Gas seal for aerospace engines and the like

1. A gas seal for aerospace engines and the like of the type having an engine housing with an engine drive shaft rotatably mounted therein, comprising:

a stationary seal housing configured for rigid connection with the engine housing;

a rotating seal plate configured for operable connection with the engine drive shaft, rotates therewith relative to said seal housing and has a seal face;

a carbon ring seal movably supported in said seal housing and including a seal face which mates with said seal face of said seal plate to create a gas seal between the engine housing and the engine drive shaft;

a plurality of pins having first ends thereof supported on said seal housing and second ends thereof slidingly connected with said carbon ring seal to permit said carbon ring seal to selectively shift axially in said seal housing toward and away from said seal plate;

a plurality of compression springs biasing said seal face of said carbon ring seal axially into a sealing relationship with said seal face of said seal plate; and wherein

said seal housing has:

an outer side adapted for communicating with a relatively high pressure portion of the engine housing;

an inner side adapted for communicating with a relatively low pressure portion of the engine housing;

a first passageway positioned such that radially interior portions of said seal faces of said seal plate and said carbon ring seal communicate with the high pressure portion of the engine housing, and radially exterior portions of said seal faces of said seal plate and said carbon ring seal communicate with the low pressure portion of the engine housing; and

a second passageway which communicates the high pressure portion of the engine housing with an exterior face of said carbon ring seal to urge said seal face of said carbon ring seal toward the said seal face of said seal plate;

said seal faces of said seal plate and said carbon ring seal are configured to create a dynamic gas film therebetween during operation from the controlled flow of gas from the high pressure portion of the engine housing to the low pressure portion of the engine housing; and including

a locking plate configured for operable connection with the engine drive shaft and rotating therewith and said seal plate relative to said seal housing; said locking plate movably supporting said seal plate to permit said seal plate to selectively shift axially toward and away from said carbon ring seal; and

a pressure balance plate configured for operable connection with the engine drive shaft and rotating therewith and said seal plate relative to said seal housing; said pressure balance plate includes an annular groove disposed adjacent an inside face of said seal plate which communicates with the high pressure portion of the engine compartment to urge said seal face of said seal plate toward said seal face of said carbon ring seal.

2. A gas seal as set forth in claim 1 , wherein:

said compression springs comprise coil springs which are retained coaxially on said pins; and including

first and second twist lock members that define a bayonet coupling, configured such that said carbon ring seal is axially converged and rotated relative to said seal housing into a locked position.

3. A gas seal as set forth in claim 1 , wherein:

said compression springs comprise coil springs which are retained coaxially on said pins.

4. A gas seal as set forth in claim 1 , including:

first and second twist lock members that define a bayonet coupling, configured such that said carbon ring seal is axially converged and rotated relative to said seal housing into a locked position.

5. A gas seal as set forth in claim 1 , wherein:

said pins comprise a plurality of flexible spring pins having first ends thereof supported on said seal housing and second ends thereof slidingly connected with said carbon ring seal to permit said carbon ring seal to selectively shift axially in said seal housing toward and away from said seal plate.

6. A gas seal as set forth in claim 5 , wherein:

said compression springs are supported on said flexible spring pins and bias said seal face of said carbon ring seal axially into a sealing relationship with said seal face of said seal plate.

7. A gas seal as set forth in claim 6 , including:

a first twist lock member associated with said seal housing:

a second twist lock member associated with said carbon ring seal and configured to mate with said first twist lock member associated with said seal housing to securely yet detachably retain said carbon ring seal in said seal housing; and wherein

said second ends of said flexible spring pins are laterally flexible relative to said first ends of said flexible spring pins and can resiliently deflect in a generally circular fashion during mutual rotation of said seal housing and said carbon ring seal to facilitate engagement and disengagement of said first and second twist lock members.

8. A gas seal as set forth in claim 5 , wherein:

said spring pins have a generally columnar shape, and are constructed from a high temperature polymer to facilitate selected resilient lateral flexure.

9. A gas seal as set forth in claim 1 , wherein:

said carbon ring seal has an annularly-shaped exterior face disposed generally opposite said seal face of said carbon ring seal, and includes a plurality of axially extending circumferentially spaced apart apertures receiving therein first ends of said pins and the associated first ends of said compression springs mounted thereon to facilitate sliding axial alignment between said carbon ring seal and said seal housing, and to reduce the mass of said carbon ring seal for improved dynamic alignment between said seal faces of said carbon ring seal and said seal plate.

10. A gas seal as set forth in claim 1 , wherein:

said carbon ring seal includes an outwardly protruding annularly-shaped base with a cylindrically-shaped outer surface with a low friction coating thereon; and including

a low friction secondary seal mounted in said seal housing and having a radially inwardly oriented seal face made from a low friction carbon with lubricity which abuts with said outer surface of said base of said carbon ring seal to create a secure gas seal, yet permit sliding motion therebetween as said carbon ring seal shifts axially.