Shaft sealing device

A shaft sealing device includes a gland having a flange with an axial hole, a coolant inlet, and a coolant outlet. A shaft sleeve is extended through the axial hole and mounted around a rotary shaft. A plurality of flexible elements extend through a plurality of through-holes in a retainer and each include two ends respectively presaging against two friction ring assemblies, allowing joint rotation of the shaft sleeve and the rotary shaft. The retainer further includes a first tangent groove having an inner end in communication with the axial hole and an outer end in communication with the coolant inlet. The retainer further includes a second tangent groove having an inner end in communication with the axial hole and an outer end in communication with the coolant outlet. Each of the first and second tangent grooves has a width decreasing from the inner end toward the outer end.

BACKGROUND OF THE INVENTION

The present invention relates to a shaft sealing device and, more particularly, to a shaft sealing device with a dual sealing structure.

U.S. Pat. No. 6,935,633 issued Aug. 30, 2005 discloses a shaft sealing device including a sleeve, a flange, a seat ring, a compression ring, and a retaining ring. The sleeve is mounted on a rotary shaft of a machine and provided with an outer flange and a rotary ring mounted thereto. The flange is mounted on the machine and has an axial hole for supporting the sleeve that is rotatably extended therethrough. The flange further has a plurality of passages extending from the axial hole through an outer peripheral surface thereof for supplying and cycling fluid such as coolant. Thus, coolant can be fed into the axial hole via the passages for lubricating purposes. The seat ring is mounted in the axial hole of the flange and abuts against the rotary ring. The compression ring is fixed in the axial hole of the flange and includes a plurality of positioning holes and a plurality of tangent grooves. A flexible member is received in each positioning hole. The retaining ring is mounted around the sleeve and located between the seat ring and the compression ring. A plurality of engaging members are formed on a side of the retaining ring and engaged in the tangent grooves of the compression ring. The retaining member biased by the flexible members can only move in the axial direction and can not rotate. Thus, the retaining member presses the seat ring against the rotary ring, providing frictional contact between the seat ring and the rotary ring and, thus, providing enhanced sealing effect. However, the shaft sealing device of U.S. Pat. No. 6,935,633 is of a single-sealing type that is still less efficient in sealing effect than a dual-sealing structure more commonly utilized.

U.S. Patent Application Publication No. 2007/0246891 A1 discloses a shaft-sealing device including a shaft-mounting seat, a shaft-supporting mechanism, and a liquid guiding member. The shaft-mounting seat is mounted on a machine and includes a shaft bore for rotatably receiving a rotary shaft thereof. The shaft-mounting seat further includes a coolant inlet and a coolant outlet. Two seat rings are mounted in the shaft bore. The shaft-supporting mechanism includes a sealing-ring positioning assembly, two pushing members, a sleeve body, first and second rotatable sealing rings, and a sleeve-mounting member. The shaft-supporting mechanism is mounted around the rotary shaft for sealing purposes, with coolant flowing through the coolant inlet and the coolant outlet for lubricating purposes. The shaft-sealing device of U.S. Patent Application Publication No. 2007/0246891 A1 is of a dual-sealing type that provides more reliable sealing effect than a single sealing type. However, the friction between the seat rings and the first and second rotatable sealing rings is insufficient, since there is no mutual coupling arrangement therebetween.

A need exists for a shaft sealing device of a dual-sealing type to provide a reliable sealing effect.

