Pneumatic safety coupler

1. A coupling assembly for a compressed air circuit comprising:

(a) locking means for releasably engaging first and second sub-assemblies located at respective ends of first and second air lines, the first air line being connected to a tool adapted for compressed air operation, and the second air line being connected to a supply of compressed air,

(b) valve means for controlling the flow of compressed air between the first and second air lines, the valve means being connected to the second sub-assembly and being slidably movable between a first position where it allows compressed air flow, and a second position where it prevents compressed air flow, such that when the locking means are engaged, the valve means can be positioned in either the first position or the second position, and

(c) stop means for preventing disengagement of the first and second sub-assemblies when the valve means is in the first position,

where said locking means includes pairs of first and second locking claws being twistable between locked and unlocked positions, and

where said stop means includes a pair of stop arms which, when the valve means is in the first position, are slid between interlocking pairs of first and second locking claws so as to prevent the locking claws being twisted to their unlocked positions, and when the valve means is in the second position, are slid away from between interlocking pairs of first and second locking claws so as to allow twisting of the locking claws to their unlocked positions.

2. The coupling assembly of claim 1 further including latch means for selectively preventing movement of the valve means from the second position to the first position.

3. The coupling assembly of claim 2 wherein the latch means comprise a pair of latch pins which are pivotally mounted to the stop arms.

4. The coupling assembly of claim 3 wherein the latch pins are biased to pivot to a position where they abut against an obstructing wall of the second sub-assembly when the sleeve is in its second position.

5. The coupling assembly of claim 2 wherein the valve means is a sleeve having a body portion and a flared collar.

6. The coupling assembly of claim 5 wherein the stop arms are integrally connected to the flared collar.

7. The coupling assembly of claim 5 wherein the sleeve has an annular air flow cavity and an annular air vent cavity that are divided by an isolator wall that includes a sealing means which, when the sleeve is in its second position, provides an airtight sealing against a dividing wall of the second sub-assembly.

8. The coupling assembly of claim 7 wherein the dividing wall separates an air-in pressurized chamber of the second sub-assembly from an air-out, atmospherically pressured chamber of the second sub-assembly, and each of the two chambers have air flow ports, and wherein the airtight sealing of the isolator wall against the dividing wall prevents compressed air flow from the pressurized chamber to the atmospherically pressured chamber via the air flow ports.

9. A coupling assembly for a compressed air circuit operable with first and second air lines each having an inlet end and an outlet end,

said first air line having its outlet end connectible to a tool adapted for compressed air operation and its inlet end connectible to a second coupling sub-assembly,

said second air line having its inlet end connectible to a supply of compressed air and its outlet end connectible to said first coupling sub-assembly, comprising:

(a) a locking device on said second coupling sub-assembly for releasably connecting together said first and second coupling sub-assemblies,

(b) a valve for controlling the flow of compressed air between said first and second air lines, said valve being coupled to said second sub-assembly and being slidably movable between a first position where it allows compressed air flow and a second position where it prevents compressed air flow, such that when the locking device has connected together the first and second coupling sub-assemblies, the valve can be positioned in either the first position or the second position,

(c) said locking device further comprising: (i) locking claws movable between a first position for preventing disconnection of said first and second sub-assemblies when said valve is in its first position, and a second position which allows said disconnection when said valve is in its second position, and (ii) a stop element including a pair of stop arms selectively movable to a first position where they prevent said locking claws from being moved to their unlocked positions, and a second position where they no longer prevent said movement of the locking claws to their unlocked positions.

10. The coupling assembly of claim 9 further including a latch for selectively preventing movement of said valve from the second position to the first position.

11. The coupling assembly of claim 10 wherein the valve is a sleeve that has a body portion and a flared collar.

12. The coupling assembly of claim 11 wherein the stop arms are integrally connected to the flared collar.

13. The coupling assembly of claim 11 wherein the sleeve has an annular air flow cavity and an annular air vent cavity that are divided by an isolator wall that includes a seal element which, when the sleeve is in its second position, provides an airtight seal against a dividing wall of the second sub-assembly.

14. The coupling assembly of claim 13 wherein the dividing wall separates an air-in pressurized chamber of the second sub-assembly from an air-out, atmospherically pressured chamber of the second sub-assembly, and each of the two chambers have air flow ports, and wherein the airtight sealing of the isolator wall against the dividing wall prevents compressed air flow from the pressurized chamber to the atmospherically pressured chamber via the air flow ports.

15. A coupling assembly for a compressed air circuit operable with first and second air lines each having an inlet end and an outlet end,

said first air line having its outlet end connectible to a tool adapted for compressed air operation and its inlet end connectible to a second coupling sub-assembly,

said second air line having its inlet end connectible to a supply of compressed air and its outlet end connectible to said first coupling sub-assembly, comprising:

(a) a locking device on said second coupling sub-assembly for releasably connecting together said first and second coupling sub-assemblies,

(b) a valve for controlling the flow of compressed air between said first and second air lines, said valve being coupled to said second sub-assembly and being slidably movable between a first position where it allows compressed air flow and a second position where it prevents compressed air flow, such that when the locking device has connected together the first and second coupling sub-assemblies, the valve can be positioned in either the first position or the second position,

said locking device further comprising: (i) locking claws movable between a first position for preventing disconnection of said first and second sub-assemblies when said valve is in its first position, and a second position which allows said disconnection when said valve is in its second position, and (ii) a stop element including a pair of stop arms selectively movable to a first position where they prevent said locking claws from being moved to their unlocked positions, and a second position where they no longer prevent said movement of the locking claws to their unlocked positions,

(c) a latch for selectively preventing movement of said valve from the second position to the first position,

wherein the latch comprises a pair of latch pins which are pivotally mounted to the stop arms.

16. A coupling assembly for a compressed air circuit operable with first and second air lines each having an inlet end and an outlet end,

said first air line having its outlet end connectible to a tool adapted for compressed air operation and its inlet end connectible to a second coupling sub-assembly,

said second air line having its inlet end connectible to a supply of compressed air and its outlet end connectible to said first coupling sub-assembly, comprising:

(a) a locking device on said second coupling sub-assembly for releasably connecting together said first and second coupling sub-assemblies,

(b) a valve for controlling the flow of compressed air between said first and second air lines, said valve being coupled to said second sub-assembly and being slidably movable between a first position where it allows compressed air flow and a second position where it prevents compressed air flow, such that when the locking device has connected together the first and second coupling sub-assemblies, the valve can be positioned in either the first position or the second position;

said locking device further comprising: (i) locking claws movable between a first position for preventing disconnection of said first and second sub-assemblies when said valve is in its first position, and a second position which allows said disconnection when said valve is in its second position, and (ii) a stop element including a pair of stop arms selectively movable to a first position where they prevent said locking claws from being moved to their unlocked positions, and a second position where they no longer prevent said movement of the locking claws to their unlocked positions, and

(c) a latch for selectively preventing movement of said valve from the second position to the first position,

wherein said latch comprises a pair of latch pins which are pivotally mounted to the stop arms, and

wherein said latch pins are biased to pivot to a position where they abut against an obstructing wall of the second sub-assembly when the sleeve is in its second position.