Equipment with replaceable connection element and process valve assembly

Abstract

Operating equipment (10), in particular control head, positioner, positioner and / or sensor control, for process automation for use in an area where there is a risk of explosion and dusts, in particular electrically conductive dusts, may be present, comprising: a wall structure (1) serving as the housing of the equipment (10) comprising a first wall structure section (5) defining a first housing interior (11) and a second wall structure section (6) defining a second housing interior (12) separate from the first housing interior (11), wherein a first circuit arrangement (21) is arranged in the first housing interior (11) and the first housing interior (11) is enclosed dust-tight by the first wall structure section, so that dust cannot penetrate into the first housing interior (11) and the explosion safety of the first housing interior is ensured by the dust-tight enclosure, where in the second housing interior (12) one or more circuits (24) are arranged and all circuits (23) arranged in the second interior (12) form an intrinsically safe second circuit arrangement (22) so that even if dust penetrates the second housing interior (12), no explosion-triggering heating and / or sparking is possible through the second circuit arrangement (22) and the explosion safety of the second housing interior (12) is ensured by the intrinsically safe design of the second circuit arrangement (22), wherein the device (10) has a replaceable connection element (7) which is part of the second wall structure section (6), wherein the connection element has one or more fluid connections (16, 17).

Description

The invention relates to a working medium, in particular a control head, positioner, positioner and / or a sensor control, for process automation for use in an environment in which there is a risk of explosion and dusts can occur. The dusts mentioned here and below are in particular electrically conductive dusts.The operating means comprises a wall structure which serves as a housing of the operating means and comprises a first wall structure section which defines a first housing interior region. The wall structure further includes a second wall structure portion defining a second housing interior region separate from the first housing interior region. A first circuit arrangement is arranged in the first housing interior region and the first housing interior region is surrounded in a dust-tight manner by the first wall structure section, such that the dusts cannot penetrate into the first housing interior region and the dust-tight enclosure ensures explosion safety of the first housing interior region.From the prior art, operating means with a sealed housing interior are known. WO 2009 / 09569 A1 describes, for example, a positioner which has a watertight housing for protecting sensitive electrical components.Furthermore, U.S. Pat. No. 7,647,940 B2 describes a valve control with separate chambers for mechanical and electrical components.DE 10 2012 108 414 A1 relates to an electronic device having a housing for accommodating electronic components.DE 10 2010 030 924 A1 relates to an electronics housing for an electronic device or device formed therewith.DE 30 37 783 A1 relates to a Zener barrier.DE 601 12 780 T2 relates to a drive mechanism.It is an object of the invention to configure the working medium such that, when used in an environment in which there is a risk of explosion and dusts, in particular electrically conductive dusts, can occur, explosion safety is ensured without the function and / or possible adaptations of the working medium being excessively restricted.This object is achieved by a working medium according to claim 1. one or more circuits are arranged in the second housing interior region of the working medium and all circuits arranged in the second interior region form an overall intrinsically safe second circuit arrangement, so that even if the dusts penetrate into the second housing interior region no explosion-triggering heating and / or sparking is possible by the second circuit arrangement and the overall intrinsically safe design of the second circuit arrangement ensures the explosion safety of the second housing interior region. The operating medium has a replaceable connecting element which is part of the second wall structure section, wherein the connecting element has one or more fluid connections.Overall, therefore, a working medium divided into two housing interior regions results, in which a different type of ignition protection is used in each housing interior region. In the first housing interior region, explosion protection is achieved in particular by the ignition protection type "protection by housing Ex t", and in the second housing interior region 12 by an overall intrinsically safe embodiment of the first circuit arrangement. An overall intrinsically safe design can also be referred to as single-circuit intrinsic safety.Because the first housing interior region is closed in a dust-tight manner, the first circuit arrangement does not necessarily have to be designed as a whole in an intrinsically safe manner; i.e. the first circuit arrangement can also be designed such that there would be the risk of an explosion-triggering short circuit in the event of penetration of dust. In the case of the not altogether intrinsically safe embodiment, in particular a multi-circuit intrinsic safety can be present; that is to say a plurality of circuits which are intrinsically safe in each case are present. A not entirely intrinsically safe design can also be referred to in this case as existing multi-circuit intrinsic safety. In the first housing interior region, the requirements for the first circuit arrangement accommodated there are consequently lower, so that the first circuit arrangement can also comprise very