Patent Application
20210071655
The present disclosure claims the benefit of German Patent Application No. DE 2019124065.4 filed Sep. 9, 2019, the entire contents of which are hereby incorporated herein by reference.
The invention relates in general to the sound attenuating design and installation of housing parts or covers on noise-emitting components. Particularly in the case of covers which are predominantly of flat and planar design and which as a result of fixings at the outer edges and less stiffened flat areas have surfaces which tend to vibrate with an associated emission of noise into the environment, noise protection measures are required.
Modern electric vehicles run almost noiselessly as far as the drivetrain is concerned, as a result of which other vehicle components, which also generate vibrations and noises, are now increasingly perceived to be a disturbance.
The transmission of disturbing noises into the vehicle interior leads to losses of comfort for driver and passengers. In addition, the transmission of disturbing noises into the surroundings results in noise pollution for the environment, which should be kept low in order to increase the acceptance of the vehicles and possibly also in order to comply with legal requirements.
In this context, the electric compressor, or to be precise the refrigerant compressor of the vehicle air conditioning system, also comes into focus as a noise source with regard to measures to reduce noise emissions.
The inverter cover of an electric compressor spans the inverter with the circuit board and is therefore part of the compressor housing. This cover is of planar and largely flat design, and covers the circuit board of the compressor. Due to the need to minimise the weight and installed size of the components, the possibilities for low-noise-emission design of the housing are sometimes limited.
Particularly in the case of air conditioning systems of more modern design, noises are increasingly perceived which were in the background in the case of conventional combustion-engine-powered vehicles and their accepted noise emissions. In the past, these sounds were masked and obscured and previously were not or were hardly perceived by the driver and the surroundings. One noise-emitting component of an electric vehicle is the electrically driven compressor of the air conditioning system.
The task of the invention is to make available a sound attenuation arrangement for an inverter cover of an electric compressor, which reduces internal and external sound radiation and therefore should increase the comfort and acceptance of the vehicle with an electric compressor for the air conditioning system.
The task of the invention is solved by means of a sound attenuation arrangement for an inverter cover with the features shown and described herein.
The task of the invention is solved in particular by a sound attenuation arrangement for an inverter cover of an electric compressor, which in addition to fasteners for the inverter cover on the compressor housing of the electric compressor also contains sound attenuation means to reduce noise emission via the inverter cover. The sound attenuation means is made up of a screw with a screw head and a screw shaft and contains a damping element on the screw head. The screw is joined via the screw shaft to the compressor housing, and via the damping element arranged on the screw head to the inverter cover, in a manner that transmits and absorbs vibrations.
According to the concept, via the screw, which is also referred to as a damping screw, one or more contacts are made with a sound attenuating element between the inverter cover and the internal wall, the compressor or the compressor housing. By means of the screw and the damping element, these additional contacts exert a force and hence a dampening effect on the inverter cover, which leads to a reduction in vibrations and hence to minimised radiation of sound waves into the vehicle interior and into the surroundings.
In an embodiment, the sound attenuation means is arranged in the central area of the inverter cover.
In another embodiment, several sound attenuation means are arranged by means of sound-absorbing connections between the compressor housing and the inverter cover in such a way that a vibration of the inverter cover and hence associated noise emissions are largely prevented.
The sound attenuation means, which is designed as a screw, is particularly preferably additionally designed to fix the circuit board to the circuit board frame and/or to the compressor housing. This ensures that a screw which may already be provided on the compressor for fixing the circuit board can be made suitable for an additional function of sound absorption by providing a damping element. Thus an additional advantage is created as a result of reducing the noise emissions in combination with the required fixing of the circuit board in the compressor.
An advantageous design of the invention consists in the screw having an integrated washer or a circuit board fixing element, with which the circuit board is indirectly fixed in place via the screw.
It is furthermore advantageous if the damping element of the damping means is made as an injection moulded part of silicone or of rubber.
Alternatively, the damping element of the damping means is made as a spring or gel cushion, by means of which vibrations can likewise be effectively absorbed.
It is particularly advantageous if the damping element is designed to push or clip onto the screw head of the screw. This means the damping element can be pushed or clipped onto conventional and already present screws for fixing the circuit board inside the inverter of the electric compressor, for example as a retrofit. In comparison with conventionally already used electric compressors, this measure then results in a reduction in the noise emissions of the electric compressor.
The damping element is advantageously vulcanised or glued onto the screw head of the screw, with the result that alternatively or cumulatively to the form-fitting connection a force-locked or material-bonded connection of the damping element to the screw head is ensured over the lifetime of the electric compressor.
In another embodiment, the screw is designed to be installable together with the damping element, which can also be achieved if the damping element is combined with the screw head not in a material-bonded manner but for example only in a form-fitting manner.
For the screw head drive, the screw head is advantageously designed as a slot, hex socket, hexalobular internal, triple square, Robertson, or cross-slot head.
It is particularly advantageous if the screw shaft of the screw is designed to be sufficiently long that via the screw-in depth into the corresponding receptacle in the compressor housing or in the circuit board frame, the damping strength of the damping element of the damping means is designed adjustably. As a result of screwing in the screw, the force and accordingly the damping decreases, since a lower force is exerted at the end of the damping element on the inverter cover. In the other case of reduced screw-in depth, the force and accordingly the damping increases in accordance with the elastic properties of the damping element.
The screw shaft of the screw is advantageously designed with an M3 or also M4 external thread corresponding to the receptacle in the compressor housing or in the circuit board frame.
According to the invention, the damping element is designed to be frustoconical in shape with an angle of inclination α (alpha) of 92° to 178° or with an angle of inclination β (beta) of 2° to 89° relative to the center line. Thus the truncated cone of the damping element sits with the base up or down on the screw.
At the same time, the truncated circular cone of the damping element advantageously has a height of 2 mm to 18 mm.
The advantages of the invention consist in the fact that a sound attenuation arrangement can be made available efficiently with equipment of low complexity, which effectively and with a minimum of complexity reduces the noise emissions of the component via the inverter cover. The sound attenuation takes place via a sound-absorbing material as a damping element, which can be produced at very low cost and is of constructively simple design.
According to further development of the invention, the sound attenuation means can be equipped with an additional function of fixing the circuit board, as a result of which in a particularly advantageous way two technical functions and tasks can be realised or solved with one technical element.
It is furthermore advantageous that within the sound attenuation arrangement, the damping element can also be retrofitted to electric compressors with corresponding inverter covers, by using already existing screws inside the housing and subsequently adding corresponding damping elements to their screw heads.
The costs of the additional retrofitting of the components for sound attenuation are low compared to complex design measures to stiffen housing parts and covers or to create additional attachment points for these parts.
Further details, features and advantages of designs of the invention result from the following description of example embodiments with reference to the associated drawings. They show:
a) to d): Sound attenuation means with variants of damping elements.
Finally,
In
a) to d) shows various sound attenuation means, which consist of a screw 4 and damping elements 8 correspondingly arranged on the screw head. The geometry of the depicted damping elements 8 is frustoconical, with the damping elements 8 having different heights and angles of inclinations of the edges.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102019124065.4 | Sep 2019 | DE | national |
