Circuit breaker

Claim 2

A circuit breaker comprising: means defining a first orifice positionable in a first fluid stream so that the fluid of such stream can pass therethrough and undergo a first pressure drop; means defining a second orifice positionable in a second fluid stream so that the fluid of such stream can pass therethrough and undergo a second pressure drop; means responsive to the ratio of said pressure drops reaching a predetermined value for at least substantially reducing the flow rate of the first fluid stream; means responsive to the pressure drop across at least one of said orifices for automatically varying the area of said second orifice to maintain the pressure drop thereacross substantially constant over a range of flow rates therethrough; means for correspondingly varying the area of said first orifice so that the pressure drop thereacross is substantially constant; and said orifices being open during normal operation of the circuit breaker.

Claim 3

A circuit breaker as defined in claim 1 wherein said orifices are of substantially equal area whereby said pressure drops are substantially equal for substantially the same flow rates of said fluid streams, and said predetermined ratio is about one to one.

Claim 4

A circuit breaker as defined in claim 1 wherein said means responsive to the ratio of the pressure drops includes a shut off valve.

Claim 5

A circuit breaker as defined in claim 1 wherein the areas of said orifices are variable from substantially completely closed positions to open positions.

Claim 6

A circuit breaker as defined in claim 1 wherein said means for varying includes a Slide valve, said circuit breaker including means responsive to the pressure downstream of said second orifice exceeding the pressure immediately upstream of said second orifice for closing said slide valve whereby said slide valve also serves as a check valve.

Claim 7

A circuit breaker as defined in claim 1 wherein said means responsive to the ratio of the pressure drops includes a valve member, said first orifice being of slightly larger area than said second orifice whereby for equal flow rates the pressure drop across the second orifice is greater than the pressure drop across the first orifice, the pressure drop across the second orifice being used to hold the valve member open whereby the valve member need not be spring biased open.

Claim 8

A hydraulic fuse for use with a hydraulic device comprising: means defining a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device; means defining a return conduit for carrying hydraulic fluid away from the hydraulic device; means defining a supply orifice in said supply conduit through which the fluid can flow, the flow of fluid through said supply orifice causing a first pressure drop; means defining a return orifice in said return conduit through which the fluid can flow, the flow of fluid through said return orifice causing a second pressure drop; a valve member at least partially in said supply conduit and movable between an open position in which the valve member leaves the supply conduit open and a closed position in which the valve member substantially shuts down flow through the supply conduit; means for applying a first force to said valve member having a magnitude which is a function of the first pressure drop and tending to move the valve member to said closed position; means for applying a second force to said valve member having a magnitude which is a function of the second pressure drop and tending to move the valve member to said open position whereby the valve member is controlled by said first and second pressure drops; reservoir means for supplying additional fluid under pressure to said supply conduit downstream of said supply orifice; and said reservoir means including a reservoir, a piston in said reservoir movable in a first direction to expel the fluid in the reservoir toward the hydraulic device, means for retarding movement of said piston in said first direction and conduit means for conducting the fluid from the reservoir to the supply conduit downstream of the supply orifice.

Claim 9

A hydraulic fuse for use with a hydraulic device comprising: means defining a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device; means defining a return conduit for carrying hydraulic fluid away from the hydraulic device; means defining a supply orifice in said supply conduit through which the fluid can flow, the flow of fluid through said supply orifice causing a first pressure drop; means defining a return orifice in said return conduit through which the fluid can flow, the flow of fluid through said return orifice causing a second pressure drop; a valve member at least partially in said supply conduit and movable between an open position in which the valve member leaves the supply conduit open and a closed position in which the valve member substantially shuts down flow through the supply conduit; means for applying a first force to said valve member having a magnitude which is a function of the first pressure drop and tending to move the valve member to said closed position; means for applying a second force to said valve member having a magnitude which is a function of the second pressure drop and tending to move the valve member to said open position whereby the valve member is controlled by said first and second pressure drops; reservoir means for supplying additional fluid under pressure to said supply conduit downstream of said supply orifice; and said reservoir means including a reservoir, a piston in said reservoir movable in a first direction to expel the fluid in the reservoir toward the hydraulic device, means for retarding movement of said piston in said first direction and conduit means for conducting the fluid from the reservoir to the supply conduit downstream of the supply orifice.

Claim 10

A hydraulic fuse as defined in claim 7 including means for maintaining the pressure drop across both of said orifices substantially equal for equal flow rates to and from the hydraulic device, said supply orifice being slightly larger in area than said return orifice whereby for the same pressure drop supply flow can exceed return flow.

