INTERFERENCE-FREE LINEAR DRIVE

Description

[0001] The invention relates to a linear drive with a split gearbox housing, an electric motor connected to the gearbox housing and housed in a motor housing, and an interference-suppressed electric motor which drives a rotor housed in the motor housing. The shaft is supported at a rear end in a rear bearing and at a front end. Current is transmitted to the rotor via a commutator, and the shaft drives a worm gear which in turn meshes with a worm wheel. This worm wheel is non-rotatably connected to a spindle on which a spindle nut runs. The spindle nut is held non-rotatably and axially adjustable in a guide tube and is adjustable along the longitudinal axis of the guide tube. The spindle nut is connected to a lifting tube.

[0002] Such a linear drive is preferably used for the automatic adjustment of movable parts of reclining and seating furniture, i.e., pieces of furniture.

[0003] A linear drive of the same type is known from WO 2013 / 068329 of the applicant. Further prior art is known from CN 204 538 891 U, WO 2019 / 091 997 A1, WO 2013 068 329 A1, US 2103 / 0 285 494 A1, DE 20 2016 104 185 U1, DE 196 58 233 A1, DE 10 2009 027 370 A1, DE 10 2011 055 337 A1, DE 10 2010 102 790 A1, DE 90 13 006 U1, DE 201 08 888 U1 and DE 20 2012 000 412 U1.

[0004] In such linear drives, the interference-suppressed electric motor is constructed as a closed unit comprising a pot-shaped motor housing. This housing contains the motor's rotor, mounted on the shaft, and the electrical components required for its operation, such as circuit boards, the commutator, the brushes for powering the commutator, diodes, Hall sensors for position measurement, capacitors and coils for interference suppression, and the corresponding wiring. The front of the pot-shaped, enclosed motor housing is closed by a metal plate, often referred to as a bearing plate, through which the driven motor shaft protrudes. This bearing plate is typically crimped or otherwise positively locked to the motor housing, which is preferably made of steel, and usually has holes on its front for mounting it to the gearbox housing.

[0005] US 2002 / 149283 A1 describes a linear actuator with a gearbox housing and an interference suppression board.

[0006] EP 75777 A1 describes a geared motor with motor housing and gear-worm arrangement.

[0007] DE 3513155 A1 describes a drive motor for a device such as a washing machine, wherein the motor has a circuit board which can serve as a carrier for interference suppression components. Disadvantages of the current state of the art

[0008] A state-of-the-art linear drive or gearbox typically has the following "electronic components" which are arranged on separate circuit boards and which must be individually installed and connected or wired: Connection for organized distribution (This can be implemented without a circuit board and as "random wiring" for cost reasons; usually, a pluggable motor cable is also provided to connect the drive to the controller.) Brush holder for contacting and / or powering the commutator. Limit switches (Usually, two spaced-apart limit switches with an associated diode and connecting leads are arranged on a mounting strip. Hall sensor only for drives where position information is to be recorded.

[0009] These individual circuit boards, and possibly additional boards, are installed separately within the motor housing. Mounting and installing the individual components in the confined space of the motor housing, with its rotating rotor and commutator, along with all the associated wiring, is relatively complex and time-consuming. The available space is also limited by the design of the motor housing. If wires need to be routed past the brush holder or brushes, this is particularly critical, as the wires could come into contact with the rotating parts and be partially damaged. Current technologies typically use several separate circuit boards, which must be installed separately within the motor housing and connected to each other via wires, for example...the brush carrier for connection to the commutator, a circuit board for evaluating the signals of the limit switches, which usually limit the position and range of the spindle nut, a circuit board with Hall sensors for detecting the rotational movement of the rotor, and the interference suppression board, on which the electrical and / or electronic components for reducing radio interference are already arranged at the source, e.g. by smoothing the current rise during switching operations using series resistors, capacitors and chokes.

[0010] In addition, an externally and separately arranged relay board with at least one relay is often provided, with which the higher motor current can be controlled via the limit switches to limit the adjustment travel of the spindle nut. Technical problem / task

[0011] Based on the aforementioned prior art and its associated disadvantages, the invention addresses the technical problem / objective of providing a generic linear drive that at least partially avoids the aforementioned disadvantages and is, in particular, easier to assemble, resulting in a lower susceptibility to assembly errors and thus lower scrap rates. invention

[0012] This is already achieved according to the invention by the independent claim. Advantageous, but not essential, further developments are described in the dependent claims.

