Patent Application
20050035554
This application claims priority to UK Patent Application No. GB0312185.2, filed May 28, 2003, the disclosure of which is hereby incorporated herein by reference.
This invention relates to damper devices for mechanical seals and mechanical seals comprising such damper devices. The invention particularly relates to damper devices for absorbing noise produced by the mechanical seals, for example noise produced by the seal faces of the mechanical seals due to poor lubrication conditions.
A mechanical seal comprises a “floating” component and a “static” component. The floating component has a flat annular end face, i.e. a seal face that is directed towards a complementary seal face of the static component. The components are urged together, usually by means of one or more spring members, in order to close the seal faces together to form a sliding seal.
When a mechanical seal is in use then either the floating or static component rotates. The rotating component is usually referred to as the “rotary component” and its seal face is referred to as the “rotary seal face”. The non-rotating component is referred to as the “stationary component” and its seal face is referred to as the “stationary seal face”.
The mechanical seals in which the floating component is rotary are often described as “rotary seals”. However, if the floating component is stationary then the mechanical seal is commonly described as a “stationary seal”.
If the rotary and stationary components are pre-assembled and pre-set prior to despatch from the manufacturing premises then these types of mechanical seals are known as “cartridge seals”. Alternatively, if the rotary and stationary components are despatched individually (unassembled) from the seal manufacturing premises, then the mechanical seal is known as a “component seal”.
Mechanical seals are used to seal a variety of different process media. The general industry term which defines the area of the mechanical seal that is adjacent the process media is “inboard” and the term which defines the area adjacent the atmospheric side is “outboard”.
Mechanical seals are used in a wide variety of industrial applications and operating conditions. Typically, mechanical seal faces require a fluid film to both lubricate and cool them during operation. In mechanical seals with a single seal configuration the fluid film is usually the process media and this may be a gas or liquid. In a dual seal application, the fluid film may be either process media or a secondary fluid known as a buffer or barrier fluid. Secondary fluids are usually a gas maintained at a higher pressure than the process fluid.
A number of conditions determine the nature and effectiveness of the fluid film between the seal faces and these include sealing pressure, seal face geometry and seal face balance. The lubricating properties of the fluid film are also important. It has been found that a gas film is a poorer lubricant than a liquid fluid film and results in a thinner fluid film between the seal faces of a seal.
Fluid films that provide very little lubrication between the seal faces and a high pitch squeaking sound often occurs. The noise is undesirable and is most uncomfortable to a user of the equipment that incorporates a mechanical seal.
Therefore it would be advantageous to in some way reduce the volume of the noise generated from the seal faces, particularly when they are operating in poor fluid film conditions.
Embodiments of the invention seek to overcome this problem by providing means to minimise the transmission of the noise. The means are sufficient to at least reduce the level of noise and may even prevent any noise from being transmitted.
A first aspect of the invention provides a damper device for a mechanical seal having a seal face assembly, the damper device comprises support means arranged relative to the seal face assembly such that a predetermined gap is formed between the support means and the seal face assembly and also comprises damping means disposed in the predetermined gap in order to minimise the transmission of noise produced by the mechanical seal.
Preferably, the support means are arranged relative to a rotary seal face assembly.
Preferably, the support means are arranged relative to a stationary seal face assembly.
The support means may be arranged relative to a radial outer surface of the seal face assembly and/or arranged relative to an axial outer surface of the seal face assembly.
A second aspect of the invention provides a damper device for a mechanical seal having a gland plate, the damper device comprises support means arranged relative to the gland plate such that a predetermined gap is formed between the support means and the gland plate and also comprises damping means disposed in the predetermined gap in order to minimise the transmission of noise produced by the mechanical seal.
Preferably, the damper device of the first and second aspects of the invention include damping means comprising an elastomeric material suitable for absorbing noise. In this case, the damping means may comprise an O-ring.
Preferably, the damper device of the first and second aspects of the invention includes damping means comprising a plastic material suitable for absorbing noise.
The damper device of the first and second aspects of the invention may include damping means that comprise a lip-type seal.
