WO2008039061A1

WO2008039061A1 - Coupling system for placing pneumatic or hydraulic control elements in flow communication with one another

Info

Publication number: WO2008039061A1
Application number: PCT/NL2007/000240
Authority: WO
Inventors: Bas Gerard Hodzelmans
Original assignee: Asco Controls B.V.
Priority date: 2006-09-25
Filing date: 2007-09-25
Publication date: 2008-04-03
Also published as: NL1033110C2; EP2069674A1

Abstract

A coupling system for placing pneumatic or hydraulic control elements (2) in flow communication with one another, in particular in the process industry, comprising at least two pneumatic or hydraulic control elements (2) which are provided with connection ports (2'), a coupling which is designed to place two adjacent connection ports (2' ) in flow communication, in which the connection ports (2') and the coupling are provided with complementary screw thread parts (3'). The coupling comprises at least two separate coupling parts (3) which are each designed to be connected by means of the complementary screw thread parts (3') to one of said connection ports (2'), in which the coupling is a sleeve coupling which comprises at least two parts which slidably engage in the axial direction, in which at least one sealing element (5) is provided between the parts which slidably engage.

Description

COUPLING SYSTEM FOR PLACING PNEUMATIC OR HYDRAULIC CONTROL ELEMENTS IN FLOW COMMUNICATION WITH ONE

ANOTHER

The present invention relates to a coupling system for placing pneumatic or hydraulic control elements in flow communication with one another, in particular in the process industry.

Many pneumatic and hydraulic control elements, such as pressure regulators, filters, non-return valves, cocks, valves, etc. are provided ex works with connection ports with internal screw thread. For economic reasons, it is therefore preferable to use these in order to couple the control elements to one another. However, when the ports are provided with conical screw thread, this causes the problem that the screw-in depth and thus the distance between the control elements can vary. At the same time, a fixed position of the control elements is usually desirable. Given the current prior art, determining the position in situ is a method which is out of date. A major drawback of the use of the conical, optionally sealing, screw thread is the screw-in depth of the coupling, which varies, depending on the tolerances of the screw thread. In the process industry, NPT screw thread is generally used. The tolerance with regard to the screw-in depth is approximately +/- 1 turn per screw thread. Thus, the deviation can double for each screwed-in coupling. If sealing tape is used, the variations may become even greater. When two parts are coupled by means of two screw-in couplings which are connected to one another at a fixed distance, the variation in the distance between the control elements is thus possibly several turns. In many cases, it is desirable to screw the control elements onto a support. Particularly in the case of several control elements being coupled together, it remains to be seen if it is desirable to make the couplings supporting too. Screw-in couplings which use the existing connection ports are in fact not able to absorb moments which act around the centre axis of the connection. They could loosen as a result. In addition, they are not designed to support (heavy) control elements . An alternative is the use of coupling blocks which are placed between the control elements . The control elements and/or coupling blocks then have to be provided with chambers for the benefit of, for example, O-ring sealings and with corresponding (screw) connections by means of which the control elements and the coupling blocks are connected. In many cases, the latter option is not available or there is not sufficient space.

Known pneumatic or hydraulic control units for operating an actuator usually comprise several control valves, a pressure-reducing valve, a filter unit, etc. as control elements. These control elements are then, for example, installed on a wall panel, with connecting pieces being screwed into the connection ports of the control elements .

These connecting pieces are in turn connected to flexible hoses or suitably bent rigid pipelines, for example by means of a compression fitting. These thus form a coupling and flow communication between the control elements .

One of the disadvantages of such a control unit is the fact that it takes up a considerable amount of space, its production is labour intensive and it is susceptible to damage, particularly at the couplings, as a result of which leakage may occur.

With other known pneumatic or hydraulic control units for operating an actuator, the control elements are connected directly to one another, and in this case come to lie virtually against one another. In this case, installation on a wall panel does not take place. The coupling comprises, for example, a connecting piece which can be screwed into the connection ports of a control element with both ends in order to place these in flow communication with one another. In some cases, additional connecting elements, such as tension rods, are arranged as an addition between the control elements in order to make the unit sufficiently rigid.

One of the disadvantages thereof is the fact that the assembly of control elements and couplings is not very flexible, usually requires additional connecting elements and is difficult to access. If no additional connecting elements are used, the rigidity of the construction has to be provided by the control elements and by the connecting pieces. This places high demands on the connecting pieces and on the connection between the connecting pieces and the control elements .

It is an object of the present invention to at least partly eliminate the abovementioned disadvantages and/or to provide a usable alternative .