[0013] According to the invention, the rear shaft bearing is mounted in the motor housing, and the front shaft bearing is arranged or mounted in the gearbox housing. Furthermore, at least the electrical and / or electronic components required for interference suppression of the electric motor are arranged on an interference suppression board, which is located between the front shaft bearing and the commutator, the interference suppression board being located in the gearbox housing. The electrical and / or electronic components can, in particular, include one or more chokes and at least one capacitor.

[0014] According to the invention, this interference suppression board is arranged in the area between the gearbox and the motor. This means that the motor housing, which is preferably cup-shaped, is closed at the rear and open at the front, so that the interference suppression board is located outside the motor housing, i.e., within the gearbox housing. This gearbox naturally offers significantly more space for mounting and wiring, allowing for faster, simpler, and less error-prone installation. Furthermore, this design offers the advantage of integrating the previously multiple separate circuit boards onto the interference suppression board. This eliminates the need to install and wire multiple separate boards and test them for correct functionality, further reducing the potential for errors and considerably simplifying installation.According to the invention, only the main wiring needs to be arranged in the area between the worm gear and the commutator.

[0015] All electromagnetic waves that can affect surrounding electrical devices, whether wired or wireless, are neutralized by appropriately arranging coils and capacitors.

[0016] The linear actuator is preferably used as a furniture actuator, particularly preferably for adjusting a swiveling head or foot section of a hospital bed. It is understandable to those skilled in the art that it can generally be used for adjusting mechanical devices of all kinds, especially for adjusting a movable component relative to a stationary component.

[0017] Preferably, the interference suppression board also has all the necessary electrical connections.

[0018] Furthermore, the interference suppression board preferably has all wiring in the form of conductive traces, so that all electronic components can be soldered or plugged in. The interference suppression board preferably comprises the connection for orderly distribution, the brush holder, at least one limit switch, and preferably one or more Hall sensors on a single circuit board.

[0019] In the embodiment according to the invention, the motor housing also encloses the rotating rotor with the driven shaft and preferably accommodates the permanent magnets, which surround the rotor on the outside in its installed position, thus providing an electric motor with good efficiency, smooth running, and a high degree of performance. The motor housing is preferably designed as a deep-drawn steel body or as a steel pot. The gearbox housing is preferably designed as an injection-molded plastic part.

[0020] Preferred embodiments include attaching the interference suppression board to the gearbox housing. According to the invention, this can now be done in the entire area between the front end of the motor housing and the beginning of the gearbox components, which significantly simplifies installation and wiring.

[0021] Preferably, the interference suppression board comprises a brush holder and / or a limit switch and / or a relay and / or a cable connector, which can thus be integrally arranged on the interference suppression board.

[0022] In contrast to the prior art, the motor housing is fundamentally open, meaning it does not include a front bearing shield that restricts the installation space. This allows areas outside the motor housing, but within the gearbox housing, to be used for arranging components. For example, the front bearing for supporting the shaft, which is normally located in the bearing shield, is positioned within the gearbox housing, significantly improving the shaft's smooth running.

[0023] In a preferred further development, the gearbox housing comprises a partition wall which divides the gearbox housing into a gearbox section containing the gearbox components and grease, and a rear section facing the motor housing, in which the motor housing is arranged or received in the gearbox housing.

[0024] In the preferred embodiment, this partition wall includes a through-opening for the shaft and is particularly preferably provided with a bearing seat into which the front shaft bearing can be inserted to support the shaft. A further preferred embodiment provides a corresponding seat for receiving a sealing element, in particular a radial shaft seal, which, in its installed position, is arranged coaxially with the front shaft bearing around the shaft.

[0025] The motor housing is further designed to accommodate the rear bearing, preferably by providing a bearing receptacle, preferably cylindrical and with a reduced diameter compared to the motor housing, into which the rear bearing can be inserted. This bearing receptacle can, for example, be designed as a reduced cylindrical protrusion on the motor housing, adapted to accommodate or support the rear bearing.

[0026] Thus, the shaft of the electric motor is supported at the rear end in the motor housing when installed, and at the front end, which is equipped with the worm gear, in the gearbox housing, preferably in a partition wall of the gearbox housing.

