Fluid operated piston circuit breaker with floating position valve actuator

Claim 2

A circuit breaker having an actuating system comprising a pair of a first force producing means producing a large force in one direction and a second force producing means producing a smaller force in a direction opposite to the above direction, and actuating rod connecting said first and second force producing means with each other in such a manner as to establish a first differential force relationship therebetween, force reducing means adapted to move toward and away from said first force producing means for reducing the force produced by said first force producing means when brought into engagement therewith so as to establish a second differential force relationship between said first force producing means in such a state and said second force producing means, means for controlling the movement of said force reducing means toward and away from said first force producing means and controlling the application of fluid under pressure to said first force producing means for selectively establishing one of said two differential force relationships thereby selectively biasing said actuating rod in one of the making and breaking directions so as to correspondingly actuate the breaker section operatively connected to said actuating rod, and means responsive to the movement of said actuating rod for controlling the application of fluid under pressure to said first force producing, means after said force reducing means has moved away from said first force producing means and maintaining said force reducing means in a floating position spaced from said first force producing means.

Claim 3

A circuit breaker having an actuating system as claimed in claim 1, in which the difference between the forces is larger in said first differential force relationship than that in said second differential force relationship, and said actuating rod is biased in the breaking direction when said first differential force relationship is established, while said actuating rod is biased in the making direction when said second differential force relationship is established, thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 4

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member and to follow the movement of said signal responsive valve member in one direction after said signal responsive valve member has moved away therefrom, said movable valve seat following the movement of said signal responsive valve member taking finally a floating position spaced from said signal responsive valve member, another valve member movable in response to the movement of said actuating rod for controlling the application of fluid under pressure to said signal responsive valve member, Means mounted on said actuating rod for imparting a making force thereto, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 5

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member and to follow the movement of said signal responsive valve member in one direction after said signal responsive valve member has moved away therefrom, said movable valve seat following the movement of said signal responsive valve member taking finally a floating position spaced from said signal responsive valve member, another valve member movable in response to the movement of said actuating rod for controlling the application of fluid under pressure to said signal responsive valve member, Means mounted on said actuating rod for imparting a making force thereto, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 6

A circuit breaker having an actuating system as claimed in claim 3, in which said means for removing the fluid under pressure applied to said signal responsive valve member includes a fluid discharge passage which opens in said valve box at a position intermediate of the entire moving stroke of said signal responsive valve member.

Claim 7

A circuit breaker having an actuating system as claimed in claim 3, in which said movable valve seat is provided with a flange portion making substantially fluid-tight sliding engagement with the inner wall surface of said valve box and a spring normally biasing movable valve seat toward said signal responsive valve member, said movable valve seat being urged away from said signal responsive valve member by the difference between the fluid pressures acting upon opposite surfaces of said flange portion, and each of said means for removing the fluid under pressure applied to said movable valve seat and means for removing the fluid under pressure applied to said signal responsive valve member comprises electromagnetic valve means including a valve element in fluid-tight engagement with a fluid discharge port, a magnet producing a holding magnetic flux for attracting and holding said valve element in the port closing position against the fluid pressure acting upon said valve element in the port opening direction, and a coil producing a cancelling magnetic flux for urging said valve element to the open position in response to the application of a valve actuating signal, said cancelling magnetic flux passing through said valve element in a direction opposite to the direction of said holding magnetic flux and passing through said magnet in the same direction as that of said holding magnetic flux.

Claim 8

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member and to follow the movement of said signal responsive valve member in one direction after said signal responsive valve member has moved away therefrom, said movable valve seat following the movement of said signal responsive valve member taking finally a floating position spaced from said signal responsive valve member, a control valve member movable in response to the movement of said actuating rod for shutting off the supply of the fluid under pressure to said signal responsive valve member during the movement of said actuating rod in the breaking direction, a making force imparting valve member mounted on the other end of said actuating rod in another valve box opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive vale member being controlled by disengaging said movable valve seat from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 9

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member and to follow the movement of said signal responsive valve member in one direction after said signal responsive valve member has moved away therefrom, said movable valve seat following the movement of said signal responsive valve member taking finally a floating position spaced from said signal responsive valve member, a control valve member movable in response to the movement of said actuating rod for shutting off the supply of the fluid under pressure to said signal responsive valve member during the movement of said actuating rod in the breaking direction, a making force imparting valve member mounted on the other end of said actuating rod in another valve box opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive vale member being controlled by disengaging said movable valve seat from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 10

