Electric motor of a motor vehicle

Abstract

The invention relates to an electric motor (10) of a motor vehicle (2), comprising a housing (18) having a maintenance opening (44) into which a maintenance screw (46) is screwed. The maintenance screw (46) is bonded to the maintenance opening (44) by means of an adhesive (56). Furthermore, the invention relates to a motor scooter (4).

Description

[0001] The invention relates to an electric motor of a motor vehicle having a housing with a maintenance opening. Furthermore, the invention relates to a motor scooter.

[0002] Motor vehicles typically have a main drive for propulsion. This includes, for example, an internal combustion engine. If the motor vehicle is a scooter, the internal combustion engine is usually small and designed as a single-cylinder, especially since the power requirement is usually less than 10 kW. To increase efficiency, it is possible to electrify the main drive and thus use an electric motor. An electric motor also reduces noise, especially since the main drive of a scooter usually has comparatively poor sound insulation.

[0003] A brushed commutator motor, for example, is used as an electric motor. However, due to its design, there is direct mechanical contact between the rotor and stator, which results in friction and increased heat generation. Wear is also increased. Alternatively, a brushless electric motor can be used. This has a stator arranged in a usually hollow-cylindrical motor housing with several electrical coils that are interconnected to form electrical phases.

[0004] The force applied by the electric motor is determined by the electrical current it carries. This makes it necessary to control or regulate the electrical current carried. In order to achieve a compact design and a comparatively high level of tightness, the electronics used for this purpose are usually located in the same housing as the other components of the electric motor. To enable certain servicing tasks to be carried out even after installation, the housing usually has a maintenance opening through which access to the components of the electric motor located inside the housing is guaranteed without the motor having to be completely disassembled. It is also possible to provide additional fastening elements below such a maintenance opening, which must be loosened in order to disassemble the electric motor.Typically, a maintenance screw is screwed into the maintenance opening to prevent the ingress of coarse foreign particles. To prevent the ingress of finer foreign particles and moisture, a sealing element, usually an O-ring, is also present, which is usually located between the head of the maintenance screw and the edge of the maintenance opening.

[0005] In principle, it is possible for anyone to loosen the maintenance screw and thus gain access to the components inside the housing, or to at least partially disassemble the electric motor and / or remove and / or modify individual components. In this way, for example, the electrical current drawn during operation can be generally increased, thus increasing the power of the electric motor. However, this may, on the one hand, result in the scooter losing its registration. On the other hand, this increases wear and tear, or consequential damage may occur. In this case, it is not clear to the manufacturer of the electric motor whether the electric motor has been tampered with, which could lead to warranty claims being wrongly fulfilled.

[0006] The invention is based on the object of specifying a particularly suitable electric motor of a motor vehicle and a particularly suitable scooter, wherein manipulation security is advantageously increased and wherein manufacturing costs are expediently reduced.

[0007] With regard to the electric motor, this object is achieved according to the invention by the features of claim 1 and with regard to the scooter by the features of claim 10. Advantageous further developments and refinements are the subject of the subclaims.

[0008] In its assembled state, the electric motor is a component of a motor vehicle, preferably a land-based vehicle. The electric motor is suitable, in particular intended, and configured for this purpose. The electric motor is expediently suitable, intended, and configured to be powered by an on-board electrical system of the motor vehicle, which, for example, carries a direct voltage of 12 V, 24 V, or 48 V.

[0009] The motor vehicle is, for example, a passenger car, a truck, or a bus. For example, the electric motor is a component of an auxiliary unit, such as an electric motor-driven adjustment drive or an electric motor-driven pump. However, the electric motor is particularly preferably a component of a main drive of the motor vehicle. In this case, a speed of travel of the motor vehicle is set, in particular, depending on the current supplied to the electric motor. In this case, the motor vehicle is expediently a two-wheeled motor vehicle, for example a bicycle or, particularly preferably, a motor scooter and thus a so-called e-scooter. Alternatively, in the two-wheeled motor vehicle, the electric motor is used in an adjustment drive or other auxiliary unit.