[0027] According to the invention, the area between the commutator and the front bearing point in the gearbox housing is therefore available for the arrangement of the interference suppression board and related wiring, which is also particularly easy to access during assembly or maintenance.

[0028] Optionally, a motor housing can also be provided, i.e., a component that encloses the motor housing on the outside and can be connected to the gearbox housing at a mounting edge. This motor housing can be used for further sealing of the motor housing, in particular to provide a high IP rating or assurance of a splash-proof or pressure-tight design of the linear drive. In addition, this motor housing conceals the motor housing on the outside, so that the motor housing does not function as a separate, but rather as an integral component of the linear drive.

[0029] However, it is also sufficient if only the motor housing is connected to the gearbox housing, particularly if this connection is sealed to achieve the desired IP certification or sealing. This is preferably achieved by applying a sealant, such as silicone or similar material, between the outer surface of the motor housing and the inner surface of the gearbox housing, permanently sealing the gap or annular gap between the joining partners. In other words, the motor housing is sealed within the gearbox housing.

[0030] To increase rigidity, the motor housing can have a radially outwardly widening shoulder, preferably located in the front third of the motor housing, so that a rear motor housing section with a smaller outer diameter and a front motor housing section that is preferably 10 to 20 percent larger than the rear motor housing section are formed. Preferably, this front motor housing section extends into or is connected to the gearbox housing, preferably being inserted into it.

[0031] Preferably, the interference suppression board also includes the carbon brushes for connection to and operation with the commutator. These carbon brushes, or holders for the carbon brushes, are particularly preferably integrated onto the board, but can also be attached to it as an additional snap-on component.

[0032] Preferably, at least one limit switch is arranged on the interference suppression board. In the preferred embodiment, this limit switch is arranged on the front side in the installed position, and a pushrod sits in this limit switch with a rear end, wherein a front end is mounted relatively slidably in a receiving wall in the gearbox housing and is particularly preferably covered with a rubber cap.

[0033] Furthermore, the interference suppression board can include at least one relay with which the higher motor current of approximately 6 amps for the electric motor can be controlled via the limit switches.

[0034] For precise displacement measurement of the shaft or rotor, the interference suppression board in the preferred embodiment comprises at least one Hall sensor, preferably two Hall sensors, which surround the shaft externally or radially, i.e., are arranged around a through-hole for the shaft. Optical or GMR sensors can also be used instead of the Hall sensors.

[0035] In the preferred embodiment, the gearbox housing is multi-part, in particular two-part, and preferably comprises a housing part designed for connection with the electric motor, which in particular has a nozzle for receiving the motor housing, as well as a housing cover for closing the gearbox housing.

[0036] The housing parts are preferably designed to be separable for assembly and maintenance. Preferably, the housing parts abut each other at a separation plane. In a splash-proof embodiment, a circumferential flange with a sealing element formed thereon is provided at the separation plane. This sealing element preferably comprises a sealing groove and a complementary sealing lip or a sealing projection, which, in the installed position, engage to seal the joint between the housing parts.

[0037] In the preferred embodiment, the gearbox driven by the electric motor comprises a worm gear driven by the worm, which in turn can be connected to a spindle in a rotationally fixed manner. The connection between the worm gear and the spindle can be either direct or, preferably as a backup solution, via an intermediate coupling that detachably connects the worm gear to a spindle holder that non-rotatably accommodates the spindle. For example, the worm gear can include a lateral splined shaft, and the spindle holder has a complementary splined shaft flange projecting radially from a cylindrical receiving stub for the spindle, with a correspondingly shaped splined shaft or profile structure that corresponds to the profile structure of the inside of the coupling.In its resting position, the coupling connects the worm gear to the spindle holder, and the coupling is only actuated for an emergency release, preferably by pulling the coupling against a spring acting between it and the worm gear.

[0038] In the preferred embodiment, a spindle nut connected to the lifting tube runs on the spindle, which is held in the guide tube in a rotationally fixed and axially adjustable manner and is adjustable along its longitudinal axis.

[0039] Another embodiment provides for the integration of a brake into the interference suppression board. In the preferred embodiment, the stationary magnets are arranged on the interference suppression board. These can either be integrated directly into it or arranged in a magnetic holder that can be attached to the interference suppression board.

