Encapsulated drive with an electric motor

Abstract

The present invention relates to an encapsulated drive (10) with an electric motor (12) which has an output shaft (14). According to the invention, the electric motor (12) is completely and the output shaft (14) is at least partially enclosed in a housing (16). The output shaft (14) is aligned axially with and connected to a shaft coupling (18) along its axis of rotation. The shaft coupling (18) extends to the outside through an opening (20) in the housing (16), and a flameproof ignition gap (22) is formed between the shaft coupling (18) and the housing (16).

Description

[0001] The present invention relates to an encapsulated drive with an electric motor which has an output shaft, according to the preamble of claim 1.

[0002] For various applications, drives with an electric motor must be used, and these drives must be encapsulated. When operating in an environment where explosive gases or gas mixtures may be present, encapsulation prevents such gases from entering the drive. In the event that a gas or gas mixture nevertheless accumulates inside the encapsulated drive, the encapsulation must ensure that, if the gas is ignited by a spark, the encapsulation and all seals and penetrations will withstand the resulting explosion. This prevents the explosion from spreading to the surrounding gas mixture.

[0003] Well-known encapsulated drives require special electric motors, which are complex to manufacture and therefore expensive.

[0004] It is therefore the object of the present invention to create an encapsulated drive in which the manufacturing costs are reduced.

[0005] This problem is solved by an encapsulated drive according to the characterization of claim 1.

[0006] According to the invention, the electric motor is completely and the output shaft is at least partially arranged in an encapsulated housing. The output shaft is axially aligned with and connected to a shaft coupling along its axis of rotation. At least one section of the shaft coupling extends to the outside through an opening in the housing, and a flameproof ignition gap is formed between the shaft coupling and the housing.

[0007] Such an encapsulated drive according to the present invention offers the advantage that a normal industrial motor can be combined with the housing to form an explosion-proof drive of the type of ignition protection EX-d by encapsulating it.

[0008] In rotating machines, such a shaft bushing from the interior of an EX-d enclosure is subject to very high requirements (tight tolerances, etc.) for the sealing gap (according to DIN 60079-1). The present invention provides a flameproof cylindrical connection using a simple shaft coupling. The integration of the electric motor into a comparatively simple EX-d enclosure enables the use of standard industrial motors in EX applications. This simple arrangement offers a very cost-effective solution, particularly for low-power and / or low-speed applications where no maintenance is required during the service life.

[0009] Preferred embodiments are set out in the dependent claims.

[0010] Preferably, the shaft coupling is rotatably mounted on the housing by means of at least one bearing, optionally with a first and a second bearing arranged offset from each other along the axis of rotation. Using only one bearing is a simpler solution. The precise alignment of the output shaft, and consequently of the shaft coupling in the housing, defines the standard-compliant design of the ignition gap. Adjustment screws for the electric motor can be provided for this purpose. The use of two bearings simplifies the standard-compliant design of the ignition gap. This is particularly advantageous if the electric motor manufacturer does not provide specifications regarding the alignment and bearing arrangement of the output shaft.

[0011] Preferably, the shaft coupling is rotationally symmetrical and has a radially oriented flange. Optionally, the two bearings can be arranged on opposite sides of the flange.

[0012] The first bearing is preferably arranged radially around the shaft coupling between the side of the flange facing away from the electric motor and an end section of the housing.

[0013] The optional second bearing can also be arranged radially around the shaft coupling between the side of the flange facing the electric motor and the electric motor.

[0014] A particularly preferred embodiment of the invention is one in which the ignition protection gap is formed between the housing and an outwardly facing end surface of the flange.

