CH616721A5 - Switching device for a pneumatically actuated double-acting cylinder, especially for the drive of doors - Google Patents

Description

The invention relates to a switching device for a pneumatically operated, double-acting cylinder, in particular for driving doors, with two cylinder connections, in the connections of which to a pressure medium source and to a pressure medium outlet valve means are switched.

In a known switching device of this type for a pneumatic cylinder for actuating a swing door, the valves assigned to the cylinder are actuated electromagnetically. For this purpose, electrical limit switches are provided which are actuated depending on the position of the piston rod extending out of the cylinder. This switching device has the disadvantage that it uses electrical devices in addition to pneumatic devices and is therefore cumbersome and expensive to build. Furthermore, it cannot be used in potentially explosive areas. An additional disadvantage of the known switching device is that it cannot initiate a new starting process when the swing door is in position between two limit switches.

The invention has for its object to avoid these disadvantages and to provide a purely pneumatic switching device which carries out the desired control automatically and reliably with the least means.

This is achieved according to the invention in that the valve means have an initial position in which the first cylinder port is vented and the second cylinder port is shut off by a check valve downstream of the valve means, and they have a working position in which the first cylinder port with the pressure medium source and the second cylinder connection is connected to the pressure medium outlet, and that the second cylinder connection is connected to a control connection of the valve means, the pressure of which loads a closing member against the force of a spring in the direction of the working position.

In this way, the switching device works purely pneumatically. It also builds simply and only requires known, mass-produced elements; Limit switches are completely eliminated. Above all, the switching device can be started again from any position of the piston rod.

Further particularly advantageous refinements of the subject matter of the invention result from the dependent claims, the description and the drawing.

The drawing shows an exemplary embodiment of the subject matter of the invention. This shows in

Fig. 1 shows a first embodiment of the switching device and in

Fig. 2 shows a second embodiment of the switching device.

Fig. 1 shows a switching device 10 with a double-acting cylinder 11 and a 5-way 2-position valve 12. The cylinder 11 has a piston 13 and a piston rod 14 which actuates a swing door via a linkage, not shown, which from a rest position to both Is swung out and is centered by hinge hinges with springs in their rest position. The piston 13 separates a cylinder space 15 with an associated first cylinder port 16 from an annular space 17 with an associated second cylinder port 18. The cylinder 11 has end position damping 19, which takes effect when the piston rod 14 is retracted.

The 5/2-way valve 12 is pilot-controlled and has in the usual way a first (21) and second consumer connection 22, an inlet connection 23, a return connection 24 and a fifth outlet connection 25. A closing member 26 of the directional control valve 12 is centered by a spring 27 in an initial position 28, in which the inlet connection 23 with the first consumer connection 21, the return connection 24 with the second consumer connection 22 and the outlet connection 25 are blocked. The closing member 26 can also assume a working position 29, in which the first consumer connection 21 with the outlet connection 25, the second consumer connection 22 with the inlet connection 23 and the return connection 24 are blocked.

In the 5/2-way valve 12, the outlet connection 25 via a first line 31 to a pressure medium source 32, the inlet connection 23 via a second line 33 with an adjustable throttle point 34 to a pressure medium outlet 35 and

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Return connection 24 is connected via a third line 36 to a check valve 37 securing the connection 24 to the pressure medium outlet 35. A fourth line 38 connects the first consumer connection 21 to the first cylinder connection 16 and a fifth line 39 connects the second consumer connection 22 to the second cylinder connection 18. A control line leads from the second cylinder connection 18

41 to a control connection 42 of the 5/2-way valve 12; it is also connected to the pressure medium outlet 35 via a sixth line 43 with a second check valve 44 securing the pressure medium outlet 35.

The operation of the switching device 10 is as follows:

A swing door, not shown, is in operative connection with the piston rod 14 so that when the swing door is pivoted clockwise or counterclockwise from the spring-centered rest position, the piston rod 14 is pulled out of the cylinder 11.

If the swing door is in the rest position, the piston rod 14 is fully retracted. The closing member 26 is centered in the starting position 28 by the spring 27. As a result, the pressure medium source 32 is blocked, the first cylinder connection 16 is vented via the fourth line 48, the directional control valve 12 and the second line 33, and the second cylinder connection 18 is blocked off by the sixth line 43 with a second check valve 44.

Is achieved by briefly moving the swing door manually or mechanically, e.g. pulled out clockwise, the piston rod 14, so builds up in the annular space 17, which is via the control line 41 at the control port

42 acts and deflects the closing member 26 against the force of the spring 27 in the working position 29. Pressure medium now flows from the pressure medium source 32 via the directional control valve 12 into the cylinder space 15 and presses the piston 13 to the left. Air pushed out of the cylinder chamber 17 escapes via the fifth line 39, the directional control valve 12 and the second line 33 throttled to the pressure medium outlet 35 or via the sixth line 43 and the second check valve 44 to the pressure medium outlet 35. The piston rod 14 is thus initiated when pneumatic Start signal fully extended, the back pressure effective when extending keeps the closing member 26 in the working position 29. If the piston rod 14 is finally fully extended, the dynamic pressure in the annular space 17 is completely reduced via the adjustable throttle point 34, as a result of which the spring 27 presses the closing member into the starting position 28. The springs in the door hinge strips of the swing door now pull the swing-out swing door back into its rest position, the piston rod 14 being retracted. Air can escape from the cylinder space 15 via the directional control valve 12 and the throttle point 34; the piston 13 can suck air into the annular space 17 via the check valve 37, the directional control valve 12 and the fifth line 39. In order to prevent the closing swing door swinging beyond its rest position and causing a start signal in the opposite direction, the cylinder 11 has end position damping 19.