[0040] In a further development, the interference suppression board can include a Bluetooth module on the side facing away from the motor. This module can also be located on a separate board, which is soldered to the interference suppression board or attached in another suitable manner. The Bluetooth module can also be integrated directly onto the interference suppression board as a chip, in particular by soldering.

[0041] In the preferred embodiment, a bus system, in particular a CAN bus system, is provided for communication between the processor and other components. Alternatively, a proprietary bus structure similar to a 2-wire differential bus is used.

[0042] To ensure good electrical contact and achieve the best possible electrical shielding, the interference suppression board is preferably round and located at the outer edge of the steel motor housing. Contact is preferably made directly with the housing, or alternatively via intermediate contact elements.

[0043] The outer diameter of the circuit board corresponds approximately to the outer diameter of the steel casing of the motor housing. According to the invention, the circuit board is positioned at the front face of the motor casing, makes contact with it, and together with the steel casing forms a Faraday cage for shielding purposes. The circuit board thus acts as a shield against EMC interference inside the motor.

[0044] This configuration is particularly preferred for achieving a full-surface, i.e., ring-shaped, contact across the entire circumference. Alternatively, numerous individual contacts are provided, at least 5, preferably more than 10.

[0045] Furthermore, in a first and simplified embodiment, the interference suppression board has power supply connections which are supplied with electrical energy from a mains-powered voltage supply via a plug connector through an opening in a housing part, the gearbox housing, or the motor housing. At least two power supply connections are provided, and preferably the power supply connections only carry electrical energy when the electric motor is to be operated.

[0046] In another embodiment, a constant voltage is applied to the supply terminals, and the interference suppression board features corresponding relays and / or semiconductor switches, as mentioned earlier, which switch the electric motor on or off in the desired direction of rotation, or switch it off when the spindle nut, coupled to the spindle, reaches a predetermined position. A control circuit for operating the relays and / or semiconductor switches, also located on the interference suppression board, may also be included. In any case, the interference suppression board also has motor connections that are electrically connected to the motor's brushes.

[0047] As described in more detail at the beginning, the brush holder or brush carrier is designed to hold and guide the carbon brushes. During operation of the electric motor, the brushes themselves are constantly pressed against the rotating commutator by spring tension. The electrical connection between the brushes and the motor terminals can be made by the spring itself, provided it is made of an electrically conductive material. The spring is attached to the brush holder and its free end, the end furthest from the brush, is electrically connected to a motor terminal on the interference suppression board.

[0048] Alternatively, the brush is equipped with a flexible cable connected to the corresponding motor terminal. If the brush holder is made of an electrically conductive material, each brush is equipped with one, and each brush holder is soldered to the respective corresponding motor terminal in a material-bonded and electrically conductive manner.

[0049] In one version where the brush holder is made of plastic, interference suppression components are provided that are directly connected to the brush holder. The brush holder can, for example, . The brush holder features electrical conductors that are fixed and at least partially attached to its surface. These conductors are designed to be soldered to electrical components such as interference suppression components consisting of capacitors and / or coils or chokes.

[0050] In another embodiment, sections of these respective conductor tracks are electrically connected to the motor terminals of the interference suppression board. The connection is preferably designed as a contact connection.

[0051] Preferably, the interference suppression board is provided with conductor tracks on both sides (dual-layer board). In the preferred embodiment, all conductor tracks, or a predetermined selection, particularly those facing the motor (signal, control, and ground lines), form a shielding mesh, wherein the mesh size / spacing of these conductor tracks is smaller than the wavelength of the electromagnetic interference to be suppressed. The conductor tracks facing the motor interior are either ground planes or have a subordinate function, which are connected to ground via interference suppression components. The critical conductor tracks containing the important and sensitive electronics, i.e., those transmitting small signals, as well as the Bluetooth unit, are located on the side of the interference suppression board facing away from the motor / motor housing and thus towards the gearbox.

[0052] Alternatively, the interference suppression board can be designed as a multilayer board with an additional conductor-carrying layer, where one layer forms the shielding and can form an electrical potential, e.g. the ground potential.

[0053] An alternative embodiment involves arranging an electronic component in an external control housing. This could, for example, be the Bluetooth radio module. In this configuration, the remaining interior area of ​​the gearbox housing adjacent to the motor is preferably provided with an electrically conductive coating for shielding purposes.

