Pneumatic Control System

Abstract

The disclosure relates to a pneumatic control system for a working cylinder, which pneumatic control system enables resistance-free manual motion of the device driven by the working cylinder in the event of a failure or switch-off of the compressed air supply and is independent of electrical supply. The problem is solved by means of a pneumatic control system having a double-acting working cylinder, the two chambers of which can be connected oppositely to a compressed air source and a compressed air outlet by means of a controllable supply device having two operating positions, an independently resetting 3/2-way valve switchable by means of a control pressure being arranged before each chamber in a connecting line to the supply device, which 3/2-way valves connect the chambers to bleeding outlets in a first switching position and to the supply device in a second switching position, and a parallel circuit of a check valve and a throttle point being arranged before each chamber, the check valves of which parallel circuits block in the backflow direction, wherein the two 3/2-way valves assume the first switching position in the idle position and can be switched by means of a common control line, which is connected to both connecting lines to the supply device downstream of the 3/2-way valves by means of a changeover valve, and the parallel circuits are arranged in the connecting lines downstream of the respective 3/2-way valves.

Claims

1. A pneumatic control system with a dual-action working cylinder whose two chambers can be connected by means of a controllable supply device having two operating positions in an opposing manner to a compressed air source and a compressed air outlet, and there is arranged upstream of each chamber in a connection line to the supply device in each case an independently returning 3/2-way valve which can be switched with a control pressure, which valves connect the chambers in a first switching position to ventilation outlets and connect them in a second switching position to the supply device, and there is arranged upstream of each chamber a parallel circuit comprising a non-return valve and a throttle location whose non-return valves block in the return flow direction, wherein the two 3/2-way valves in the idle position assume the first switching position and can be switched by means of a common control line which is connected downstream of the 3/2-way valves by means of a shuttle valve to both connection lines to the supply device and the parallel circuits are arranged in the connection lines in each case downstream of the 3/2-way valves.

2. The pneumatic control system as claimed in claim 1, wherein the throttle locations are each formed with an adjustable throttle.

3. The pneumatic control system as claimed in claim 1, wherein the 3/2-way valves are pretensioned in a spring-loaded manner into the idle position.

4. The pneumatic control system as claimed in claim 1, wherein that the supply device is formed by a precontrolled 5/2-way valve (7).

5. The pneumatic control system as claimed in claim 1, wherein the supply device is formed from two pre-controlled 3/2-way valves which are each associated with a chamber.

6. The pneumatic control system as claimed in claim 1, wherein the chamber which is opposite the chamber which is acted on with pressure in each case is ventilated in an initial portion of the piston path additionally via an additional opening, line or additional outlet.

7. The pneumatic control system as claimed in claim 1, wherein both chambers are constructed with additional ventilation openings which are each radially arranged at the beginning of an end portion of the piston path and which connect the chambers in each case via ventilation lines to non-return valves downstream of the parallel circuit to the connection lines (5, 6) which are associated therewith.

Description

[0017] Advantageous developments of the invention will be appreciated below from the description of a preferred embodiment of the invention illustrated with reference to the Figure, in which:

[0018] FIG. 1 is a schematic circuit diagram of a pneumatic control system according to the invention.

