JPH0155354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanical seal assembly particularly suitable for use in the chemical industry.

Mechanical seal assemblies that are combined with a stationary housing and a rotating shaft to provide a fluid seal with each other are well known. The housing accommodates a pump impeller connected to the rotating shaft. A mechanical seal assembly is used to substantially eliminate leakage of pumped fluid from the housing. Generally, such mechanical seal assemblies include a seal ring coupled to a housing and a seal ring coupled to a rotating shaft, the seal rings having opposing sealing surfaces such that one or more of the sealing surfaces Both are pressed against each other by an elastic pressing force. Such a construction leaves the resilient device exposed to either the pumped fluid and the air or other fluid. If the propelled fluid is a chemically active fluid, it can corrode and damage the elastic device and/or other parts of the assembly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mechanical seal assembly in which a spring biasing a seal ring can be protected by a jacket, and the jacket can be prevented from being damaged even by high pressure fluid.

The present invention provides a mechanical seal assembly that is particularly suitable for use with chemically active fluids, including a stationary seal ring adapted to be connected to a housing and a rotatable seal ring adapted to be connected to a rotatable shaft. a rotatable seal ring having a rotatable seal ring; opposing sealing surfaces of the seal ring; a retainer connected to the rotatable shaft and spaced from the rotatable seal ring; a coil disposed between the rotatable seal ring and the stationary seal ring so as to be biased towards the stationary seal ring, the coil having both ends fitted into the rotatable seal ring and the reduced diameter portion of the retainer; spring and
a fluid-impermeable flexible jacket surrounding the coil spring and supported by the outer periphery of the coil spring, the fluorine-containing jacket being contracted against the coil spring so as to contact a portion of the coil spring; a flexible jacket made of ethylene propylene synthetic resin; and a device for sealing an end of the jacket to the retainer and the rotatable seal ring, the device being around the jacket and connecting the retainer and the rotatable seal ring. an O-ring received within a groove of a rotatable seal ring.

The mechanical seal assembly described herein is specifically constructed for use in chemical applications where corrosive fluids are handled, and chemically impermeable covers are used to seal the various parts of the assembly. Protected from contact with corrosive fluids.
Specifically, the mechanical seal assembly includes a conventional rotating seal ring, a stationary seal ring, and a coil spring that presses the seal rings together. A heat shrinkable plastic tube surrounds the spring and is sealed at one end to the spring retainer and at the other end to the seal ring, and is preferably made of fluoroethylene propylene material. Other resilient materials may also be used to enclose the spring, in which case another method of joining the sleeve or jacket to the end member would be required.

Embodiments of the mechanical seal assembly according to the present invention will be described below.

This mechanical seal assembly is generally coded 1
0 and includes a stationary seal ring 12 sealed to a multi-part housing 14 by an O-ring 16, and a rotating seal ring 18;
These seal rings 12 and 18 have opposing sealing surfaces 20 and 22, respectively. The seal ring 18 is pressed against the seal ring 12 by a coil spring 24.
One end of the spring 24 surrounds and frictionally engages the reduced diameter portion 26 of the seal ring 18, and the other end of the spring 24 surrounds and frictionally engages the reduced diameter portion 28 of the spring retainer 30. The latter is connected to the rotating shaft 32 by a set screw 34 and sealed thereto by an O-ring 35. Since the retainer 30 is connected to the rotation shaft 32 and the spring 24, the seal ring 18 is attached to the rotation shaft 32.
It is designed to rotate with the

A sleeve or jacket 36 surrounds spring 24 and extends over portions of seal ring 18 and retainer 30. sleeve 36
One end of the seal ring 18 is received within the annular groove 38 of the seal ring 18 and secured within the groove 38 by an O-ring 40. The other end of the sleeve 36 is the retainer 30
is received within an annular groove 42 of and secured within groove 42 by an O-ring 44.

Sleeve 36 preferably comprises a heat shrink tube of fluoroethylene propylene (FEP). Portions of mechanical seal assembly 10 can be configured as a cartridge, ie, retainer 30, seal ring 18, and spring 24 can be assembled into one mandrel. A predetermined length of FEP tube is slid onto the assembled section and O-rings 40 and 44 are then inserted into appropriate grooves 38 and 4, respectively.
2. Heated air is then blown over the tube to deflate the tube,
Shape as shown. These parts are then removed from the mandrel and further assembled with seal ring 12.

For use at high pressures, multiple layer sleeves or jackets can be used.

Other resilient materials may be used to house the spring 24, but would require another method to join the sleeve or jacket to the end member. Spring 24 serves to provide radial support for the sleeve or jacket, allowing the seal assembly to operate at much higher pressures than would be possible without such spring radial support.

According to the present invention, the jacket that protects the coil spring from the fluid to be sealed can be contracted and brought into contact with the coil spring and supported by the coil spring itself, so the jacket can withstand high pressure using inexpensive materials. It can be manufactured as follows. Additionally, since the jacket can be made of relatively flexible material, it does not interfere with the limited axial movement of the seal ring. Furthermore, since the spring device that presses the seal ring is composed of a coil spring, the assembly itself can be made at a lower cost than the mechanical seal assembly shown in Reference 1.

[Brief explanation of drawings]

The accompanying drawings are partial longitudinal cross-sectional views of a mechanical seal assembly according to the present invention. 10... Mechanical seal assembly, 12... Fixed seal ring, 14... Housing, 16, 3
5, 40, 44... O ring, 18... Rotating seal ring, 20, 22... Seal surface, 24... Coil spring, 26, 28... Portion with reduced diameter, 30... Retainer, 32... ... Rotating shaft, 36 ... Sleeve or jacket, 3
8,42...groove.

Claims (1)

Claims: 1. A mechanical seal assembly particularly suitable for use with chemically active fluids, comprising: a stationary seal ring adapted to be connected to a housing; and a stationary seal ring adapted to be connected to a rotatable shaft. a rotatable seal ring adapted to rotate; opposing sealing surfaces of the seal ring; a retainer connected to the rotatable shaft and spaced from the rotatable seal ring; a seal ring disposed between the rotatable seal ring and the stationary seal ring to bias the seal ring toward the stationary seal ring, the ends fitting into the rotatable seal ring and the reduced diameter portion of the retainer; a fluid-impermeable flexible jacket surrounding the coil spring and supported by the outer periphery of the coil spring, the jacket being attached to the coil spring so as to be in contact with a portion of the coil spring; a flexible jacket made of a fluoroethylene propylene synthetic resin shrunken against the retainer; a device for sealing an end of the jacket to the retainer and the rotatable seal ring; a mechanical seal assembly comprising: an O-ring and an O-ring received within a groove of the retainer and the rotatable seal ring.