ELECTRIC DRIVE

Description

[0001] The invention relates to an electric drive (1) comprising a molded housing (2) with a cavity (3) for receiving a stator (4), which can be mounted in or against a first demolding direction (6), and a connector (5) integrally formed with the housing (2), which can be connected to a mating connector whose insertion direction is aligned in or against a second demolding direction (7), wherein the first demolding direction (6) and the second demolding direction (7) differ from each other by at least 10° and at most 170°. Electric drives are frequently used in environments requiring IP sealing. They are also often subject to high temperature fluctuations, either from the environment or from heat generated within the drive. These temperature differences lead to significant pressure differentials in the sealed housings, which can cause damage within the drive.To prevent this, pressure equalization must be ensured. This can be achieved in various ways. With a hermetic seal, pressure equalization can be accomplished using a bellows that can expand. Often, however, it is sufficient if gases can pass through the housing, but liquids cannot. A number of suitable pressure equalization membranes are known for this purpose, which, for example, consist of a tightly woven fabric, sometimes comprising several layers. Attaching such usually flexible components to a rigid housing requires considerable effort, additional parts, and extra process steps. A simpler option is to weld a plastic membrane, whose permeability is achieved, for example, by stretching, onto a housing. Possible materials for such membranes include polytetrafluoroethylene (PTFE), polyethersulfone (PES), or nylon.

[0002] Welded joints of such thin membranes cannot, by their very nature, withstand significant forces. A known hazard to this joint is water jets striking the pressure equalization element at high pressure. This external impact can damage or destroy the joint or the membrane. To prevent this, covers are already in use that at least prevent a direct water jet from reaching the pressure equalization element. This, in turn, increases manufacturing costs.

[0003] DE 197 12 209 A1 discloses a hydraulic power unit for a hydraulic control and / or regulating device, in particular for anti-lock braking and / or slip-controlled motor vehicle braking systems, with control and regulating electronics arranged in a regulator housing and with a valve block connected to the regulator housing, on which, in addition to other functional elements connected to each other via pressure medium channels, at least one electrical drive element for one or more pressure generator elements is arranged, wherein cavities associated with the electrical drive element are connected via a pressure equalization opening.are ventable and wherein the electrical drive element is connected to the control electronics via a connection component comprising an electrical conductor, wherein the cavities are provided as a channel opening into the pressure equalization opening, through which or in whose wall electrical conductors of the connection components run at least in the section adjoining the pressure equalization opening.

[0004] JP 6-88195 U shows an engine venting structure for an engine with a connector section that has a vent hole to allow the inside of the engine to be vented to the outside.

[0005] JP 9-121510 A further describes a motor with a vent connected to the motor yoke. A fan-side end bracket with an air passage is provided, which draws air from a fan.

[0006] The object of the invention is to provide pressure equalization in an existing drive of the described type, which can be achieved with virtually no additional effort and yet ensures good protection of a pressure equalization device.

[0007] This problem is solved by the features of claim 1. Because the housing (2) has a vent channel (8) which runs parallel to the second demolding direction (7) and establishes a connection between the cavity (3) and the environment of the electric drive (1), no additional slide is required in an injection mold, since a slide is already necessary for demolding the connector contour, which can also be used for demolding a vent channel (8) that establishes a connection between the cavity and the environment.

[0008] Advantageously, this vent channel (8) is provided to be closed by a gas-permeable and liquid-repellent pressure equalization element (9). One way to attach this pressure equalization element (9) is by welding it directly onto the housing using ultrasound or laser beams.

[0009] Alternatively, the pressure equalization medium (9) could be bonded to the housing (2). However, bonded joints are very sensitive to mechanical and chemical stresses, making this method unsuitable in many applications.

[0010] The pressure equalization device can be a porous rubber part, consisting of pressed rubber particles.

[0011] For easier assembly and fastening, the pressure equalization device (9) consists of a retaining collar with an enlarged diameter and a passage area with a smaller diameter. The passage area is pressed or clamped into the vent channel.

[0012] Since the vent channel (8) has a conical shape at least in sections for manufacturing reasons, the pressure equalization medium can have a constant or a slightly tapered cross-section over its installation length and can be securely held in the vent channel (8).