[0019] According to FIG. 1, a pneumatic control system according to the invention has a pneumatic drive which is constructed as a dual-action working cylinder 1. The dual-action working cylinder 1 serves to open and close a vehicle door which is not illustrated in FIG. 1 by means of the movement of the piston 2. The two chambers 3 and 4 of the working cylinder 1 are connected by means of connection lines 5 and 6 to the supply device which is constructed as an electromagnetically precontrolled 5/2-way valve 7. The 5/2-way valve is precontrolled by means of the electromagnetic precontrol device 8 and has two working connections 9, 9 for connecting to the two connection lines 5 and 6 to the two chambers 3 and 4 of the dual-action working cylinder 1, and a compressed air connection 10 and two compressed air outlets 11 and 11 (exhaust air outlets). The 5/2-way valve 8 is pretensioned in according to the illustration of FIG. 1 with a resilient device 12 in a spring-loaded manner in a first operating position which is referred to as an idle position and in which the connection line 6 is connected to the compressed air connection 10. In the two connection lines 5 and 6, there are arranged upstream of the chambers 3 and 4, downstream in each case, 3/2-way valves 13 and 13 which can be switched with a control pressure. The two 3/2-way valves 13 and 13 each have a first connection 14 and 14 for connecting to the chambers 3, 4 and a second connection 15, 15 for connecting to the working connections 9, 9 of the 5/2-way valve 7. Furthermore, 3/2-way valves 13 and 13 have ventilation outlets 16, 16. The precontrol of the 3/2-way valves 13 and 13 is carried out by means of the control connections 17, 17 and the common control line 18. The control line 18 draws the control pressure via the shuttle valve 19 and the connection lines 5, 6 downstream of the 3/2-way valves 13 and 13 from the working connections 9, 9 of the 5/2-way valve 7. The 3/2-way valves 13 and 13 have two switching positions, wherein they are pretensioned in accordance with the illustration of FIG. 1 in each case by means of a resilient device 20, 20 in a spring-loaded manner into a first switching position which is referred as the idle position and in which the chambers 3 and 4 of the working cylinder 1 are connected to the ventilation outlets 16 and 16. In the connection lines 5, 6, there are arranged downstream of the 3/2-way valves 13 and 13 and upstream (that is to say, in the direction of the chambers 3, 4) of the branches of the connection line portions 5a, 6a to the shuttle valve 19 in each case parallel circuits comprising non-return valves 21, 21 and adjustable throttle locations 22, 22 whose non-return valves 21, 21 block in the return flow directionthat is to say, downstream. The chambers 3, 4 are constructed with ventilation openings 23, 23 which are arranged radially in each case at the beginning of an end portion of the piston path and which connect the chambers 3, 4 in each case via ventilation lines 24, 24 to non-return valves 25, 25 downstream of the parallel circuit to the portions 5a, 6a of the connection lines 5, 6. The compressed air connection 10 the 5/2-way valve 7 can be connected by means of the hand-operable emergency tap 26 manually either via the working connection 27 to the compressed air connection 28 (which is connected to a compressed air source which is not illustrated in FIG. 1) or the ventilation connection 29.

[0020] The pneumatic control system illustrated in FIG. 1 operates when acted on with compressed air as follows: the emergency tap 26 is open, wherein it is connected via the compressed air connection 10 via the working connection 27 and the compressed air connection 28 of the emergency tap 26 to a compressed air source. If the 5/2-way valve 7, in accordance with the illustration in FIG. 1, is in the first operating position thereof which is at the same time an idle position, the compressed air connection 10 is connected to the working connection 9. Via the connection line 6, the shuttle valve 19 and the non-return valve 21 are acted on in a parallel manner. The shuttle valve 19 opens as a result of the application of pressure via the branch 6a of the connection line 6, whereby the control line 18 is acted on and both 3/2-way valves 13 and 13 are moved via the control connections 17, 17 from the first switching position (the pretensioned idle position) counter to the pretensionings of the resilient devices 20, 20 into their second switching position in each case. In this second switching position, the first connections 14 and 14 are connected to the second connections 15, 15. Via the connection line 6, the non-return valve 21 opens as a result of the application of pressure. Via the opened 3/2-way valve 13, the chamber 4 of the working cylinder is acted on with pressure (aerated). The piston 2 thereby moves from the chamber 4 in the direction of the chamber 3 and a vehicle door driven by the working cylinder 1 opens. The chamber 3 is ventilated in an initial portion of the movement of the piston 2 via the ventilation opening 23, the ventilation line 24, the connection line portion 5a, the connection line 5, the working connection 9 and the compressed air outlet 11 which is connected thereto in the first operating position of the 5/2-way valve, wherein the non-return valve 25 opens as a result of the action of pressure. At the same time, the chamber 3 in this portion of the movement of the piston is also ventilated to a smaller extent via the control line 5 and the opened 3/2-way valve 13, wherein the non-return valve 24 blocks and air is discharged via the throttle location 22 and into the connection line 5 at the working connection 9. As soon as the piston 2 moves over the ventilation opening 23 which is arranged at the beginning of the end portion of the movement thereof, it seals it at the peripheral side so that air can no longer escape from the chamber 3 via the ventilation opening 23. From this point of the movement of the piston 2, the chamber 3 is exclusively ventilated via the control line 5, the opened 3/2-way valve 13 and the throttle location 22. As a result of the delayed emptying via the narrowed cross-section of the throttle location 22, the pressure in the chamber 3 acts as a counter-pressure, which damps the movement of the piston in the end position portion and consequently the opening movement of the vehicle door.