complex circuits. In particular, the first circuit arrangement can also comprise security barriers, for example a resistor connected as a security barrier diode and / or a resistor connected as a security barrier.The requirements imposed on the second circuit arrangement accommodated in the second housing interior are higher--here all circuits must be intrinsically safe overall; that is, even when dust is being loaded, no explosion-causing heating and / or spark formation is possible. Accordingly, the second housing interior preferably accommodates only simple circuits, such as analog-to-digital converters or digital-to-analog converters, which are also intrinsically safe as a whole.For this purpose, the second housing inner region does not have to be designed to be dust-tight and / or in particular does not have to be verified and / or certified for its dust tightness, and it is expediently also not. This makes it possible to change and / or adapt the second wall structure section without major effort; finally, no dust tightness has to be ensured for the second housing interior region and also no verification / certification has to take place in this regard, so that an adaptation does not entail any major effort.Thus, explosion safety can be ensured with the operating means according to the invention without the function and / or adjustment possibilities being excessively restricted as a result.Exemplary details and embodiments are explained below with reference to the figures. This shows FIG. 1 shows a schematic illustration of a resource, and FIG. 2 is a schematic illustration of a process valve assembly.FIG. 1 shows a working medium 10, which is here exemplarily designed as a control head, positioner and / or positioner, preferably for controlling a valve drive 20 and / or a valve fitting 30. Alternatively, the operating medium 10 can also be designed differently; for example, the operating medium 10 can also be a sensor control; that is, a device with which sensors are controlled and / or read out. In principle, the operating medium 10 is an electrical device for process automation, which is used in a region in which there is a risk of explosion and in which dusts, in particular electrically conductive dusts, can occur.The operating medium 10 comprises a wall structure 1. the wall structure 1 serves as a housing for the operating medium 10. the wall structure 1 has a first wall structure section 5 and a second wall structure section 6.The first wall structure portion 5 defines a first housing interior region 11 and the second wall structure portion 6 defines a second housing interior region 12. A first circuit arrangement 21 is arranged in the first housing inner region 11 and a second circuit arrangement 22 is arranged in the second housing inner region 12.Explosion resistance in the two housing interior regions 11 and 12 is achieved in different ways:Explosion-proof is ensured in the first housing inner region 11 by the first housing inner region 11 being surrounded in a dust-proof manner by the first wall structure section 5, so that the dusts cannot penetrate into the first housing inner region 11.In this way, it is prevented that the dusts penetrate into the first housing inner region 11 and can lead there to a short circuit in the first circuit arrangement 21, which could cause explosion-triggering spark formation and / or explosion-triggering heating.In the first housing inner region 11, explosion safety is consequently achieved by dust-proof enclosure.In the second housing inner region 12, on the other hand, explosion safety is achieved by an overall intrinsically safe design of the second circuit arrangement 22. The second circuit arrangement 22 is formed by all the circuits 24 present in the second housing interior region 12. Due to the overall intrinsically safe design of the second circuit arrangement 22, even if the dusts penetrate into the second housing inner region 12, no explosion-triggering heating and / or sparking is possible due to the second circuit arrangement 22. Thus, in the second housing interior region, explosion safety is achieved by the overall intrinsically safe design of the second circuit arrangement 22.The subdivision into the two housing interior regions 11, 12 and the different guarantee of explosion safety in the two housing interior regions 11, 12 is advantageous since the wall structure 1 or the housing of the operating means can thus be adapted more easily.Thus, only a part of the wall structure 1-namely the first wall structure section 5-must be dust-tight, while the second wall structure section 6 does not necessarily have to be dust-tight. In particular, add-on elements, such as connection elements, which are part of the second wall structure section 6, can thus be easily adapted, changed or exchanged without the need to achieve, verify and / or certify dust tightness of the second housing inner region 12.Complex circuits, in which an overall intrinsically safe design would be very expensive, can be accommodated in the first housing inner region 11, where they are protected from the electrically conductive dust by the first wall structure section 11 and therefore do not necessarily have to be overall intrinsically safe.Exemplary details of the operating means 10 are explained below.First of all, regarding the basic structure and the basic function of the operating means 10:The operating medium 10 is in particular an electrical and / or fluidic device that can be handled as a physical unit and has the housing 2 that represents the outer wall of the operating medium 10. The housing 2 can be integral or can consist of several sections, in the latter case expediently all sections of the housing 2 being firmly connected to one another. The housing 2 is formed by at least a part of the wall structure 1-in the example shown by the outer walls of the wall structure 