[0015] The housing can have an end cover that incorporates the housing opening, and preferably a cup-shaped bearing sleeve with a further opening in the base of the bearing sleeve is arranged within this cover. The base of the bearing sleeve then protrudes from the opening in the end cover, and the shaft coupling from the further opening of the bearing sleeve. Providing such a bearing sleeve offers the advantage that a particularly stiff and wear-resistant material, such as a metal, can be used for mounting the bearings. Other sections of the housing can thus be injection-molded more cost-effectively and easily from a (softer) plastic. Conversely, if the housing is made of a metal, for example, aluminum, a separate bearing sleeve can be omitted.

[0016] Preferably, the end surface of the flange is provided that the inner surface of the bearing sleeve forms the (first) ignition protection gap.

[0017] The end cover preferably forms a second ignition protection gap with the housing, and further preferably an outer side of the cup-shaped bearing sleeve with the opening forms a third ignition protection gap.

[0018] Providing ignition protection gaps in all openings, penetrations and joints of housing parts ensures the explosion protection of the housing.

[0019] Preferably the bearing or bearings are arranged inside the bearing sleeve when several bearings are provided.

[0020] The end cover and the bearing sleeve can also be formed in one piece. This will be the case, in particular, if the one-piece design is to be formed from a single metal.

[0021] A fourth ignition protection gap is preferably provided between the shaft coupling and the output shaft.

[0022] At least two, preferably three, motor mounting and / or adjustment screws can be provided on the housing to secure the electric motor against the at least one bearing and / or to adjust the ignition gap. This offers the advantage that the standards for ignition gaps can be met even if, for example, only one bearing is used.

[0023] A closable filling opening can be provided on the housing for filling the housing with an explosion suppressant. The filling opening can preferably be closed with a screw, which forms a fifth ignition-protection gap with the housing.

[0024] In an alternative embodiment of the present invention, the (first) ignition protection gap is formed between the opening of the housing or between a housing end that forms the opening of the housing and a section of the shaft coupling, which is arranged on a side of the bearing facing away from the electric motor. A separate housing end offers the advantage that a different material (e.g., a metal sleeve) can be used here as well than for other sections of the housing.

[0025] Here too, at least one bearing, or preferably two bearings, can be provided, which are arranged within a bearing sleeve that connects to the housing end in the direction of the electric motor.

[0026] Alternatively, the housing can be made of metal, and the ignition-protection gap can be formed between the opening of the housing and the shaft coupling. The bearing(s) can then be arranged directly between the housing and a flange of the shaft coupling.

[0027] The invention will now be explained in more detail by way of example with reference to the attached figure.

[0028] This shows: Fig. 1 to Fig. 3 a first embodiment of a drive according to the invention; and Fig. 4 to Fig. 6 a second embodiment of a drive according to the invention.

[0029] The Fig. Figures 1 to 6 show two alternative embodiments of an encapsulated drive 10 according to the invention, comprising an electric motor 12 which has an output shaft 14. In the Fig. 1 and Fig. 4 These two configurations are shown in an exploded view, in which Fig. 2 and Fig. 5 in a cross-sectional view, and in the Fig. 3 and Fig. 6 in a top view in the assembled state.

[0030] In both alternative embodiments of the invention, the drive 10 includes an electric motor 12 with an output shaft 14. The electric motor 12 is completely and the output shaft 14 partially enclosed in a housing 16, which is designed to be explosion-proof. Explosion-proof enclosure is understood to mean a flameproof enclosure in which all necessary penetrations, for example for electrical cables for the electric motor, are designed to be ignition-proof.

[0031] The output shaft 14 is axially aligned with and connected to a shaft coupling 18 along its axis of rotation. The connection between the output shaft 14 and the shaft coupling 18 is designed by means of a shaft coupling fastening screw 54 (e.g., a setscrew) such that torques from the output shaft 14 can be transmitted to the shaft coupling 18.

[0032] In both embodiments, the shaft coupling 18 extends to the outside through an opening 20 in the housing 16. A flameproof ignition gap 22 is formed between the shaft coupling 18 and the housing 16.