[0054] Apart from the linear drive according to the invention, a comparative example not belonging to the invention relates to an assembly comprising a gearbox housing designed to accommodate an interference suppression board and to arrange an electric motor that drives a gearbox arranged in the gearbox housing.

[0055] Further features and advantages of the present invention will become clear with reference to the following description of preferred embodiments and the accompanying figures. Since components of embodiments can be positioned in a number of different orientations, the directional terminology serves only for illustration and is in no way restrictive.

[0056] It is understood that other embodiments may be used and structural or logical modifications made without deviating from the scope of protection of the present invention. The following detailed description is not to be interpreted restrictively. Within the scope of this description, the terms "connected," "attached," and "integrated" are used to describe both direct and indirect connections, direct or indirect connections, and direct or indirect integrations. In the figures, identical or similar elements are designated with the same reference numeral where appropriate. The representations in the figures are substantially to scale. However, to illustrate details, certain areas may be shown to be clearly exaggerated in size, which is recognizable to those skilled in the art.Furthermore, the drawings may be simplified for illustrative purposes and do not include every detail that may be present in practical implementation.

[0057] In the figure description, directional terminology such as "top," "bottom," "front," "back," "anterior," "rear," etc., is used in reference to the orientation of the described figure(s). Since components of embodiments can be positioned in a number of different orientations, the directional terminology serves for illustration and is in no way restrictive. It is understood that other embodiments may be used and structural or logical modifications may be made without deviating from the scope of protection of the present invention. The following detailed description is not to be understood in a restrictive sense. Within the scope of this description, the terms "connected," "attached," and "integrated" are used to describe both a direct and an indirect connection, a direct or indirect connection, and a direct or indirect integration.

[0058] Unless otherwise specified, the indefinite and definite articles do not refer to a single component but are to be understood as "at least one." The terminology includes the aforementioned words, variations thereof, and similar meanings. Furthermore, it should be understood that the terms "approximately," "essentially," and similar terms, when used in conjunction with the dimensions and a property of a component of the invention, do not describe the described dimension and property as a strict limit or parameter and do not exclude minor variations thereof that are functionally similar. At a minimum, descriptive parts with numerical parameters also include variations of these parameters according to the mathematical and manufacturing principles in the prior art, e.g., rounding, deviations and other systematic errors, manufacturing tolerances, etc. Finally, in the case of several identical components, orFor the sake of clarity, only one element at a time is marked with a reference symbol.

[0059] They show: Figure 1 shows a perspective cross-section through the gearbox housing of a linear drive according to the invention; Figure 2 shows a top view of the linear drive according to the invention. Figure 1 Figure 3 shows a perspective cross-section of an alternative embodiment of the linear drive according to the invention through the gearbox and motor housings; Figure 4 shows an enlarged perspective front view of the gearbox housing and the intermediate wall of the gearbox housing; Figure 5 shows an enlarged cross-section in detail to illustrate the limit switch; Figure 6 shows an enlarged perspective detail view of the cable connection on the gearbox housing; and Figure 7 shows a perspective view of the linear drive with the motor housing removed.

[0060] Accordingly, the linear drive according to the invention essentially consists of a gearbox housing 2, a motor housing 4 inserted at the end into this gearbox housing 2, and a hollow cylindrical guide tube 6 in which a spindle nut 8 is longitudinally displaceable via the linear drive and which drives a lifting tube 46.

[0061] The gearbox housing 2 in turn comprises two housing parts that can be joined together at a joint, namely a rear housing part 2.1, which is designed to receive the motor housing 4, and a front housing part 2.2, which closes the gearbox housing 2 and simultaneously surrounds the guide tube 6 on both sides in a shell-like manner with the gearbox housing 2.

[0062] The rear housing section 2.1 has a substantially hollow cylindrical interior, which is divided approximately at the midpoint of its overall length by a partition 2.3 extending transversely through this interior into a front gearbox section facing the gearbox and a rear motor section facing the motor. A shaft 10, driven by an electric motor 25, projects through a central opening in this partition 2.3 into the front gearbox section. The shaft 10 is supported in this partition 2.3 by a front shaft bearing 12, which in this case is a rolling bearing. A radial shaft seal 14 is also installed on the front surface of the partition 2.3 facing the gearbox compartment to seal the motor compartment. At the front free end of the shaft 12, it has a worm 16 which meshes with the worm gear 18 extending transversely to the longitudinal axis of the shaft 10.This worm gear 18 is non-rotatably connected to a hollow cylindrical spindle holder 20, into which the spindle 22 is in turn non-rotatably inserted. The spindle nut 8 runs on this spindle 22 and is thus adjustable relative to the stationary guide tube 6 between an extension position determined by a front limit switch and a retraction position determined by a rear limit switch.

