Apparatus and method for detecting a liquid contaminant in a rotating cavity of an electric machine

An electric machine comprising:

• a stator,
• a rotor rotatably coupled to said stator and having an internal cavity,
• a magnetic field source mounted to said stator and transmitting a magnetic field across a gap between said stator and said rotor;
• an interrogation circuit mounted to said rotor and having a coil magnetically coupled to said magnetic field source across said gap via said magnetic field, and a distal circuit portion having electrical contacts separated by a spacing fluidly communicating with the cavity, the interrogation circuit configured for influencing the magnetic field when a change in an impedance of said liquid occurs in the spacing;
• and
• a detection circuit mounted to said stator, the detection circuit having a coil electromagnetically coupled to said magnetic field and a detector configured for detecting the influence of the interrogation circuit on the magnetic field;
• wherein said interrogation circuit is a first interrogation circuit, said electric machine comprising a second interrogation circuit having a distal circuit portion being positioned at a depth within said internal cavity different than a depth of said distal circuit portion of said first interrogation circuit.

An electric machine comprising:

• a stator,
• a rotor rotatably coupled to said stator and having an internal cavity,
• a magnetic field source mounted to said stator and transmitting a magnetic field across a gap between said stator and said rotor;
• an interrogation circuit mounted to said rotor and having a coil magnetically coupled to said magnetic field source across said gap via said magnetic field, and a distal circuit portion having electrical contacts separated by a spacing fluidly communicating with the cavity, the interrogation circuit configured for influencing the magnetic field when a change in an impedance of said liquid occurs in the spacing;
• and
• a detection circuit mounted to said stator, the detection circuit having a coil electromagnetically coupled to said magnetic field and a detector configured for detecting the influence of the interrogation circuit on the magnetic field;
• further comprising a controller having a processor and a memory having stored thereon instructions that when executed by said processor perform the step of:
• generating an alert upon determining that said detected influence is a variation of impedance of at least 10 percent.

An electric machine comprising:

• a stator,
• a rotor rotatably coupled to said stator and having an internal cavity,
• a magnetic field source mounted to said stator and transmitting a magnetic field across a gap between said stator and said rotor;
• an interrogation circuit mounted to said rotor and having a coil magnetically coupled to said magnetic field source across said gap via said magnetic field, and a distal circuit portion having electrical contacts separated by a spacing fluidly communicating with the cavity, the interrogation circuit configured for influencing the magnetic field when a change in an impedance of said liquid occurs in the spacing;
• and
• a detection circuit mounted to said stator, the detection circuit having a coil electromagnetically coupled to said magnetic field and a detector configured for detecting the influence of the interrogation circuit on the magnetic field;
• wherein said interrogation circuit has a first resistor connected in series between an electrical conductor and a first one of the of the electrical contacts, and a second resistor connected in parallel to the electrical contacts.

An electric machine comprising:

• a stator,
• a rotor rotatably coupled to said stator and having an internal cavity,
• a magnetic field source mounted to said stator and transmitting a magnetic field across a gap between said stator and said rotor;
• an interrogation circuit mounted to said rotor and having a coil magnetically coupled to said magnetic field source across said gap via said magnetic field, and a distal circuit portion having electrical contacts separated by a spacing fluidly communicating with the cavity, the interrogation circuit configured for influencing the magnetic field when a change in an impedance of said liquid occurs in the spacing;
• and
• a detection circuit mounted to said stator, the detection circuit having a coil electromagnetically coupled to said magnetic field and a detector configured for detecting the influence of the interrogation circuit on the magnetic field;
• wherein said coils of said interrogation and detection circuits are axially spaced-apart from a rotation axis of said rotor and become circumferentially aligned with each other across said gap at a given relative rotational position between the rotor and the stator, wherein said electromagnetic coupling occurs when the coils approach, reach, and depart from the circumferential alignment due to the rotation of the rotor;
• further comprising a controller having a processor and a memory having stored thereon instructions that when executed by said processor perform the step of:
• monitoring the electrical condition of the detection circuit when the coils are circumferentially misaligned from one another for influences indicative of malfunction.

A method for detecting a liquid contaminant in an internal cavity of a hollow housing rotatably mounted to a base, said method comprising:

• transmitting a magnetic field across a gap between said base and said hollow housing;
• said magnetic field driving a coil in said internal cavity and circulating a current into an interrogation circuit having electrical contacts coupled to said coil and separated from one another by a spacing fluidly communicating with said internal cavity, the interrogation circuit influencing said magnetic field when a change in an impedance occurs in said spacing;
• and
• using a detection circuit mounted to said base and having a coil electromagnetically coupled to said magnetic field, detecting said influence of said interrogation circuit on said magnetic field;
• further comprising, using a controller, generating an alert upon determining that said influence occurring in said detection circuit is a variation of impedance of at least 10 percent.

A method for detecting a liquid contaminant in an internal cavity of a hollow housing rotatably mounted to a base, said method comprising:

• transmitting a magnetic field across a gap between said base and said hollow housing;
• said magnetic field driving a coil in said internal cavity and circulating a current into an interrogation circuit having electrical contacts coupled to said coil and separated from one another by a spacing fluidly communicating with said internal cavity, the interrogation circuit influencing said magnetic field when a change in an impedance occurs in said spacing;
• and
• using a detection circuit mounted to said base and having a coil electromagnetically coupled to said magnetic field, detecting said influence of said interrogation circuit on said magnetic field;
• further comprising, using a controller, matching a pattern of said detected influence to one of a plurality of reference influence patterns, and generating a signal associated with the matched one of the reference influence patterns.