Linear drive unit with threaded spindle nut drive

Abstract

The invention relates to a linear drive unit with a guide housing group and a carriage group mounted thereon for linear movement. At least one electric drive motor with a stator and a rotor, and a threaded spindle-nut drive driven by the drive motor and driving the carriage group are arranged in a guide housing of the guide housing group. The threaded spindle-nut drive has a threaded spindle connected to the carriage group and a spindle nut connected to the rotor. The threaded spindle penetrates the drive motor. The present invention develops a compact linear drive unit.

Description

[0001] The invention relates to a linear drive unit with a guide housing group and with a carriage group mounted on the latter so as to be linearly movable, wherein at least one electric drive motor with a stator and a rotor and a threaded spindle nut drive driven by the drive motor and driving the carriage group are arranged in a guide housing of the guide housing group.

[0002] From DE 10 2014 017 542 A1 a linear drive unit is known whose motor shaft is connected to the threaded spindle by means of a coupling.

[0003] The present invention is based on the problem of developing a compact linear drive unit.

[0004] This problem is solved by the features of the main claim. The threaded spindle-nut drive comprises a threaded spindle connected to the slide assembly and a spindle nut connected to the rotor. The threaded spindle penetrates the drive motor.

[0005] The linear drive unit has a spindle nut connected to the drive motor rotor and mounted rotatably in the guide housing. The spindle nut meshes with a threaded spindle that is non-rotatably connected to the slide assembly. The threaded spindle penetrates the drive motor, allowing the overall length of the drive motor to be used as the stroke length. This allows for a space-saving design despite the linear drive unit's large stroke.

[0006] Further details of the invention emerge from the subclaims and the following description of schematically illustrated embodiments. Fig. 1: Linear drive unit; Fig. 2: Rear view of the linear drive unit; Fig. 3: Longitudinal section of the Fig. 1; Fig. 4: Guide housing body with attachments; Fig. 5: Longitudinal section of the Fig. 4; Fig. 6: Slide group with guide rail removed;

[0007] The Fig. 1 shows a linear drive unit (10). This comprises a guide housing group (20) arranged, for example, stationary on a machine and a carriage group (120) movable relative thereto. The carriage group (120) is mounted on the guide housing group (20) so as to be displaceable in the longitudinal direction (5) of the linear drive unit (10).

[0008] The longitudinal direction (5) of the linear drive unit (10) can be oriented in space at any angle from zero degrees to ninety degrees inclusive relative to a horizontal plane. The following describes a linear drive unit (10) whose longitudinal direction (5) lies in a horizontal plane and whose carriage group (120) is arranged above the guide housing group (20).

[0009] Four mounting brackets (11) arranged on both sides of the guide housing group (20) are used to attach the linear drive unit (10), e.g., to a machine table. The electrical power supply is provided, for example, via a supply connection (12) connected to the rear end face of the linear drive unit (10). See. Fig. 2. For example, a voltage of 24 volts or 48 volts is applied to this connection. It is also conceivable to arrange a power source in the linear drive unit (10). The linear drive unit (10) can then be operated electrically independently. In the illustrations of the Fig. 2, a logic connection (13) and two communication connections (14) are also provided. By means of these connections (13, 14), for example, data and / or signals are exchanged with a higher-level controller. It is also conceivable to combine the logic connection (13) and the communication connection (14) or the communication connections (14) into one connection. If necessary, a combination of one or both of the latter connections (13, 14) with the supply connection (12) is also conceivable. The data and / or signals can also be exchanged wirelessly with the higher-level controller. In the exemplary embodiment, the logic connections (13) and the communication connections (14) are operated with a voltage of 24 volts.

[0010] For the communication connection (14), protocols according to IEC 61800-7, IEC 61131-3, IEC 61131-9, etc. are used. Connection of fieldbuses is also conceivable.

[0011] The guide housing group (20) has a cuboid-shaped envelope contour. It comprises a guide housing (21) in which a drive unit (61) and a control and regulation unit (111) are arranged. On the outside of the guide housing (21), for example, two lubrication connections (22, 23) are arranged on each side. Rail guide shoes (27) are located on the guide housing (21) as part of the guide housing group (20).

[0012] The Fig. Figure 3 shows a longitudinal section of the linear drive unit (10). The guide housing group (20) has a guide housing body (51) that is connected to the rear (24) by means of an operating and connection panel (25), see Figure 1. Fig. 2, is closed. The front side (26) is penetrated by a threaded spindle (92) of a threaded spindle-nut drive (91).