Claim 11

A hydraulic fuse for use with a hydraulic device comprising: means defining a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device; means defining a return conduit for carrying hydraulic fluid away from the hydraulic device; means defining a supply orifice in said supply conduit through which the fluid can flow, the flow of fluid through said supply orifice causing a first pressure drop; means defining a return orifice in said return conduit through which the fluid can flow, the flow of fluid through said return orifice causing a second pressure drop; a valve member at least partially in said supply conduit and movable between an open position in which the valve member leaves the supply conduit open and a closed position in which the valve member substantially shuts down flow through the supply conduit; means for applying a first force to said valve member having a magnitude which is a function of the first pressure drop and tending to move the valve member to said closed position; means for applying a second force to said valve member having a magnitude which Is a function of the second pressure drop and tending to move the valve member to said open position whereby the valve member is controlled by said first and second pressure drops; second valve means responsive to the flow rate through the return orifice for correspondingly varying the areas of said orifices so that the pressure drops across each of said orifices will be substantially the same over a range of flow rates when the flow rates to and from the actuator are substantially the same; and the valve member being downstream of the supply orifice and all of the fluid flowing in the supply conduit to the valve member passing through said supply orifice.

Claim 12

A hydraulic fuse for use with a hydraulic device comprising: means defining a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device; means defining a return conduit for carrying hydraulic fluid away from the hydraulic device; means defining a supply orifice in said supply conduit through which the fluid can flow, the flow of fluid through said supply orifice causing a first pressure drop; means defining a return orifice in said return conduit through which the fluid can flow, the flow of fluid through said return orifice causing a second pressure drop; a valve member at least partially in said supply conduit and movable between an open position in which the valve member leaves the supply conduit open and a closed position in which the valve member substantially shuts down flow through the supply conduit; means for applying a first force to said valve member having a magnitude which is a function of the first pressure drop and tending to move the valve member to said closed position; means for applying a second force to said valve member having a magnitude which Is a function of the second pressure drop and tending to move the valve member to said open position whereby the valve member is controlled by said first and second pressure drops; second valve means responsive to the flow rate through the return orifice for correspondingly varying the areas of said orifices so that the pressure drops across each of said orifices will be substantially the same over a range of flow rates when the flow rates to and from the actuator are substantially the same; and the valve member being downstream of the supply orifice and all of the fluid flowing in the supply conduit to the valve member passing through said supply orifice.

Claim 13

A hydraulic fuse as defined in claim 9 wherein said hydraulic fuse includes biasing means for resisting the opening of said second valve means.

Claim 14

A circuit breaker comprising: a body having first and second fluid passages therein; first means defining a first orifice in said first passage; second means defining a second orifice in said second passage, said orifices being of about the same area so that the pressure drops across said orifices are about the same for equal flow rates; a slide valve in said first fluid passage having first and second sets of pressure responsive faces, each of said sets of pressure responsive faces including generally opposed pressure responsive faces; first passage means for supplying fluid under pressure from upstream and downstream of said first orifice to the opposed faces, respectively, of said first set of pressure responsive faces with the net effect being the urging of the slide valve toward a closed position in which substantially no fluid can flow through said first passage; second passage means for supplying fluid from upstream and downstream of said second orifice to the opposed faces, respectively, of said second set of pressure responsive faces with the net effect being the urging of said slide valve toward an open position in which fluid can flow through said first passage; a reservoir in communication with the first fluid passage downstream of said slide valve; and means for expelling fluid from the reservoir into the first passage downstream of said slide valve.

Claim 15

A circuit breaker comprising: a body having first and second fluid passages therein; first means defining a first orifice in said first passage; second means defining a second orifice in said second passage, said orifices being of about the same area so that the pressure drops across said orifices are about the same for equal flow rates; a slide valve in said first fluid passage having first and second sets of pressure responsive faces, each of said sets of pressure responsive faces including generally opposed pressure responsive faces; first passage means for supplying fluid under pressure from upstream and downstream of said first orifice to the opposed faces, respectively, of said first set of pressure responsive faces with the net effect being the urging of the slide valve toward a closed position in which substantially no fluid can flow through said first passage; second passage means for supplying fluid from upstream and downstream of said second orifice to the opposed faces, respectively, of said second set of pressure responsive faces with the net effect being the urging of said slide valve toward an open position in which fluid can flow through said first passage; a reservoir in communication with the first fluid passage downstream of said slide valve; and means for expelling fluid from the reservoir into the first passage downstream of said slide valve.