This object is achieved by a coupling system according to claim 1. Pneumatic or hydraulic control elements can now advantageously be coupled to one another in a simple manner with a fixed intermediate distance. The medium is guided through the coupling parts which are screwed into the connection ports of the pneumatic or hydraulic control element. Neither the screw-in depth nor the position of these parts is relevant any more in this case. Very advantageously, the sleeve coupling does not have a supporting function. A separate mechanical connection between the control elements is sufficient. The coupling system thus provides a widely usable connecting facility for control elements. In this context, a control element is to be understood as referring to a component through which a medium can be passed and by means of which the flow can be influenced or the properties thereof can be monitored or measured. This includes a control valve for optionally shutting off the medium flow, a pressure-reducing valve for optionally reducing the medium pressure, a filter unit for filtering the medium, pressure gauges, etc.

Due to the fact that the control elements can be fixed, and the sleeve coupling offers freedom of movement, it is possible to provide a strong and reliable system using few components and requiring little installation effort. The system does not need much space, can be used immediately and reduces the risk of leakage considerably. The system is also able to cope well with differences in temperature.

An additional advantage is the fact that it is now possible to provide a fixed distance between the connection ports of the control elements. This makes it possible to determine the position of the control elements completely without having to use space-consuming flexible elements, such as hoses. Alternatively, control elements are used having optionally normalized special connection ports for use with the corresponding base plates. One side of the control element is then attached to a support, for example screwed onto a base plate. This works particularly well if control elements are connected in parallel.

The control elements can now advantageously be attached to the support in fixed positions, which may, for example, be at predetermined intermediate distances from one another. Thus, it is possible to provide the support with a standard pattern of installation points. Installation slots and the like are no longer required. Also, the mounting positions are advantageously not dependent on the differences in tolerances of the screw thread connection between the control elements and the coupling parts. Thus, it is always possible to achieve a reliably sealing screw thread connection.

Very advantageously, the screw thread connection no longer has to be disconnected in the event of maintenance, replacement and the like, as the sleeve coupling itself can be disassembled. This is particularly advantageous in the case of stainless steel screw thread connections, as these may otherwise become damaged quickly. The control elements can thus be replaced in a simple manner at any time.

Further preferred embodiments are defined in the subclaims .

The invention also relates to an assembly comprising a support and a coupling system according to claims 16 and 17, as well as to the use of the coupling system according to claims 18-20.

The invention will be explained below in more detail with reference to the attached drawings, in which: Fig. 1 shows a first embodiment having two coupling parts;

Fig. 2 shows a preferred embodiment having an external pipe;

Fig. 3 shows a third embodiment having an internal pipe;

Fig. 4 shows a variant of Fig. 2 having an additional connection;

Fig. 5 shows a variant of Fig. 2 having a cartridge; Fig. 6 shows a variant of Fig. 2 having a non-return valve; and

Fig. 7 shows an application in the process industry.

Fig. 1 shows a kind of basic embodiment with the sleeve coupling comprising two screw-in coupling parts (3) which can slide over one another. Fitting and/or removal of the screw-in coupling parts (3) can be effected by using a tool which engages with an internal or external hexagon or, for example, on two flat faces.

The pneumatic or hydraulic control elements (2) are indicated in a simplified manner as rectangular blocks. By means of screws (1), they are attached to a support (4) , which may, for example, be a thick plate or a bent profiled section, which may also form part of a machine or apparatus. The screw-in coupling parts (3) can move axially with respect to one another and rotate about one another because they are provided with a sliding fit. The sealing is achieved by an elastic element, such as an 0-ring (5) . Obviously, it is possible to connect several control elements in series.

Fig. 2 is an illustration of the sleeve coupling comprising two screw-in parts (3) and an external pipe (6) . The two screw-in parts (3) seal the interior of the pipe (6) by means of an elastic seal (5) . In the situation illustrated, the pipe (6) adjoins the control elements (2) on both sides. The length of the pipe (6) is chosen in such a manner that it corresponds to the desired fixed distance between the control elements (2) . In addition, the pipe (6) is now advantageously delimited on both sides, so that it will always be in sealing contact with the seals (5) . The length of this coupling can be varied in a simple manner by changing the length of the pipe (6) . The pipe (6) is able to absorb pressure forces. This is the case when the pressure of the medium in the coupling is lower than the ambient pressure. Fig. 2 shows an asymmetrical variant having a relatively large and a relatively small threaded connection. In one variant, the pipe can also be chosen to be shorter than the desired fixed distance between the control elements. The pipe is then free to slide to and fro slightly or to absorb expansions of the coupling, respectively.

