Abstract
A sound attenuation arrangement for an inverter cover of an electric compressor, which is characterised in that in addition to fasteners for the inverter cover on the compressor housing of the electric compressor, a sound attenuation means for reducing noise emission via the inverter cover is provided, where the sound attenuation means is made up of a screw with a screw head and a screw shaft, and in that on the screw head a damping element is arranged, where the screw is in contact via the screw shaft with the compressor body, and via the damping element arranged on the screw head with the inverter cover, in a manner that absorbs vibrations.
Claims
1. A sound attenuation arrangement for an inverter cover of an electric compressor, fasteners for the inverter cover on a housing of the electric compressor; and a sound attenuation means for reducing noise emission via the inverter cover, wherein the sound attenuation means further comprises: a screw with a screw head and a screw shaft; and a damping element arranged on the screw head, wherein the screw is in contact via the screw shaft with a compressor body and via the damping element arranged on the screw head with the inverter cover in a manner that absorbs vibrations, wherein the damping element is attached to the screw head and the damping element includes a hollow cylindrical recess.
2. The sound attenuation arrangement according to claim 1, wherein the sound attenuation means is arranged in a central area of the inverter cover.
3. The sound attenuation arrangement according to claim 1, wherein a plurality of the sound attenuation means is provided for a sound-absorbing linking of the housing and the inverter cover.
4. The sound attenuation arrangement according to claim 1, wherein the screw fixes a circuit board to a circuit board frame and/or to the housing.
5. The sound attenuation arrangement according to claim 4, wherein the screw has an integrated washer or a circuit board fixing element.
6. The sound attenuation arrangement according to claim 1, wherein the damping element is an injection moulded part made of silicone or made of rubber.
7. The sound attenuation arrangement according to claim 1, wherein the damping element is a spring or a gel cushion.
8. The sound attenuation arrangement according to claim 1, wherein the damping element pushes or clips onto the screw head of the screw.
9. The sound attenuation arrangement according to claim 1, wherein the damping element is vulcanised or glued onto the screw head of the screw.
10. The sound attenuation arrangement according to claim 1, wherein the screw is installable together with the damping element.
11. The sound attenuation arrangement according to claim 1, wherein the screw head is a slot, a hex socket, a hexalobular internal, a triple square, a Robertson, or a cross-slot head.
12. The sound attenuation arrangement according to claim 4, wherein the screw shaft is sufficiently long that via a screw-in depth into a corresponding receptacle in the housing or in the circuit board frame, a damping strength of the damping element is adjustable.
13. The sound attenuation arrangement according to claim 1, wherein the screw shaft includes an M3 or M4 external thread.
14. The sound attenuation arrangement according to claim 1, wherein the damping element is frustoconical in shape with an angle of inclination α of 92° to 178° or β of 2° to 89° relative to a center line of the damping element.
15. The sound attenuation arrangement according to claim 14, wherein a truncated circular cone of the damping element has a height of 2 mm to 18 mm.
Description
DESCRIPTION OF THE DRAWINGS
(1) 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:
(2) FIG. 1: Inverter cover according to the prior art,
(3) FIG. 2: Detailed view of a non-damped inverter cover,
(4) FIG. 3: Sound attenuation means,
(5) FIG. 4: Sound attenuation means with integrated washer,
(6) FIG. 5: Sound attenuation means with fixed circuit board,
(7) FIG. 6: Sound attenuation means with recessed damping element,
(8) FIG. 7: Side view of sound attenuation means, and
(9) FIG. 8 a) to d): Sound attenuation means with variants of damping elements.
DETAILED DESCRIPTION
(10) FIG. 1 shows an inverter cover 1 of an electric compressor, which covers the region of the electric compressor which accommodates the inverter with the circuit board for the electronics of the component. In this design according to the prior art, sound waves 5 are transmitted from the inside of the component via the space between the inverter cover 1 and the circuit board 2 to the inverter cover 1. This causes the inverter cover 1 to vibrate, which leads to sound radiation to the outside. The circuit board 2 is fixed in a circuit board frame 3 by a screw 4. The circuit board frame 3 in turn is fastened to the compressor or, to be precise, to the compressor housing.
