5 is a perspective view of the main body; FIG. 6 shows a perspective view of the evaluation module from the environment; and FIG. 7 shows a perspective view of the evaluation module from the main body.FIG. 1 shows a perspective view of an actuator 10 according to the invention. the actuator 10 comprises a housing 20 which is composed of a main body 30 and a first and a second end block 21; 22. The main body 30 is made of aluminum by extrusion so as to extend with a constant cross-sectional shape along the rotation axis 11. A threaded spindle 40 is rotatably accommodated in the housing 20 with respect to a rotational axis 11, wherein the threaded spindle 40 protrudes from the housing 20 at a first end 41 by a drive pin 46. The drive pin 46 may be rotatably coupled to an electric motor (not shown) to move the boom 50.The extension arm 50 which is displaceable in the direction of the axis of rotation 11 projects out of the housing 20 on the side facing away from the first end 41 of the threaded spindle 40, namely the same in which position the extension arm 50 is located. The extension arm 50 passes through the second end block 22 with a tube-like section 51, the outer shape of which is circular cylindrical with respect to the axis of rotation 11. Preferably, the first end block 21 is provided with a seal which seals against said outer shape. At its free end, the tubular section 51 is provided with an articulated head 53, wherein other fastening means are also possible, for example a threaded pin concentric to the axis of rotation 11.In the region of the main body 30, an evaluation module 60 is arranged, which can be operated and / or read from the environment 12.Reference should also be made to the two optional bearing journals 25, which are fastened to the first end block 21 in such a way that they define a common pivot axis. Instead of the bearing journals 25, other fastening means can be provided, for example a further joint head.FIG. 2 shows a longitudinal section of the actuator 10 according to FIG. 1, the threaded spindle 40 is mounted on the housing 20 rotatably with respect to the axis of rotation 11 by means of a pivot bearing 43. The pivot bearing 43 comprises four separate angular ball bearings, the outer ring of which is accommodated in the first end block 21, wherein the corresponding inner rings are accommodated in each case at the first end 41 of the threaded spindle 40. The pivot bearing 43 is fastened in the first end block 21 by means of a clamping nut 23, wherein it is on the threaded spindle 40 by means of an adjusting nut 44. The adjusting nut 44 is designed such that it can be clamped against the threaded spindle 40 in a defined screw position in order to set the prestress of the rotary bearing 43.The threaded spindle 40 is received in sections in the first cavity 31 of the main body 30. The end of the tubular section 51 of the extension 50 there is firmly connected to a threaded nut 52, which is in screw engagement with an external thread on the threaded spindle 40. The screw engagement mentioned is in the present case designed in the manner of a planetary screw drive, wherein it can also be designed as a ball screw drive or as a sliding screw drive.The second end 42 of the threaded spindle 40 remote from the first end 41 projects into the tubular section 51 in each position of the extension 50. The inner circumferential surface of the tubular section 51 is in the present case formed in a circular cylinder with respect to the axis of rotation 11, wherein the second end 42 of the threaded spindle 40 is supported there by an optional end support 47. The end support 47 prevents torsional bending oscillations of the threaded spindle 40 at a high speed in conjunction with a long threaded spindle 40.FIG. 3 shows a partial longitudinal section of the actuator 10 according to FIG. 1, wherein the sectional plane is rotated about the axis of rotation 11 in relation to FIG. 2 such that the first sensor 61 is visible. The main body 40 has first and second cavities 31; 32 separated by a continuous wall so that fluid cannot pass from the first cavity 31 into the second cavity 32. The fluid is, for example, oil, with which a screw drive in the form of a planetary screw drive is cooled and / or lubricated. An electrical first cable runs in the second cavity 32 to the evaluation module (no. 60 in FIG. 1 ). The first cable 63 exits the main body at the end, passing into a drilled channel system 68; 69 in the first end block 21. The axial channel section 68 continues the second cavity 32 in