Butterfly valve

Claim 2

A butterfly valve comprising an annular valve body, a ring-shaped elastic valve seat fitted to an inner circumference of the valve body, said valve seat having diametrically opposed openings, an annular sliding face around each of the openings and at least a pair of recesses charged with lubricant on each sliding face, said pair of recesses being disposed symmetrically with respect to the respective opening of the valve seat, a valve stem pivotally fitted to the valve body through the openings of the valve seat, and a valve disk fitted to the valve stem, said valve disk having a pair of annular sliding faces around the valve stem, each sliding face of the valve disk slidably contacting a respective corresponding sliding face of the valve seat during rotation of the valve disk.

Claim 3

A butterfly valve as claimed in claim 1, wherein each of said recesses has a semi-spherical profile.

Claim 4

A butterfly valve as claimed in claim 2, wherein the sliding face of the valve seat is divided into annular zones in each of which at least a pair of the recesses are disposed symmetrically with respect to the opening of the valve seat.

Claim 5

A butterfly valve as claimed in claim 1, wherein each of said recesses has the shape of an elongated groove extending radially from the vicinity of the opening of the valve seat.

Claim 6

A butterfly valve as claimed in claim 1, wherein each of said recesses has the shape of an annular groove disposed concentrically with the opening of the valve seat.

Claim 7

A butterfly valve as claimed in claim 1, wherein each of the recesses is surrounded with a latticed protrusion.

Claim 8

A butterfly valve as claimed in any one of claims 1 to 6, further comprising lubricant supplying means for supplying lubricant from the exterior of the butterfly valve to said recesses, said lubricant supplying means having a bore formed in the valve body with one end open to the exterior of the butterfly valve, an annular chamber formed around the stem and communicating with said bore, and another bore communicating said annular chamber with said recesses.

Claim 9

A butterfly valve as claimed in claim 7, wherein said lubricant supplying means further comprises a check valve provided at said bore of the valve body to prevent a counter flow of the lubricant from said bore to the exterior of the butterfly valve.

Claim 10

A butterfly valve as claimed in claim 1, wherein said valve seat has plural pairs of recesses including said pair of recesses, for charging with lubricant, on each sliding face, each sliding face of the valve seat is divided into annular zones in each of which each of said plural pairs of the recesses are disposed symmetrically with respect to the opening of the valve seat in each zone.

Claim 11

A butterfly valve comprising, an annular valve body, a ring-shaped elastic valve seat fitted to an inner circumference of the valve body, said valve seat having diametrically opposed annular protrusions, each of which is formed with an opening at the center thereof, an upper face of each said protrusion defining an annular flat sliding face with at least a pair of recesses for charging with lubricant, each said pair of recesses being disposed symmetrically with respect to a respective opening of the valve seat, a valve stem pivotally fitted to the valve body through the openings of the valve seat, and a rigid valve disk fitted to the valve stem, said valve disk having a pair of annular flat sliding faces around the valve stem corresponding to the sliding face of the valve seat, each sliding face of the valve disk slidably contacting a respective corresponding sliding face of the valve seat during rotation of the valve disk.

Claim 12

A butterfly valve comprising, an annular valve body, a ring-shaped elastic valve seat fitted to an inner circumference of the valve body, said valve seat having diametrically opposed annular protrusions, each of which is formed with an opening at the center thereof, an upper face of each said protrusion defining an annular flat sliding face with at least a pair of recesses for charging with lubricant, each said pair of recesses being disposed symmetrically with respect to a respective opening of the valve seat, a valve stem pivotally fitted to the valve body through the openings of the valve seat, and a rigid valve disk fitted to the valve stem, said valve disk having a pair of annular flat sliding faces around the valve stem corresponding to the sliding face of the valve seat, each sliding face of the valve disk slidably contacting a respective corresponding sliding face of the valve seat during rotation of the valve disk.

Claim 13

A butterfly valve as claimed in claim 10, wherein each of said recesses has a semi-spherical profile.

Claim 14

A butterfly valve as claimed in claim 11, wherein the sliding face of the valve seat is divided into annular zones in each of which at least a pair of the recesses are disposed symmetrically with respect to the opening of the valve seat.

Claim 15

A butterfly valve as claimed in claim 10, wherein each of said recesses has the shape of an elongated groove extending radially from the vicinity of the opening of the valve seat.

Claim 16

A butterfly valve as claimed in claim 10, wherein each of said recesses has the shape of an annular groove disposed concentrically with the opening of the valve seat.

Claim 17

A butterfly valve as claimed in claim 10, wherein each of the recesses is surrounded with a latticed protrusion.

Claim 18

A butterfly valve as claimed in any one of claims 10 to 15, further comprising lubricant supplying means for supplying lubricant from the exterior of the butterfly valve to said recesses, said lubricant supplying means having a bore formed in the valve body with one end open to the exterior of the butterfly valve, an annular chamber formed around the stem and communicating with said bore, and another bore communicating said annular chamber with said recesses.

Claim 19

A butterfly valve as claimed in claim 16, wherein said lubricant supplying means further comprises a check valve of the lubricant from said bore to the exterior of the butterfly valve.

Claim 20

A butterfly valve as claimed in claim 10, wherein each annular sliding face is provided with plural pairs of recesses including said pair of recesses, for charging with lubricant, and each said annular sliding face is divided into annular zones in each of which each of said plural pairs of the recesses are disposed symmetrically with respect to each opening of the valve seat respectively.

Claim 21

A butterfly valve comprising an annular valve body, a ring-shaped elastic valve seat fitted to an inner circumference of the valve body, said valve seat having diametrically opposed openings, an annular flat sliding face around each of the openings and cavities charged with lubricant on the sliding face, each of said cavities having a semi-spherical profile, at least a pair of the cavities disposed symmetrically in respect to each respective opening of the valve seat in each of concentrical annular zones with the opening, dividing imaginarily each sliding face of the valve seat, a valve stem pivotally fitted to the valve body through the openings of the valve seat, and a rigid valve disk fitted to the valve stem, said valve disk having a pair of annular flat sliding faces around the valve stem, each sliding face of the valve disk slidably contacting a respective corresponding sliding face of the valve seat during rotation of the valve disk.

Claim 22

A butterfly valve comprising an annular valve body, a ring-shaped elastic valve seat fitted to an inner circumference of the valve body, said valve seat having diametrically opposed openings, an annular flat sliding face around each of the openings and cavities charged with lubricant on the sliding face, each of said cavities having a semi-spherical profile, at least a pair of the cavities disposed symmetrically in respect to each respective opening of the valve seat in each of concentrical annular zones with the opening, dividing imaginarily each sliding face of the valve seat, a valve stem pivotally fitted to the valve body through the openings of the valve seat, and a rigid valve disk fitted to the valve stem, said valve disk having a pair of annular flat sliding faces around the valve stem, each sliding face of the valve disk slidably contacting a respective corresponding sliding face of the valve seat during rotation of the valve disk.

Claim 23

A butterfly valve as claimed in claim 19, further comprising lubricant supplying means for supplying lubricant from the exterior of the butterfly valve to said cavities, said lubricant supplying means having a bore formed in the valve body with one end open to the exterior of the butterfly valve, an annular chamber formed around the stem and communicating with said bore, and another bore communicating said annular chamber with said cavities.

Claim 24

A butterfly valve as claimed in claim 20, wherein said lubricant supplying means further comprises a check valve provided at said bore of the valve body to prevent a counter flow of the lubricant from said bore to the exterior of the butterfly valve.