BRIEF SUMMARY OF THE INVENTION

The present invention solves this need and other problems in the field of shaft sealing by providing, in a preferred form, a shaft sealing device including a gland having a flange with an axial hole. The gland further includes a coolant inlet in communication with the groove and a coolant outlet in communication with the axial hole. A shaft sleeve is extended through the axial hole of the gland and adapted to be mounted around a rotary shaft of a machine to rotate therewith. The shaft sleeve includes an end cap on an end thereof and a drive collar on the other end thereof. The end cap includes a first drive pin, and the drive collar includes a second drive pin. A first friction ring assembly includes a first rotatable friction ring mounted around the shaft sleeve and a first stationary friction ring mounted around the shaft sleeve. The first rotatable friction ring is coupled with the first drive pin. A second friction ring assembly includes a second rotatable friction ring mounted around the shaft sleeve and a second stationary friction ring mounted around the shaft sleeve. The second rotatable friction ring is coupled with the second drive pin. A guiding assembly is mounted between the first and second friction ring assemblies. The guiding assembly includes first and second compression rings mounted around the shaft sleeve and a retainer mounted around the shaft sleeve and between the first and second compression rings. The retainer includes first and second sides and a plurality of through-holes extending from the first side through the second side. A flexible element extends through each through-hole and includes a first end pressing against the first compression ring and a second end pressing against the second compression ring. Thereby, the first compression ring pushes the first stationary friction ring to press against the first rotatable friction ring while the second compression ring pushes the second stationary ring to press against the second rotatable friction ring. The first compression ring includes a plurality of first blocks slideably received in a plurality of first key ways of the retainer. The second compression ring includes a plurality of second blocks slideably received in a plurality of second key ways in the retainer. The retainer further includes a first tangent groove having a first inner end in communication with the axial hole and a first outer end in communication with the coolant inlet. The first tangent groove further includes first and second sidewalls and a first arcuate bottom wall interconnected between the first and second sidewalls. The first arcuate bottom wall includes a first inner edge located on an inner periphery of the retainer and a first outer edge. A first spacing between the first inner edge and the first side of the retainer is smaller than a second spacing between the first outer edge and the first side of the retainer. The first tangent groove has a width decreasing from the first inner end towards the first outer end. The retainer further includes a second tangent groove having a second inner end in communication with the axial hole and a second outer end in communication with the coolant outlet. The second tangent groove further includes third and fourth sidewalls and a second arcuate bottom wall interconnected between the third and fourth sidewalls. The second arcuate bottom wall includes a second inner edge located on the inner periphery of the retainer and a second outer edge. A third spacing between the second inner edge and the first side of the retainer is smaller than a fourth spacing between the second outer edge and the first side of the retainer. The second tangent groove has a width decreasing from the second inner end towards the second outer end.

In the most preferred form, the gland further includes a restraining ring mounted in the axial hole of the flange. The restraining ring includes a first restraining flange on an inner periphery thereof to limit axial movement of the first stationary friction ring. A cover is mounted in a positioning groove in a side of the flange and includes an axial hole through which the rotary shaft extends. The cover further includes an annular wall extending outward from a side thereof in a direction parallel to an extending direction of the axial hole thereof. The annular wall includes a second restraining flange on an inner periphery thereof to limit axial movement of the second stationary friction ring. The first outer edge of the first arcuate bottom wall of the first tangent groove is located on the second side of the retainer and spaced from an outer periphery of the retainer. A first opening is formed between the second side of the retainer and the restraining ring and adjacent to the first outer end of the first tangent groove. The first opening communicates the first outer end of the first tangent groove with the coolant inlet. The second outer edge of the second arcuate bottom wall of the second tangent groove is located on the second side of the retainer and spaced from the outer periphery of the retainer. The second side of the retainer and the restraining ring include a second opening formed therebetween and adjacent to the second outer end of the second tangent groove. The second opening communicates the second outer end of the second tangent groove with the coolant outlet.

The present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings.

Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “third”, “fourth”, “inner”, “outer”, “end”, “portion”, “section”, “longitudinal”, “axial”, “radial”, “lateral”, “annular”, “outward”, “spacing”, “width”, and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

A shaft sealing device according to the preferred teachings of the present invention is shown in the drawings and generally includes a gland1, a shaft sleeve2, first and second friction ring assemblies3and5, and a guiding assembly4. Gland1is mounted to a machine6having a rotary shaft61. Shaft sleeve2is securely mounted around rotary shaft61to rotate therewith. First and second friction ring assemblies3and5and guiding assembly4are mounted around shaft sleeve2, with guiding assembly4sandwiched between first and second friction ring assemblies3and5. Friction contact between guiding assembly4and first and second friction ring assemblies3and5provides a dual-sealing structure for machine6.