[0013] The pressure equalization device can be located at the outer or inner end of the vent channel (8), provided that accessibility during the assembly process is ensured in both cases. Preferably, the pressure equalization device (9) is pressed or clamped into the vent channel. This allows for easy and secure installation.

[0014] The housing (2) has a round outer contour in its basic form, which is flattened at or around the vent channel (8). This facilitates the supply and welding of a pressure equalization medium (9). A welding sonotrode can be of a simple design and lie flat against the housing. According to an advantageous embodiment of the invention, it is proposed that the electric drive (1) is mounted on an application and that the pressure equalization medium (9) is covered by a gas-permeable housing section (10) of the application. This cover can deflect water jets while still allowing gas exchange by maintaining a small gap between the housing (2) and the housing section (10) of the application. Such an application could be an oil pump, a water pump, an SCR pump, or a centrifugal separator.

[0015] To ensure gas permeability, it may be advantageous for the housing area (10) to have a chamfer (11) or other recess on a side facing the pre-formed housing (2). Particular attention is paid to ensuring that such geometries do not require any additional effort.

[0016] No additional effort is required, in particular, if the electric drive (1) is already fully or partially immersed in the application.

[0017] Such geometries, already existing without pressure equalization means (9), but ideally suited for covering them to protect against water jets, are sealing contours. The housing area (10) of the application is joined over the housing (2) of the electric drive (1), leaving a gap (14) in which a seal (12) is arranged.

[0018] O-rings are often used for such purposes, but other molded seals, e.g. lip seals, are also suitable.

[0019] The venting channel (8) does not necessarily have to be continuously straight, but can consist of a radial section (25) and an axial section (26). This does not increase the number of tool slides required, since the axial section (26) is parallel to the first demolding direction (6) and the radial section (25) is parallel to the second demolding direction (7).

[0020] The vent channel (8) can in principle have almost any cross-sectional shape, but circular or elliptical cross-sections are preferred because the required tool geometries are easier to manufacture and allow for a longer service life.

[0021] To facilitate gas exchange and still obtain a large contact area for the pressure equalization element (9), the vent channel (8) can consist of a plurality of parallel channels.

[0022] When using multiple parallel channels, for economic reasons they should be covered by a single pressure equalization element (9).

[0023] The electric drive according to the invention can be used in a variety of applications, e.g. in an oil pump, a water pump, an SCR pump, a vacuum pump or a centrifugal separator.

[0024] Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 a partial section of an electric drive, Fig. 2 a first variant of the electric drive, Fig. 3 a second variant of the electric drive, Fig. 4 a third variant of the electric drive, Fig. 5 a first cross-sectional shape of a ventilation duct, Fig. 6 a second cross-sectional shape of a ventilation duct and Fig. 7 a third cross-sectional shape of a ventilation duct.

[0025] Note: Reference mark with Index and corresponding reference symbols without Indexes denote details with the same name in the drawings and the drawing description. These details refer to the use of a different embodiment, the prior art, and / or are variants. For the sake of simplicity, the claims, the introductory description, the list of reference numerals, and the summary contain only reference numerals without indexes.

[0026] Fig. 1Figure 1 shows a partial section of an electric drive, the special feature of which is that a slide tool is always required for demolding a housing 2, because a connector 5, which is integral to the housing, and in particular its insertion direction and thus the demolding direction 7, is oriented here at 90° to the demolding direction 6 of a cavity 3, which corresponds to a direction opposite to the mounting direction of a stator 4. A vent channel 8 is arranged in the housing 2 between the cavity 3 and an environment 15 of the electric drive. A pressure equalization element 9 is arranged at an outer, environment-adjacent end of the vent channel 8. To protect against water or steam jets and other impairments, the pressure equalization element 9 is covered by a housing section 10 of an application, leaving a gap 16 through which gases from the cavity 3 and the vent channel 8 can escape.

[0027] At one end of the housing section 10, facing the housing 2 and the connector 5, a chamfer 11 is provided, which ensures additional access to the pressure equalization medium and facilitates the installation of a seal 12, which is inserted in a space 14 between the housing section 10 of the application and the housing 2 of the electric drive. The seal 12 is made of elastomer material and is in the form of an O-ring.