1.The direction of the width of the operating medium 10 is also to be referred to as the x-direction and the direction of the height of the operating medium 10 is to be referred to as the z-direction. The direction of depth (which is normal to the drawing plane) will be referred to as the y-direction. The x-direction, y-direction and z-direction are oriented orthogonally to one another.The operating medium 10 is expediently designed to be placed on the valve drive 20 and / or the valve fitting 30. For this purpose, a corresponding mechanical interface (not shown in FIG. 1 ) can be provided on the underside of the housing 2.As shown in FIG. 2, the operating medium 10 can form a process valve assembly 40, for example together with the valve drive 20 and the valve fitting 30. For the sake of better clarity, the operating medium 10, the valve drive 20 and the valve fitting 30 are shown spaced apart from one another in FIG. 2 ; in fact, however, the operating medium 10 can be placed on the valve drive 20 and the valve drive 20 can be placed on the valve fitting 30.By way of example, the operating medium 10 has a display 3 arranged on the outside of the housing 2, in particular a graphic display, with which, for example, an operating state of the operating medium 10 can be displayed.Furthermore, the operating means 10 is expediently designed to communicate with a superordinate control unit (not shown), for example a programmable logic controller, PLC, in order to obtain commands for controlling the valve drive 20 and / or the valve fitting 30 and / or in order to transmit feedback, for example a sensor value and / or status information, to the superordinate control. For this purpose, the operating medium 10 comprises one or more communication circuits 25, which are in particular part of the first circuit arrangement 21.The operating medium 10 is furthermore designed as an example, in particular to provide an activation, in particular by means of fluidic signals, of the valve drive 20 and / or of the valve fitting 30 on the basis of commands received from the superordinate controller. For this purpose, the operating medium 10 has a control circuit 27, for example one or more microcontrollers 37, 38, in which in particular a control and / or regulator model is stored, which is adapted to the valve drive 20 and / or the valve fitting 30 and by the use of which the control takes place. The control circuit 27 is in particular part of the first circuit arrangement 21.Furthermore, the operating medium 10 expediently has a fluid device 28, in particular one or more valves, preferably one or more pilot valves, which is actuated by the control circuit 27 and which, on the basis of this actuation, provides fluidic signals for the valve drive 20 and / or the valve fitting 30.The operating medium 10 expediently has a plurality of external connections 16, 17, in particular fluidic connections. The connections 16, 17 can be arranged in particular on a removable connection element 7, which expediently forms part of the housing 2. Expediently, the connections 16, 17 serve to provide a fluidic connection to the fluid device 28. Via the connections 16, 17, the fluid device 28 can be fluidically connected, for example, to a pressure fluid source (not shown) and / or to one or more pressure chambers 47 of the valve drive 20. In particular, the operating medium 10 is designed to output fluidic signals for controlling the valve drive 20 and / or the valve fitting 30 via one or more of the connections 16, 17.For example, fluidic signals are output to one or more pressure chambers 47 of the valve drive 20 to actuate one or more pistons 46 of the valve drive 20, which in turn actuates a drive shaft 48. The drive shaft 48 is coupled to a valve member 49 arranged in a process fluid channel 51. The position of the valve member 49 can thus be changed by the control carried out by the operating medium 10 and consequently influence a process fluid flowing through the process fluid channel 51.Expediently, the drive shaft 48 is furthermore coupled to a shaft 14 of the operating medium 10, which is arranged in particular in the first housing inner region 11. The shaft 14 is in turn coupled to a rotation angle measuring unit 15 expediently arranged in the first housing inner region 11 and / or to a position indicator 4.As already mentioned, the inner region enclosed by the housing 2 is divided into a first housing inner region 11 and a second housing inner region 12. The first housing interior 11 and the second housing interior 12 are, for example, two partial volumes, which do not overlap one another, of a total volume enclosed by the housing 2. According to a preferred embodiment, the first housing inner region 11 and the second housing inner region 12 together represent the entire inner region of the housing 2 or of the operating medium 10. Preferably, the first housing interior 11 represents more than 50% of the total interior; and the second housing interior 12 represents more than 20%, 30%, or 40% of the total interior.The first housing interior 11 is dust-tightly closed by the first wall structure section 5 with respect to the environment of the operating medium 10 and / or with respect to the second housing interior 12, in particular according to IP 6 x.The two housing interior regions 11, 12 can expediently be divided into a plurality of subareas 41, 42, 43, 44, 45, for example by the second printed circuit board 32 and / or the third printed circuit board 33.The housing interior regions 11, 12 are defined by the wall structure sections 5, 6. The wall structure sections 5, 6 are expediently integral components of the wall structure 1 or of the operating medium 10.The division into the two housing interior regions 11, 12 is effected by means of the wall structure 1, in particular by means of wall elements 8, 9 of the wall structure 1 projecting