According to the preferred form shown, gland1includes a flange11, a restraining ring12, a cover13, and a guide plate14. Flange11includes an axial hole111extending in a longitudinal direction thereof. Flange11further includes a positioning groove112in a side thereof. Further, flange11includes a coolant inlet113extending from an outer periphery thereof through an inner periphery thereof in a radial direction perpendicular to the longitudinal direction and in communication with axial hole111. Flange11further includes a coolant outlet114annularly spaced from coolant inlet113and extending from the outer periphery thereof through the inner periphery thereof in the radial direction and in communication with axial hole111. Coolant can flow from outside into axial hole111via coolant inlet113and then exit axial hole111via coolant outlet114. Restraining ring12is mounted in axial hole11of flange11and includes a first restraining flange121in an inner periphery thereof for restraining movement of second friction ring assembly5. Restraining ring12further includes a positioning hole122in a side thereof. Note that restraining ring12can be integrally formed with flange11as a single continuous monolithic piece.

Cover13is engaged in positioning groove112of flange11and includes an axial hole131. Cover13further includes an annular wall132extending from a side thereof in a direction parallel to a longitudinal direction of axial hole131. A second restraining flange134is formed on an inner periphery of annular wall132for restraining movement of first friction ring assembly3. Further, cover13includes a positioning hole133in the other side thereof at a location adjacent axial hole131. Guide plate14is coupled to the other side of cover13and in the most preferred form shown is a semi-circular ring, with guide plate14including first and second arcuate end faces141and142respectively on two ends thereof. A positioning pin143is formed on each of two sides of guide plate14to respectively engage with positioning hole133of cover13and positioning hole122of restraining ring12for positioning guide plate14in place.

According to the preferred form shown, shaft sleeve2includes an end cap21formed on an end thereof and a drive collar22is removably mounted to the other end of shaft sleeve2. According to the most preferred form shown, the other end of shaft sleeve2includes a plurality of fixing holes24, drive collar22includes a plurality of screw holes222aligned with fixing holes24, and a plurality of screws25are extended through screw holes222and fixing holes24to fix drive collar22on shaft sleeve2. A pumping groove23is formed on an outer periphery of shaft sleeve2between end cap21and drive collar22. When shaft sleeve2rotates, pumping groove23guides coolant to lubricate first and second friction ring assemblies3and5. End cap21includes a first drive pin211formed on an inner periphery thereof and facing pumping groove23. Drive collar22includes a second drive pin221formed on an inner periphery thereof and facing pumping groove23. First drive pin211couples with first friction ring assembly3, and second drive pin221couples with second friction ring assembly5.

According to the preferred form shown, first friction ring assembly3includes a first rotatable friction ring31and a first stationary friction ring32both made of abrasion-resistant material. A drive portion311is formed on a side of first rotatable friction ring31for coupling with first drive pin211of shaft sleeve2, and a seal face312is formed on the other side of first rotatable friction ring31. A seal face321is formed on a side of first stationary friction ring32, and a pressing portion322is formed on the other side of first stationary friction ring32. Seal face321of first stationary friction ring32is in friction contact with seal face312of first rotatable friction ring31.