[0033] In both embodiments, at least one first bearing 26 and optionally a second bearing 28 are provided for supporting the shaft coupling 18 in the housing 16. Both bearings 26 and 28 are arranged radially around the shaft coupling 18 so that it is rotatably mounted within the housing 16. A flange 30 is arranged on the shaft coupling 18, and the two bearings 26 and 28 are mounted offset from each other along the axis of rotation. Both bearings 26 and 28 are arranged on opposite sides of the flange 30. The first bearing 26 is arranged radially around the shaft coupling 18 between the side of the flange 30 facing away from the electric motor 12 and an end cover 32 of the housing 16. The second bearing 28 is arranged opposite the first bearing 26 on the other side of the flange 30, and thus on the side facing the electric motor 12.

[0034] In the embodiment of the Fig. 1 to 3 the ignition protection gap 22 is formed between the housing 16 and an outwardly facing end surface 24 of the flange.

[0035] Also in the first embodiment according to the Fig. In figures 1 to 3, the housing 16 has an end cover 32 which includes the opening 20 of the housing 16. In this exemplary embodiment of the invention, a cup-shaped bearing sleeve 34 is provided within the opening 20 of the housing, with a further opening 36 in a base of the bearing sleeve 34. Providing a separate bearing sleeve 34 offers the advantage that the housing 16 can be largely made of a plastic material, and the bearing sleeve 34 can be designed in a more rigid and wear-resistant form made of a metal. By providing such a bearing sleeve 34, the two bearings 26 and 28 are permanently and precisely arranged within the housing 16, thus ensuring a consistently accurate adjustment of the ignition gap 22.This is important because any change in the position and orientation of the two bearings 26 and 28 can lead to a failure to meet the relevant standards for the design of the ignition protection gap 22 and can result in an increased risk of explosion.

[0036] Alternatively, it can also be provided that the housing 16 is made entirely of a metal material, so that the provision of a separate bearing sleeve 34 is not necessary.

[0037] In order to ensure the explosion-proof encapsulation of the entire housing, all other openings and gaps on the housing 16 must also be designed to be explosion-proof and flameproof.

[0038] In the first embodiment of the Fig. Sections 1 to 3 of the housing feature a filling opening 46, which is designed to be closed with a screw 50. This filling opening 46 allows cavities within the housing 16 to be filled with an explosion-reducing agent. Such explosion-reducing agents can be suitable gases or solids that prevent or suppress an explosion of any gases that may have entered the housing. For example, such agents can reduce the flame temperature or propagation speed, or the turbulence of explosive gases within the housing. The free volume within the housing, which could be filled by intruding gases, can also be reduced in this way. A further ignition-protection gap 48 is provided at the filling opening 46, formed between the screw 50 and the housing 16.The filling opening 46 is located on an end cover 32 of the housing 16, which closes off the housing 16 and carries the bearing sleeve 34. A protective gap 38 is also provided between this end cover 32 and the rest of the housing 16.

[0039] Since in the embodiment of Fig. Since the bearing sleeve 34 is arranged in the opening 36 of the end cover 32 (1 to 3), a further ignition protection gap 40 is also provided between the bearing sleeve 34 and the end cover 32. An additional ignition protection gap 42 is also arranged between the output shaft 14 and the shaft coupling 18, as well as between adjusting screws 44 (ignition protection gap 58) and a base of the housing 16. These three adjusting screws 44 serve to fix and adjust the electric motor 12 so that, in particular, the ignition protection gap 22 is designed in accordance with standards. The ignition protection gap 22 is the most critical of all the ignition protection gaps, as it is formed between a rotating component in the form of the shaft coupling 18 and a stationary component in the form of the bearing sleeve 34.

[0040] For fastening the end cover 32, in the embodiment of the Fig. Four fastening screws 52 are provided for positions 1 to 4. These screws extend through the end cover 32 to corresponding threads in a main part of the housing 16. The end cover 32 also has mounting inserts 53, which serve to mount the drive 10 at a point of use. Such mounting inserts 53 are also provided on the housing 16 of the Fig. 4 to 6 are planned.