into the interior region of the housing 2. the wall structure 1 has, by way of example, the wall element 8 projecting inward in the x direction from a side wall of the housing 2 and the wall element 9 projecting upward in the z direction from the bottom wall of the housing 2, which wall elements meet in the interior region of the housing 2. The wall elements 8 and 9 are expediently each designed in the form of strips. The wall element 8 is oriented with its largest surface normal to the z-direction and the wall element 9 is oriented with its largest surface normal to the x-direction. The wall element 8 and the wall element 9 form part of the first wall structure section 5 and the second wall structure section 6, respectively. the wall elements 8 and 9 provide a dust-proof separation of the first housing inner region 11 from the second housing inner region 12.By way of example, a part of the first wall structure section 5, in particular the wall element 8, is formed by a first printed circuit board 31 arranged in the housing 2. Preferably, the first printed circuit board 31 is also part of the second wall structure section 6.The first printed circuit board 31 is exemplarily aligned horizontally, i.e. in a y-z plane, and expediently runs over the entire width of the volume enclosed by the housing 2. The first printed circuit board 31 rests on the wall element 9 and is expediently supported by the latter. By way of example, the first printed circuit board 31 and the wall element 9 form a T-shaped structure.The contact points between the first printed circuit board 31 and the side wall of the housing 2 and between the first printed circuit board 31 and the wall element 9 are dust-proof. The first printed circuit board 31 itself is likewise designed to be dust-proof.The first printed circuit board 31 expediently has a plurality of layers which are bonded to one another in particular by means of so-called prepregs-that is to say textile semi-finished fiber-matrix products preimpregnated with resins. Furthermore, the first printed circuit board 31 has at least one printed circuit board core-that is to say two copper foils with a prepreg therebetween. The prepreg or the printed circuit board core isolates the two housing interior regions 11, 12 from one another, in particular in the sense of explosion protection.Furthermore, the printed circuit board 31 can comprise one or two outer prepregs and / or outer printed circuit board cores, between which electrical lines are routed. Expediently, these lines of the one or two prepregs and / or printed circuit board cores are separated dust-tightly from the second housing inner region 12 and / or the first housing inner region 11. The electrical lines run in particular in inner layers of the first printed circuit board 31.Expediently, an electrical line runs in the first printed circuit board 31, which electrical line provides an electrical connection between the first circuit arrangement 21 and the second circuit arrangement 22.The first housing inner region 11 will be discussed in more detail below:The x-z cross section of the first housing interior 11 corresponds, by way of example, to an L (rotated through 180 degrees). the first wall structure section 5 enclosing the first housing interior 11 comprises the upper wall of the housing 2, a first (right) side wall of the housing 2, a section of the lower wall of the housing 2, the wall elements 8, 9 and a section of a second (left) side wall of the housing 2. the first housing interior 11 is closed in a dust-tight manner according to IP 6 x.The first housing interior region 11 serves in particular to accommodate the main part of the electrical system and electronics of the operating medium 10. The entire electrical system and electronics accommodated in the first housing inner region 11 is also to be referred to as the first circuit arrangement 21.The first circuit arrangement 21 comprises one or more communication circuits 25 for communication with an external unit, in particular the superordinate controller. The communication circuit 25 comprises, for example, one or more digital and / or analog interfaces 26, 36, in particular an analog current interface 26. Furthermore, the first circuit arrangement preferably comprises the control circuit 27. Expediently, the first circuit arrangement 21 further comprises electrical connection terminals.By way of example, the control circuit 27, the analog current interface 26 and / or a safety barrier 35 are accommodated on the first printed circuit board 31.Expediently, a third printed circuit board 33 is also arranged in the first housing inner region 31, which for example runs parallel to the first printed circuit board 31. The digital / analog interfaces 36 and / or the rotation angle measuring unit 15 are expediently arranged on the third printed circuit board 33. The third printed circuit board 33 runs, by way of example, between the wall element 9 and the first (right) side wall of the housing 2.The various circuits of the first circuit arrangement 21 expediently each comprise one or more circuits 23. the circuits 23 are each designed intrinsically safe; i.e. each of the circuits 23 individually fulfills the ignition protection type intrinsic safety (Ex i). As long as no electrically conductive dust penetrates into the first housing inner region 11, the explosion safety of the first housing inner region 11 is accordingly ensured.According to one possible embodiment, the first circuit arrangement 21 is not designed to be intrinsically safe overall. For example, the first circuit arrangement 21 can be designed in such a way that potential differences between nodes of different circuits 23 would form an explosion-causing spark and / or an explosion-causing heating during dust fill and short circuit. Furthermore, the first circuit arrangement 21 can comprise one or more