[0010] The electric motor is, for example, a brushed commutator motor. However, the electric motor is particularly preferably designed to be brushless. The electric motor is preferably a brushless direct current (BLDC) motor and expediently a synchronous motor. The electric motor has a housing, within which a stator is preferably arranged. The housing is, for example, at least partially hollow cylindrical or has at least one hollow cylindrical section, and the stator is preferably also hollow cylindrical and arranged concentrically with the housing. The housing is expediently made of a metal, such as aluminum, i.e., pure aluminum or an aluminum alloy.

[0011] The electric motor expediently has a rotor, which is also arranged in the housing. The rotor itself is preferably connected to a shaft, which is in particular rotatably mounted. Suitably, the rotor is arranged concentrically to the shaft, which is in particular concentrically arranged to the housing and / or the stator. For example, the shaft is rotatably mounted about its axis, which corresponds in particular to a rotor axis, and by means of which an axial direction of the electric motor is defined. In this case, the motor axis is the same as the axis of rotation of the shaft and / or the rotor axis. Preferably, the rotor is circumferentially surrounded by the stator, i.e. in the radial direction of the electric motor.

[0012] The electric motor suitably comprises electronics that serve to supply current to electromagnets arranged in the housing, which are, for example, a component of the rotor or preferably of the stator. The electronics are suitable, in particular provided and configured, for this purpose. For example, the electronics comprise a bridge circuit, wherein the number of bridges expediently corresponds to a number of phases to which the electromagnets are connected. In particular, the electronics comprise a so-called B6 circuit if the electric motor has a total of three phases. The electronics expediently have a printed circuit board to which any semiconductor switches are preferably connected, by means of which the bridge circuit is expediently implemented. This simplifies assembly. The electronics are preferably also arranged within the housing so that the electronics are protected from environmental influences.In particular, the housing provides a motor compartment and an electronics compartment, with the electronics compartment housing the electronics, and the stator and rotor in the motor compartment. Suitably, the electronics compartment and the motor compartment are separated from each other.

[0013] The housing has a maintenance opening. The maintenance opening allows access to the components of the electric motor arranged inside the housing from outside the housing. A maintenance screw is screwed into the maintenance opening, and the maintenance screw expediently fills the maintenance opening completely. In this case, the maintenance opening suitably has an internal thread, whereas the maintenance screw has an external thread, and the two threads engage with each other. This allows subsequent loosening of the maintenance screw from the maintenance opening without destroying the housing. Therefore, subsequent maintenance and / or servicing of the electric motor can be carried out via the maintenance opening. Loosening the maintenance screw from the maintenance opening is comparatively easy and does not require the comparatively complicated disassembly of the electric motor, which simplifies maintenance.

[0014] The maintenance screw is glued to the maintenance opening using an adhesive. Thus, in addition to being held to the housing by means of the threads, the maintenance screw is also glued to the housing, creating an at least partially material-to-material connection between them. The adhesive is in particular a plastic, for example a thermoplastic. The adhesive is preferably hardening, so that after the maintenance screw has been installed in the maintenance opening, the adhesive hardens, creating a secure connection between the two. In this way, screwing the maintenance screw into the maintenance opening is comparatively easy, and in particular, the adhesive is distributed. In contrast, subsequent loosening of the maintenance screw requires increased force.

[0015] Because of the adhesive, when the maintenance screw is removed from the maintenance opening, the adhesive, i.e. the adhesive layer at least partially formed by the adhesive, is broken up and the bond is thus released. As a result, the initial torque that must be applied to the maintenance screw in order to be released from the maintenance opening is increased. When the electric motor is examined as part of a warranty claim and / or as part of an inspection, the maintenance screw is released from the maintenance opening and the required torque is recorded. If this torque is increased, the adhesive layer was still intact and the maintenance screw had not yet been removed from the maintenance opening. If, on the other hand, only a small torque is required, the adhesive layer was already damaged and, for example, the adhesive had already been removed.However, this is only the case if the maintenance screw has already been removed from the maintenance opening once. In this case, it is likely that the electric motor and the components accessible via the maintenance opening have already been examined or, for example, tampered with at least once. In summary, the torque required to remove the maintenance screw can be used to determine whether an unauthorized opening of the electric motor has already occurred, resulting in tampering or at least a potential tampering.