alignment parallel to the axis of rotation 11, wherein it leads radially outwards past the pivot bearing 43. At the end of the axial channel section 68, a radial channel section 69 is arranged, which is oriented perpendicular to the axis of rotation 11, wherein it leads out of the first end block 21 opposite the adjusting nut 44. The radial channel section 69 is drilled from radially outside into the first end block 21, the corresponding opening being closed by a closure screw 67.The first sensor 61 is installed in the radial channel section 69, which is designed as an inductive proximity switch. It is arranged at a small distance from the adjusting nut 44 so that it can detect the recesses there (no. 45 in FIG. 4 ).The first sensor 61 is clamped against the wall of the radial channel portion 69 by a clamping screw 66 so that it does not move relative to the first end block 21 during operation.Furthermore, FIG. 3 shows the clamping nut 23, with which the outer rings of the pivot bearing 43 are clamped against the first end block 21 in the direction of the axis of rotation 11. The clamping nut 23 has an external thread on its outer circumference, which is screwed into an adapted internal thread in the first end block 21. In addition, a sealing ring 24 in the form of a radial shaft sealing ring is installed in the clamping nut 23. Its sealing lip abuts the threaded spindle 40, wherein the latter comprises a separate sleeve 49, which forms the corresponding sealing surface, which is circular cylindrical with respect to the axis of rotation 11. The sleeve 49 is pressed onto the remaining threaded spindle 40.FIG. 4 shows a perspective partial view of the threaded spindle 40 with the pivot bearing 43 and the first sensor 61, The clamping nut 23 is provided with a flange 27 which projects radially outwards beyond the pivot bearing 43 with respect to the axis of rotation 11 so that it is arranged opposite an end face of the first end block. A plurality of fixing screws 26 are screwed into the flange 27, which are aligned parallel to the axis of rotation 11. The fixing screws are in the present case each designed as threaded pins with tips, wherein they are tightened so firmly that the tip plastically deforms the mentioned end face in order to secure the rotational position of the clamping nut 23.Furthermore, the adjusting nut 44 can be seen in FIG. 4, with which the prestress of the rotary bearing 43 is adjusted. The adjusting nut 44 is screwed onto an external thread on the threaded spindle 40. It comprises a clamping device 48 which is designed, for example, according to EP 3 105 462 B1. The clamping device 48 has elastically movable sections which can be clamped against the mentioned external thread by means of clamping screws in order to secure the rotational position of the adjusting nut 44 in a frictionally locking manner.On the outer circumferential surface of the adjusting nut 44 a plurality of recesses 45 are arranged, which are arranged uniformly distributed over the circumference of the adjusting nut 44. The recesses 45 are each formed as circular blind holes which are formed identically to one another. The recesses 45 are arranged in the detection region of the first sensor 61, so that the rotational speed of the threaded spindle 40 can be measured with the first sensor 61 by counting the measurement pulses per unit time caused by the recesses 45.It can also be seen in FIG. 4 how the first cable 63 is guided past the rotary bearing 43 on the outside.FIG. 5 is a perspective view of the main body 30, and the main body 30 is made of aluminum by extrusion molding. It therefore extends with the constant cross-sectional shape visible in FIG. 5 along the axis of rotation 11. Arranged on the inside is a first cavity 31, which is arranged concentrically with respect to the axis of rotation 11, wherein the threaded spindle (no. 40 in FIG. 2 ) and the extension arm (no. 50 in FIG. 2 ) are arranged there. The first cavity 31 is delimited from the remaining cavities 32; 33 by uninterrupted walls, so that fluid which is located in the first cavity 31 cannot enter the remaining cavities 32; 33, at least not via the main body 30.The second cavity 32 and the further cavities 33 are identical to one another, wherein in each case they are oriented differently. They are designed such that the square outer shape is adapted to the shape of the first cavity 31 in the sense of saving material. The second cavity 32 is the one in which the evaluation module (No. 60) and the first and second cables (No. 63; 64 in FIG. 