[0063] The motor housing 4 has at its rear end a bearing seat 4.3 which is essentially dome- or stub-shaped and protrudes from the rear wall, in which a rear shaft bearing 44 can be inserted flush, which supports the shaft 10 at the rear shaft end in the motor housing 4.

[0064] In the direction of the electric motor 24, the interference suppression board 26 according to the invention is arranged in the motor section of the gearbox housing 2, and is fastened by means of two spacer screws 28, 30, which are screwed into the partition wall 2.3.

[0065] In the direction of the electric motor 24, a commutator 32 is arranged around or on the shaft 10, and on the rear side of the interference suppression board 26 facing the electric motor 24, two diametrically opposed brushes are provided in corresponding brush holders 26.1 and 26.2, which are screwed onto the interference suppression board 26. A relay 26.3 is also mounted on this rear side of the interference suppression board, which switches the operating current of the electric motor 24 through the limit switches.

[0066] On its front side, the interference suppression board 26 has two threaded bushings 26.4, 26.5 for receiving the spacer screws 28, 30. Furthermore, a limit switch 26.6 is arranged on the front side of the interference suppression board 26, into which a pushrod 34 engages. This pushrod extends through a corresponding opening in the partition 2.3 into the gear section of the gearbox housing 2 and is covered by a media-tight rubber cap 36. This pushrod 34 thus actuates the rear limit switch to limit the insertion distance of the spindle nut 8 in the guide tube 6.

[0067] The Figures 3 and 4Figure 1 shows an alternatively designed linear drive according to the invention. In this design, the motor housing 38 has a front motor housing section 40.1 in the front housing area, which is inserted into the gearbox housing 40. This front motor housing section 40.1 is radially widened outwards to increase stiffness by forming a shoulder compared to a longer rear motor housing section 40.2. In its installed position, this front motor housing section 40.1 sits in an inner shoulder 40.1 of the gearbox housing 40, on which the interference suppression board 26 is also arranged.

[0068] Furthermore, a cable connector 26.7 is arranged on the interference suppression board 26, which projects radially laterally from the interference suppression board 26 and, in its installed position, is located in one of the Figure 6The enlarged cylindrical cable gland 42 with external mounting thread can be inserted in a rotationally secure manner. This design thus provides a sealed anti-rotation device for the cable connector 26.7 in the gearbox housing 30.

[0069] As in the first embodiment, the motor housing 28 has at its rear end a bearing insert 38.3 which projects substantially dome- or stub-shaped from the rear wall of the motor housing 28, into which a rear shaft bearing 44 can be inserted flush and which thus supports the shaft 10 at its rear end in the motor housing 28.

[0070] Figure 7 Figure 1 shows a perspective top view of the linear drive with the motor housing 4 removed, showing the interference suppression board 26, the brush holders 26.1 and 26.2 mounted on it, and the relay 26.3. Accordingly, the linear drive includes at its rear end a rear clevis 50 inserted into the gearbox housing 40, which is Figure 7 The linear drive is arranged on the left side and has a front fork head 50 connected to a lifting tube 46 at its front end, via which the linear drive can be clamped or positioned between two components to be adjusted. This could, for example, be a hospital bed, which is connected at its rear end to a crossbar of the bed frame and at its front fork head to a foot or head section of the bed or frame that can be pivoted relative to the frame. Suppressed linear actuator Reference symbol list

