Electric motor

Abstract

The invention relates to an electric motor (2) which has motor electronics (18). The motor electronics (18) are accommodated in an electronics compartment (20), wherein the pressure in the electronics compartment (20) is less than 300 mbar.

Description

[0001] Description

[0002] electric motor

[0003] The invention relates to an electric motor having motor electronics.

[0004] When such an electric motor is operating, noise can be generated by the motor electronics. These noises are based, for example, on thermal noise (Johnson noise), flicker noise, and / or burst noise.

[0005] Such noises can be perceived by a user as disturbing or distracting.

[0006] The invention is based on the object of providing an electric motor in which noise emissions from the motor electronics are avoided or at least reduced.

[0007] This object is achieved according to the invention by an electric motor having the features of claim 1. Advantageous further developments and refinements are the subject of the subclaims.

[0008] The electric motor comprises motor electronics, also referred to as electronics for short. The motor electronics expediently serve to control the electric motor. In particular, a motor winding of the electric motor, namely a rotor winding or a stator winding, can be energized by the motor electronics. For example, the motor electronics comprise a number of semiconductor switches connected in a bridge circuit, a driver, and / or a power controller. The motor electronics are housed in an electronics compartment. For example, the electronics compartment is formed by a motor housing. The electronics compartment expediently encloses a receiving area for the motor electronics in a fluid-tight manner, i.e., gas- and liquid-tight.

[0009] The pressure, in particular the air pressure and / or the ambient pressure, in the electronics compartment is less than 300 mbar (0.3 bar).

[0010] Since sound intensity is approximately proportional to air density or air pressure, such a comparatively low pressure increases sound resistance. This prevents or at least dampens the propagation of noise generated by the engine electronics or one of its components. Such a component is, for example, a semiconductor element, in particular a semiconductor switch, a capacitor, or a transformer.

[0011] A rough vacuum is ideally set in the electronics compartment. In other words, the air pressure in the electronics compartment is between 300 mbar and 10' 3 mbar, for example, between 300 mbar and 1 mbar. At a pressure between 300 mbar and 1 mbar (rough vacuum), a significant reduction in sound intensity is already achieved, although a rough vacuum is comparatively easy to achieve and therefore cost-effective.

[0012] For a particularly strong reduction in sound transmission, the pressure in the electronics compartment is less than or equal to 1 mbar, according to a practical design of the electric motor. For example, the pressure is between 10" 3 mbar and 1 mbar. In other words, a fine vacuum exists in the electronics compartment.

[0013] For example, the electronics compartment is formed by a trough-like receptacle with an electronics compartment base and an (electronics compartment) side wall that protrudes upwards from the electronics compartment base and is, in particular, monolithically formed onto the electronics compartment base (compartment base). The receptacle is closed with an electronics compartment cover. The electronics compartment cover is joined to the side wall in a fluid-tight manner during assembly or after assembly. For example, a potting material or an adhesive is used for this purpose. For example, the cover comprises a groove-like receptacle into which the potting material or adhesive and the free end of the side wall are received.

[0014] To create a pressure in the electronics compartment that is lower than the ambient pressure, i.e., a pressure of less than 300 mbar, in particular between 300 mbar and 1 mbar, the electronics compartment has a valve through which the air is removed from the electronics compartment, in particular pumped out. For example, the valve is a check valve, a vacuum valve, or a bellows valve. This valve is, for example, incorporated into the side wall of the electronics compartment. The valve is preferably located in the electronics compartment lid, so that the valve is relatively easily accessible.

[0015] For example, after reducing the pressure in the electronics compartment, the valve is sealed fluid-tight. For example, the valve is sealed with a valve cover and / or sealed with a valve cover. This prevents air from (especially gradually) entering the electronics compartment during the electric motor's operating life.

[0016] An opening in the electronics compartment cover, for example for ventilation or pressure equalization in the electronics compartment, is not required.

[0017] For example, the electric motor comprises a further electrical or electronic component which is arranged outside the electronics compartment, in other words outside the fluid-tight enclosed receiving area.

[0018] According to a suitable embodiment of the electric motor, the electric motor includes water cooling for the motor electronics and / or for the stator. Water cooling also enables cooling at reduced pressure and the associated reduced thermal conductivity of the air in the electronics compartment. The electric motor is suitably a motor for a radiator fan or the electric motor for a traction drive of an electrically powered vehicle.

[0019] An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. The single figure shows a schematic sectional view of an electric motor having electronics housed in an electronics compartment.

[0020] The figure schematically shows an electric motor 2 in longitudinal section. This is embodied here as a brushless DC motor with an internal rotor. The electric motor 2 is, for example, an electric motor for a radiator fan.

[0021] The electric motor 2 comprises a motor housing 4, in which a rotor 6 and a stator 8 are accommodated. The rotor 6 has a number of permanent magnets (not shown further) and is rotatably mounted about a rotation axis R by means of a (rotor) shaft 10.

[0022] The stator 8 of the electric motor 2 comprises a laminated core carrying a number of coils 12, each wound from a coil wire (winding wire, insulating wire) 14 in a manner not shown in detail. The coil wire ends of the coil wire 14 are interconnected in a predetermined manner using an interconnection unit 16 of the electric motor 2. The coils 12 are expediently interconnected in a star or delta configuration.

[0023] The interconnection unit 16, also referred to as an interconnection ring or interconnection unit, is arranged in the axial direction A above the stator 8 and is joined to it in a manner not shown in more detail. Here and in the following, the axial direction A refers to a direction parallel (coaxial) to the rotational axis R of the electric motor 2. The electric motor 2 also comprises motor electronics 18, also referred to as electronics. This comprises, for example, a printed circuit board and a number of electrical or electronic components in a manner not shown in more detail. For example, a driver for the electric motor 2 and / or a bridge circuit and a control device therefor are formed using the electronics. In particular, the electric motor 2 can be energized using the motor electronics 18, wherein for this purpose the motor electronics 18 is connected to a current or voltage source external to the motor (not shown in more detail).