6 ) and the second sensor (No. 62 in FIG. 6 ) are arranged.Starting from the second cavity 32 toward the bypass 12, the main body 30 is provided with an aperture 34, in which the evaluation module 60 is accommodated. The shape of the aperture 34 is adapted to the evaluation module in such a way that it can be installed there without any gaps. A shoulder 38 is provided over the entire circumference of the opening 34, on which the evaluation module is glued with an endlessly revolving glued seam (no. 70 in FIG. 7.The aperture 34 delimits a first and a second section 35; 36 of the second cavity 32 from one another, wherein the second sensor (no. 62) in FIG. 6 is arranged in the second section 36.Reference is made to the circular screw recesses 37 in the four corners of the main body 30, where screw bolts are screwed in, by means of which the first and the second end block are fastened to the main body 30.FIG. 6 shows a perspective view of the evaluation module 60 from the environment 12. The evaluation module 60 comprises a plate-like plastic housing 73 which is adhesively bonded into the shoulder (no. 38 in FIG. 5 ). A display 65 is installed in the plastic housing 73, which display is designed, for example, as a color bar. The color bar can illuminate green in the basic state, and it can also illuminate yellow and red. Different lengths of the color bar can be assigned to the different colors. Further, the resin case 73 is provided with a female connector 71. The evaluation module 60 is supplied with electric current via the socket 71. Furthermore, the measurement data determined with the evaluation module 60 can be transmitted to a superordinate control device, wherein data exchange in the opposite direction is also possible. The data exchange explained above is optional.The second sensor 62 is designed as a temperature sensor in the present case, wherein it is arranged in the second section (no. 36 in FIG. 5 ) of the second cavity. It is connected via an electrical second cable 64 to the electronic board (no. 72 in FIG. 7 ) of the evaluation module 60. On the opposite side of the evaluation module 60, the electrical first cable 63 is connected, which leads to the first sensor via the first section (no. 35 in FIG. 5 ) of the second cavity.FIG. 7 shows a perspective view of the evaluation module 60 from the main body. The electronic board 72 of the evaluation module 60 can be seen, which preferably comprises a microprocessor with which the evaluation of the measurement data explained above is carried out. The display 65 is soldered to the electronic board 72 while being fixed to the resin case 73. The plastic housing 73 is provided with an adhesive seam 70, which is preferably designed in the form of a double-sided mounting adhesive tape.Reference numerals denote reference numerals10 Actuator 11 Axis of rotation 12 Environment of the actuator 20 Housing 21 First end block 22 Second end block 23 Clamping nut 24 Sealing ring 25 Bearing journal 26 Fixing screw 27 Flange 30 Main body 31 First cavity 32 Second cavity 33 Further cavity 34 Aperture 35 First section of the second cavity 36 Second section of the second cavity 37 Screw recess 38 Shoulder 40 Threaded spindle 41 First end 42 Second end 43 Pivot bearing 44 Adjusting nut 45 Recess 46 Drive journal 47 End support 48 Clamping device 49 Sleeve 50 Arm 51 Tubular section 52 Threaded nut 53 Joint head 60 Evaluation module 61 First sensor 62 Second sensor 63 First cable 64 Second cable 65 Display 66 Clamping screw 67 Locking screw 68 Axial channel section 69 Radial channel section 70 Adhesive seam 71 Socket 72 Electronic board 73 Plastic housing

Claims

Actuator (10) having a housing (20), a cantilever (50) and a threaded spindle (40), wherein the threaded spindle (40) is mounted on the housing (20) such that it can rotate with respect to a rotational axis (11) by means of a pivot bearing (43) adjacent to its first end (41), wherein the cantilever (50) protrudes from the housing (20) such that it can be displaced in the direction of the rotational axis (11), wherein a second end (42) of the threaded spindle (40) facing away from the pivot bearing (43) protrudes into a tube-like section (51) of the cantilever (50), regardless of the position in which the cantilever (50) is located, wherein the cantilever (50) is in screw engagement with the threaded spindle (40) in the interior of the housing (20), wherein the housing (20) comprises a main body (30) which extends along the rotational axis (11) with a constant cross-sectional shape, wherein said