According to the preferred form shown, guiding assembly4includes first and second compression rings42and43and a retainer41between first and second compression rings42and43. Retainer41includes opposite first and second sides44and46and a plurality of through-holes411extending from first side44through second side46. A flexible element413extends through each through-hole411. Retainer41further includes a plurality of screw holes412extending from an outer periphery thereof through an inner periphery thereof. A screw414is received in each screw hole412. The inner periphery of retainer41further includes a plurality of first key ways415extending from first side44through second side46and a plurality of second key ways416extending from first side44through second side46. First and second tangent grooves417are formed in second side46of retainer41. First tangent groove417includes an inner end56(FIG. 5) in communication with an axial hole54of retainer41and an outer end58in communication with coolant inlet113. More specifically, first tangent groove417includes first and second sidewalls60and62and an arcuate bottom wall64interconnected between first and second sidewalls60and62. Arcuate bottom wall64includes an inner edge66located on the inner periphery of retainer41and spaced from first side44. Arcuate bottom wall64further includes an outer edge68located on second side46and spaced from the outer periphery of retainer41and shorter than inner edge66. Note that a spacing between inner edge66and first side44is smaller than that between outer edge68and first side44. Arcuate bottom wall64further includes first and second arcuate lateral edges70and72. First arcuate lateral edge70is interconnected between an end of inner edge66and an end of outer edge68. Second arcuate lateral edge72is interconnected between the other end of inner edge66and the other end of outer edge68. An opening74(FIG. 2) is defined between second side46of retainer41and restraining ring12adjacent to outer end58of first tangent groove417and communicates outer end58of first tangent groove417with coolant inlet113. Note that first tangent groove417has a width decreasing from inner end56toward outer end58. Similarly, second tangent groove417includes an inner end56in communication with axial hole54and an outer end58in communication with coolant outlet114. More specifically, second tangent groove417includes first and second sidewalls60and62and an arcuate bottom wall64interconnected between first and second sidewalls60and62. Arcuate bottom wall64includes an inner edge66located on the inner periphery of retainer41and spaced from first side44. Arcuate bottom wall64further includes an outer edge68located on second side46and spaced from the outer periphery of retainer41and shorter than inner edge66. Note that a spacing between inner edge66and first side44is smaller than that between outer edge68and first side44. Arcuate bottom wall64further includes first and second arcuate lateral edges70and72. First arcuate lateral edge70is interconnected between an end of inner edge66and an end of outer edge68. Second arcuate lateral edge72is interconnected between the other end of inner edge66and the other end of outer edge68. An opening74(FIG. 2) is defined between second side46of retainer41and restraining ring12adjacent to outer end58of second tangent groove417and communicates outer end58of second tangent groove417with coolant outlet114. Note that second tangent groove417has a width decreasing from inner end56toward outer end58.

First compression ring42includes a plurality of first blocks421extending from a side thereof and movably received in first key ways415of retainer41. Second compression ring43includes a plurality of second blocks431extending from a side thereof and movably received in second key ways416of retainer41.

According to the preferred form shown, second friction ring assembly5includes a second rotatable friction ring51and a second stationary friction ring52both made of abrasion-resistant material. A drive portion511is formed on a side of second rotatable friction ring51for coupling with second drive pin221of shaft sleeve2, and a seal face512is formed on the other side of second rotatable friction ring51. A seal face521is formed on a side of second stationary friction ring52, and a pressing portion522is formed on the other side of second stationary friction ring52. Seal face521of second stationary friction ring52is in friction contact with seal face512of second rotatable friction ring51.

In assembly, shaft sleeve2is mounted on rotary shaft61of machine6to rotate therewith. First rotatable friction ring31and first stationary friction ring32of first friction ring assembly3are mounted on shaft sleeve2with drive portion311of first rotatable friction ring31coupled with first drive pin211of end cap21, and with seal face321of first stationary friction ring32in friction contact with seal face312of first rotatable friction ring31.

Cover13of gland1is mounted around shaft sleeve2with shaft sleeve2extending through axial hole131and annular wall132. Second restraining flange134of cover13restrains axial movement of first stationary friction ring32. Positioning pin143on a side of guide plate14is engaged in positioning hole133of cover13. First and second compression rings42and43and retainer41are mounted around shaft sleeve2. Screws414are extended through screw holes412of retainer41to fix retainer41to the inner periphery of annular wall132of cover13. First compression ring42abuts against pressing portion322of first stationary friction ring32. First blocks421of first compression ring42are slideably received in first tangent grooves415of retainer41. Second blocks431of second compression ring43are slideably received in second key ways416of retainer41. Thus, first and second compression rings42and43can not rotate but can slide in the axial direction. Through-holes411of retainer41allow two ends of each flexible element413extending therethrough to respectively press against first and second compression rings42and43, providing a cushioning effect for axial movement of first and second compression rings42and43. Cover13keeps first and second compression rings42and43inside flange11, providing an integral design and avoiding falling of flexible elements413during assembly and disassembly.