protective barriers 35 which could be bridged by the dusts, whereby in turn intrinsic safety would be canceled and heating and / or spark formation caused by an electrical short circuit would be possible. The first circuit arrangement 21 can be configured in such a way that the penetration of dust is prevented by the dust-proof first wall structure section 5. When designing the first circuit arrangement 21, therefore, the risk of invading dusts does not have to be taken into account.One, several or all electrical / electronic functional units contained in the first housing interior region 11, in particular the first circuit arrangement 21, are expediently not contained in the second housing interior region 12.Now to the second housing inner region 12:The second housing inner region 12 has, by way of example, a rectangular x-z cross section. The second housing interior region 12 is enclosed by the second wall structure section 6, which exemplarily comprises a section of the bottom wall of the housing 2, the wall element 9, the wall element 8, a section of the second (left) side wall of the housing 2 and the connection element 7.In contrast to the first housing inner region 11, the second housing inner region 12 does not necessarily have to be surrounded in a dust-tight manner, in particular not according to IP 6 x, and this is also not exemplary.The second housing inner region 12 serves in particular to accommodate the main part, preferably all, of the fluidic functional units of the operating medium 10. The fluidic functional units present in the second housing inner region 12 can also be referred to as the fluid device 28 overall.The fluid device 28 expediently comprises one or more valves, for example one or more pilot valves and / or a pressure booster or booster.Furthermore, an actuator device 34 and / or a sensor device 29 can be arranged in the second housing inner region 12. The actuator device 34 is, for example, an electromagnetic or electrodynamic actuator, in particular a voice coil. The sensor device 29 comprises, for example, a pressure sensor.The second circuit arrangement 22 is furthermore located in the second housing inner region 12. The second circuit arrangement 22 comprises in particular all circuits or circuits 24 which are associated with the fluid device 28, the sensor device 29 and / or the actuator device 34.For example, the second circuit arrangement 22 comprises an activation and / or read-out circuit of the actuator device 34, sensor device 29 and / or of the fluid device 28, for example one or more valves, in particular pilot valves.The drive and / or read-out circuit comprises in particular an analog-to-digital converter and / or a digital-to-analog converter.For example, the second circuit arrangement 22 receives analog sensor signals from the sensor device 29, converts these into digital signals by means of the read-out circuit and provides the digital signals to the control circuit 27 in the first housing interior 11, for example via the electrical connection running through the first printed circuit board 31.Furthermore, the second circuit arrangement 22 can receive digital control signals from the control circuit 27 via the electrical connection running through the first printed circuit board 31, convert these into analog control signals by means of the control circuit and control the actuator device 34 with the analog control signals.By way of example, a second printed circuit board 32 is furthermore arranged in the second housing inner region 12. Expediently, the second circuit arrangement 22, the sensor device 29 and / or the actuator device 34 is arranged on the second printed circuit board 32.The operating medium 10 further comprises a replaceable add-on element, in particular a connection element 7, which is part of the second wall structure section 6. The attachment element is, for example, a connection plate.By way of example, the add-on element represents a part of the housing 2-and thus the outer wall of the operating medium 10. The attachment element is part of the second wall structure section 6 and separates the second housing interior region 12 from the environment of the operating medium 10. The add-on element is in particular embodied to be non-metallic.Since the second housing inner region 12 does not have to be closed in a dust-tight manner, lower requirements apply to the add-on element, so that it can be adapted or modified without great effort.The add-on element is designed as a connection element 7 and has one or more fluid connections-here the fluid connections 16 and 17. Expediently, the add-on element is fastened by an in particular releasable fastening means 18, for example a screw.One, more or all fluidic and / or electrical / electronic functional units contained in the second housing inner region 12, in particular the second circuit arrangement 22, the fluid device 28, the sensor device 29 and / or the actuator 34, are expediently not contained in the first housing inner region 11. Furthermore, the first wall structure section 5 expediently does not comprise the add-on element.Explosion safety is ensured in the second housing inner region 12 by the fact that the second circuit arrangement 22 (which comprises all the circuits 24 arranged in the second housing inner region 12) is designed to be intrinsically safe overall. The "overall intrinsically safe design" can also be referred to as "single-circuit intrinsic safety". What is ultimately meant is that the second circuit arrangement 22 remains intrinsically safe even when the dusts enter the second housing interior region 12. The risk of spark formation or unacceptably high heating due to electrical short circuits caused by electrically conductive dust is thereby prevented.This single-circuit intrinsic safety can be achieved in various ways.For example, the second circuit arrangement 22 can be