Claim 16

A circuit breaker as defined in claim 11 wherein said first and second means includes a second slide valve movable in said first and second fluid passages to partially define said orifices and to vary the areas thereof.

Claim 17

A circuit breaker as defined in claim 12 including means responsive to the pressure drop across said second orifice for controlling the position of said second slide valve to increase the areas of said orifices in response to an increase in the pressure drop across said second orifice and to decrease the areas of said orifices in response to a reduction in the pressure drop across said second orifice.

Claim 18

A circuit breaker as defined in claim 13 including resilient means for urging said second slide valve in a direction to reduce the areas of said orifices, said means for expelling including a piston movable in at least one direction in said reservoir and biasing means for retarding the movement of said piston in said one direction.

Claim 19

A circuit breaker for use with a hydraulic device comprising: a supply conduit for supplying fluid under pressure to the hydraulic device; a return conduit for carrying fluid away from the hydraulic device; valve means in said supply conduit responsive to the quantity of fluid flowing through said supply conduit exceeding by a predetermined amount the quantity of fluid flowing through the return conduit for closing said supply passage; reservoir means for providing a small quantity of fluid to said supply conduit intermediate said valve means and the hydraulic device to thereby cause fluid flow in said return conduit to cause opening of said valve means for start up; and means responsive to the quantity of fluid flowing through said return conduit being at least about equal to the quantity of fluid flowing through the supply conduit for holding said valve means open.

Claim 20

A circuit breaker for use with a hydraulic device comprising: a supply conduit for supplying fluid under pressure to the hydraulic device; a return conduit for carrying fluid away from the hydraulic device; valve means in said supply conduit responsive to the quantity of fluid flowing through said supply conduit exceeding by a predetermined amount the quantity of fluid flowing through the return conduit for closing said supply passage; reservoir means for providing a small quantity of fluid to said supply conduit intermediate said valve means and the hydraulic device to thereby cause fluid flow in said return conduit to cause opening of said valve means for start up; and means responsive to the quantity of fluid flowing through said return conduit being at least about equal to the quantity of fluid flowing through the supply conduit for holding said valve means open.

Claim 21

A circuit breaker as defined in claim 15 wherein said reservoir means includes a reservoir, first conduit means providing communication between said reservoir and a location in said supply conduit upstream of said valve means, second conduit means for providing communication between said reservoir and a location in said supply conduit downstream of said valve means, a piston movable in said reservoir to expel fluid therein through said second conduit means into said supply conduit, and resilient means for retarding the movement of said piston in a direction tending to expel fluid from the reservoir through said second conduit means into said supply conduit.

Claim 22

A hydraulic device comprising: a body having first and second fluid passages therein; a valve member movable in both of said passages to define therewith first and second orifices of variable area in the first and second passages, respectively; resilient means for urging said valve member in a direction tending to reduce the areas of said orifices; and said valve member having first and second pressure responsive faces, said first pressure responsive face being exposed to fluid in said second passage upstream of said second orifice and said second pressure responsive face being exposed to fluid in said second passage downstream of said second orifice, said pressure responsive faces being arranged so that the pressure drop across said second orifice influences the position of said valve member with an increase in the pressure drop across said second orifice tending to move the valve member to increase the areas of said orifices; said valve member being positioned to define said orifices at least during normal operation of the hydraulic fuse whereby all of the fluid flowing downstream of the valve member passes through said first orifice; a shut off valve means in said first passage downstream of said valve member and responsive to the ratio of the pressure drops across said orifices being in a predetermined ratio for closing said first passage; a reservoir; first and second conduits for connecting said reservoir to locations in said first passage upstream and downstream, respectively, of said shut off valve means; and means in said reservoir at least partially responsive to a pressure differential in said conduits for expelling fluid from the reservoir and through said second conduit to said first passage.

Claim 23

A hydraulic device comprising: a body having first and second fluid passages therein; a valve member movable in both of said passages to define therewith first and second orifices of variable area in the first and second passages, respectively; resilient means for urging said valve member in a direction tending to reduce the areas of said orifices; and said valve member having first and second pressure responsive faces, said first pressure responsive face being exposed to fluid in said second passage upstream of said second orifice and said second pressure responsive face being exposed to fluid in said second passage downstream of said second orifice, said pressure responsive faces being arranged so that the pressure drop across said second orifice influences the position of said valve member with an increase in the pressure drop across said second orifice tending to move the valve member to increase the areas of said orifices; said valve member being positioned to define said orifices at least during normal operation of the hydraulic fuse whereby all of the fluid flowing downstream of the valve member passes through said first orifice; a shut off valve means in said first passage downstream of said valve member and responsive to the ratio of the pressure drops across said orifices being in a predetermined ratio for closing said first passage; a reservoir; first and second conduits for connecting said reservoir to locations in said first passage upstream and downstream, respectively, of said shut off valve means; and means in said reservoir at least partially responsive to a pressure differential in said conduits for expelling fluid from the reservoir and through said second conduit to said first passage.