[0016] Furthermore, the adhesive securely holds the maintenance screw in the maintenance opening, preventing it from accidentally coming loose from the opening even in the event of vibrations from the electric motor. No preloading of the maintenance screw is required, which means that it can be screwed into the maintenance opening with a comparatively low torque during installation. This type of connection is also comparatively temperature-resistant compared to, for example, the use of an element that provides preloading.

[0017] For example, the maintenance screw is only provided with the adhesive at certain points and / or the part of the maintenance screw head facing the housing. However, it is particularly preferred that the external thread of the maintenance screw is provided with the adhesive. Since the external thread is screwed into the maintenance opening, this ensures that the adhesive actually comes into contact with the maintenance opening. In other words, this ensures that the adhesive is located between the maintenance screw and the housing and is in contact with both, resulting in a secure bond. This way, there is no need to check whether the maintenance screw is actually bonded to the maintenance opening, and rejects are reduced.

[0018] For example, the external thread is only coated with adhesive at specific points or along a line running parallel to the longitudinal axis of the maintenance screw. However, it is particularly preferred that the external thread be coated with adhesive all around. For example, the entire external thread is coated with adhesive, which makes application easier. For example, the maintenance screw is dipped into the adhesive before it is screwed into the maintenance opening. Alternatively, the adhesive can only be used to form a ring, which reduces the amount of adhesive required. Due to the extensive application to the external thread, the adhesive is therefore arranged all around the circumference between the maintenance screw and the maintenance opening, so that the housing is tightly sealed using the adhesive.In other words, the maintenance opening is sealed liquid-tight by means of the adhesive and the maintenance screw, so that even if splashed or jetted water hits it, it cannot penetrate the housing. This means that no additional housing is required when installing the electric motor in the vehicle, which reduces manufacturing costs. It is also not necessary to use an additional sealing element, and in particular, the connection between the maintenance screw and the housing is sealing-element-free, with the exception of the adhesive. In particular, there is no O-ring, which reduces material costs. Furthermore, the comparatively complicated installation of the O-ring is avoided, which simplifies assembly. This eliminates one work step during assembly, and fewer tools are required to assemble the electric motor.

[0019] For example, the maintenance screw has a standardized screw head drive, such as Phillips or Torx. This means no special tool is required to screw in the maintenance screw. However, it is particularly preferred that the screw head drive be proprietary and, in particular, non-standardized. This means that a special tool is required to remove the maintenance screw, which further increases tamper security.

[0020] Particularly preferably, the housing has a housing body by means of which the stator and the rotor are surrounded. In particular, the housing comprises a cover which is fastened to the housing body. The cover is expediently only mounted once the corresponding components, for example the rotor, the stator or any electronics, are arranged in the housing. For example, the housing body comprises the maintenance opening. Preferably, however, the cover comprises the maintenance opening. If the maintenance opening is damaged due to careless loosening of the maintenance screw, or if the adhesive cannot be completely removed from the maintenance opening after loosening, the electric motor can be reused by replacing only the cover. This reduces the number of parts of the electric motor that need to be replaced, and therefore reduces maintenance costs.

[0021] The housing preferably comprises a motor compartment within which the rotor and / or stator, if any, are arranged. For example, the motor compartment is closed by means of the cover, and a bearing shield, for example, is formed by means of the cover. The housing particularly preferably comprises an electronics compartment within which any electronics are arranged. The electronics compartment is expediently separated from the motor compartment, preferably by means of a (different) bearing shield. Suitably, the electronics compartment is covered by the cover. In this way, access to the electronics compartment, in particular to the electronics arranged therein, is possible via the maintenance opening. In this way, a comparatively precise inspection and / or maintenance of the electric motor is possible even with a comparatively small maintenance opening, especially since, in the case of the electronics, essentially no comparatively large mechanical components need to be inspected.For example, the lid is intended solely to cover the electronics compartment. However, it is particularly preferred that the lid at least partially form a heat sink, through which the heat generated in the electronics compartment is dissipated to the environment. For this purpose, the lid has, in particular, an enlarged surface on the side facing away from the electronics compartment, preferably cooling fins.