[0028] The housing 2 is closed by a housing cover 13 (metal or plastic). An O-ring 17 is inserted into a groove 23 between the housing 2 and the housing cover 13. A circuit board 13 is arranged between the housing cover 13 and the housing 2.

[0029] A conductor 19 extends from connector 5 through the housing 2 in the opposite direction to the second demolding direction 7, bending once and leading towards the circuit board 18 in the direction of the first demolding direction 6, where it makes contact with the circuit board. The conductor 19 is made of stamped sheet metal and is joined to the housing 2 by primary forming (overmolded).

[0030] Also shown are a stator lamination stack 20, an insulating body 21, a winding 22, and a locking tab 24 on the connector 5. The circuit board 18 is supported by the insulating body 21.

[0031] The housing is made of glass fiber reinforced PPS (polyphenylene sulfide). Alternatively, polyphthalamides (PPA), in particular PA6T / 6I, PA66-GF or other engineering plastics, can be used.

[0032] Fig. 2Figure 1 shows a first variant of an electric drive 1a, comprising a housing 2a, a housing cover 13a, a circuit board 18a, a stator 4a, a housing section 10a of an application, a seal 12a between the housing 2a and the housing section 10a, an O-ring 17a inserted in a groove 23a of the housing 2a and arranged between the housing 2a and the housing cover 13a, and a pressure equalization device 9a. In contrast to the first embodiment, the pressure equalization device 9a is mounted internally at the inner end of the vent channel 8a. At this location, it is even better protected from external influences. Furthermore, a stator lamination stack 20a, an insulating body 21a and a winding 22a are components of the stator 4a, a chamfer 11a on the housing area 10a and a conductor medium 19a, which is joined to the housing 2a by primary forming and is contacted with the circuit board 18a.

[0033] Fig. 3Figure 1 shows a second variant of an electric drive 1b, comprising a housing 2b, a housing cover 13b, a circuit board 18b, a stator 4b, a housing section 10b of an application, a seal 12b between the housing 2b and the housing section 10b, an O-ring 17b inserted in a groove 23b of the housing 2b and arranged between the housing 2b and the housing cover 13b, and a pressure equalization element 9b. The vent channel 8b is conical in this case, and the pressure equalization element 9b is held in the vent channel 8b as a frustoconical component by frictional engagement. The pressure equalization element is designed as a sintered body. Furthermore, a stator lamination stack 20b, an insulating body 21b and a winding 22b are components of the stator 4b, a chamfer 11b on the housing area 10b and a conductor medium 19a, which is joined to the housing 2b by primary forming and is contacted with the circuit board 18b.

[0034] Fig. 4Figure 1 shows a third variant of an electric drive 1c, comprising a housing 2c, a housing cover 13c, a circuit board 18c, a stator 4c, a housing section 10c of an application, a seal 12c between the housing 2c and the housing section 10c, an O-ring 17c inserted in a groove 23c of the housing 2c and arranged between the housing 2c and the housing cover 13c, and a pressure equalization device 9c. In contrast to the first embodiment, the pressure equalization device 9c is mounted internally at the inner end of the vent channel 8c. Also in contrast to the first variant, the vent channel is not straight but angled. A radial section 25a is aligned parallel to the second demolding direction 7c, and an axial section 26c is aligned parallel to the first demolding direction 6c. At this point, it is even better protected from external influences than in the first variant.Furthermore, a stator lamination stack 20c, an insulating body 21c and a winding 22c are components of the stator 4c, a chamfer 11c on the housing area 10c and a conductor medium 19c, which is joined to the housing 2c by primary forming and is contacted with the circuit board 18c.

[0035] The invention is not limited to the examples shown; rather, a multitude of variants and arrangements are conceivable, and other types of pressure equalization devices and housing geometries can also be used. In principle, the housing could also be made of die-cast metal, in which case the pressure equalization device would have to be attached by a method other than welding.

[0036] Fig. 5Figure 1 shows a first cross-sectional view of a vent channel 8d in a housing 2d, with a connector 5d. The cross-section of the vent channel 8d is circular. One end of the vent channel 8d is covered by a pressure equalization element 9e. Two conductor elements 19d, a locking lug 24d, and a seal 12d are also shown.