[0071] 2 Gearbox housing 2.1 Rear housing section 2.2 Front housing section 2.3 Partition 4 Motor housing 4.3 Bearing insert 6 Guide tube 8 Spindle nut 10 Shaft 12 Front shaft bearing 14 Radial shaft seal 16 Worm 18 Worm gear 20 Spindle holder 22 Spindle 24 Electric motor 26 Interference suppression board 26.1, 26.2 Brush holder / Brush carrier 26.3 Relay 26.4, 26.5 Threaded bushing 26.6 Limit switch 26.7 Cable connector 26.8 Hall sensor 28, 30 Spacer screws 32 Commutator 34 Pushrod 36 Rubber cap 38 Motor housing 38.1 Front motor housing section 38.2 Rear motor housing section 38.3 Bearing insert 40 Gearbox housing 40.1 Inner shoulder 42 Cable gland 44 Rear shaft bearing 46 Lifting tube 48 Rear clevis 50 Front clevis

Claims

1. A linear drive comprising a transmission housing (2), an interference-suppressed electric motor (24) which is connected to the transmission housing (2) and is accommodated in a motor housing (4) and by way of a rotor accommodated in the motor housing (4) drives a shaft (10) which is mounted on a rear shaft end in a rear shaft bearing (44) and is mounted on a front shaft end, a commutator (32) for current transmission to the rotor, electrical and / or electronic components for interference suppression of the electric motor (24), wherein the shaft (10) by means of a worm (16) drives a transmission arranged in the transmission housing (2) for displacement of a lift tube (46) guided longitudinally displaceably in a guide tube (6), wherein the rear shaft bearing (44) is mounted in the motor housing (4), the front shaft bearing (12) is arranged or mounted in the transmission housing (2; 40) and the electrical and / or electronic components required for interference suppression of the electric motor (24) are arranged on an interference suppression circuit board (26) arranged between the front shaft bearing (12) and the commutator (32), wherein the interference suppression circuit board (26) is arranged in the transmission housing (2), CHARACTERISED IN THAT the motor housing (4) has a motor jacket formed as a steel jacket and that the interference suppression circuit board (26) is located at the front of the motor jacket, contacts the motor jacket and together with the steel jacket forms a Faraday cage.

2. A linear drive as set forth in claim 1 CHARACTERISED IN THAT the interference suppression circuit board (26) includes carbon brushes for connection to the commutator (32).

3. A linear drive as set forth in claim 2 CHARACTERISED IN THAT the carbon brushes are arranged on a brush holder which is or can be connected to the interference suppression circuit board (26).

4. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT at least one limit switch (26.7) is arranged on the interference suppression circuit board (26).

5. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT at least one relay (26.3) and / or at least one Hall sensor (26.8) is arranged on the interference suppression circuit board (26).

6. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the motor housing (4; 40) is in the form of a deep-drawn steel casing.

7. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the motor housing (4; 40) includes a bearing receiving means (4.3; 40.3) for the rear shaft bearing (44).

8. A linear drive as set forth in claim 7 CHARACTERISED IN THAT the bearing receiving means (4.3; 40.3) is in the form of a protruding projection of a reduced outside diameter for embracingly receiving or mounting the rear shaft bearing (44).

9. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the motor housing (4; 38) extends into the transmission housing (2; 40) and is sealingly connected thereto.

10. A linear drive as set forth in claim 9 CHARACTERISED IN THAT the motor housing (4; 38) has a rear housing portion (38.2) of a smaller outside diameter and that adjoining said rear housing portion (38.2) with a step is a front housing portion (38.1) which is enlarged in relation to the rear housing portion (38.2) by 10 to 20 percent and which can be connected to the transmission housing (40).

11. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the interference suppression circuit board (26) is arranged in the edge region of the motor housing (4) and that contacting of the interference suppression circuit board (26) with the housing takes place directly or via intermediate contact means.

12. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the outer diameter of the interference suppression circuit board (26) corresponds to the outer diameter of the steel jacket of the motor housing (4).

13. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the transmission housing (2; 40) comprises several housing parts which are or can be releasably connected to each other.

14. A linear drive as set forth in one of the preceding claims CHARACTERISED IN THAT the transmission includes a worm gear (18) which meshes with the worm (16) and which in turn can be non-rotatably connected to a spindle (22).

15. A linear drive as set forth in claim 14 CHARACTERISED IN THAT the spindle (22) is non-rotatably received in a spindle holder which can be non-rotatably connected to the worm gear (18) by way of a clutch and / or THAT running on the spindle (22) is a spindle nut (8) which is connected to the lift tube (46) and which is held non-rotatably and axially displaceably in the guide tube (6) and is displaceable along the longitudinal axis thereof.