[0013] The Fig. 4 and Fig. 5 shows the guide housing body (51) with some attachments. The guide housing body (51) has the shape of a tube with a square outer cross-section. It is made, for example, from an aluminum material. The edge length of the square is, for example, 22% of the length of the guide housing body (51) oriented in the longitudinal direction (5). On the side surfaces (54) of the guide housing body (51), engagement grooves (52, 53) are formed on both sides parallel to the upper and lower sides. The lower engagement grooves (52) serve to accommodate the fastening claws (11). The upper engagement grooves (53) are, for example, sensor grooves (53).

[0014] The guide housing body (51) bears in the illustrations of the Fig. 4 and Fig. 5 a guide rail (121). The guide rail (121), which is T-shaped, is part of the slide group (120). It is displaceably mounted on the guide housing body (51) in the area adjacent to the front side (26) of the linear drive unit (10) by means of four rail guide shoes (27) screwed to the guide housing body (51). The rail guide shoes (27) can be designed as recirculating ball shoes. In the illustrations of the Fig. 4 and Fig. 5, the guide rail (121) projects freely toward the rear side (24). In the illustrated example, the guide rail (121) is supported along 37% of its length.

[0015] A lubrication adapter (28) of the guide housing group (20) is located between the two rail guide shoes (27). This adapter is hydraulically connected to the lubrication connection (23) of the guide housing (21). Lubricant pressed into the lubrication adapter (28) from the lubrication connection (23) is further displaced to the guide rail (121). For this purpose, the lubrication adapter (28) has T-shaped lubricant channels (29). If necessary, a lubrication control device can be provided to monitor sufficient lubrication of the pairing between the guide rail (121) and the rail guide shoes (27). It is also conceivable to automate the addition of lubricant. For example, individual doses of lubricant can be added depending on the operating hours and / or the distance traveled by the guide rail (121) relative to the rail guide shoes (27).

[0016] In the guide housing (21), the lubricant is conveyed from the lubrication connection (23) through an annular channel (31) to the lubrication adapter (28). In the exemplary embodiment, this annular channel (31) is defined by two O-rings (32) spaced apart in the longitudinal direction (5) and the outer ring (85) of a rolling bearing (84), see. Fig. 3.

[0017] In the direction of the Fig. 4 and Fig. 5 At the projecting end of the guide rail (121), a stop block (33) is arranged next to the rail guide shoes (27). This stop block (33) limits the stroke of the slide group (120) relative to the guide housing group (20) when the slide group (120) is extended.

[0018] A measuring sensor (34) protrudes from the guide housing (21). This interacts with a scale (125) arranged on the slide (122) of the slide group (120), see. Fig. 6. In the exemplary embodiment, the measuring sensor (34) and the scale (125) form a linear, e.g., magnetic, absolute position measuring system (34, 125). This position measuring system (34, 125) is part of a position control loop arranged in the linear drive unit (10). The position control loop monitors and controls the position of the carriage group (120) relative to the guide housing group (20).

[0019] The drive unit (61) comprises a drive motor (62), the threaded spindle-nut drive (91), and a braking and / or clamping device (101). The drive motor (62) has a stator (63) fixed in the guide housing (21), which encloses a rotor (64). The stator (63) is made, for example, from a steel material. The motor shaft (65) fastened in the rotor (64) is designed as a multi-part hollow shaft. The stepped motor shaft (65) penetrates the drive motor (62) in the longitudinal direction (5). The drive motor (62) is designed, for example, as a brushless DC motor.

[0020] The motor shaft (65) is mounted in the guide housing body (51) by means of three roller bearings (81, 84, 87). A first roller bearing (81) is arranged on the side of the drive unit (61) facing the control and regulation unit (111). It is designed as a deep groove ball bearing sealed on both sides. This bearing position forms the floating bearing of the motor shaft bearing. The inner ring (82) is fixed to the motor shaft (65). The outer ring (83) is mounted for axial displacement in the longitudinal direction (5).

[0021] The fixed bearing consists of two adjacent roller bearings (84, 87). In the illustrated embodiment, these are designed as identical, sealed deep groove ball bearings. The inner rings (86, 89) and the outer rings (85, 88) are made of a steel material. It is also conceivable to use a double-row deep groove ball bearing, a double-row angular contact ball bearing, etc. The nominal size of the fixed bearing, determined by the inner diameter, is, for example, 1.75 times the nominal size of the floating bearing. A shaft nut (66) and an end flange (67) secure the position of the fixed bearing on the motor shaft (65).