Alternatively, it is possible to produce a coupling with an internal pipe (6), see Fig. 3. However, the pipe (6) will then be able to slide to and fro to some degree in the screw-in parts (3) . It should be noted that the sealing elements (5) which are provided in the internal peripheral wall surface of the screw-in coupling parts (3) in Fig. 3 can, if desired, also be provided in the external peripheral wall surface of the internal pipe (6) . Especially the externally applied coupling pipe is advantageous, as it is axially secured between the control elements and offers better possibilities for extension.

If the coupling pipe (6) is extended, this offers the opportunity of providing additional connections. Fig. 4 shows an example of a T- connection. The fact that the branch can rotate freely is an attractive feature. It can be rotated about 360° and can be positioned in the optimum position, as a result of which any stresses are reduced. Of course, it is possible to produce several branches with an internal thread or external thread or to provide, for example, compression fittings or a welded connection. The arrows indicating the flow direction have been drawn at random.

The pipe offers the possibility of inserting or providing separate sub-control elements. It is, for example, possible to slide nonreturn valves, pressure-regulating valves, restrictions or combinations thereof as a ^cartridge' into the pipe (6) . Securing may^¬ be necessary and can be effected, for example, by means of securing rings in the pipe. Fig. 5 shows an example of such a cartridge, without the exact functionality being indicated. The cartridge (7) is provided with an elastic sealing element (8) and secured by means of two securing rings (9) . Very advantageously, this results in a more compact assembly.

Some sub-control elements can be placed directly in the pipe, for example a non-return valve (10) as illustrated in Fig. 6. The exact opening pressure depends on the screw-in depth of the screw-in parts (3) . This disadvantage does not have to outweigh the advantage of a lower cost price.

The medium can only flow in the direction of the arrows . The nonreturn valve (10) is then pushed open counter to the direction of the force of a spring (11) . In the illustrated, closed position, an elastic sealing element (12) provides sealing. It may be possible to reduce the number of parts further. The drawing only forms an indication of the operational principle.

Cocks are often used as sub-control elements and can also be incorporated into the coupling pipe. Just as with the T-piece, the operating button can be rotated over 360° about the axis of the coupling pipe.

Fig. 7 shows an example of a practical application for the process industry. It illustrates a manifold for operating a single-acting pneumatic cylinder (spring return) which in turn operates, for example, a large butterfly valve in an installation. The supplied compressed air is filtered and its pressure is reduced by means of a filter regulator (15) . One or two (as illustrated) 3/2 magnetic valves (16) act as control valves and guide the air towards the cylinder or vent the cylinder. In that case, the air is blown off via dampers (17) . Should the pressure of the supplied compressed air suddenly be reduced, a non-return valve provided in a sleeve coupling (18) according to the invention can prevent the pressure in the cylinder from dropping. Thus, the undesired displacement of the cylinder can be prevented. The pneumatic control elements are screwed onto an omega-shaped profiled section (19) . Of course, several configurations are possible, such as, for example, operating double- acting cylinders using 5/3 valves.

Many variants are possible in addition to the embodiments shown. Thus, the coupling parts and/or the parts which can slide in the axial direction with respect to one another can be of a different shape. Advantageously, the freedom of movement in the axial direction of the parts which slidably engage in the axial direction is greater than 0.3 cm, in particular greater than 0.5 cm. This freedom of movement is substantially determined by the minimum and maximum overlap which both parts can have with one another, measured from the sealing element. Very advantageously, the sleeve coupling is designed such that the freedom of movement in the axial direction of the parts which slidably engage in the axial direction is greater than the axial length of the connecting sections of the coupling parts, for example the section which, following coupling to the control element, is recessed therein. This makes it possible to arrange the sleeve coupling between the control elements after these control elements have already been fitted in fixed positions with respect to one another, since the sleeve coupling, in the retracted position, fits between the control elements, thus making it possible to connect the coupling parts to the connection ports by screwing in. Furthermore, the sealing elements can also be provided in the internal peripheral wall surfaces and/or in the external peripheral wall surfaces of the parts located opposite one another. Also, the coupling parts can be made from plastic, metal or other materials.

The parts of the sleeve coupling, which parts slidably engage in the axial direction, preferably engage with one another with a tight- fitting sliding fit and can in this case rotate with respect to one another about the longitudinal axis. However, if desired, it is also possible to provide a clearance between the parts and/or limit the rotation.

