Junction box for an electric machine

Abstract

Terminal box (1) for an electric machine, wherein the terminal box (1) - a lid (2) and - connection means having electrical contacts (3) for supply lines of the electrical machine includes wherein the cover (2) has a through-hole and the terminal box (1) is designed such that a fastening screw (4) suitable for mounting the terminal box to a housing of the electrical machine can be passed through the through-hole through the terminal box (1) to engage in an internal thread inside the housing, wherein the terminal box (1) can be fixed in a position freely chosen with respect to a rotation angle by tightening the fastening screw (4), wherein the junction box (1) - a base (5) for direct mounting on the housing of the electric machine, - a frame (6) and - a clipboard arranged in the base (7) includes wherein the terminal block (7) has the connecting means and the frame (6) can be mounted on the base (5) so as to be rotatable by stepless 360° as long as the fastening screw (4) is not screwed into the internal thread, wherein the clamping board (7) comprises first fastening means (8) for captive and free-running mounting of the frame (6), wherein the frame (6) is freely rotatable on the base (5), wherein the clamping board (7) comprises second fastening means (9) for captive mounting of the frame (6) which are suitable for pressing the frame (6) onto the base (5) so that the frame (6) is no longer freely rotatable on the base and wherein the fastening means (8,9) are designed as snap connectors which can each be snapped over a collar of the frame.

Description

[0001] The invention relates to a terminal box for an electrical machine, such as an electric motor or generator, into which cable glands for supply lines must be inserted. Examples of electric motors that have such a terminal box are three-phase asynchronous motors, synchronous machines, or DC machines.

[0002] Depending on the environment in which such electrical machines are operated, the junction box must meet certain protection standards. Different protection standards require different measures for protection against moisture, dust, unauthorized access, etc., which must also be implemented by the junction box.

[0003] The terminal box contains connection points to which the user of the electrical machine can connect power supply lines. For example, in the case of a three-phase asynchronous motor, these connection points are implemented on a terminal block to which the stator leads of the asynchronous machine are already pre-connected. The customer then connects the supply lines to this terminal block to provide power to the windings of the electrical machine.

[0004] In addition to the power supply lines, signal lines are often routed into the junction box and connected there; these are used for motor monitoring or motor protection. Such lines are usually attached separately to terminal blocks inside the junction box.

[0005] Furthermore, an earthing connection must be provided inside the junction box, via which an earthing cable can be connected to earth the housing of the electrical machine.

[0006] The terminal box is usually permanently mounted on the housing of the electric machine. Since the installation conditions of the electric machine at the customer's site are generally unknown beforehand, the position and orientation of the terminal box can often be varied within certain limits during installation to accommodate the prevailing conditions on site.

[0007] From DE 10 2007 019 005 A1, a terminal box for routing cables connected to an electrical machine is known. This terminal box has a closed cover surface and at least three side surfaces arranged on this cover surface, wherein these side surfaces are inclined relative to the cover surface and wherein at least one of these side surfaces has a feed-through opening for routing an electrical cable. Furthermore, the terminal box has an opening opposite the cover surface for inserting a terminal connection into the terminal box and a mounting section for attaching the terminal box to the electrical machine. The terminal box also includes means for changing the direction in which the electrical cable is inserted into the terminal box.

[0008] From DE 20 2007 005 463 U1, a wall-mounted junction box for data cables is known, comprising a cover cap for receiving wall-mounted cables and a lower base part located on the back of a cover plate, which includes connector plugs for data cables and a terminal block for the conductors of the cables laid in the wall. The cover cap has a hole in the center through which a screw can be inserted, so that the cover cap and the lower base part can be assembled in any relative orientation.

[0009] The invention is based on the objective of providing a terminal box for an electric machine that can be positioned as flexibly as possible on the housing of the electric machine.

[0010] The problem is solved by a junction box with the features according to claim 1.

[0011] The invention is based on the understanding that the greatest possible flexibility in mounting the terminal box on the electric machine with respect to a suitable angle of rotation is achieved when the terminal box is permanently positioned on the electric machine housing using only a single fastening screw, wherein the fastening screw is guided centrally through the terminal box cover and the terminal box itself. When the fastening screw is screwed into the thread of the electric machine housing and tightened, the screw head presses the cover, and thus the entire terminal box, against the electric machine housing. In this way, the terminal box can be attached to the electric machine with very little effort and very quickly.