embodied as a single intrinsically safe circuit overall or can also consist solely of a single intrinsically safe circuit overall.If only a single (intrinsically safe) circuit is present, there is no possibility at all that any dust that has penetrated could establish an electrical connection between two (intrinsically safe) circuits and thus could cancel the respective intrinsic safety.Furthermore, the single-circuit intrinsic safety of the second circuit arrangement 22 can be achieved in that no safety barrier, in particular no Zener barrier, no diode acting as safety barrier and / or no current-limiting resistor acting as safety barrier is present in the second housing inner region 12.If no safety barrier is present in the second housing inner region 12, then no safety barrier can be bridged by penetrated electrically conductive currents (which in turn would result in the intrinsic safety being canceled).Expediently, at least one safety barrier 35, in particular at least one Zener barrier, is arranged in the first housing inner region 11. The safety barrier 35 is electrically connected to the second circuit arrangement 22 and limits a voltage and / or a current of the second circuit arrangement 22.Furthermore, the single-circuit intrinsic safety can be achieved by the second circuit arrangement 22 being designed in such a way that, during the intended operation of the second circuit arrangement 22, the maximum potential difference occurring between two nodes of the second circuit arrangement 22 is below a predetermined threshold value, with the result that even in the case of a short circuit between two nodes of the second circuit arrangement caused by dust which has penetrated, no explosion-triggering spark formation and / or explosion-triggering heating, for example by a glow discharge, takes place.Preferably, all possible potential differences between all possible combinations of nodes are below the threshold value.According to one possible configuration, the second circuit arrangement 22 is not designed to be intrinsically safe overall. According to a further possible embodiment, no second circuit arrangement 22 is present in the second housing inner region 12.In the following, further aspects and advantages of the operating medium 10, in particular compared to the prior art, will be discussed in detail.The prior art is that an explosion-proof operating medium or its housing and all attachments which are part of the housing and thus also determine the tightness of the housing are subject to the requirements of the ignition protection type (Ex t) provided that a plurality of intrinsically safe circuits are present in the housing and the operating medium is intended to meet certain standards for operation in the region with electrically conductive combustible dusts, for example IEC / EN 60079-31 and IEC / EN 60079-0.Operating means in process automation are often designed for areas with explosion risk, e.g. according to the ATEX guidelines and / or according to IECEx.Areas with the risk of explosion are, for example, areas in which combustible gases or combustible dusts occur.The environments (zones) for combustible gases or combustible dusts are defined separately; they do not usually occur together. Resources are normally still designed for both areas simultaneously to keep the number of different designs low. Since both areas must be considered, the design of such resources is sometimes very complex. In addition, a working medium designed as a positioner, control head and / or positioner comprises both fluidic, in particular pneumatic, and electrical functional units.As a rule, such operating means are designed with the ignition protection type "protection by housing" (Ex t). Operating means of this type frequently have a plurality of circuits (e.g. supply lines with a plurality of control circuits, in particular communication circuits and / or control circuits), which are each designed intrinsically safe (Ex i) in themselves, but in which it is possible that in the presence of electrically conductive dusts (e.g. zone 20; zone 21) an electrical short circuit occurs between two intrinsically safe circuits, as a result of which explosive spark formation and / or heating can in turn occur. For this reason, a defined type of housing protection (e.g. IP6x according to IEC / EN 60529) is generally obligatory in the case of such operating means.A dust-proof design of the housing is expensive, especially in the presence of nonmetallic housing parts (e.g. seals). To verify dust tightness, extensive tests are required, for example, under extended temperature requirements, aging due to storage, UV light tests, shock tests, etc. It is particularly problematic that these comprehensive checks are also required in the case of changes of an already verified housing and must be verified by a designated location (approval location).This significantly restricts changes in the fluidic functional units of the operating medium. Those fluidic functional units which form part of the housing must also be dust-tight, so that the housing as a whole is dust-tight. Particularly in the case of these fluidic functional units, high flexibility is frequently desired. For example, it is desired to be able to change or replace an externally mounted attachment element with another. It may also be desired to modify the material of an attachment element forming part of the housing, for example a pressure intensifier housing and or a cassette for pneumatic functions. However, in order to ensure the dust-proof construction, all of these changes would require the above-described complicated tests to be carried out, in particular if non-metallic parts of the housing were involved.Furthermore, it is generally necessary to provide electrical functional units in the pneumatic functional units; for example, circuits for controlling pilot