Secondary sealing element
A secondary sealing element comprises a base body ( 12 ) made of a synthetic material and comprising a base portion ( 13 ) and a seal portion ( 14 ) which each comprise coaxially aligned, axially adjacent through bores ( 17, 31 ) for the passage of a component, and an annular disc element ( 25 ) accommodated in the base portion and comprising a through bore ( 30 ) coaxially aligned with the through bores in the base and seal portions and being made of a material which differs from that of the base body. In the unloaded state, the through bore ( 30 ) of the annular disc element ( 25 ) has a radial dimension d which is greater than that D 2 of the through bore ( 31 ) in the seal portion ( 14 ) and smaller than that D 1 in the base portion ( 13 ) of the base body ( 12 ). The annular disc element consists of a carbon material. An important field of application for the secondary sealing element is that of mechanical face seals for sealing relatively moveable components.
1. A secondary seal element including a base body made of a synthetic material, said base body comprising a base portion and a seal portion, said base and seal portions including coaxially aligned, axially adjacent through bores for the passage of a component, and an annular disc element accommodated in said base portion and including a through bore coaxially aligned with the through bores in the base and seal portions, said annular disc element being formed of a material which differs from that of the base body, wherein in the unloaded state, the through bore of said annular disc element has a radial dimension d which is greater than that D 2 of the through bore of said seal portion and smaller than that D 1 of said base portion of the base body, wherein the annular disc element is formed of a carbon material, and wherein the annular disc element is disposed in a recess in an end face of the base portion and projects axially beyond the end face and further in such manner so that a pressurized fluid can exert a radially inward force on at least a portion of a radially outermost surface of the annular disc element when the secondary seal element is in a loaded state.
2. The secondary seal element according to claim 1 , wherein the synthetic material of the base body comprises PTFE.
3. The secondary seal element according to claim 1 , wherein the seal portion comprises a pair of radially spaced resilient web elements having opposed outwardly directed sealing surfaces.
4. The secondary seal element according to claim 3 , further comprising means for radially expanding the web elements in a resilient manner.
5. The secondary seal element according to claim 1 , wherein the base portion has an essentially rectangular cross section.
6. A mechanical face seal device comprising a pair of cooperating seal rings of which one is urged towards the other by an axial bias force and is axially moveably disposed on a sleeve, wherein for the purpose of sealing said one sealing seal ring with respect to the sleeve, a secondary seal element is disposed in a thrust ring seated on the sleeve in an axially moveable manner for transmitting said bias force, the secondary seal element including a base body made of a synthetic material, said base body comprising a base portion and a seal portion, said base and seal portions including coaxially aligned, axially adjacent through bores for the passage of a component, and an annular disc element accommodated in said base portion and including a through bore coaxially aligned with the through bores in the base and seal portions, said annular disc element being formed of a material which differs from that of the base body, wherein in the unloaded state, the through bore of said annular disc element has a radial dimension d which is greater than that D 2 of the through bore of said seal portion and smaller than that D 1 of said base portion of the base body, wherein the annular disc element is formed of a carbon material, and wherein the annular disc element is disposed in a recess in an end face of the base portion and projects axially beyond the end face and further in such manner so that a pressurized fluid can exert a radially inward force on at least a portion of a radially outermost surface of the annular disc element when the secondary seal element is in a loaded state, and wherein the sleeve is formed of a material having a coefficient of thermal expansion which essentially corresponds to that of the carbon material of the annular disc element.
7. The mechanical face seal device according to claim 6 , wherein the sleeve is formed of tungsten carbide.