[0021] If the 5/2-way valve 7 is moved by the electromagnetic precontrol device 8 counter to the pretensionings of the resilient device 12 into the second operating position thereof, the compressed air connection 10 is connected to the working connection 9. Via the connection line 5, the shuttle valve 19 and the non-return valve 21 are acted on in parallel. The shuttle valve 19 opens as a result of the application of pressure via the portion 5a of the connection line 5 in the opposite direction, whereby the control line 18 is acted on via the connection line 5, 5a and both 3/2-way valves 13 and 13 are moved via the control connections 17, 17 counter to the pretensionings of the resilient devices 20, 20 into the second switching position thereof in each case. The chamber 3 of the working cylinder 1 is acted on with pressure (aerated) via the open 3/2-way valve 13 and the connection line 5. The piston 2 thereby moves from the chamber 3 in the direction of the chamber 4 and a vehicle door driven by the working cylinder 1 closes. The chamber 4 is in an initial portion of the movement of the piston ventilated via the ventilation opening 23, the ventilation line 24, the connection line portion 6a, the connection line 6, the working connection 9 and the compressed air output 11 connected thereto in the second operating position of the 5/2-way valve 7, wherein the non-return valve 25 opens as a result of the action of pressure. At the same time, the chamber 4 in this portion of the movement of the piston is also ventilated to a lesser extent via the control line 6 and the opened 3/2-way valve 13, wherein the non-return valve 21 blocks and air is discharged via the throttle location 22 into the connection line 6 at the working connection 9. As soon as the piston 2 moves over the ventilation opening 23 which is arranged at the beginning of the end portion of the movement thereof, it seals it at the peripheral side so that air can no longer escape from the chamber 5 via the ventilation opening 23. From this point of the movement of the piston 2, the chamber 4 is exclusively ventilated via the control line 6, the opened 3/2-way valve 13 and the throttle location 22. As a result of the delayed emptying via the narrowed cross-section of the throttle location 22, the pressure in the chamber 4 acts as a counter-pressure which damps the movement of the piston 2 in the end position portion and consequently the closure movement of the vehicle door.

[0022] The sealing action of the piston 2 with respect to the ventilation openings 23 and 23 is improved by it being constructed at both ends thereof with seals, for example, sealing rings which are arranged at the peripheral side.

[0023] The illustration of FIG. 1 shows the pneumatic control in the ventilation position thereof in which the vehicle door driven by the working cylinder 1 can be moved (opened or closed) manually in a resistance-free manner. Via the compressed air connection 10, no air pressure is provided since it is switched off via the emergency tap 26 by the compressed air connection 10 being connected via the working connection 27 to the ventilation connection 29 of the emergency tap 26. In this position, regardless of the operating position of the 5/2-way valve via the working connections 9 and/or 9, no air pressure is provided. The control line 18 and the control connections 17, 17 of the 3/2-way valves 13 and 13 are thereby also not acted on with pressure. The 3/2-way valves 13 and 13 are located as a result of the pretensionings of the resilient devices 20, 20 in the first switching position thereof, the idle position. In this first switching position, the first connections 14 and 14 of the 3/2-way valves 13 and 13 are in each case connected to the ventilation outlets 16, 16. Both chambers 3, 4 of the working cylinder 1 are completely ventilated via the ventilation outlets 16, 16 without the air which is urged during the movement having to pass the cross-section narrowings of the throttle locations 22, 22 since these are arranged only downstream of the 3/2-way valves 13, 13. The piston 2 can be moved in a resistance-free manner from the chamber 4 in the direction of the chamber 3 or in the opposing direction and the vehicle door can be readily opened or closed. The same behavior is seen in the event of a failure of the compressed air supply regardless of the position of the emergency tap 26.

LIST OF REFERENCE NUMERALS

[0024] 1 Working cylinder

[0025] 2 Piston

[0026] 3, 4 Chamber

[0027] 5, 6 Connection line

[0028] 5a, 6a Connection line portion

[0029] 7 5/2-way valve

[0030] 8 Precontrol device

[0031] 9, 9, 27 Working connection

[0032] 10, 28 Compressed air connection

[0033] 11, 11 Compressed air outlet

[0034] 12, 20, 20 Resilient device

[0035] 13, 13 3/2-way valves

[0036] 14, 14 First connection

[0037] 15, 15 Second connection

[0038] 16, 16 Ventilation outlet

[0039] 17, 17 Control connection

[0040] 18 Control line

[0041] 19 Shuttle valve

[0042] 21, 21, 25, 25 Non-return valve

[0043] 22, 22 Throttle location

[0044] 23, 23 Ventilation opening

[0045] 24, 24 Ventilation line

[0046] 26 Emergency tap

[0047] 29 Ventilation connection