WO2019166604A1

WO2019166604A1 - Pressure sensor

Info

Publication number: WO2019166604A1
Application number: PCT/EP2019/055094
Authority: WO
Inventors: Jan SCHØN; Thorsten BRORSON OTTE; Søren KJELDSEN
Original assignee: Grundfos Holding A/S
Priority date: 2018-03-02
Filing date: 2019-03-01
Publication date: 2019-09-06
Also published as: CN111801561A; EP3759450A1

Abstract

The invention relates to a pressure sensor with at least one measuring element (64) and with at least one fluid channel (70) which is arranged in a sensor body (34) and which connects a pressure sensing opening (74) to the measuring element (64), wherein the fluid channel (70) comprises at least one cross-sectional and/or directional change, and wherein at least one section of the fluid channel (70), in which channel the mentioned at least one cross-sectional and/or directional change is situated, is formed in a structure (44) of the sensor body (34) which is manufactured in a generative manufacturing method.

Description

[01] The invention relates to a pressure sensor as well as to a pump assembly with such a pressure sensor,

[02] Pressure sensors which are to detect fluid pressures in the most varied of facilities or machines are known. This for example is the case concerning pump assemblies, in particular centrifugal pump assemblies, with regard to which it can be desirable to detect for example the outlet pressure and/or the differential pressure between the Inlet and outlet [03] In such pressure sensors, it is common to connect the actual pressure measuring elements via fluid channels to pressure sensing openings which are positioned in the facility parts or flow paths, in which the pressure is to be measured. The problem of such sensors is the fact that undesirable damage to the measuring elements or a comprising of the measuring result, for example due to contamination, can occur. Damage to the measuring elements can occur for example due to large pressure fluctuations, or occurrences of cavitation can arise.

[04] It is the object of the invention to improve a pressure sensor to the extent that damage to a measuring element can be prevented. Furthermore, it is the object of the invention to provide a pump assembly with such an improved pressure sensor.

[05] This object is achieved by a pressure sensor with the features which are specified in claim 1 , as well as by a pump assembly with the features which are specified in claim 21. Preferred embodiments are to be derived from the dependent claims, the subsequent description as well as the attached figures.

[06] The pressure sensor according to the invention comprises at least one measuring element and at least one fluid channel which is arranged in the sensor body. The fluid channel connects a pressure sensing opening to the measuring element and therefore transmits the pressure from the pressure sensing opening to the measuring element, preferably by way of the fluid channel being filled with the fluid, in which the pressure is to be measured. According to the invention, one envisages the fluid channel comprising at least one cross-sectional change and/or directional change. It is possible to damp pressure shocks in the channel by way of such direction changes, by way of reflection at the walls, so that sudden pressure changes do not act upon the actual measuring element as an impulse. The risk of damage can be reduced by way of this. Furthermore, expansion spaces or damping spaces which can serve for reducing occurrences of cavitation can be created by cross-sectional changes. Moreover, structures, in which particles can settle, in order to prevent these from accumulating directly on the measuring element or compromising the measuring result can also be formed.

[07] According to the invention, one envisages at least a section of the fluid channel, in which the mentioned at least one cross-sectional and/or directional change is situated, being formed in a structure of the sensor body which has been formed or generated in a generative or additive manufacturing method. Such generative manufacturing methods are also called 3D printing. Herein, it can be the case for example of a selective laser melting, selective laser sintering, electron beam melting or other generative or additive manufacturing methods. These manufacturing methods have the advantage that very complex structures which are very difficult to produce or are not possible to produce at all in conventional, material-removing or primary shaping manufacturing methods, can be produced. Complicated direction changes or cross-sectional changes of the fluid channel can therefore be formed without any problem. Furthermore it is possible to arrange complex structures in a small place, thus, reducing the overall size of the pressure sensor. The generative manufacturing method for this opens up very new possibilities. A metal powder is preferably melted on with the help of an electron beam or laser beam, so that the structure is formed in a layered manner.

[08] According to a preferred embodiment the fluid channel is connected to at least one measuring element receiver which is designed for receiving the measuring element. This means the measuring element is attached to the measuring element receiver. Preferably said measuring element receiver is formed in the structure which is manufactured in a generative manufacturing method. This allows to manufacture at least a part of the fluid channel and the measuring element receiver in one piece by the generative manufacturing method.

[09] Preferably the measuring element is arranged on a circuit board which is arranged inside a sensor housing. Preferably the entire sensor housing is formed by a generative manufacturing method. In particular the parts containing fluid channels may be manufactured in one piece with the sensor housing or portions of the sensor housing surrounding a receiving space inside which the electronic circuit board containing the measuring element is contained.

[10] The structure which is manufactured in a generative manufacturing method is preferably a structure of plastic or metal. Particularly preferably, the structure is manufactured from a rust-free stainless steel. For this, a powder for example of rust-free stainless steel is melted on and deposited in a layered manner in the generative manufacturing process. However, other metals or in particular also metal mixtures or other material combinations can be brought into the desired shape in the generative manufacturing method,

[1 1] The structure which is manufactured in the generative manufacturing method and which forms the section of the fluid channel is particularly preferably designed as one piece. This is advantageous since the number of required interfaces which are to be sealed off can thus be reduced, so that the reliability of the pressure sensor can be increased and the assembly simultaneously simplified,

[12] According to a preferred embodiment of the invention, the fluid channel comprises several direction changes and in particular a zigzag and/or meandering course within the structure which is manufactured In a generative manufacturing method. Pressure impulses which propagate in the fluid channel from the pressure sensing opening towards the measuring element are damped or reduced by way of these several direction changes, so that damage to the measuring element can be prevented.