[0012] In an advantageous embodiment of the invention, the terminal box can be fixed in a position selected with respect to a specific angle of rotation by tightening the mounting screw. Before the mounting screw is tightened, the orientation of the terminal box on the machine housing can be freely selected. Once a suitable mounting position has been determined in this way, the mounting screw is tightened, thus fixing its position and orientation on the housing of the electric machine. The orientation of the terminal box can be varied by up to 360°, in particular steplessly. Alternatively, a detent mechanism is also conceivable, which allows the user to select the angle of rotation in discrete angular increments.

[0013] An advantageous embodiment of the invention is characterized in that the terminal box comprises a base for direct mounting on the housing of the electric machine, a frame, and a terminal board arranged in the base, wherein the terminal board has the connection means and the frame can be mounted on the base so as to be rotatable by 360°, in particular continuously, or positioned or fixed in a predetermined grid, as long as the fastening screw is not screwed into the internal thread. In this embodiment, the terminal board is first fixed to the base on the housing of the machine, for example, with one or more screws. The base has, in particular, a round base surface. Subsequently, the frame is snapped onto the base. The frame is initially freely rotatable on the base, so that a desired orientation of the frame, suitable for connecting the supply lines, can be selected.The cover is then placed on the frame, and the fastening screw is inserted through the through-hole and through the terminal box into the internal thread of the machine housing. Screwing in the fastening screw secures the entire terminal box in the previously selected position on the housing of the electric machine.

[0014] An advantageous embodiment of the invention comprises first fastening means for captive and free-play mounting of the frame. In this way, the frame can initially be captively held by the clamping board even without a fastening screw, while the free-play design allows the frame to be freely rotated up to 360° on the base.

[0015] Furthermore, an embodiment of the invention is advantageous in which the terminal block comprises second fastening means for the captive mounting of the frame, which are suitable for pressing the frame onto the base so that the frame can no longer rotate freely on the base. These second fastening means ensure that the initially selected desired position of the frame is fixed before the fastening screw needs to be tightened. Subsequently, when the fastening screw is screwed through the cover of the terminal box into the internal thread of the electrical machine housing, the orientation of the terminal box can no longer be so easily and unintentionally changed.

[0016] In a further advantageous embodiment of the invention, a particularly simple pre-assembly of the frame onto the housing of the electric machine is achieved by designing the fastening means as snap connectors. The first fastening means, designed as snap connectors, initially create a captive but loosely fitting hold of the frame on the base and thus on the housing of the electric machine. After selecting the desired position or aligning the frame on the base, the second fastening means, also designed as snap connectors, can then be actuated. This releases the loosely fitting hold of the frame by means of a press connection, thus preventing the frame from rotating. Alternatively, spring elements with locking positions are also conceivable.

[0017] To prevent bending or damage to the terminal box cover during assembly, an embodiment of the invention is advantageous in which the terminal block has a support element arranged in its center, which is penetrated by a bore through which the fastening screw can be guided inside the terminal box. The support element is designed such that the cover and the base can be pressed against the support element by tightening the fastening screw. Such a support element can have the form of a dome that rests against the housing of the terminal box on both sides, i.e., on the cover and oppositely on the base. Without this dome, tightening the fastening screw would cause the cover to bend against the base. Because the cover and base are separated from each other by the dome, such bending, which could lead to damage to the terminal box, is prevented.

[0018] An electric machine, in particular an electric motor, with a terminal box according to one of the previously described embodiments, in which the connection means of the terminal box are electrically connected to the winding ends of a winding of the electric machine, offers a customer maximum flexibility when integrating the machine into an existing infrastructure. This is primarily because the customer can mount the terminal box on the machine in any desired position with respect to the angle of rotation.