A circuit breaker having an actuating system as claimed in claim 6, in which said actuating rod extends through a grounded reservoir filled thereinside with compressed air, a portion of compressed air in said grounded reservoir being supplied to said signal responsive valve member and said making force imparting valve member accommodated in the valve boxes disposed at opposite end portions of said grounded reservoir, and the breaker section is supported on a tubular insulator upstanding from said grounded reservoir to be electrically insulated from said grounded reservoir, said breaker section being connected to said actuating rod by an actuating rod of electrical insulator.

Claim 11

A circuit breaker having an actuating system as claimed in claim 6, in which a first differential force relationship is established between said signal responsive valve member and said making force imparting valve member connected to each other by said actuating rod due to the fact that different fluid pressures are applied to said valve members in directions opposite to each other and the total fluid pressure applied to said signal responsive valve member differs from or is higher than the total fluid pressure applied to said making force imparting valve member, while a second differential force relationship is established between said signal responsive valve member and said making force imparting valve member when said movable valve seat movable toward and away from said signal responsive valve member for controlling the total fluid pressure applied thereto is brought into engagement with said signal responsive valve member due to the fact that the total fluid pressure applied to said signal responsive valve member is now lower than the total fluid pressure applied to said making force imparting valve member, said movable valve seat being moved toward and away from said signal responsive valve member and the fluid pressure applied to said signal responsive valve member being controlled for selectively establishing one of said two differential force relationships thereby selectively biasing said actuating rod in one of the making and breaking directions so as to correspondingly actuate the breaker section operatively connected to said actuating rod.

Claim 12

A circuit breaker having an actuating system as claimed in claim 6, in which the fluid under pressure acting upon said signal responsive valve member differs in property from the fluid under pressure acting upon said making force imparting valve member.

Claim 13

A circuit breaker having an actuating system as claimed in claim 6, in which said making force imparting valve member imparts the force biasing said actuating rod in the making direction by being urged by the pressure difference between a high-pressure chamber and a low-pressure chamber and is composed of a pair of valve elements which engage individual valve seats in fluid-tight relation during the making and breaking operations respectively, by being urged by said pressure difference in the making direction so as to close a communication passage between said pressure chambers and act to allow for complete communication of said high-pressure chamber with said low-pressure chamber through said passage for a predetermined period of time after the making or breaking operation has started, thereby temporarily eliminating the pressure difference between said pressure chambers.

Claim 14

A circuit breaker having an actuating system as claimed in claim 6, in which said means for removing the fluid under pressure applied to said signal responsive valve member includes a fluid discharge passage which opens in said valve box at a position intermediate the entire moving stroke of said signal responsive valve member.

Claim 15

A circuit breaker having an actuating system as claimed in claim 6, in which said movable valve seat is provided with a flange portion making substantially fluid-tight sliding engagement with the inner wall surface of said valve box and a spring normally biasing said movable valve seAt toward said signal responsive valve member, said movable valve seat being urged away from said signal responsive valve member by the difference between the fluid pressures acting upon opposite surfaces of said flange portion, and each of said means for removing the fluid under pressure applied to said movable valve seat and said means for removing the fluid under pressure applied to said signal responsive valve member comprises electromagnetic valve means including a valve element in fluid-tight engagement with a fluid discharge port, a magnet producing a holding magnetic flux for attracting and holding said valve element in the port closing position against the fluid pressure acting upon said valve element in the port opening direction, and a coil producing a cancelling magnetic flux for urging said valve element to the open position in response to the application of a valve actuating signal, said cancelling magnetic flux passing through said valve element in a direction opposite to the direction of said holding magnetic flux and passing through said magnet in the same direction as that of said holding magnetic flux.