The screw thread on the coupling parts is preferably formed by a conical screw thread, in particular so-called NPT screw thread. This advantageously secures itself on the connection ports provided with screw thread during screwing in.

The coupling system according to the invention is particularly suitable for use in the process industry, for example as a control unit for operating an actuator. In particular, the coupling system made up of control elements and sleeve couplings forms a control unit for controlling a piston-cylinder system by means of which a valve in a process stream line can be opened and closed. To this end, the control unit comprises at least one control valve and a filter unit as control elements.

Thus, a coupling system is provided which is user-friendly and inexpensive to produce, can be fitted and removed, does not have to absorb excessively great forces and does not constitute an obstacle to installing pneumatic or hydraulic control elements in fixed positions.

Claims

1. Coupling system for placing pneumatic or hydraulic control elements (2) in flow communication with one another, in particular in the process industry, comprising:

- at least two pneumatic or hydraulic control elements (2) which are provided with connection ports (2' ) ;

- a coupling which is designed to place two adjacent connection ports (2' ) in flow communication; in which the connection ports (2' ) and the coupling are provided with complementary screw thread parts (3' ) , characterized in that the coupling comprises at least two separate coupling parts (3) which are each designed to be connected by means of the complementary screw thread parts (3' ) to one of said connection ports (2' ) , in which the coupling is a sleeve coupling which comprises at least two parts which slidably engage in the axial direction, in which at least one sealing element (5) is provided between the parts which slidably engage .

2. Coupling system according to one of the preceding claims, in which the control elements (2) are provided with fastening means (1) for securing the control elements (2) on a support (4), without fixing the coupling parts (3) themselves with respect to one another.

3. Coupling system according to one of claims 1-2, in which the parts which slidably engage in the axial direction are formed by said coupling parts (3) which are designed to be connected by means of the complementary screw thread parts (3' ) to one of said connection ports (2').

4. Coupling system according to one of claims 1-2, in which the sleeve coupling furthermore comprises an additional coupling element (6) which slidably engages with said coupling parts (3) which are designed to be connected by means of the complementary screw thread parts (3') to one of said connection ports (2'), and in which the sealing elements (5) are provided between the coupling parts (3) and the additional coupling element (6) .

5. Coupling system according to claim 4, in which the additional coupling element (6) is an internal or external tubular element.

6. Coupling system according to one of claims 4-5, in which the additional coupling element (6) is provided with a branch.

7. Coupling system according to one of claims 4-6, in which the additional coupling element (6) accommodates a sub-control element, such as a non-return valve (10) , pressure-regulating valve, restriction or combinations thereof.

8. Coupling system according to claim 7, in which the sub-control element is accommodated in a cartridge (7) .

9. Coupling system according to one of claims 4-8, in which the additional coupling element comprises a cock.

10. Coupling system according to one of the preceding claims, in which the parts which slidably engage in the axial direction engage with one another by means of a sliding fit.

11. Coupling system according to one of the preceding claims, in which the parts which slidably engage in the axial direction also engage rotatably.

12. Coupling system according to one of the preceding claims, in which the coupling parts (3) which are designed to be connected to one of said connection ports (2' ) by means of the complementary screw thread parts are provided with conical screw thread parts, in particular NPT screw thread.

13. Coupling system according to one of the preceding claims, in which the coupling parts (3) which are designed to be connected to one of said connection ports (2' ) by means of the complementary screw thread parts (3' ) are provided with an external or internal profiling with which tools can engage.

14. Coupling system according to one of the preceding claims, in which the control elements (2) comprise at least one control valve (16) .

15. Coupling system according to claim 14, in which the control elements (2) furthermore comprise a filter unit (15) .

16. Assembly of a support (4) and a coupling system according to one of the preceding claims, in which the at least two pneumatic or hydraulic control elements (2) are fixedly connected to the support (4), in which the at least two separate coupling parts (3) provide a flow communication between the two adjacent connection ports (2' ) , and to this end are each connected to one of said connection ports

(2') by means of the complementary screw thread parts (3')_/ in which the at least two parts which slidably engage in the axial direction engage sealingly as a sleeve coupling by means of the at least one sealing element (5) which is provided between the parts of the sleeve coupling which slidably engage with one another.

17. Assembly according to claim 16, in which the control elements (2) are provided on the support (4) at fixed intermediate distances from one another .

18. use of a coupling system according to one of the preceding claims in the process industry.

19. use of a coupling system according to one of the preceding claims in a control unit for operating an actuator.

20. use according to claim 19, in which the actuator is a piston- cylinder system for opening and closing a valve in a process stream line.