Shaft seal assembly with contaminant detection system

A motor for a pump, the motor comprising:

• a housing;
• a rotatable shaft extending through an opening in the housing;
• and
• a seal assembly surrounding the shaft and sealing against contaminants outside the housing at the opening, the seal assembly comprising:
• a stationary member surrounding the shaft and affixed to the housing;
• a rotatable member secured to an adjacent portion of the shaft, the rotatable member and the stationary member forming a fluid passage connecting an interior of the housing to an exterior of the housing;
• a first sealing member having an inner diameter encircling the rotatable shaft and a second sealing member having an inner diameter encircling the rotatable shaft, the first and second sealing members dividing the fluid passage into an interior section exposed to the interior of the housing, an open section exposed to the exterior of the housing, and a sealed section disposed between and sealed from the interior section and the open section, wherein the first sealing member inner diameter has a length that is different from the length of the second sealing member inner diameter, wherein the first sealing member and the second sealing member are secured to the stationary member;
• and
• at least one sensor disposed within the sealed section, the sensor configured to sense the contaminants within the sealed section.

A method for securing a seal assembly to a motor housing, the seal assembly sealing a rotating shaft entering the housing from contaminants, the method comprising:

• securing a stationary member to the housing so as to surround the rotating shaft;
• securing a rotatable member to an adjacent portion of the rotating shaft for rotation therewith;
• positioning the rotatable member adjacent the stationary member to form a fluid passage therebetween, the fluid passage connecting an interior of the housing and an exterior of the housing;
• providing a first sealing member having a first inner diameter encircling the rotating shaft and a second sealing member having a first inner diameter encircling the rotating shaft, the first and second sealing members positioned to sealingly divide the fluid passage into an interior section exposed to the interior of the housing, an open section exposed to an exterior of the housing, and a sealed section disposed between the interior section and the open section, wherein the first sealing member inner diameter has a length that is different from a length of the second sealing member, wherein the first sealing member and the second sealing member are secured to the stationary member to sealingly engage the rotatable shaft;
• and
• positioning a sensor in the sealed section to sense contaminants in the sealed section.

A method for detecting the loss of seal integrity, the seal having a first sealing member, a second sealing member, and a third sealing member forming a sealed section for sealing a bearing cavity against contaminants, the method comprising:

• positioning a first sealing member having an inner diameter around a rotating shaft;
• positioning a second sealing member having an inner diameter around the rotating shaft;
• positioning a third sealing member between the first and second sealing members, the first, second and third sealing members forming the sealed section, the third sealing member having an inner diameter around the rotating shaft of a length different from a length of the first and second sealing member inner diameters, wherein the first and second sealing members are secured to a stationary member of the seal and the third sealing member is secured to a rotating member of the seal;
• and
• monitoring the sealed section with a sensor to detect the presence of contaminants in the sealed section.

A seal assembly for sealing a fluid passageway from contaminants, the fluid passageway formed by a rotating shaft entering an opening in a housing, the fluid passageway connecting an interior of the housing and an exterior of the housing, the seal assembly comprising:

• a first sealing member and a second sealing member dividing the fluid passage into an interior section exposed to the interior of the housing, an open section exposed to the exterior, and a sealed section fluidly sealed between the interior section and the open section;
• a stationary member surrounding the shaft and affixed to the housing, wherein the first sealing member and the second sealing member are secured to the stationary member;
• a rotatable member secured to an adjacent portion of the shaft, the rotatable member and the stationary member dividing the fluid passage connecting the interior of the housing to the exterior of the housing, wherein the stationary member and the rotatable member are intermeshed to form a labyrinth in the fluid passageway;
• a port formed in the stationary member extending from the labyrinth through the stationary member such that during rotation of the rotatable member, contaminants exit the labyrinth through the port prior to entering the sealed section;
• and
• a sensor disposed within the sealed section, the sensor configured to sense the contaminants within the sealed section.

A method for securing a seal assembly to a motor housing, the seal assembly sealing a rotating shaft entering the housing from contaminants, the method comprising:

• securing a stationary member to the housing so as to surround the rotating shaft;
• securing a rotatable member to an adjacent portion of the rotating shaft for rotation therewith;
• positioning the rotatable member adjacent the stationary member to form a fluid passage therebetween, the fluid passage connecting an interior of the housing and an exterior of the housing;
• providing a first sealing member and a second sealing member on the stationary member to sealingly divide the fluid passage into an interior section exposed to the interior of the housing, an open section exposed to an exterior of the housing, and a sealed section disposed between the interior section and the open section;
• and
• positioning a sensor in the sealed section to sense contaminants in the sealed section.