[0022] For example, the cover is fastened to the housing body by means of the maintenance screw. However, the cover is particularly preferably fastened to the housing body by means of another fastening element, preferably by means of a fastening screw. In contrast, the cover is not fastened to the housing body by means of the maintenance screw. This reduces the load on the maintenance screw, and when mounting the cover to the housing, it is not necessary to take the adhesive into account, which makes assembly easier. In particular, the maintenance screw is not screwed into the housing body and is spaced apart from it, so that the sole function of the maintenance screw is essentially just to close the maintenance opening. This allows the maintenance screw and the maintenance opening to be optimized to merely provide access to the housing, in particular their respective sizes.On the other hand, the fastening screw can, for example, have a reduced diameter, which is why the part of the housing body into which the fastening screw is screwed can be designed to be comparatively delicate, which reduces weight.

[0023] For example, the maintenance opening can be arranged essentially arbitrarily or based on the design requirements of the housing. This makes it possible to maintain a high level of mechanical integrity of the housing despite the maintenance opening. However, the position of the maintenance opening is particularly preferably determined such that a functional element is arranged below it. Thus, the functional element is located in particular on an axis of the maintenance opening / maintenance screw in the assembled state, and the axis at least partially penetrates the functional element. In this way, access to the functional element is possible via the maintenance opening.

[0024] The functional element is, for example, a plug or a pin to which a specific electrical voltage is applied, particularly depending on the operating state of the electric motor. Alternatively, the functional element is, for example, a signal generator, such as an LED. In a further alternative, the functional element is, for example, a screw by means of which two components of the electric motor are fastened to one another. For example, to disassemble the electric motor, it is first necessary to loosen the screw. Preferably, the maintenance opening is incorporated in the cover, and the cover can be removed from the housing body simply by loosening the screw.

[0025] For example, only a single maintenance screw and a corresponding maintenance opening are provided. However, the electric motor particularly preferably comprises a plurality of such maintenance screws, which are screwed into a respective maintenance opening and bonded using a respective adhesive. For example, the maintenance screw and / or the adhesive used are different. However, they are particularly preferably identical to one another, so that identical parts can be used. Due to the plurality of maintenance openings, comparatively extensive maintenance / servicing of the electric motor is also possible after its manufacture. The number of maintenance openings expediently corresponds to the number of phases of the electric motor. The number of maintenance openings is particularly preferably greater than 2, 3, 4, or 5. The number of maintenance openings is particularly preferably less than 10 or 9.This allows for comprehensive maintenance, requiring only the removal of the maintenance screw. However, the mechanical integrity of the housing is only slightly compromised.

[0026] The scooter has two wheels that, in its intended condition, rest on a road. At least one of the wheels is driven by a main drive of the scooter. The main drive comprises an electric motor with a housing that has a maintenance opening into which a maintenance screw is screwed. The maintenance screw is bonded to the maintenance opening using an adhesive.

[0027] The main drive, expediently the electric motor, is particularly suitable, intended, and configured to be powered by the scooter's electrical system, which, for example, carries a direct voltage of 12 V, 24 V, or 48 V, or more than 100 V. In particular, the speed of the electric vehicle is determined depending on the current supplied to the electric motor. The electric motor is preferably a brushless direct current (BLDC) motor and expediently a synchronous motor.

[0028] The further developments and advantages explained in connection with the electric motor can also be transferred to the scooter and vice versa.

[0029] An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawings: Fig. 1 schematically shows a motor vehicle in the form of a scooter, with a main drive comprising an electric motor, Fig. 2, Fig. 3 shows a perspective or sectional view of the electric motor, which includes several maintenance openings and several maintenance screws, Fig. 4 perspective view of one of the maintenance screws. And Fig. 5 shows a sectional view of the maintenance screw screwed into one of the maintenance openings.

[0030] Corresponding parts are provided with the same reference numerals in all figures.

[0031] In Fig. 1 shows a simplified schematic representation of a motor vehicle 2, namely an electric vehicle, in the form of a motor scooter 4. The motor scooter 4 has two wheels 6, one of which is driven by a main drive 8. The main drive 8 comprises an electric motor 10, which is a brushless direct current (BLDC) motor. The electric motor 10 drives a transmission (not shown in detail) that is operatively connected to one of the wheels 6. The electric motor 10 is operated by means of an on-board electrical system, which is fed by a battery 12 providing an electrical direct voltage of 12 V. The battery 12 feeds a converter (not shown in detail) of an electronics unit 14 of the electric motor 10, which comprises a bridge circuit. The converter supplies current to (electrical) phases of a stator 16 of the electric motor 10.

