Shaft grounding ring and method for production thereof
A method for producing a shaft grounding ring includes providing a shaft grounding ring having an annular main body and contact elements arranged on the main body. The contact elements are electrically conductive and plastic-based. The contact elements are configured to establish an electrically conductive sliding contact with a circumferential surface of a shaft or of a sleeve placed onto the shaft. The contact elements are elastically bendable such that the contact elements are configured to preload the electrically conductive sliding contact. Additionally, the method includes thermally preconditioning the shaft grounding ring before use.
1 . A method for producing a shaft grounding ring (E), comprising:
providing a shaft grounding ring (E) having an annular main body (EG) and contact elements (EK) arranged on the main body (EG), the contact elements (EK) being electrically conductive and plastic-based, the contact elements (EK) being configured to establish an electrically conductive sliding contact (K) with a circumferential surface (C) of a shaft (W) or of a sleeve (H) placed onto the shaft (W), the contact elements (EK) being elastically bendable such that the contact elements (EK) are configured to preload the electrically conductive sliding contact (K); and
thermally preconditioning the shaft grounding ring (E) such that the plastic-based contact elements (EK) undergo thermal aging before use,
wherein thermally preconditioning the shaft grounding ring (E) comprises heating the shaft grounding ring to a defined temperature range from 75 degrees Celsius to 180 degrees Celsius for a time period between 15 minutes and 120 minutes,
wherein thermally preconditioning the shaft grounding ring (E) comprises an inherent bending elasticity based preloading of the contact elements (EK) of the shaft grounding ring (E) during the thermal preconditioning, and
wherein preloading the contact elements (EK) of the shaft grounding ring (E) during the thermal preconditioning comprises preloading the contact elements (EK) on a diameter of a test shaft (PW), the diameter of the test shaft (PW) corresponding to a diameter of the circumferential surface (C) of the shaft or of the sleeve.
2 . A shaft grounding ring (E), wherein the shaft grounding ring (E) is produced according to the method of claim 1 .
3 . The method of claim 1 , wherein the thermal aging of the plastic-based contact elements (EK) is configured such that a subsequent thermal load arising during use of the shaft grounding ring (E) only negligibly affects the elasticity of the contact elements (EK).
4 . The method of claim 1 , wherein thermally preconditioning the shaft grounding ring (E) comprises thermally preconditioning the shaft grounding ring (E) such that the plastic-based contact elements (EK) undergo thermal aging before use in establishing the electrically conductive sliding contact (K).
5 . A shaft grounding ring (E), comprising:
an annular main body (EG) having contact elements (EK) arranged on the main body (EG), the contact elements (EK) being electrically conductive and plastic-based, the contact elements (EK) being configured to establish an electrically conductive sliding contact (K) with a circumferential surface (C) of a shaft (W) or of a sleeve (H) placed onto the shaft (W), the contact elements (EK) being elastically bendable such that the contact elements (EK) are configured to preload the electrically conductive sliding contact (K),
wherein the shaft grounding ring (E) is configured to be thermally preconditioned such that the plastic-based contact elements (EK) are configured to be thermally aged before use,
wherein thermally preconditioning the shaft grounding ring (E) comprises heating the shaft grounding ring to a defined temperature range from 75 degrees Celsius to 180 degrees Celsius for a time period between 15 minutes and 120 minutes,
wherein thermally preconditioning the shaft grounding ring (E) comprises an inherent bending elasticity based preloading of the contact elements (EK) of the shaft grounding ring (E) during the thermal preconditioning, and
wherein preloading the contact elements (EK) of the shaft grounding ring (E) during the thermal preconditioning comprises preloading the contact elements (EK) on a diameter of a test shaft (PW), the diameter of the test shaft (PW) corresponding to a diameter of the circumferential surface (C) of the shaft or of the sleeve.
6 . The shaft grounding ring of claim 5 , wherein the contact elements (EK) comprise a thermally stable plastic provided with at least one electrically conductive filler.
7 . An electric machine (EM 2 ), comprising:
a housing (GE);
a stator(S);
a rotor (R) coupled to a rotor shaft (RW), the rotor shaft (RW) being mounted in the housing (GE); and
the shaft grounding ring (E) of claim 5 , the shaft grounding ring (E) grounding the rotor shaft (RW) with respect to the housing (GE).
8 . An electric axle drive unit (EX) for a motor vehicle, comprising:
a housing (GA);
a shaft (DS 1 , DS 2 ) mounted in the housing (GA); and
the shaft grounding ring (E) of claim 5 , the shaft grounding ring (E) grounding the shaft (DS 1 , DS 2 ) with respect to the housing (GA).
9 . A transmission (G) for a motor vehicle, comprising:
a housing (GG);
a shaft (GW 2 ) mounted in the housing (GG); and
the shaft grounding ring (E) of claim 5 , the shaft grounding ring (E) grounding the shaft (GW 2 ) with respect to the housing (GG).
10 . The transmission (G) of claim 9 , wherein the shaft (GW 2 ) is an output shaft of the transmission (G).
11 . The transmission (G) of claim 9 , further comprising an electric machine (EM), the shaft (GW 2 ) being drivable by the electric machine (EM).
12 . The shaft grounding ring of claim 5 , wherein the contact elements (EK) being thermally aged only negligibly affects the elasticity of the contact elements (EK) during a subsequent thermal load arising during use of the shaft grounding ring (E).
13 . The shaft grounding ring of claim 5 , wherein the shaft grounding ring (E) is thermally preconditioned such that the plastic-based contact elements (EK) are thermally aged before use in establishing the electrically conductive sliding contact (K).