[0041] For the supply of electrical power, the following applies to both embodiments: Fig. Each of the 1 to 6 parts has a fire-resistant cable gland 56.

[0042] In the Fig. 2 and Fig. A pulley 60 is mounted on the shaft coupling 18, which can, for example, form a frictional or positive connection to a belt drive. The pulley 60 is secured against rotation or falling off by a fastening screw 70.

[0043] In the embodiment of the Fig. 4 to 6 a drive 10 is presented, which is different from the drive 10 of the Fig. 1 to 3 can be implemented with a reduced number of ignition protection gaps. As in the embodiment of the Fig. In figures 1 to 4, the first ignition protection gap 22 is provided between an opening 20 in the housing 16 and the shaft coupling 18. In the embodiment of Fig. 4 to 6 are formed by a housing end 62, which in this embodiment is provided as an optional element of the housing 16. Similar to the bearing sleeve 34 of the Fig. 4 to 6, this housing end 62 can be made of a metallic material, and further sections of the housing 16 can be made of a plastic. This ensures sufficient stability for the housing end 62 and the bearing sleeve 34.

[0044] In addition to the ignition protection gap 22, a further ignition protection gap 66 is provided at the housing end 62 between the housing end 62 and the further housing 16, so that with two ignition protection gaps 22 and 66, the area of ​​the drive 10 around the shaft coupling 18 is completely explosion-proof and flame-resistant. Naturally, the cable entry 56 is also provided here as in the embodiment of Fig. 1 to 3 flame-resistant.

[0045] In the embodiment of the Fig. 4 to 5 the housing 16 is not as in the embodiment of the Fig. 1 to 3 are closed by an end cover 32, but on the side opposite the opening 20 with a cover 68, wherein a flameproof ignition protection gap is again provided between the cover 68 and the remaining sections of the housing 16.

[0046] In the embodiment of the Fig. In steps 1 to 3, the electric motor 12 is inserted into the open housing 16 from the front, and then the end cover 32 is mounted. In the embodiment of the Fig. 3 to 6 the electric motor 12 is inserted from the rear into the open housing 16 and then the cover 68 is fitted.

[0047] In the embodiment of the Fig. 4 to 6 inside the housing 16 a motor mount 64 is arranged, to which the motor 12 is attached with four motor mounting screws 72. Reference symbol list 10 Drive 12 Electric motor 14 Output shaft 16 cases 18 Shaft coupling 20 Opening 22 Ignition protection gap 24 End area of ​​30 26 first camp 28 second camp 30 flange 32 End cover 34 Bearing sleeve (optional) 36 Opening 38 Ignition protection gap 40 Ignition protection gap 42 Ignition protection gap 44 motor mounting and adjustment screws 46 Filling opening 48 Ignition protection gap 50 screws 52 mounting screws for 32 53 assembly inserts 54 Shaft coupling mounting screw 56 Cable entry 58 Ignition protection gap 60 Pulley 62 Housing end cap (optional) 64 Motor mount 66 Ignition protection gap 68 lids 70 Mounting screw for pulleys 60 72 engine mounting screws