Flange11of gland1is mounted around shaft sleeve2with pumping groove23of shaft sleeve2located in axial hole111of flange11. Restraining ring12is received in axial hole111of flange11, and positioning hole122of restraining ring12is engaged with positioning pin143on the other side of guide plate14. Cover13is engaged in positioning groove112of flange11. With reference toFIG. 4, guide plate14is located in axial hole111of flange11with first arcuate end face141in alignment with a portion of an inner peripheral face of coolant inlet113, and with second arcuate end face142in alignment with a portion of an inner peripheral face of coolant outlet114. Note that guide plate14has an outer side in intimate contact with an inner periphery of flange11. Gland1is fixed to a side of machine6with rotary shaft61extending through axial hole111of flange11.

Second rotatable friction ring51and second stationary friction ring52of second friction ring assembly5are mounted on shaft sleeve2with second compression ring43pressing against pressing portion522of second stationary friction ring52, and with seal face512of second rotatable friction ring51in friction contact with seal face521of second stationary friction ring52. First restraining flange121of restraining ring12restrains axial movement of second stationary friction ring52. Screws25are extended through screw holes222of drive collar22and positioning holes24to fix drive collar22to the other end of shaft sleeve2. Thus, gland1, shaft sleeve2, first friction ring assembly3, guiding assembly4, and second friction ring assembly5are prevented from disengaging from rotary shaft61, and shaft sleeve2and rotary shaft61are fixed to each other.

With reference toFIGS. 1,2, and4, a dual-sealing structure is provided by gland1, shaft sleeve2, first and second friction ring assemblies3and5, and guiding assembly4of the shaft sealing device according to the preferred teachings of the present invention. Coolant inlet113and coolant outlet114of flange11are coupled with a coolant circulating device (not shown) for supplying coolant into axial hole111of flange11through coolant inlet113. Note that coolant is efficiently guided into axial hole111of flange11by first arcuate end face141of guide plate14and by first tangent groove417of retainer41to move heat resulting from friction in first and second friction ring assemblies3and5. Coolant is then efficiently guided to coolant outlet114by second tangent groove417of retainer41and second arcuate end face142of guide plate14. Then, coolant flows from coolant outlet114to coolant circulating device. Lubrication is, thus, provided to assure smooth operation of machine6.

Note that retainer41is fixed in axial hole111of flange11with first blocks421of first compression ring42slideably engaged in first key ways415of retainer41, and with second blocks431of second compression ring43slideably engaged in second key ways416of retainer41. Thus, first and second compression ring42and43can not rotate. However, first compression ring42, when biased by flexible elements413, can slide relative to retainer41in the axial direction to push first stationary friction ring32pressing against first rotatable friction ring31. Similarly, second compression ring43, when biased by flexible elements413, can slide relative to retainer41in the axial direction to push second stationary friction ring52pressing against second rotatable friction ring51. Enhanced sealing effect is, thus, provided.

The shaft sealing device having a single-sealing structure disclosed in U.S. Pat. No. 6,935,633 can only be utilized in working environments without volatile or toxic gases, but the shaft sealing device having a dual-sealing structure according to the preferred teachings of the present invention can be utilized in tough working environments with volatile or toxic gases. Furthermore, compared to the shaft sealing device disclosed in U.S. Patent Application Publication No. 2007/0246891 A1, first and second compression rings42and43of the shaft sealing device having a dual-sealing structure according to the preferred teachings of the present invention can smoothly move first and second stationary friction rings32and52in the axial direction to enhance the sealing effect of first and second friction ring assemblies3and5due to the specific arrangement between guiding assembly4and first and second friction ring assemblies3and5. An enhanced prevent leakage effect is, thus, provided. Further, first and second compression rings42and43utilize common flexible elements413and, thus, have a less complicated structure. Further, the specific shape of first tangent groove417of retainer41can efficiently and smoothly guide coolant from coolant inlet113to axial hole111of flange11, and the specific shape of second tangent groove417of retainer41can efficiently and smoothly guide coolant from axial hole111of flange11to coolant outlet114. The heat-dissipating effect is, thus, enhanced.