Claim 24

A circuit breaker for use with a hydraulic device comprising: means defining a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device; means defining a return conduit for carrying hydraulic fluid away from the hydraulic device; means defining supply orifice means in said supply conduit through which the fluid can flow, the flow of fluid through said supply orifice means causing a first pressure drop; means defining return orifice means in said return conduit through which the fluid can flow, the flow of fluid through said return orifice means causing a second pressure drop; a valve member at least partially in said supply conduit and movable between an open position in which the valve member leaves the supply conduit open and a closed position in which the valve member substantially shuts down flow through the supply conduit; means for applying a first force to said valve member having a magnitude which is a function of one of the pressure drops and tending to move the valve member to said closed position; means for applying a second force to said valve member having a magnitude which is a function of the other of the pressure drops and tending to move the valve member to said open position whereby the valve member is controlled by said first and second pressure drops; and means for increasing the effective areas of both of said orifice means automatically in response to an increase in prEssure drop across at least one of said orifice means.

Claim 25

A circuit breaker for use with a hydraulic device comprising: means defining a supply conduit for supplying hydraulic fluid under pressure to the hydraulic device; means defining a return conduit for carrying hydraulic fluid away from the hydraulic device; means defining supply orifice means in said supply conduit through which the fluid can flow, the flow of fluid through said supply orifice means causing a first pressure drop; means defining return orifice means in said return conduit through which the fluid can flow, the flow of fluid through said return orifice means causing a second pressure drop; a valve member at least partially in said supply conduit and movable between an open position in which the valve member leaves the supply conduit open and a closed position in which the valve member substantially shuts down flow through the supply conduit; means for applying a first force to said valve member having a magnitude which is a function of one of the pressure drops and tending to move the valve member to said closed position; means for applying a second force to said valve member having a magnitude which is a function of the other of the pressure drops and tending to move the valve member to said open position whereby the valve member is controlled by said first and second pressure drops; and means for increasing the effective areas of both of said orifice means automatically in response to an increase in prEssure drop across at least one of said orifice means.

Claim 26

A circuit breaker as defined in claim 18 wherein said means for increasing the effective area of said first orifice means includes a valve member, said circuit breaker including spring means for biasing at least one of said valve members.

Claim 27

A circuit breaker as defined in claim 18 including means for supplying limited quantities of additional hydraulic fluid under pressure to the hydraulic device to thereby tend to increase return flow a limited amount.

Claim 28

A circuit breaker for use with a hydraulic device comprising: a first conduit for supplying hydraulic fluid under pressure to the hydraulic device; a second conduit for carrying hydraulic fluid away from the hydraulic device; a shut off valve member movable to block said supply conduit; means for normally urging said shut off valve member in an opening direction; means including restricted passage means in said first and second conduits for measuring flow in said first and second conduits; flow summing means associated with said shut off valve member for causing said valve member to move in a closing direction in response to said measuring means when the flow in said first conduit exceeds the flow in said second conduit by a predetermined amount; and control valve means disposed in said first and second conduits and effective in response to small pressure differentials reflecting increases in flow demand by said hydraulic device to increase the flow through said circuit breaker and to maintain substantially constant pressure differentials across the restricted passage means as such flow through the circuit breaker is increased.

Claim 29

A circuit breaker for use with a hydraulic device comprising: a first conduit for supplying hydraulic fluid under pressure to the hydraulic device; a second conduit for carrying hydraulic fluid away from the hydraulic device; a shut off valve member movable to block said supply conduit; means for normally urging said shut off valve member in an opening direction; means including restricted passage means in said first and second conduits for measuring flow in said first and second conduits; flow summing means associated with said shut off valve member for causing said valve member to move in a closing direction in response to said measuring means when the flow in said first conduit exceeds the flow in said second conduit by a predetermined amount; and control valve means disposed in said first and second conduits and effective in response to small pressure differentials reflecting increases in flow demand by said hydraulic device to increase the flow through said circuit breaker and to maintain substantially constant pressure differentials across the restricted passage means as such flow through the circuit breaker is increased.