If the swing door is just half closed during the closing process and a new start signal is given by a new manual or mechanical movement of the swing door, the piston rod 14 is fully extended again from the respective position. The swing door can therefore be started from any position between the rest position and the fully open end position.

This advantageous mode of operation is possible both when pivoting the swing door from its rest position in a clockwise direction and when pivoting counterclockwise.

FIG. 2 shows a second switching device 50, which differs from that according to FIG. 1 as follows, the same reference numerals being used for the same parts.

The 5/2-way valve 12 now serves as a pilot valve for a main control valve 51, which is connected in a working line 52 between the pressure medium source 32 and the first cylinder port 16.

The main control valve 51 has an inlet connection 53, a return connection 54 and a consumer connection 55. Its closing member 56 is held in a starting position 58 by a spring 57, in which it blocks the inlet connection 53 and connects the other two connections 54, 55 to one another. From the pressure in a control connection 59, it can be brought into a working position 61 in which the two parts of the working line 52 are connected to one another. A second control line 62 leads from the control connection 59 via a timer 63 and a throttle check valve 64 connected downstream of the latter to the first consumer connection 21 of the pilot valve 12. The check valve 64 secures the timer 63.

The throttle point 34 in the second line 33 and the sixth line 43 with a second check valve 44 according to FIG. 1 are omitted in FIG. 2.

The operation of the switching device 50 is in principle largely the same as that of the switching device 10 according to FIG. 1, with the exception that the extended piston rod 14 can remain in its position for an adjustable time before it is retracted by the swing door.

When the swing door is in the rest position, the locking members 26 and 56 are spring-centered in their starting position 28 and 58, respectively. The cylinder chamber 15 and the second control line 62 with timer 63 are vented and the pressure medium source 32 is shut off.

If a dynamic pressure builds up in the annular space 17 by moving the swing door and thus a start signal is given, the closing member 26 of the pilot valve 12 moves into the working position 29. Compressed air now passes from the pressure medium source 32 via the pilot valve 12, the throttle check valve 64 and the timer 63 into the Control port 59 and presses the closing member 56 of the main control valve 51 in the working position 61. Now pressure medium can flow into the cylinder space 15 and the piston rod 14 fully extend. The dynamic pressure occurring in the annular space 17 - the return port 24 is not vented in the starting position 28 - holds the pilot valve 12 in the working position and thus controls the main control valve 51. When the piston rod 14 is fully extended, the dynamic pressure in the annular space 17 decreases, the pilot valve 12 switches to the starting position 28 and the main control valve 51 only switches back to the starting position 58 when the pressure from the timing element 63 via the throttle check valve 64 has been reduced to such an extent that the spring 57 can reset the closing member 56. The throttle check valve 64 with adjustable throttle can thus be used to select the length of time during which the swing door is to remain in its fully open end position before it is brought back into its rest position by the springs in the door hinges.

With the switching device 50, the swing door can also be restarted from any intermediate position; it is irrelevant whether the swing door had been swung clockwise or counterclockwise.

A particularly simple construction and purely pneumatic construction is thus possible with the switching devices shown. Of course, changes are possible without departing from the spirit of the invention.

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Claims (5)

616721 PATENT CLAIMS 1. Switching device for a pneumatically operated, double-acting cylinder, in particular for driving doors, with two cylinder connections, in the connections of which to a pressure medium source and to a pressure medium outlet valve means are connected, characterized in that the valve means (12; 51) have a starting position (28 ; 58) in which the first cylinder port (16) is vented and the second cylinder port (18) is shut off by a check valve (37) downstream of the valve means (12), and they have a working position (29; 61) in which the first cylinder connection (16) is connected to the pressure medium source (32) and the second cylinder connection (18) is connected to the pressure medium outlet (35), and that the second cylinder connection (18) is connected to a control connection (42) of the valve means (12; 51) , the pressure of which loads a closing member (26) against the force of a spring (27) in the direction of the working position (29). 2. Switching device according to claim 1, characterized in that the valve means are designed as a 5-way 2-position valve (12), the closing member (26) of which is loaded by the spring (27) in the direction of the starting position (28), that the second cylinder connection (18) can be relieved via a second check valve (44) connected in parallel with the valve (12) and that a throttle (34) is connected in the connection from an inlet connection (23) of the valve (12) to the outlet (35). 3. Switching device according to claim 1, characterized in that the valve means as a pilot valve (12) switched into the connections between the second cylinder connection (18) on the one hand and the pressure medium source (32) and check valve (37) on the other hand and as a between the first cylinder connection (16) and pressure medium source (32) switched and influenced by the pilot valve (12) main control valve (51) are formed. 4. Switching device according to claim 3, characterized in that the main control valve is a 3-way, 2-position valve (51), the closing member (56) of which is loaded by a spring (57) has an initial position (58) in which it is the pressure medium source (32 ) blocked and the first cylinder port (16) vented, while it can be brought by the pressure of a second control line (62) into a working position (61) in which the pressure medium source (32) is connected to the first cylinder port (16) that the The pilot valve is a 5-way, 2-position valve (12), the closing member (26) of which in a spring-centered starting position (28) vents the second control line (62) and connects it to the pressure medium source (32) in the working position (29) and into the second control line (62) a throttle check valve (64) and a timing element (63) are connected in series. 5. Switching device according to claim 4, characterized in that the throttle check valve (64) between the timing element (63) and the pilot valve (12) is connected and the check valve (64) protects the timing element (63).