[0019] The invention will now be described and explained in more detail with reference to the exemplary embodiments shown in the figures. The figures show: Fig. 1 an electric motor with an embodiment of the terminal box according to the invention, Fig. 2 a base and a terminal block of the junction box, Fig. 3 a frame of the junction box mounted on the base, Fig. 4 a first embodiment of a terminal block of the junction box, Fig. 5 the back of the clipboard according to the first embodiment Fig. 6. the clipboard Fig. 4 after its mounting on a housing of an electric motor, Fig. 7 a second embodiment of a terminal block of the junction box, Fig. 8 the back of the clipboard according to the second embodiment and Fig. 9 the clipboard after Fig. 6 after its mounting on a housing of an electric motor.

[0020] Fig. Figure 1 shows an electric motor 11 with an embodiment of the terminal box 1 according to the invention. The electric motor 11 is a three-phase asynchronous machine with a squirrel-cage rotor. Inside the terminal box 1 are connection points to which three-phase supply lines can be connected in order to supply the stator windings of the electric motor 11 with current and thus drive the machine. The terminal box 1 has bores 12 through which the supply lines can be guided into the terminal box 1 and where they can be fixed by means of cable glands.

[0021] Furthermore, a cover 2 of the terminal box 1, shown closed here, is visible. This cover 2 is attached to a frame 6 by means of a fastening screw 4, which passes through a central bore in the cover 2 and engages in a thread within a housing of the electric motor 11. If this fastening screw 4 is loosened, the cover 2 can be removed, for example, to connect the supply lines through bore 12 to the stator windings of the electric motor. After removing the fastening screw 4, the frame 6 of the terminal box 1 can then rotate freely on the electric motor. This allows, for example, a different orientation of the terminal box 1 than the one shown to be chosen due to specific installation requirements. This can be useful, for instance, due to a particular cable routing of the supply lines.

[0022] Following this, the cover 2 is placed back onto the frame 6 and the fastening screw 4 is tightened. Once the fastening screw 4 has been tightened securely, the frame 6 is fixed in its orientation.

[0023] Fig. Figure 2 shows a base 5 and a clipboard 7 of the in Fig. The terminal box 1 shown in Figure 1 comprises three electrical contacts 3 to which the phase cables of the three-phase supply lines can be connected. In addition, an earthing terminal 12 is provided, via which the housing of the electric machine can be earthed. The terminal box 7 and the base 5 are firmly connected to the housing of the electric motor 11 by a screw 13.

[0024] Fig. Figure 3 shows a frame 6 of the junction box 1 mounted on the base 5. The frame 6 is placed on the base 5 and held in place by initial fasteners 8, which are designed as snap connectors and are part of the terminal block 7. The snap connectors ensure that, once engaged, the frame 6 is held with some play on the base 5 and the terminal block 7. However, the frame 6 can still rotate freely within 360° on the base 5. This allows the user to position the frame as desired.

[0025] The terminal block 7 includes a dome-shaped support element 10, which is penetrated by a bore in the center. After the user has determined the position of the frame 6 and mounted the supply lines on the terminal block 7, the Fig. The cover 2 shown in Figure 1 is placed on the frame 6, and the fastening screw 4 is passed through the bore in the cover 2 and through the bore in the support element 10 and screwed into the internal thread in the housing of the electric motor. Tightening the fastening screw 4 presses the cover 2 against the support element 10 and the base 5 against the machine housing. The entire terminal box 1 is thus fixed in the selected position or orientation. Simultaneously with this fixing, the cover 2, frame 6, and base 5 are pressed together, so that seals arranged between these elements ensure a dust- and moisture-proof closure of the terminal box 1.

[0026] The support element 10 is not strictly necessary. In particular, if the cover 2 is sufficiently rigid, it can also absorb the stress generated by the fastening screw 4 on its own.

[0027] Fig. Figure 4 shows a first embodiment of a terminal block 7 of the junction box 1. The terminal block 7 comprises three electrical contacts for connecting customer-supplied leads, e.g., with screws and washers. Alternatively, the contact points could also be designed as threaded bolts with nuts or using cage clamp technology. An integrated star point bridge is provided within the terminal block 7, so that the terminal block 7, and thus the electric motor, is designed for operation in a star connection. In addition to the dome-shaped support element 10 already described, first and second fastening elements 8, 9 are provided, designed as snap hooks. The first fastening elements 8 are designed such that they hold the frame 6 of the junction box 1 with some play, so that it is not lost but can still be rotated on the base 5. The second fastening element 9 is longer than the first fastening element 8.To rotate the frame 6, these longer snap hooks must first be released. Only when the exact angular position of the frame 6 has been selected are these snap hooks snapped outwards over the collar of the frame 6, thereby pressing the frame 6 of the terminal box 1 downwards onto the base 5 and thus onto the motor housing. The position of the frame 6 is thereby fixed by friction.