[0032] In Fig. 2 is perspective and in Fig. 3 shows a sectional view of the electric motor 10. The electric motor 10 has a housing 18 with a housing body 20 made of aluminum. The housing body 20 provides a motor compartment 22, within which the stator 16 is arranged. The stator 16 is hollow cylindrical and comprises a plurality of electromagnets. The stator 16 circumferentially surrounds a hollow cylindrical rotor 24, which is fastened in a rotationally fixed manner to a shaft 26. The shaft 26, in turn, is rotatably mounted by means of two bearings 28, one of the bearings 28 being connected to a bottom of the essentially pot-shaped housing body 20. The other bearing 28 is fastened to a bearing plate 30, which is inserted into the housing body 20 and runs parallel to the bottom of the housing body 20. The bearing shield 28 is attached to the inside of the housing body 20, and the rotor 24 is arranged between the two bearings 28.

[0033] On the side of the bearing plate 30 facing away from the motor compartment 22, an electronics compartment 32 is formed by the housing body 20, and within which the electronics 14 is arranged. On the side opposite the bearing plate 30, the electronics compartment 32 is covered by a cover 34 made of aluminum. The cover 34 has a plurality of cooling fins 36 on the side facing away from the electronics compartment 32, so that the cover 34 also serves as a heat sink. The electronics 14 arranged in the electronics compartment 20 has a printed circuit board 38 arranged parallel to the bearing plate 30, to which the electrical / electronic components required for supplying current to the stator 16 are connected. The printed circuit board 38 is supplied via a connector 40 that is electrically connected to the vehicle electrical system and that is plugged into a mating connector (not shown in detail) that extends through the wall of the housing body 20.

[0034] The cover 34 is attached to the housing body 20 by means of several fastening screws 42. For this purpose, the fastening screws 42 are guided from the outside of the housing 18 through corresponding recesses in outwardly facing tabs of the cover 30 and inserted into corresponding recesses in the housing body 20 at the ends, where they are screwed in place. To prevent the penetration of foreign particles and moisture between the cover 30 and the housing body 20, a circumferential seal (not shown in detail) is arranged there.

[0035] To simplify maintenance of the electronics 14, which does not require the complete removal of the cover 30, the cover has a total of eight maintenance openings 44, into each of which a maintenance screw 46 is screwed. Fig. 2, one of the maintenance screws 46 is removed from the associated maintenance opening 44, and in Fig. 3 shows the section through one of the maintenance screws 46.

[0036] In Fig. 4 is one of the identical maintenance screws 46 in perspective and in Fig. 5 in a sectional view, wherein the screw is screwed into the associated maintenance opening 44. Each maintenance screw 46 has a screw head 48, which, when installed, rests against the outside of the cover 34. The respective screw head 48 has a screw head drive 50 of a proprietary design. In the example shown, the screw head drive 50 is based on a Torx drive, with an additional pin. In this way, no extensive modification of a standardized screw head drive is required when creating the maintenance screws 46, although a special tool is still required for the installation and removal of the maintenance screws 46.

[0037] A cylindrical screw body 52 is formed on each screw head 48, arranged perpendicular to the screw head 48 and having an external thread 54. The length of the screw body 52 is essentially the thickness of the cover 18 in the area of ​​the respective maintenance opening 44, so that the functionality of the electronics 14 is not impeded by the wall screws 46. Furthermore, the provision of additional electrical insulation or the like is not necessary.

[0038] The external thread 54 is completely covered with an adhesive 56. When installing the maintenance screws 46, the adhesive 56 is applied in liquid form to the external thread 54 of the respective maintenance screw 46, with the same adhesive 56 being used for each of the maintenance screws 46. To install the maintenance screws 46, they are screwed into the respective associated maintenance opening 44, with the external thread 54 of the respective maintenance screw 46 engaging with an internal thread of the associated maintenance opening 44. After the maintenance screws 46 have been installed, the adhesive 56 hardens. In summary, one of the maintenance screws 46 is screwed into each maintenance opening 44, and each maintenance screw 46 is bonded to the associated maintenance opening 44 by means of the adhesive 56.