Claims

[1] Enclosed drive (10), with an electric motor (12) which has an output shaft (14), characterized by , that the electric motor (12) is completely and the output shaft (14) is at least partially enclosed in a sealed housing (16), the output shaft (14) is aligned axially with and connected to a shaft coupling (18) along its axis of rotation, at least one section of the shaft coupling (18) is led outwards through an opening (20) of the housing (16), and A flameproof ignition protection gap (22) is formed between the shaft coupling (18) and the housing (16). [2] Encapsulated drive (10) according to claim 1, characterized by , that the shaft coupling (18) is rotatably mounted on the housing by means of at least one first (26), preferably with a first and a second bearing (26, 28) arranged offset from each other along the axis of rotation. [3] Encapsulated drive (10) according to claim 2, characterized by , that the shaft coupling (18) is rotationally symmetrical and has a radially oriented flange (30), and optionally the two bearings (26, 28) are arranged on opposite sides of the flange (30). [4] Encapsulated drive (10) according to claim 3, characterized by , that the first bearing (26) is arranged radially around the shaft coupling (18) between the side of the flange (30) facing away from the electric motor (12) and an end section (32) of the housing (16). [5] Encapsulated drive (10) according to claim 3 or 4, characterized by , that the second bearing (28) is located between the side of the flange (30) which is located is facing the electric motor (12) and is arranged radially around the shaft coupling to the electric motor (12). [6] Encapsulated drive (10) according to one of claims 3 to 5, characterized by, that the ignition protection gap (22) is formed between the housing (16) and an outwardly facing end surface (24) of the flange (30). [7] Encapsulated drive (10) according to any one of claims 3 to 6, characterized by , that the housing (16) has an end cover (32) which includes the opening (20) of the housing (16), and within which preferably a cup-shaped bearing sleeve (34) with a further opening (36) in a base of the bearing sleeve (34) is arranged, wherein the bearing sleeve (34) protrudes with its base from the opening (20) of the end cover (32) and the shaft coupling (18) protrudes from the further opening (36) of the bearing sleeve (34). [8] Encapsulated drive (10) according to claim 7, characterized by , that the end surface (24) of the flange (30) forms the ignition protection gap (22) with an inner side of the bearing sleeve (34). [9] Encapsulated drive (10) according to claim 7 or 8, characterized by, that the end cover (32) forms a second ignition protection gap (38) with the housing (16). [10] Encapsulated drive (10) according to one of claims 7 to 9, characterized by , that an outer surface of the cup-shaped bearing sleeve (34) forms a third ignition protection gap (40) with the opening (20). [11] Encapsulated drive (10) according to any one of claims 7 to 10, characterized by , that the bearing (26) or bearings (26, 28) are arranged inside the bearing sleeve (34). [12] Encapsulated drive (10) according to one of claims 7 to 11, characterized by , the end cover (32) and the bearing sleeve (34) are formed in one piece. [13] Encapsulated drive (10) according to any one of the preceding claims, characterized by , that a fourth ignition protection gap (42) is provided between the shaft coupling (18) and the output shaft (14). [14] Encapsulated drive (10) according to any of the claims relating back to claim 2, characterized by, that at least two, preferably three motor mounting and adjustment screws (44) are provided in the housing (16) to fix the electric motor (12) against the at least one bearing (26) and / or to adjust the ignition protection gap (22). [15] Encapsulated drive (10) according to any one of the preceding claims, characterized by , that a closable filling opening (46) on the housing (16) is provided for filling the housing (16) with an explosion suppression means, wherein the filling opening (46) can preferably be closed with a screw (50) which forms a fifth ignition protection gap (48) with the housing (16). [16] Encapsulated drive (10) according to any one of the preceding claims, characterized by, that the ignition protection gap (22) is formed between the opening (20) of the housing (18) or between a housing end (62) which forms the opening (20) of the housing (18) and a section of the shaft coupling which is arranged on a side of the first bearing (26) which is facing away from the electric motor (12). [17] Encapsulated drive (10) according to claim 16, characterized by , that at least one bearing (26), preferably two bearings (26, 28) are provided, which are arranged within a bearing sleeve (34) which connects to the housing end (62) in the direction of the electric motor (12). [18] Encapsulated (10) according to claim 17, characterized by, that the housing (16) is made of a metal and the ignition protection gap (22) is formed between the opening (20) of the housing (16) and the shaft coupling (18), and preferably the bearing(s) (26, 28) are arranged directly between the housing (16) and a flange (30) of the shaft coupling (18).

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