cross-sectional shape delimits a first and a second cavity (31; 32) from one another in such a way that no fluid can pass from the first cavity (31) into the second cavity (32) in the region of the main body (30), wherein the threaded spindle (40) and the extension arm (50) are each arranged at least in sections in the first cavity (31), characterized in that the main body (30) has an aperture (34) which runs radially with respect to the axis of rotation (11) and connects the second cavity (32) to the environment (12), wherein the aperture (34) is closed by an evaluation assembly (60), wherein the aperture (34) delimits a first and a second section (35; 36) of the second cavity (32) from one another, wherein the first section (35) is arranged in the region of the first end (41) of the threaded spindle (50), wherein the second section (36) is arranged in the region of the second end (42) of the threaded spindle (40), wherein a first sensor (61) is fastened to the housing (20) in such a way that it can detect the interior of the housing (20), wherein it is electrically connected to the evaluation assembly (60) via a first cable (63), wherein the first cable (63) is introduced at the end face into the first section (35) of the second cavity (32) of the main body (30), wherein a second sensor (62) is arranged within the second section (36) of the second cavity (32), wherein the second sensor (62) is electrically connected to the evaluation assembly (60) via a second cable (64), wherein the second cable (64) is arranged completely in the second cavity (32).Actuator (10) according to Claim 1, wherein the first sensor (61) is an inductive proximity switch, with which a rotational speed of the threaded spindle (40) can be measured.Actuator (10) according to one of the preceding claims, wherein the first sensor (61) is arranged on the side of the pivot bearing (43) facing away from the main body (30).Actuator (10) according to one of the preceding claims, wherein an adjusting nut (44) is arranged in the detection region of the first sensor (61), with which adjusting nut the pivot bearing (43) is fastened to the threaded spindle (40), wherein the adjusting nut (44) has at least one recess (45), which can be detected with the first sensor (61).Actuator (10) according to one of the preceding claims, wherein a sealing ring (24) is arranged between the pivot bearing (43) and the first cavity (31) in the direction of the axis of rotation (11), which sealing ring is installed such that no fluid can pass from the first cavity (31) to the pivot bearing (43).Actuator (10) according to one of the preceding claims, wherein the housing (20) comprises a first and a second end block (21; 22) which are fastened to opposite ends of the main body (30) in the direction of the axis of rotation (11), wherein the first end block (21) is arranged in the region of the first end (41) of the threaded spindle (40), wherein the pivot bearing (43) is accommodated in the first end block (21), wherein it is fastened there by a clamping nut (23).The actuator of claim 6 when appended to claim 5, wherein the sealing ring (24) is received in the clamping nut (23).Actuator according to claim 6 or 7, wherein the clamping nut (23) comprises a flange (27) arranged opposite an end face of the first end block (21), wherein at least one fixing screw (26) is screwed into the flange (27), which is respectively aligned parallel to the axis of rotation (11), wherein it is supported on said end face.Actuator (10) according to one of the preceding claims, wherein the second sensor (62) is designed as a temperature sensor.The actuator (10) of claim 9, wherein the second sensor (62) is thermally coupled to a circumferential wall of the second cavity (32) toward the first cavity (31).Actuator (10) according to one of the preceding claims, wherein the evaluation module (60) has a first and a second operating mode, wherein the first operating mode is settable when the first cavity (31) is filled with oil to at least 30%, wherein otherwise the second operating mode is settable, wherein in the first operating mode a display on a display (65) of the evaluation module (60) depends on a temperature measured by the second sensor (62).Actuator (10) according to Claim 11, wherein, in the second operating mode of the evaluation module (60), a travel path of the boom (50) can be determined using the first sensor (61), wherein a display on a display (65) of the evaluation module (60) depends on the said travel path.

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