(11) FIG. 2 shows a detail from FIG. 1 enlarged. It shows the screw 4, which is screwed into the circuit board frame 3 via a thread, and which fixes the circuit board in place. The screw 4 has a screw head 6 and a screw shaft 11. As the screw 4 is screwed into the circuit board frame 3, the lower edge of the screw head 6 acts on a circuit board fixing element 7, which presses the circuit board 2 against a support and therefore mechanically fixes it in place. As a result of its mechanical movements to compress the refrigerant, the electric compressor generates vibrations, which are transferred via the circuit board frame 3 and the circuit board 2. These vibrations or, to be precise, the sound waves 5 also excite vibrations in the inverter cover 1, as a result of which sound waves 5 are then emitted outwards into the surroundings.
(12) Finally, FIG. 3 depicts a design of the invention whereas the sound attenuation means the screw 4 is retrofitted with a damping element 8 for the function of sound absorption, which is attached to the screw head which it covers. The damping element 8 is made of an elastic material such as silicone or rubber for example, and mechanically creates the connection between the screw 4 and the inverter cover 1. As a result, vibrations of the circuit board frame 3 and of the component of the electric compressor and of the circuit board 2 joined to it via the circuit board fixing element 7 and the threaded fastening of the screw 4 in the circuit board frame 3 are transferred to the damping element 8, which absorbs the vibrations in the elastic material by linking the damping element 8 to the inverter cover 1. The inverter cover 1 is therefore able to carry out vibrations only to a reduced extent and as a result emits fewer sound waves into the surroundings.
(13) In FIG. 4, the sound attenuation means is complemented by a washer 9 integrated into the screw in addition to the circuit board fixing element 7.
(14) FIG. 5 shows the sound attenuation arrangement with the mechanical connection of the screw 4, the circuit board fixing element 7 and the screw head 6 via the damping element 8 towards the inverter cover 1. The compressor housing 10 forms the frame for supporting the circuit board 2 of the inverter.
(15) FIG. 6 and FIG. 7 depict sound attenuation means, which are designed as a screw 4 with a screw head 6 and a screw shaft 11 as well as an integrated washer 9. In the depicted designs, the damping elements 8 are attached to the screw head 6, with the screw head in FIG. 6 being shown in cross-section. The damping elements 8 are of hollow cylindrical design. Via the hollow cylindrical recess, the screw head 6 is reachable with tools from above through the damping element 8 and therefore the screw 4 can be fitted together with the damping element 8. By screwing the screw 4 into the corresponding thread, depending on the screw-in depth the position of the damping element 8 within the sound attenuation arrangement can be exactly positioned in order to achieve maximum sound absorption in the damping element 8.
(16) FIG. 8 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. FIG. 8a) depicts a screw 4 with a damping element 8, which has a height of 3 mm to 18 mm. The damping element 8 according to FIG. 8b) has a height between 2 mm and 18 mm. FIG. 8c) depicts a damping element 8, where the slope of the truncated cone with the angle of inclination β is between 2° and 89°. In comparison with this, FIG. 8d) depicts a damping element 8 in which the damping element 8 has an angle of inclination α of at least 92° to 178°. The various ranges of the angle of inclination α and β result in correspondingly oppositely oriented truncated cones, where the distal limit of the sound attenuation means is in one case the tip of the truncated cone and in another case the base of the truncated cone. Via the design of the geometry of the damping element 8, the damping characteristics can be influenced as they can via the material of the damping element 8. Particularly preferably it is designed as an injection moulded part made of silicone, which is pushed onto the screw head of the screw 4 in a form-fitting manner. The thread diameter of the screw shaft 11 of the screw is optionally M3 or M4.
LIST OF REFERENCE NUMERALS
(17) 1 Inverter cover 2 Circuit board 3 Circuit board frame 4 Screw 5 Sound waves 6 Screw head 7 Circuit board fixing element 8 Damping element 9 Integrated washer 10 Compressor housing 11 Screw shaft