Also, the damper device of the first and second aspects of the invention may include damping means comprising a damping fluid that is suitable for absorbing noise or a vacuum that minimises the transmission of noise.
The damper device of the first and second aspects of the invention may include support means that comprise a non-metallic material suitable for absorbing noise.
A third aspect of the invention provides a mechanical seal comprising a damper device according to the first or second aspect of the invention.
For a better understanding of the present invention and to show how it may be carried into effect, reference shall now be made by way of way of example to the accompanying drawings, in which:
a and 6b depicts a fifth embodiment of the first aspect of the invention arranged with respect to a monolithic, non-shrunk fitted seal face.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims. Like reference numbers signify like elements throughout the description of the figures. It should be further understood that the terms “comprises” and/or “comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
The process media is also sealed by further secondary sealing areas. A first secondary sealing area is formed between a sleeve elastomer (5) in contact with the shaft (6) and sleeve (3). A second secondary sealing area is formed between stationary seal face (2) and stationary gland (7) using elastomer (8). A third secondary sealing area is formed between the rotary seal face (1) and the sleeve (3) using elastomer (9). A fourth secondary sealing area is formed between the gland (7) and the process chamber (not shown) using elastomer (10). A clamp ring assembly (11) contains a screw (12) that secures the sleeve (3) to the shaft (6) so that rotational drive from the shaft (6) is transmitted to the sleeve (3). Said rotational drive is transmitted to the rotary seal face (11) by at least one drive mechanism.
The damper device (20) includes a support member (23) and damping means (24). The support member (23) is arranged such that it is separated from a surface of the rotary seal face assembly in order to form at least one predetermined gap. Damping means (24) are located within the predetermined gap. A plurality of damping means (24) may be disposed within a plurality of gaps. A damper device may include a variety of different damping means (24) to reduce the transmission of the noise produced by the seal faces of a mechanical seal. The support member serves to support the damping means and help retain it in place. The damping means may serve to secure the support member in position with respect to the seal face assembly. In this case, the support member is radially spaced apart from the outer surface of the rotary seal face component holder (22) and a plurality of predetermined gaps are formed. Damping means are arranged within each gap formed between the support member (23) and the surface of the seal face assembly.
The damping means may be formed from an elastomeric material such as rubber, VITON or KAREZ as supplied by Dupont Dow elastomers, AFLAS as supplied by Asahi Glass Co., NITRILE or EPR/EPDM. The damping means may comprise at least one elastomeric O-ring. In this particular embodiment the dampening means (24) consist of five elastomeric O-rings that extend circumferentially between the outer radial surface of the rotary seal assembly and under the inner radial surface of the support member. Alternatively, the damping means may be formed from a plastic material such as TEFLON or a gasket material such as AFI may be used. Damping means formed from an elastomeric or plastic material act as energy absorbers and absorb noise produced by a mechanical seal.
The support member may be formed from a metallic and/or non-metallic material. The support member may be formed from elastomeric materials and/or plastic materials that are suitable for absorbing noise and so further help in reducing the transmission of noise produced by the mechanical seal.
The support member (52) of the damper device (51) is arranged radially with respect to the outer surface of the rotary seal face component (31) and a plurality of elastomeric O-rings (53) are disposed within the predetermined gaps.
a depicts an embodiment of the invention where the support member (110) is spaced apart from a monolithic, non-shrunk fitted seal face (111). O-rings, positioned within the predetermined gaps, contact both the outer radial surface of the seal face and inner surface of the support member.
It is evident that the invention may be arranged relative to both rotary and stationary seal face assemblies and also the gland plate. Damper devices may be arranged radially and/or axially with respect to the seal face assemblies and gland plates. The damping means may be formed from a variety of materials or it may be a vacuum. A damper device may include a plurality of damping means and may include a plurality of different types of damping means. Furthermore, the invention may be used within both rotary and stationary mechanical seals, mechanical seals with single, double or triple seal configurations, metal or rubber bellow seals, pusher seals and also cartridge seals or component seals.
Many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the present invention. All such variations and modifications are intended to be included herein within the scope of the present invention, as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| GB0312185.2 | May 2003 | GB | national |