[0024] The motor electronics 18 are accommodated in an electronics compartment 20, which here is arranged, for example, in the axial direction above the stator. The electronics compartment 20 forms a receiving space for the motor electronics 18. For this purpose, the electronics compartment 20 comprises an electronics compartment base 22 (compartment base 22) and side walls 28 that expediently extend vertically thereto. The compartment base 22 and the side walls 28 are expediently designed as a single piece, i.e., monolithic. In summary, the compartment base 22 and the side walls 28 form the, in particular, trough-like, receptacle for the motor electronics 28. The electronics compartment 20 further comprises an electronics compartment cover 30, wherein the receiving space is closed by the electronics compartment cover 30 in a fluid-tight, i.e., air- and liquid-tight manner. For this purpose, the electronics compartment cover 30 comprises a groove-like receptacle 34 on its circumference, into which the free end of the side wall 28 facing away from the compartment base 22 is received.Furthermore, an adhesive and / or a potting compound (not further shown) is introduced into the receptacle 34, by means of which a gap possibly formed between the side wall 28 and the electronics compartment cover 30 is closed in a fluid-tight manner.

[0025] In the electronics compartment, the ambient pressure or air pressure p is reduced to such an extent that sound transmission within the electronics compartment is dampened or prevented. For this purpose, the pressure p is less than 0.3 bar, i.e., less than 300 mbar, and in particular less than or equal to 1 mbar. For example, the pressure is between 300 mbar and 1 mbar (rough vacuum) or between 10" 3mbar and 1 mbar (fine vacuum). According to the exemplary embodiment shown here, a valve 30 is arranged on the cover. Using the valve, the electronics compartment 20, i.e. the receptacle for the motor electronics 18 closed by the electronics compartment cover 30, can be fluidically connected to a pump (not shown) in order to pump air out of the electronics compartment 20. The valve 32 is therefore fluidly connected and / or connectable to the receptacle for the motor electronics 18. For example, the valve 32 is designed as a check valve, as a vacuum valve, as a shut-off valve and / or as a bellows valve. Optionally, a valve outlet 36, which can be connected to the pump, is closed in a fluid-tight manner with a closure 38. In particular, the closure 38 is glued on in a fluid-tight manner.

[0026] According to an alternative not further shown, the valve 32 is incorporated into the side wall.

[0027] According to the exemplary embodiment of the electric motor 2 shown here, the receiving space for the motor electronics 18 and a receiving space for the stator 8, for the rotor 6 and for the interconnection unit 16 are separated (decoupled) from one another in a fluid-tight manner by means of the electronics compartment floor. In other words, the electronics compartment floor forms a common partition wall for the receiving space for the motor electronics 18 and for the receiving space for the stator 8. In order to contact the motor electronics 18 with the interconnection unit 16, pin-shaped feedthrough conductors 24 are provided which pass through the compartment floor. For this purpose, the feedthrough conductors 24 are each guided through a hole-like feedthrough in the compartment floor 22. For the fluid-tight design, a seal, expediently a glass seal or a rubber seal, is provided in each case, which holds the respective feedthrough conductor 24 in the feedthrough in a fluid-tight manner and electrically insulates it from the compartment floor 22.

[0028] Optionally, the electric motor has a water cooling system for cooling the motor electronics 18. This comprises, for example, a hose- or tube-like water line 26, which is led to the motor electronics 18. According to an alternative not shown in further detail, the tube-like water line 26 is additionally or alternatively connected to the stator 8, the rotor 6 and / or the interconnection unit

[0029] 16 to cool them.

[0030] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can be derived from them by those skilled in the art within the scope of the claims without departing from the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiments and / or in the claims can also be combined with one another in other ways without departing from the subject matter of the invention.

[0031] List of reference symbols

[0032] 2 electric motor

[0033] 4 engine housing

[0034] 6 Rotor

[0035] 8 Stator

[0036] 10 Rotor shaft

[0037] 12 coil

[0038] 14 coil wire

[0039] 16 interconnection unit

[0040] 18 Engine electronics

[0041] 20 Electronics compartment

[0042] 22 shelves

[0043] 24 implementation managers

[0044] 26 Water pipe

[0045] 28 (Side) wall of the electronics compartment

[0046] 30 electronics compartment cover

[0047] 32 valve

[0048] 34 groove-like receptacle p pressure

[0049] A axial direction

[0050] R rotation axis

Claims

Claims 1. Electric motor (2) with motor electronics (18), wherein the motor electronics (18) are accommodated in an electronics compartment (20), and wherein the pressure (p) in the electronics compartment (20) is less than 300 mbar.

2. Electric motor (2) according to claim 1, characterized in that the pressure (p) in the electronics compartment (20) is less than 1 mbar.

3. Electric motor according to claim 1 or 2, characterized in that the electronics compartment (20) is closed with an electronics compartment cover (30), wherein the electronics compartment cover (30) is joined in a fluid-tight manner to a wall (28) of the electronics compartment (20).

4. Electric motor according to one of claims 1 to 3, characterized by a valve (32) for removing air from the electronics compartment (20), and / or wherein the valve (32) is arranged on the electronics compartment cover (30).

5. Electric motor according to one of claims 1 to 4, characterized by water cooling for the motor electronics (18) and / or for a stator (8).

6. Electric motor according to one of claims 1 to 5, characterized in that it is provided for a cooling fan.

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