[0039] After the adhesive 56 has cured, any slots existing between the external thread 54 of each maintenance screw 46 and the internal thread of the associated maintenance opening 44 are completely filled with the respective adhesive 56, so that each maintenance opening 44 is sealed in a liquid-tight manner. As a result, despite the maintenance openings 44, the penetration of splash or jet water into the electronics compartment 32 is prevented. Accidental loosening of the maintenance screws 46 from the respective associated maintenance opening 44, for example, due to vibrations of the electric motor 10, is also avoided, without the need for a preload element or the like.

[0040] Because the adhesive 56 is liquid during assembly, only a comparatively low torque is required when installing the maintenance screws 46. Removing the maintenance screws 46, however, requires a higher torque because the adhesive layer formed by the respective adhesive 46 must be broken. This, in conjunction with the proprietary screw head drive 50, serves to prevent tampering. The torque required to remove the maintenance screws 46 also makes it possible to determine whether the respective maintenance screw 46 has already been removed without authorization at least once.

[0041] A respective functional element 58 is arranged below each maintenance opening 44. In the Fig.In the maintenance opening 44 shown in Figure 3, the functional element 58 is a screw. By means of this screw, the cover 34, namely an inwardly projecting tongue, is held to the housing body 22. Thus, it is necessary to remove this functional element 58 before the cover 34 can be removed from the housing body 20. Thus, to remove the cover 34, on the one hand, the fastening screws 42 must be loosened. It is also necessary to remove at least one of the maintenance screws 46. Consequently, based on the torque required to loosen this maintenance screw 46, it can be determined whether the cover 34 has not yet been removed from the housing body 20. For example, one of the functional elements 58, which is assigned to another maintenance opening 44, is a connector via which operating data of the electric motor 10 can be read out or operating parameters can be entered.

[0042] The invention is not limited to the exemplary embodiment described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention. List of reference symbols 2 motor vehicle 4 scooters 6 wheel 8 Main drive 10 Electric motor 12 Battery 14 Electronics 16 Stator 18 housings 20 housing bodies 22 Engine compartment 24 rotors 26 Wave 28 warehouses 30 bearing plate 32 Electronics compartment 34 lids 36 cooling fins 38 circuit board 40 plugs 42 Fixing screw 44 Maintenance opening 46 Maintenance screw 48 screw head 50 screw head drive 52 screw bodies 54 external thread 56 Adhesive 58 functional element

Claims

[1] Electric motor (10) of a motor vehicle (2), with a housing (18) which has a maintenance opening (44) into which a maintenance screw (46) is screwed, wherein the maintenance screw (46) is glued to the maintenance opening (44) by means of an adhesive (56). [2] Electric motor (10) according to claim 1, characterized by that an external thread (54) of the maintenance screw (46) is provided with the adhesive (56). [3] Electric motor (10) according to claim 2, characterized by that the external thread (54) is provided circumferentially with the adhesive (56). [4] Electric motor (10) according to one of claims 1 to 3, characterized by a proprietary screw head drive (50). [5] Electric motor (10) according to one of claims 1 to 4, characterized by that the housing (18) has a cover (34) which is fastened to a housing body (20), the cover (34) having the maintenance opening (44). [6] Electric motor (10) according to claim 5, characterized bythat an electronics compartment (32) is covered by the cover (34). [7] Electric motor (10) according to claim 5 or 6, characterized by that the cover (34) is fastened to the housing body (20) by means of a fastening screw (42). [8] Electric motor (10) according to one of claims 1 to 7, characterized by that a functional element (58) is arranged in the housing (18) below the maintenance opening (44). [9] Electric motor (10) according to one of claims 1 to 8, characterized by further maintenance screws (46) which are screwed into a respective maintenance opening (44) and glued by means of a respective adhesive (56). [10] Motor scooter (4) with a main drive (8) comprising an electric motor (10) according to one of claims 1 to 9.