valves and / or pressure sensors.From the perspective of explosion protection, the housing 2 is divided into two parts: a first housing part with the first housing inner region 11 and a second housing part with the second housing inner region 12.The first housing part is not subject to the requirements for "protection by housing" and the second housing part is not subject to the requirements.This is achieved by a defined separation of the two housing parts being carried out. This is effected in particular by means of the first printed circuit board 31, which can also be referred to as the main printed circuit board. A part of this first circuit board forms the partition wall. Furthermore, a / the part of the first printed circuit board 31 can simultaneously serve as a line feedthrough, in particular in its inner layers. The upper and lower prepregs or cores of the printed circuit board 31 then serve, in the sense of explosion protection, as insulation between the housing parts / walls.The circuits (a circuit from the explosion-proof point of view) which extend from the first housing part into the second housing part are guided (lead-through) in the inner layers of the circuit board 31. These circuits carried out withstand a dust fill by penetration of electrically conductive dust into the housing 2 without jeopardizing safety. This "one" circuit is then designed to be intrinsically safe from the perspective of explosion protection for dust and gas and remains this also in the case of said dust fill.In the first housing part, in particular a connection space (not shown) is provided, for example with electrical terminals. Furthermore, the main part of the electronics, preferably more than 90%, of the electronic components of the operating medium 10 is expediently present in the first housing part.The types of protection intrinsic safety (Ex i), encapsulation (Ex i) and / or protection by housings (Ex t) are expediently used in the first housing part. Expediently, the first housing part meets the requirements for nonmetallic housing parts in terms of explosion protection (Ex t) and the requirements for shock resistance, for example according to IEC 60079-0 and / or IEC 600079-31.In the second housing part, pneumatics, for example pilot valves and / or boosters, are provided in particular. Furthermore, pressure sensor systems and / or a distance measuring unit, for example a potentiometer, can be arranged in the second housing part.In the second housing part, the type of protection is used in particular such that intrinsic safety (Ex i) for gas and dust is also fulfilled in the case of dust fill.For the second housing part there are expediently no increased requirements for nonmetallic housing parts due to intrinsic safety for dust (Ex i). Furthermore, there are no increased requirements for impact resistance and / or UV resistance of the plastics.In summary, an electrical operating medium 10 for the explosion-risk area with combustible and / or conductive dusts is thus obtained, having a housing 2 which is divided into at least two parts. For the division, the first printed circuit board 31 is expediently used, which can also be used for carrying out circuits from the first housing part into the second housing part. The printed circuit board is expediently part of the electronics. The first housing part is preferably subject to the increased requirements of the IEC / EN 60079-31 in the "protection by housing" (Ex t) protection mode, while these requirements are expediently not applicable to the second housing part.The second housing part B is expediently subject only to the normal functional requirements on the housing without taking into account the special requirements for nonmetallic housing parts.Expediently, only one circuit between the first housing part and the second housing part is designed to be intrinsically safe in the sense of explosion protection for gas and dust.An intrinsically safe circuit can be defined, for example, according to the standard DIN / EN / IEC 60079-11. An intrinsically safe circuit can preferably be designed in such a way that no ignitable sparks (opening and closing sparks) and no unacceptably high heating can occur according to the temperature class. An intrinsically safe circuit is expediently limited in its maximum voltage, the maximum possible current, the maximum possible power that can be output, its effective electrical storage, its internal effective capacitance and its internal effective inductance.A single-circuit intrinsically safe circuit arrangement contains, for example, exclusively components which are not directly responsible for intrinsic safety. Preferably, therefore, none of the components of a single-circuit intrinsically safe circuit arrangement has an active and / or intended safety-relevant function.Furthermore, a single-circuit intrinsically safe circuit arrangement preferably does not comprise any electrical energy storage components, such as capacitors or inductances, which would require additional protective elements likewise present in the circuit in order to achieve intrinsic safety. The single-circuit intrinsically safe circuit arrangement expediently does not comprise such protective elements, in particular no resistors which limit the maximum discharge current of capacitors and / or no clamping diodes (e.g. tens of diodes) which limit the mutual inductance and thus voltage increases at an inductance.Finally, a single-circuit intrinsically safe circuit arrangement is expediently designed in such a way that each circuit node of the single-circuit intrinsically safe circuit arrangement can be connected to any other arbitrary circuit node of the same single-circuit intrinsically safe circuit arrangement without the intrinsic safety and / or explosion protection of the single-circuit intrinsically safe circuit arrangement being impaired as a result.