[0028] Fig. Figure 5 shows the reverse side of the terminal block 7 according to the first embodiment. The electrical contacts 3, intended for connecting the supply lines, are visible from below. A contact plate 16, which establishes the grounding contact to the motor housing, is also visible. The terminal block 7 further includes two locking pins 14 that precede the plug contacts and are intended to ensure a secure connection. A seal 15 of the terminal block 7, which provides a seal to the motor interior, is also visible.

[0029] Fig. 6 shows the clipboard 7 after Fig. 4 after its mounting on a housing of the electric motor 11. The first and second fastening elements 8, 9, designed as snap hooks, have snapped over the collar of the frame 6, so that it is fixed in its position and can no longer be rotated. In order to rotate the frame 6 again, the second fastening elements 9 would have to be released.

[0030] Fig. Figure 7 shows a second embodiment of a terminal block 7 of the junction box 1. In contrast to the first embodiment according to the Fig. According to sections 4 to 6, the terminal block 7 shown here can be used for both star and delta operation. To enable this, the terminal block 7 includes interchangeable jumpers 17, which can be inserted by the user according to the desired wiring configuration. Unused jumpers 17 can be stored in a storage pocket 18. The second embodiment of the terminal block 7 additionally includes further connection points 19, via which two motor protection lines can be connected.

[0031] Fig. Figure 8 shows the reverse side of the clipboard 7 according to the second embodiment. Functionally equivalent elements bear the same reference numerals as in Fig. 5.

[0032] Fig. 9, however, shows the clipboard 7 after Fig. 6 after its mounting on the housing of an electric motor. Regarding the mounting within the terminal box 1 and on the housing of the electric motor, the terminal boards differ according to... Fig. 4 to Fig. 6 or according to Fig. 7 to Fig. 9 not. Furthermore, the additional connection points 19 are visible, via which two motor protection lines can be connected.

Claims

[1] Terminal box (1) for an electric machine, wherein the terminal box (1) - a lid (2) and - connection means having electrical contacts (3) for supply lines of the electrical machine includes wherein the cover (2) has a through-hole and the terminal box (1) is designed such that a fastening screw (4) suitable for mounting the terminal box to a housing of the electrical machine can be passed through the through-hole through the terminal box (1) to engage in an internal thread inside the housing, wherein the terminal box (1) can be fixed in a position freely chosen with respect to a rotation angle by tightening the fastening screw (4), wherein the junction box (1) - a base (5) for direct mounting on the housing of the electric machine, - a frame (6) and - a clipboard arranged in the base (7) includes wherein the terminal block (7) has the connecting means and the frame (6) can be mounted on the base (5) so as to be rotatable by stepless 360° as long as the fastening screw (4) is not screwed into the internal thread, wherein the clamping board (7) comprises first fastening means (8) for captive and free-running mounting of the frame (6), wherein the frame (6) is freely rotatable on the base (5), wherein the clamping board (7) comprises second fastening means (9) for captive mounting of the frame (6) which are suitable for pressing the frame (6) onto the base (5) so that the frame (6) is no longer freely rotatable on the base and wherein the fastening means (8,9) are designed as snap connectors which can each be snapped over a collar of the frame. [2] Junction box according to claim 1, wherein the terminal board (7) has a support element (10) arranged in its center, which is penetrated by a bore through which the fastening screw (4) can be guided inside the junction box (1), wherein the support element (10) is designed such that the cover (2) and the base (5) can be pressed against the support element (10) by tightening the fastening screw (4). [3] Electric machine, in particular electric motor (11), with a terminal box (1) according to one of claims 1 or 2, wherein the connection means of the terminal box (1) are electrically connected to winding ends of a winding of the electric machine.

Images