[0022] In the exemplary embodiment, the motor shaft (65) has a main shaft (68) and a shoulder shaft (69), which are screwed together, for example. The main shaft (68) has a first bearing seat section (71), a rotor section (73), and a second bearing seat section (74). The first bearing seat section (71) has a connecting thread (72) and a groove for a retaining ring (75). Its outer diameter corresponds to the nominal size of the floating bearing. The rotor section (73), for example, has the same outer diameter. The inner diameter of the first bearing seat section (71) and the rotor section (73) is, for example, 80% of the outer diameter of these sections (71, 73). The outer diameter of the second bearing seat section (74) corresponds to the nominal size of the fixed bearing. Its inner diameter is, for example, 83% of its outer diameter. The second bearing seat section (74) carries the end flange (67), which has, for example, four threaded holes (76) and a thread (77) for the shaft nut (66).

[0023] The shoulder shaft (69) is screwed, for example, onto the first bearing seat section (71). It has a brake flange (78) on which part of the braking and / or clamping device (101) is arranged. The braking and / or clamping device (101) has a stationary part (102) fastened in the guide housing body (51) and a rotating part (103) fastened to the brake flange (78). The nominal air gap between the stationary part (102) and the rotating part (103) is at least 0.15 millimeters. The maximum nominal air gap is, for example, 0.4 millimeters. The braking and / or clamping device (101) is closed when de-energized. The braking and / or clamping force is ensured, for example, by means of a permanent magnet. The inductance of the permanent magnet is, for example, between 0.4 Henry and 0.7 Henry. For example, an operating voltage of 24 volts is used to release the brake and / or clamping device (101).The braking and / or clamping device (101) can, for example, have a strain gauge to monitor its actual tension.

[0024] Within the second bearing seat section (74), the motor shaft (65) supports a spindle nut (93) of the threaded spindle-nut drive (91). The spindle nut (93) is, for example, double-started. It engages the threaded spindle (92), which is oriented in the longitudinal direction (5) of the linear drive unit (10). In the exemplary embodiment, the threaded spindle-nut drive (91) is designed as a ball screw drive. For example, the spindle nut (93) has circumferentially guided balls.

[0025] A spindle drive lubrication system is arranged in the guide housing (21). This system has a distribution channel (35) connected to the lubrication connection (22) in the guide housing body (51), and a two-part lubrication adapter (36, 37). The distribution channel (35) is sealed on both sides in the longitudinal directions (5) by means of a sealing ring (38). The first lubrication adapter part (36) is firmly seated in the guide housing (21). It has, for example, four radial channels (39) that open into an internal circulation channel (41). Flat seals (42) on both sides of the circulation channel (41) seal the circulation channel (41) from the environment.

[0026] The second lubrication adapter part (37) is attached to the spindle nut (93) and centered on the motor shaft (65). It has, for example, six radial bores (43) that open into a lubricant reservoir (94) radially surrounding the threaded spindle (92). A flat seal (95) seals the lubricant reservoir from the environment.

[0027] The drive unit (61) is secured in the guide housing body (51) by an internal nut (79). This internal nut (79) loads a disc spring element (44) that is supported on the first lubrication adapter part (36). This allows for length compensation between the steel and aluminum components of the drive unit (61), e.g., in the event of temperature fluctuations.

[0028] The inner nut (79) carries an elastomer body (141) in the design of a structural damper. This is designed as a rotationally symmetrical hollow body. When the linear drive unit (10) is retracted, the carriage (122) strikes the elastomer body (141) and deforms it. For example, the axial deformation amounts to up to 20% of the total length of the elastomer body (141). A stop cup (142) limits the end face of the elastomer body (141). The elastomer body (141) and the stop cup (142) thus form an end position safety device (143) for the retracted linear drive unit (10). The elastomer body (141) can also be used as a lubricant reservoir for lubricating the threaded spindle nut drive (91).

[0029] The threaded spindle (92) of the threaded spindle-nut drive (91) is attached in a cantilevered manner to a slide front plate (123) of the slide (122). In the exemplary embodiment, the threaded spindle (92) is designed as a right-hand threaded spindle (92) with a constant pitch. On its end face facing the slide (122), it has two opposing wrench flats (126). When the slide (122) is mounted, these engage in a complementary anti-rotation part (127). This anti-rotation part (127) is attached to the slide front plate (123) of the slide (122). When the linear drive unit (10) is mounted, the free end of the threaded spindle (92) penetrates the drive motor (62).

