Safety valve assembly for controlling clutch and brake in power press or the like

Abstract

A valve assembly for a pressurized fluid line controlling a clutch and brake made up of a pair of valves having movable valve members with separate actuators, each of the valve members having inlet ports and outlet ports, the inlet ports being connected in series and the outlet ports being connected effectively in parallel so that both valves must be activated to pass the pressurized fluid to the control line and so that upon unwanted sticking of one of the valve members in activated position, pressure fluid to the control line is cut off and exhaust fluid from the line is promptly and directly vented.

I claim as my invention: 
     
       1. A safety valve assembly for supplying pressurized fluid from a supply line to a clutch and brake control line to energize the clutch and de-energize the brake and for alternatively exhausting fluid from the control line to an exhaust line to de-energize the clutch and energize the brake which comprises means defining a fluid supply line chamber and an intermediate chamber as well as a control line chamber and an exhaust line chamber, a first valve having a movable valve member cooperating .Badd.only .Baddend.with first and second seats, the first seat being normally closed and the second seat being normally open and having an actuator for activating such valve member, a second valve having a movable valve member cooperating .Badd.only .Baddend.with third and fourth seats, the third seat being normally closed and the fourth seat being normally open and having an actuator for activating such valve member, the first seat being interposed between the supply line chamber and the intermediate chamber and the third seat being interposed between the intermediate chamber and the control line chamber so that such seats are effectively in series with one another with pressurized fluid being passed successively through the first and third seats from the supply line chamber to the control line chamber when the valve members are simultaneously activated by the actuators, the second and fourth seats being both interposed between the control line chamber and the exhaust line chamber with such seats being effectively in parallel with one another so that in the event either one of the movable valve members, upon deactuation, sticks in its activated position (a) flow of pressurized fluid from the supply line will be .Badd.completely .Baddend.cut off and (b) .[.direct access.]. .Iadd.a direct path .Iaddend.for exhausted fluid will be provided from the control line to the exhaust line .Iadd.which bypasses said first and third seats .Iaddend.for insuring that the clutch and brake are in a safe condition. 
     
     
       2. The combination as claimed in claim 1 in which the movable valve members are each in the form of a spool having spaced, inwardly facing flanges cooperating with opposed outwardly facing valve seats with the spools being movable endwise through a limited displacement for alternative closing of the valve seats. 
     
     
       3. The combination as claimed in claim 2 in which the valve seats cooperating with a given spool are formed at the respective ends of a cylindrical insert having lateral openings formed therein. 
     
     
       4. The combination as claimed in claim 1 in which the housing means is unitary enclosing all of said chambers and seats and with means for guiding the movable valve members into seated condition with respect to the seats. 
     
     
       5. A safety valve assembly for supplying pressurized fluid from a supply line to a clutch and brake control line to energize the clutch and de-energize the brake and for alternatively exhausting the fluid from the control line to an exhaust line to de-energize the clutch and energize the brake, which comprises a first valve in the form of a double two-way valve having .Badd.only .Baddend.first and second valve seats defining a total of .Badd.only .Baddend.four ports, the seats being engaged by a valve member movable between limit positions for closing the seats alternatively, a second valve in the form of a three-way valve having .Badd.only .Baddend.third and fourth valve seats defining a total of .Badd.only .Baddend.three ports, the seats being engaged by a valve member movable between limit positions for closing the seats alternatively, separate actuating means for activating the valve members, means for interconnecting the ports associated with the first and third valve seats in series so that when the valve members are both activated, pressurized fluid is conducted in succession past the first and third valve seats, means for interconnecting the ports associated with the second and fourth valve seats in parallel so that when the valve members are both deactuated, exhausted fluid is conducted in parallel past the second and fourth valve seats and so that in the event one of the valve members, upon being deactuated, sticks in its activated position at least the second or fourth seat will remain open to provide direct escape of exhausted fluid from the control line. 
     
     
       6. The combination as claimed in claim 5 in which means are provided for signalling the sticking of one of the valve members. .Iadd. 
     
     
       7.  A safety control system for fluid actuated devices comprising housing means having a supply port, a control port and at least one exhaust port, first and second valve means in said housing means, each valve means having .Badd.only one .Baddend.supply and .Badd.only one .Baddend.exhaust valve .Iadd..[..[.members.]..]..Iaddend. .Badd.member .Baddend.movable simultaneously between a supply position in which the supply valve member is open and the exhaust valve member closed, and an exhaust position in which the exhaust valve member is open and the supply valve member is closed, means connecting the supply valve members of said first and second valve means in series between said supply and control ports, and means connecting the exhaust valve members of said first and second valve means in parallel between said control and exhaust ports, whereby the movement of either valve means to its exhaust position when the other valve means remains partially or fully in its supply position will result in a complete cutoff of fluid pressure from the supply to the control port and a direct connection from the control port to at least one of the exhaust ports, said direct connection bypassing the supply valve members of both said first and second valve means.  .Iadd.8. The combination according to claim 7, each valve means comprising a spool with inwardly facing flanges comprising the supply and exhaust valve members. .Iaddend. .Iadd.9. The combination according to claim 8, said control port being connected to a common chamber disposed between the supply and exhaust valve members of 
     
     
        said two valve means. .Iaddend. .Iadd.10.  The combination according to claim 9, said housing means comprising a single housing. .Iaddend. .Iadd.11. The combination according to claim 7, one of said valve means comprising a double two-way valve and the second valve means comprising a three-way valve, pressure responsive means on each valve for shifting it in one direction, and pilot valves connected to said lastmentioned means. .Iaddend. .Iadd.12. The combination according to claim 11, said valve means normally being in position with their supply valve members closed and their exhaust valve members open. .Iaddend. .Iadd.13. In a safety control valve system for fluid actuated devices, a housing having a supply port, a control port and an exhaust port, first and second normally closed valve means in said housing, each valve means having .Badd.only single .Baddend.facing supply and exhaust valve members, supply and exhaust valve seats alternately engageable by the supply and exhaust valve members of each valve means, a chamber between the supply and exhaust valve seats of each valve means, a direct connection between said chambers whereby they constitute a control line chamber common to both valve means, a direct connection between said control line chamber and said control port, passageway means connecting the supply valve members of both valve means in series between said supply and control ports, whereby one supply valve member is upstream and the other is downstream, means separating said control line chamber from said upstream supply valve member, and a common exhaust chamber for both valve means leading to the exhaust port, said common exhaust chamber being connected to the exhaust valve members of both valve means in parallel and being separated from said passageway means, whereby a direct exhaust passage will be provided between the control port and exhaust port through said control line chamber when either valve means is in its exhaust position, said direct exhaust passage bypassing the supply valve members of both valve means.  .Iadd.14. The combination according to claim 13, said supply and control ports being on opposite sides of said housing, said valve means being movable at right angles to the extent of the housing. .Iaddend.