Claim 16

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member and to follow the movement of said signal responsive valve member in one direction after said signal responsive valve member has moved away therefrom, said movable valve seat following the movement of said signal responsive valve member taking finally a floating position spaced from said signal responsive valve member, a control valve member movable in response to the movement of said actuating rod for shutting off the supply of the fluid under pressure to said signal responsive valve member during the movement of said actuating rod in the breaking direction, a making force imparting spring mounted on said actuating rod opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of the fluid pressure to said signal responsive valve member being controlled by disengaging said movable valve seat from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 17

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member and to follow the movement of said signal responsive valve member in one direction after said signal responsive valve member has moved away therefrom, said movable valve seat following the movement of said signal responsive valve member taking finally a floating position spaced from said signal responsive valve member, a control valve member movable in response to the movement of said actuating rod for shutting off the supply of the fluid under pressure to said signal responsive valve member during the movement of said actuating rod in the breaking direction, a making force imparting spring mounted on said actuating rod opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of the fluid pressure to said signal responsive valve member being controlled by disengaging said movable valve seat from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 18

A circuit breaker having an actuating system as claimed in claim 13, in which said means for removing the fluid under pressure applied to said signal responsive valve member includes a fluid discharge passage which opens in said valve box at a position intermediate of the entire moving stroke of said signal responsive valve member.

Claim 19

A circuit breaker having an actuating system as claimed in claim 13, in which said movable valve seat is provided with a flange portion making substantially fluid-tight sliding engagement with the inner wall surface of said valve box and a spring normally biasing said movable valve seat toward said signal responsive valve member, said movable valve seat being urged away from said signal responsive valve member by the difference between the fluid pressures acting upon opposite surfaces of said flange portion, and each of said means for removing the fluid under pressure applied to said movable valve seat and said means for removing the fluid under pressure applied to said signal responsive valve member comprises electromagnetic valve means including a valve element in fluid-tight engagement with a fluid discharge poRt, a magnet producing a holding magnetic flux for attracting and holding said valve element in the port closing position against the fluid pressure acting upon said valve element in the port opening direction, and a coil producing a cancelling magnetic flux for urging said valve element to the open position in response to the application of a valve actuating signal, said cancelling magnetic flux passing through said valve element in a direction opposite to the direction of said holding magnetic flux and passing through said magnet in the same direction as that of said holding magnetic flux.

Claim 20

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a control valve member having a portion thereof normally engaging a recess in said signal responsive valve member in said valve box and movable while following the movement of said actuating rod in the breaking direction until it is locked in a position midway of the above movement of said actuating rod, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member through said control valve member and to follow the movement of said control valve member in one direction after said control valve member has moved away therefrom, said movable valve seat following the movement of said control valve member taking finally a floating position spaced from said signal responsive valve member to shut off the supply of the fluid under pressure to said signal responsive valve member, a making force imparting valve member mounted on the other end of said actuating rod in another valve box opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled thereby selectively biasing said actuating rod in one of the making and breaking directions so as to correspondingly actuate the breaker section operatively connected to said actuating rod.

Claim 21

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a control valve member having a portion thereof normally engaging a recess in said signal responsive valve member in said valve box and movable while following the movement of said actuating rod in the breaking direction until it is locked in a position midway of the above movement of said actuating rod, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member through said control valve member and to follow the movement of said control valve member in one direction after said control valve member has moved away therefrom, said movable valve seat following the movement of said control valve member taking finally a floating position spaced from said signal responsive valve member to shut off the supply of the fluid under pressure to said signal responsive valve member, a making force imparting valve member mounted on the other end of said actuating rod in another valve box opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled thereby selectively biasing said actuating rod in one of the making and breaking directions so as to correspondingly actuate the breaker section operatively connected to said actuating rod.

Claim 22

A circuit breaker having an actuating system as claimed in claim 16, in which said means for removing the fluid under pressure applied to said signal responsive valve member includes a fluid discharge passage which opens in said valve box at a position intermediate of the entire moving stroke of said signal responsive valve member.

Claim 23

A circuit breaker having an actuating system as claimed in claim 16, in which said movable valve seat is provided with a flange portion making substantially fluid-tight sliding engagement with the inner wall surface of said valve box and a spring normally biasing said movable valve seat toward said signal responsive valve member, said movable valve seat being urged away from said signal responsive valve member by the difference between the fluid pressures acting upon opposite surfaces of said flange portion, and each of said means for removing the fluid under pressure applied to said movable valve seat and said means for removing the fluid under pressure applied to said signal responsive valve member comprises electromagnetic valve means including a valve element in fluid-tight engagement with a fluid discharge port, a magnet producing a holding magnetic flux for attracting and holding said valve element in the port closing position against the fluid pressure acting upon said valve element in the port opening direction, and a coil producing a cancelling magnetic flux for urging said valve element to the open position in response to the application of a valve actuating signal, said cancelling magnetic flux passing through said valve element in a direction opposite to the direction of said holding magnetic flux and passing througH said magnet in the same direction as that of said holding magnetic flux.