[0030] The cross-sectional view of the Fig. 3 L-shaped slides (122) have a slide plate (124) oriented perpendicular to the slide front plate (123). The cuboid-shaped slide plate (124) is attached to the guide rail (121) using fastening screws (128). Both the slide plate (124) and the slide front plate (123) have threaded holes (129). These holes can be used, for example, to attach an adapter tool.

[0031] The Fig. Figure 6 shows the slide assembly (120) without the guide rail (121) from the underside. The slide front plate (123) is molded onto the slide plate (124). The slide plate (124) has a milled recess (131) in which the guide rail (121) sits when the slide assembly (120) is mounted. The scale (125) of the position measuring system (34, 125) is arranged on an edge web (132) of the slide (122) oriented in the longitudinal direction (5). A rear web (133), also arranged on the underside, carries two elastomer bodies (146). These are designed, for example, like the elastomer body (141) described above. The two elastomer bodies (146) arranged on the rear web (133) limit the stroke of the slide assembly (120) extending relative to the guide housing assembly (20). They form an end position safety device (147) of the linear drive unit (10) when the slide group (120) is extended.In the illustrated example, the maximum stroke of the slide group (120) in the longitudinal direction (5) is 100 millimeters or 150 millimeters. The maximum stroke depends on the size of the linear drive unit (10).

[0032] The drive motor (62) of the linear drive unit (10) has an encoder (135). This is the measuring element of a speed control loop. The controller (136) of the speed control loop is located within the guide housing (21). For example, the controller (136) of the speed control loop can be identical to the controller of the position control loop. The two control loops mentioned can be arranged as cascade control loops. However, it is also conceivable to control the two control loops independently of one another. The signals from the measuring elements (125, 135) can also be evaluated together.

[0033] The linear drive unit (10) can also have a current control circuit and / or a voltage control circuit. This can also be operated by the same controller (136) as the aforementioned control circuits or by a separate controller. All electrical components of all control circuits are arranged within the guide housing (21).

[0034] The control circuits are part of the control and regulation unit (111) of the linear drive unit (10). The control circuits are galvanically isolated from the power supply of the drive motor (62) and the braking and / or clamping device (101). This allows the power components, such as the drive motor (62), to be adapted to new performance requirements independently of the control system.

[0035] The control and regulation unit (111) has, for example, a computing unit (112). This comprises, for example, a microcontroller. The computing unit (112) is used, for example, to generate specific control data for the linear drive unit (10) from the data and signals received via the input interface, i.e., the logic connections (13) and the communication connections (14). Reaching the target position, for example, to enable further functions, can also be transmitted to a higher-level controller.

[0036] A data memory and / or a program memory can also be arranged in the guide housing (21). The data memory is used to collect, for example, operating data, error messages, etc., which can be read out by an external location, e.g., maintenance personnel. This can be actual data and / or statistical data.

[0037] For example, a large number of product-specific sequence programs for the linear drive unit (10) can be stored in the program memory. The individual sequence program contains, for example, information about the product-specific stroke, the product-specific speed profile when moving the slide group (120) of the linear drive unit (10), etc. Product-specific data that is used, for example, to create new sequence programs can be stored in the data memory. To call up a sequence program, all that is needed is a program number transmitted wired or wirelessly to an input interface of the linear drive unit (10) and a start signal. After completion of the sequence program, a completion signal, for example a binary one, is transmitted to the higher-level controller. The higher-level controller can then start a follow-up program, e.g. a machining operation on a workpiece.

[0038] When using the linear drive unit (10), for example, the slide group (120) is moved relative to the guide housing group (20) from the position shown in the Fig. 1 and Fig. 2. The braking and / or clamping device (101) is released. The indicator lights (15) on the rear (24) of the guide housing (21) indicate the operating status of the linear drive unit (10), e.g., the power supplies, the status of the communication paths, etc. The movement of the carriage group (120) relative to the guide housing group (20) occurs at a predetermined speed profile. This is monitored by the speed control loop.

[0039] As soon as the target position of the slide group (120) relative to the guide housing group (20), which can be specified for example on a workpiece-specific basis, is reached, the controller (136) of the position control loop causes the drive motor (62) to stop and the electrical release current of the braking and / or clamping device (101) to be interrupted. The braking and / or clamping device (101) closes. The target position of the slide group (120) can be any position within the stroke of the slide group (120). If the target position is close to one of the end positions of the slide group (120), the elastomer bodies (141; 146) are deformed if necessary.