Claims

Operating medium (10), in particular a control head, positioner, positioner and / or sensor control, for process automation for use in an area in which there is a risk of explosion and dusts, in particular electrically conductive dusts, can occur, comprising: a wall structure (1) which serves as a housing of the operating medium (10) and comprises a first wall structure section (5) which defines a first housing inner region (11), and a second wall structure section (6) which defines a second housing inner region (12) which is separate from the first housing inner region (11), wherein a first circuit arrangement (21) is arranged in the first housing inner region (11) and the first housing inner region (11) is surrounded in a dust-tight manner by the first wall structure section, such that the dusts cannot penetrate into the first housing interior region (11) and the dust-tight enclosure ensures the explosion safety of the first housing interior region, wherein one or more circuits (24) are arranged in the second housing interior region (12) and all circuits (23) arranged in the second interior region (12) form an overall intrinsically safe second circuit arrangement (22), such that even if the dusts penetrate into the second housing interior region (12) no explosion-triggering heating and / or spark formation is possible by the second circuit arrangement (22) and the overall intrinsically safe embodiment of the second circuit arrangement (22) ensures the explosion safety of the second housing interior region (12), wherein the operating medium (10) has an exchangeable connection element (7) which is part of the second wall structure section (6), wherein the connection element has one or more fluid connections (16, 17).Operating means (10) according to claim 1, characterised bya first printed circuit board (31) which is part of the first wall structure section (5).Operating means (10) according to claim 2, characterised in that the first printed circuit board (31) is part of the second wall structure section (6).Operating medium (10) according to Claim 3, characterized in that the first printed circuit board (31) separates the first housing inner region (11) from the second housing inner region (12) in a dust-tight manner.Operating medium (10) according to Claim 2, 3 or 4, characterized in that the first printed circuit board (31) electrically connects the first circuit arrangement (21) to the second circuit arrangement (22).Operating means (10) according to one of the preceding claims, characterized in that the second circuit arrangement (22), in particular the second housing inner region (12), does not comprise a safety barrier.Operating medium (10) according to one of the preceding claims, characterized in that at least one safety barrier (35) is arranged in the first housing inner region (11), which safety barrier is electrically connected to the second circuit arrangement (22) and limits a voltage and / or a current and / or an electrical power of the second circuit arrangement (22).Operating medium (10) according to one of the preceding claims, characterized in that the overall intrinsically safe second circuit arrangement (22) is designed in such a way that, during the intended operation of the second circuit arrangement (22), the maximum potential difference occurring between two nodes of the second circuit arrangement (22) is below a predetermined threshold value, with the result that even in the event of a short circuit between two nodes of the second circuit arrangement (22) caused by dust entering, no explosion-triggering heating and / or spark formation takes place.Operating means (10) according to one of the preceding claims, characterized in that the first housing interior region (11) is designed and / or certified and / or subject to certification in accordance with the protection type IP6X.Operating means (10) according to one of the preceding claims, characterized in that the second housing interior region (12) is not designed and / or certified and / or subject to certification in accordance with the protection type IP6X.Operating medium (10) according to one of the preceding claims, characterized in that the first circuit arrangement (21) comprises one or more communication circuits (25) for communication with an external unit, in particular a superordinate controller, an analog current interface (26), one or more digital and / or analog interfaces (36) and / or a control circuit (27).Operating medium (10) according to one of the preceding claims, characterized in that a fluid device (28), in particular a valve, expediently a pilot valve, a pressure amplifier, an actuator device (34) and / or a sensor device (29) is arranged in the second housing inner region (12).Operating medium (10) according to one of the preceding claims, characterized in that the second circuit arrangement (22) comprises an activation and / or readout circuit, in particular an analog-to-digital converter and / or a digital-to-analog converter, of a fluid device (28), for example one or more valves, in particular pilot valves, and / or of a sensor device (29) and / or of an actuator device (34).Process valve module (40) comprising a working medium (10) in the form of a control head, positioner and / or positioner according to one of the preceding claims 1 to 13, a valve drive (20), on which the working medium (10) is placed and which is controlled by the working medium (10), and a valve fitting (30), which can be actuated by the valve drive, for influencing a process fluid.

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