Claim 24

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a control valve member having a portion thereof normally engaging a recess in said signal responsive valve member in said valve box and movable while following the movement of said actuating rod in the breaking direction until it is locked in a position midway of the above movement of said actuating rod, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member through said control valve member and to follow the movement of said control valve member in one direction after said control valve member has moved away therefrom, said movable valve seat following the movement of said control valve member taking finally a floating position spaced from said signal responsive valve member to shut off the supply of the fluid under pressure to said signal responsive valve member, means mounted on the other end of said actuating rod in another valve box for imparting a making force thereto, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled by disengaging said movable valve seat from said control valve member, hence from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 25

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a control valve member having a portion thereof normally engaging a recess in said signal responsive valve member in said valve box and movable while following the movement of said actuating rod in the breaking direction until it is locked in a position midway of the above movement of said actuating rod, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member through said control valve member and to follow the movement of said control valve member in one direction after said control valve member has moved away therefrom, said movable valve seat following the movement of said control valve member taking finally a floating position spaced from said signal responsive valve member to shut off the supply of the fluid under pressure to said signal responsive valve member, means mounted on the other end of said actuating rod in another valve box for imparting a making force thereto, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled by disengaging said movable valve seat from said control valve member, hence from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 26

A circuit breaker having an actuating system as claimed in claim 19, in which said actuating rod extends through a grounded reservoir filled thereinside with compressed air, a portion of compressed air in said grounded reservoir being supplied to said signal responsive valve member and said making force imparting means accommodated in the valve boxes disposed at opposite end portions of said grounded reservoir, and the breaker section is supported on a tubular insulator upstanding from said grounded reservoir to be electrically insulated from said grounded reservoir, said breaker section being connected to said actuating rod by an actuating rod of electrical insulator.

Claim 27

A circuit breaker having an actuating system as claimed in claim 19, in which a first differential force relationship is established between said signal responsive valve member and said making force imparting means connected to each other by said actuating rod due to the fact that different fluid pressures are applied thereto in directions opposite to each other and the total fluid pressure applied to said signal responsive valve member differs from or is higher than the total fluid pressure applied to said making force imparting means, while a second differential force relationship is established between said signal responsive valve member and said making force imparting means when said movable valve seat movable toward and away from said signal responsive valve member for controlling the total fluid pressure applied thereto is brought into engagement with said signal responsive valve member through said control valve member due to the fact that the total fluid pressure applied to said signal responsive valve member is now lower than the total fluid pressure applied to said making force imparting means, said movable valve seat being moved toward and away from said signal responsive valve member and the fluid pressure applied to said signal responsive valve member being controlled for selectively establishing one of said two difFerential force relationships thereby selectively biasing said actuating rod in one of the making and breaking directions so as to correspondingly actuate the breaker section operatively connected to said actuating rod.

Claim 28

A circuit breaker having an actuating system as claimed in claim 19, in which the fluid under pressure acting upon said signal responsive valve member differs in property from the fluid under pressure acting upon said making force imparting means.

Claim 29

A circuit breaker having an actuating system as claimed in claim 19, in which said making force imparting means imparts the force biasing said actuating rod in the making direction by being urged by the pressure difference between a high-pressure chamber and a low-pressure chamber and is composed of a pair of valve elements which engage individual valve seats in fluid-tight relation during the making and breaking operations respectively by being urged by said pressure difference in the making direction so as to close a communication passage between said pressure chambers and act to allow for complete communication of said high-pressure chamber with said low-pressure chamber through said passage for a predetermined period of time after the making or breaking operation has started, thereby temporarily eliminating the pressure difference between said pressure chambers.

Claim 30

A circuit breaker having an actuating system as claimed in claim 19, in which said means for removing the fluid under pressure applied to said signal responsive valve member includes a fluid discharge passage which opens in said valve box at a position intermediate of the entire moving stroke of said signal responsive valve member.

