Drive pins in a mechanical seal

Details Drive pins in a mechanical seal Drive pins in a mechanical seal

2001-08-21

2004-01-06

Sandy, Robert J. (Department: 3677)

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

C277S373000, C277S390000

Reexamination Certificate

active

06672591

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the driving mechanism of a mechanical seal face, especially where the seal face is a soft or brittle material and its drive contact gets damage in respect of high pressure and rotation.
BACKGROUND OF THE INVENTION
A mechanical seal comprises a “floating” component which is mounted axially movably around the rotary shaft of, for example a pump and a “static” component which is axially fixed, typically being secured to a housing. The floating component has a flat annular end face, i.e. its seal face, directed towards a complementary seal face of the static component. The floating component is urged towards the static component to close the seal faces together to form a sliding face seal, usually by means of one or more springs. In use, one of the floating and static components rotates; this component is therefore referred to as the rotary component. The other of the floating and static components does not rotate and is referred to as the stationary component.
Those seals whose floating component is rotary are described as rotary seals. If the floating component is stationary, the seal is referred to as a stationary seal.
If the sliding seal between the rotary and stationary components are assembled and pre-set prior to despatch from the mechanical seal manufacturing premises, the industry terminology for this is “cartridge seal”. If however the rotary and stationary components are despatched individually (unassembled) from the mechanical seal manufacturing premises, the industry terminology for this is “component seal”.
Seal faces are generally held to their relevant stationary or rotary components by a mechanism that is called drive ring. One of the common mechanisms is the use of slots on the back of seal face and lugs on the drive ring or vice versa.
FIG. 1
shows four slots on the seal face and four lugs on the drive ring.
FIG. 2
shows two lugs on the seal face and two lugs on the drive ring. Rotation will be transferred from the seal faces to the drive ring at rotary faces or vice versa at the stationary faces.
Seal faces are mainly supplied from various grades of silicon carbide, tungsten carbide, ceramics and carbon. Carbon is categorised as a soft face.
The contact between the slots and lugs in
FIGS. 1 and 2
is mainly point contact. Under point contact, soft or brittle seal faces are more prone to failure than hard faces, especially in high pressure and large seal size applications. The failure may start by notch propagation around the contact point which gradually grows until it destroys the seal face.
Instead of having lugs on the drive ring, some designs employ drive pins that are pressed firmly into holes in the drive ring. These pins cannot move or rotate from their location.
FIG. 3-2
illustrates the use of two pins to drive a lug on the seal face when the seal rotates either in clockwise or counter-clockwise direction. If the mechanical seal is designed to only rotate in one direction, one pin can be used for each lug. Alternatively, the pin may be square, cylindrical or any other shape (See
FIGS. 4-
a
and
4
-
b
).
The drive ring may also be designed to drive the seal face around the outer diameter, inner diameter or axial end of said face. This is shown in
FIG. 4
where point contacts between the lug and slot are labelled A and B.
SUMMARY OF THE INVENTION
The invention relates to a floating pin that allows the interface between the lug and the slot to be a line or face contact. Preferably the pin is of circular shank diameter, preferably with a square or rectangular head and is loosely fitted in a hole to allow free rotation of said pin about its axis.


REFERENCES:
patent: 3672689 (1972-06-01), Hadley
patent: 4917389 (1990-04-01), Baker et al.
patent: 5085250 (1992-02-01), Kendrick
patent: 5489105 (1996-02-01), Attenasio et al.
patent: 5551708 (1996-09-01), Vesey et al.
patent: 5556110 (1996-09-01), Marsi et al.
patent: 5704719 (1998-01-01), Cook et al.
patent: 6305693 (2001-10-01), Wehrle
patent: 6357753 (2002-03-01), Yamasaki et al.
patent: 6386547 (2002-05-01), Wu et al.
patent: 4415120 (1995-08-01), None
patent: 2037905 (1980-07-01), None
patent: 56-80559 (1981-07-01), None
International Search Report corresponding to International Application No. PCT/GB 99/04236; mailed Apr. 14, 2000.

Affiliated with

Also associated with

Rating

Drive pins in a mechanical seal does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Drive pins in a mechanical seal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drive pins in a mechanical seal will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3203258