[0037] Fig. 6 Figure 1 shows a second cross-sectional view of a vent channel 8e in a housing 2e with a connector 5e. The vent channel 8e consists of three parallel channels arranged side by side. A single pressure equalization element 9e covers all three channels. The pressure equalization element is welded to the housing 2e at the outer end of the multi-part vent channel 8e. Two conductor elements 19e, a locking lug 24e, and a seal 12d are also shown.

[0038] Fig. 7Figure 1 shows a third cross-sectional shape of a ventilation channel 8f in a housing 2f with a connector 5f. The ventilation channel 8f is elliptical in shape. One end of the ventilation channel 8f is covered by a pressure equalization element 9f. Two conductor elements 19f, a locking lug 24f, and a seal 12f are also shown. Reference symbol list

[0039] 1 Drive 2 Pre-formed housing 3 Cavity 4 Stator 5 Connector 6 First demolding direction 7 Second demolding direction 8 Venting channel 9 Pressure equalization device 10 Housing area 11 Bevel 12 Seal 13 Housing top 14 Gap 15 Surroundings 16 Gap 17 O-ring 18 Circuit board 19 Conductor center 20 Stator lamination stack 21 Insulator body 22 Winding 23 Slot 24 Detent lug 25 Radial section 26 Axial section

Claims

1. Electric drive (1), comprising a molded housing (2) with a cavity (3) for receiving a stator (4) which can be installed in or counter to a first demolding direction (6), a connector (5) which is formed in one piece with the housing (2) and is connectable to a mating connector, the direction of connection of which is oriented in or counter to a second demolding direction (7), the first demolding direction (6) and the second demolding direction (7) differing from each other by at least 10° and at most 170°, characterized in that the housing (2) has a vent channel (8) which extends parallel to the second demolding direction (7) and establishes a direct connection between the cavity (3) and the environment surrounding the electric drive (1), the vent channel (8) being closed by a gas-permeable and liquid-repellent pressure-equalizing means (9), and the electric drive being mounted on an application, and in that the pressure-equalizing means (9) is covered by a housing region (10) of the application in a gas-permeable manner.

2. Electric drive according to claim 1, characterized in that the pressure-equalizing means (9) consists of a plastic membrane which is welded to a housing (2) made of plastic.

3. Electric drive according to claim 1, characterized in that the pressure-equalizing means (9) is adhesively bonded to the housing (2).

4. Electric drive according to claim 1, characterized in that the pressure-equalizing means (9) consists of a porous rubber part.

5. Electric drive according to claim 3 or 4, characterized in that the pressure-equalizing means (9) comprises of a holding collar of larger diameter and a passage region of smaller diameter.

6. Electric drive according to claim 3, 4 or 5, characterized in that the pressure-equalizing means (9) has a constant or slightly tapering cross-section along its installation length.

7. Electric drive according to claim 1 and at least one of the subsequent claims, characterized in that the pressure-equalizing means is arranged at the outer or inner end of the vent channel (8).

8. Electric drive according to claim 4, 5, 6 or 7, characterized in that the pressure-equalizing means (9) is pressed or clamped into the vent channel.

9. Electric drive according to at least one of the preceding claims, characterized in that the housing (2) in its basic shape has a round outer contour, and this is flattened at or around the vent channel (8).

10. Electric drive according to any one of the preceding claims, characterized in that the housing region (10) has a chamfer (11) on a side facing toward the molded housing (2).

11. Electric drive according to claim 7 or 8 in combination with claim 10, characterized in that it is partially immersed in the application.

12. Electric drive according to claim 7, 8 or 9 in combination with at least one of the preceding claims, characterized in that a seal (12) is arranged between the housing (2) of the electric drive (1) and the housing region (10) of the application.

13. Electric drive according to claim 12, characterized in that the seal (12) is an O-ring.

14. Electric drive according to at least one of the preceding claims, characterized in that the vent channel (8) has a circular or elliptical cross-section.

15. Electric drive according to at least one of the preceding claims, characterized in that the vent channel (8) consists of a plurality of channels arranged in parallel.

16. Electric drive according to claim 15, characterized in that the plurality of parallel channels are covered by a single pressure-equalizing element (9).

17. Electric drive according to at least one of the preceding claims, characterized in that the application is an oil pump, a water pump, an SCR pump, a vacuum pump, or a centrifugal separator.