Claim 31

A circuit breaker having an actuating system as claimed in claim 19, in which said movable valve seat is provided with a flange portion making substantially fluid-tight sliding engagement with the inner wall surface of said valve box and a spring normally biasing said movable valve seat toward said signal responsive valve member, said movable valve seat being urged away from said signal responsive valve member by the difference between the fluid pressures acting upon opposite surfaces of said flange portion, and each of said means for removing the fluid under pressure applied to said movable valve seat and said means for removing the fluid under pressure applied to said signal responsive valve member comprises electromagnetic valve means including a valve element in fluid-tight engagement with a fluid discharge port, a magnet producing a holding magnetic flux for attracting and holding said valve element in the port closing position against the fluid pressure acting upon said valve element in the port opening direction, and a coil producing a cancelling magnetic flux for urging said valve element to the open position in response to the application of a valve actuating signal, said cancelling magnetic flux passing through said valve element in a direction opposite to the direction of said holding magnetic flux and passing through said magnet in the same direction as that of said holding magnetic flux.

Claim 32

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a control valve member having a portion thereof normally engaging a recess in said signal responsive valve member in said valve box and movable while following the movement of said actuating rod in the breaking direction until it is locked in a position midway of the above movement of said actuating rod, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member through said control valve member and to follow the movement of said control valve member in one direction after said control valve member has moved away therefrom, said movable valve seat Following the movement of said control valve member taking finally a floating position spaced from said signal responsive valve member to shut off the supply of the fluid under pressure to said signal responsive valve member, a making force imparting spring mounted on said actuating rod opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled by disengaging said movable valve seat from said control valve member, hence from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 33

A circuit breaker having an actuating system comprising a signal responsive valve member mounted on one end of an actuating rod in a valve box, a control valve member having a portion thereof normally engaging a recess in said signal responsive valve member in said valve box and movable while following the movement of said actuating rod in the breaking direction until it is locked in a position midway of the above movement of said actuating rod, a movable valve seat movable in said valve box toward and away from said signal responsive valve member so as to limit the range of application of fluid under pressure to said signal responsive valve member when brought into engagement with said signal responsive valve member through said control valve member and to follow the movement of said control valve member in one direction after said control valve member has moved away therefrom, said movable valve seat Following the movement of said control valve member taking finally a floating position spaced from said signal responsive valve member to shut off the supply of the fluid under pressure to said signal responsive valve member, a making force imparting spring mounted on said actuating rod opposite to said signal responsive valve member, means for removing the fluid under pressure applied to said movable valve seat, and means for removing the fluid under pressure applied to said signal responsive valve member, the application of fluid pressure to said signal responsive valve member being controlled by disengaging said movable valve seat from said control valve member, hence from said signal responsive valve member during the breaking operation, while it being controlled by said fluid removing means during the making operation for selectively biasing said actuating rod in one of the making and breaking directions thereby correspondingly actuating the breaker section operatively connected thereto.

Claim 34

A circuit breaker having an actuating system as claimed in claim 26, in which said means for removing the fluid under pressure applied to said signal responsive valve member includes a fluid discharge passage which opens in said valve box at a position intermediate the entire moving stroke of said signal responsive valve member.

Claim 35

A circuit breaker having an actuating system as claimed in claim 26, in which said movable valve seat is provided with a flange portion making substantially fluid-tight sliding engagement with the inner wall surface of said valve box and a spring normally biasing said movable valve seat toward said signal responsive valve member, said movable valve seat being urged away from said signal responsive valve member by the difference between the fluid pressures acting upon opposite surfaces of said flange portion, and each of said means for removing the fluid under pressure applied to said movable valve seat and said means for removing the fluid under pressure applied to said signal responsive valve member comprises electromagnetic valve means including a valve element in fluid-tight engagement with a fluid discharge port, a magnet producing a holding magnetic flux for attracting and holding said valve element in the port closing position against the fluid pressure acting upon said valve element in the port opening direction, and a coil producing a cancelling magnetic flux for urging said valve element to the open position in response to the application of a valve actuating signal, said cancelling magnetic flux passing through said valve element in a direction opposite to the direction of said holding magnetic flux and passing through said magnet in the same direction as that of said holding magnetic flux.