[0040] If a fault occurs, the electrical supply to the drive motor (62) can be immediately interrupted. At the same time, for example, the ventilation of the braking and / or clamping device (101) is interrupted. The braking and / or braking device (101) closes, causing the linear drive unit (10) to stop immediately. For example, internal diagnostics can be used to detect faults.

[0041] For example, the communication ports (14) can be used to update the sequence programs and / or the data in the data storage. This can be done, for example, by the operator or the manufacturer.

[0042] A combination of the individual embodiments is also conceivable. List of reference symbols: 5 Longitudinal direction 10 Linear drive unit 11 fastening clamps 12 Supply connection 13 Logic connection 14 Communication port 15 indicator lights 20 Guide housing group 21 Guide housing 22 Lubrication connection 23 Lubrication connection 24 Back 25 Control and connection panel 26 Front 27 rail guide shoes 28 lubrication adapters 29 lubricant channels 31 Ring Canal 32 O-rings 33 Stop block 34 Measuring sensor, part of the position measuring system 35 distribution channel 36 Lubrication adapter part 37 Lubrication adapter part 38 Sealing ring 39 radial channels 41 Circulation channel 42 flat gaskets 43 radial bores 44 Disc spring element, length compensation element 51 Guide housing body 52 engagement groove 53 engagement groove, sensor groove 54 side surfaces 61 Drive unit 62 drive motor 63 Stator 64 rotors 65 Motor shaft 66 Shaft nut 67 End flange 68 Main shaft 69 approach wave 71 first bearing seat section 72 connection threads 73 Rotor section 74 second bearing seat section 75 retaining ring 76 threaded holes 77 threads for (66) 78 Brake flange 79 inner nut 81 rolling bearings 82 inner ring 83 Outer ring 84 rolling bearings 85 Outer ring 86 inner ring 87 rolling bearings 88 Outer ring 89 inner ring 91 Threaded spindle nut drive 92 spindle, threaded spindle 93 spindle nut 94 Lubricant reservoir 95 Flat gasket 101 Braking and / or clamping device 102 fixed part of (101) 103 rotating part of (101) 111 Control and regulation unit 112 computing unit 120 sled group 121 guide rail 122 sleds 123 Sled front panel 124 Slide plate 125 Scale, part of the position measuring system 126 key surfaces 127 Anti-rotation part 128 fastening screws 129 threaded holes 131 milling 132 edge web 133 Back bridge 135 encoders, rotary encoders 136 controllers 141 elastomer bodies 142 stop pot 143 End position safety device 146 elastomer bodies 147 End position safety device QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 017 542 A1

[0002] Cited non-patent literature

[0000] IEC 61800-7

[0010] IEC 61131-3

[0010] IEC 61131-9

[0010]

Claims

[1] Linear drive unit (10) with a guide housing group (20) and with a carriage group (120) mounted on the latter for linear movement, wherein at least one electric drive motor (62) with a stator (63) and a rotor (64) and a threaded spindle nut drive (91) driven by the drive motor (62) and driving the carriage group (120) are arranged in a guide housing (21) of the guide housing group (20), characterized by , - that the threaded spindle-nut drive (91) has a threaded spindle (92) connected to the slide group (120) and a spindle nut (93) connected to the rotor (64) and - that the threaded spindle (92) penetrates the drive motor (62). [2] Linear drive unit (10) according to claim 1, characterized by that it has an end position safety device (143) for the retracted end position and an end position safety device (147) for the extended end position of the slide group (120). [3] Linear drive unit (10) according to claim 1, characterized by that the threaded spindle (92) is fixed in a carriage (122) of the carriage group (120) in a rotationally fixed manner. [4] Linear drive unit (10) according to claim 1, characterized by that at least one length compensation element (44) is arranged in the guide housing (21). [5] Linear drive unit (10) according to claim 1, characterized by that it has two independent lubrication systems, a first of which is a lubrication system for the threaded spindle nut drive (91) and a second of which is a lubrication system for a linear guide of the slide group (120). [6] Linear drive unit (10) according to claim 1, characterized by , - that it has at least one speed control loop and one position control loop and - that all electrical components of the said control circuits are arranged in the guide housing (21). [7] Linear drive unit (10) according to claim 6, characterized by that the position control loop has an absolute position measuring system (34, 125). [8] Linear drive unit (10) according to claim 6, characterized by that at least the drive motor (62) is galvanically isolated from the control circuits. [9] Linear drive unit (10) according to claim 1, characterized by that it has a normally closed braking and / or clamping device (101) arranged in the guide housing (21).

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