[13] According to a further preferred embodiment, the fluid channel comprises several direction changes in at least two different planes within the structure which is manufactured in a generative manufacturing method. This on the one hand has the advantage that the construction space in the sensor body can be optimally utilised, and on the other hand the damping characteristics for reducing pressure impulses can be fashioned in the shaping in several dimensions, in particular in three dimensions. Yet better damping characteristics can be realised by way of this. The generation of the fluid channel in a generative manufacturing process herein permits a very free shaping which permits complex fluid channel courses in all spatial directions. [14] Further preferably, the fluid channel within the structure which is manufactured in a generative manufacturing method has a shape which effects at least one reflection of a pressure wave, said pressure wave entering through the pressure receiving opening into the fluid channel. This is advantageous, in order to damp such pressure waves or impulses in the fluid channel before they reach the measuring element,

[ 15] According to a further special embodiment of the invention, the fluid channel within the structure which is manufactured in a generative manufacturing method comprises at least one, preferably several expansions spaces. In particular, such expansion spaces are suitable for damping sudden pressure drops, in order to prevent cavitation occurrences. Furthermore, such expansion spaces can also be used to the extent that possible contamination can accumulate there in a targeted manner, in order to prevent a blockage of the fluid channel.

[16] According to a possible embodiment of the invention the fluid channel formed within the structure which is manufactured in a generative manufacturing method comprises several direction changes and/or at least one change in cross section and/or at least one expansion space which are arranged in series. Such a structure for example allows a damping of pressure shocks as well as the reduction of cavitation or allows protection against sedimentation to protect a measuring element and/or to enhance the measurement. In particular changes in the direction of extension of the fluid channel have a damping effect for damping pressure shocks, i.e. reducing wafer hammer. For a reduction or elimination of cavitation the fluid channel preferably comprises at least one, further preferably several changes in cross sectional size or diameter, respectively. Protection against sedimentation preferably is achieved by an expansion space inside the fluid channel, i.e, an area having an enlarged cross section. To achieve a combination of these effects it is preferred to arrange those different structures in series,

[17] According to a further possible embodiment of the invention, the fluid channel within the structure which is manufactured in a generative manufacturing method comprises at least one branching, wherein the fluid channel preferably branches to several measuring elements. This arrangement has the advantage that different measurements can be simultaneously carried out. Furthermore, different channel courses having different characteristics can be generated, said characteristics each being assigned to a measuring element. The sensor can therefore be adapted to different application cases by way of the selection of the respective measuring element and by way of the fluid channel or section of a fluid channel, which matches the respective application purpose, being selected. Such branchings can also be formed very inexpensively in a generative manufacturing method.

[18] According to a further special embodiment of the invention, several fluid channels which connect one or more pressure sensing openings each to a measuring element are formed in the sensor body. Several measuring elements can be connected to a pressure receiving opening via branchings. However, it is also possible to form several fluid channels which are completely separate from one another and which each connect a measuring element to its separate pressure sensing opening. Preferably, these several fluid channels comprise at feast one section in a structure which is manufactured in a generative manufacturing method. Further preferably, these fluid channels can comprise at least one cross-sectional and/or directional change, as have been described beforehand. Such a design with several fluid channels is suitable, in the pressure sensor, for being able to measure pressures in different regions of the facility or machine, for example the differential pressure between the inlet side and the outlet side in a pump assembly. Furthermore, different measuring elements can be provided, said elements, as described beforehand, being able to be selectively activated depending on the application case of the pressure sensor. The selection of the respective measuring element can be realised in particular as in the evaluation electronics, in particular as a pure software function, so that the field of application of the pressure sensor can be broadened.

[19] According to a further preferred embodiment of the invention, the fluid channel within the structure which is manufactured in a generative manufacturing method can comprise at least one valve which is preferably likewise manufactured in a generative manufacturing method. For example, such a valve can serve for being able to activate different flow paths by way of switching over the valve, in order for example to create connections to different measuring elements. In such a valve, the movable valve element can preferably likewise be manufactured in the generative manufacturing method, so that an assembly is ideally forgone.

[20] According to a further particular embodiment of the invention, a further section of the at least one fluid channel can be formed in a component, to which the structure which is generated in a generative manufacturing method is connected by way of the generative manufacturing procedure. This means that this further section of the fluid channel can be formed in a premanufactured component, upon which the structure which is manufactured in generative manufacturing methods is then formed or printed. Thus for example one con melt the further structure onto a metallically premanufacfured base body, in which a section of the fluid channel is formed, in a generative manufacturing method. This design as the advantage that ideally only those structures which are conventionally difficult to realise are formed in the generative manufacturing method, whereas the other sections or components of the sensor body can preferably be formed in a conventional manner, for example in a primary shaping and/or material- removing manufacturing method, This is particularly advantageous since the machining times for the generative manufacturing methods are very tong.

[21] According to a further preferred embodiment of the invention, the pressure sensor is designed as a differential pressure sensor, concerning which a first fluid channel is connected to a first side of the differential pressure measuring element and a second fluid channel is connected to a second side of the differential pressure measuring element. The fluid channels preferably each end in a pressure sensing opening, through which the pressure can enter the fluid channel or can act in the fluid channel. At least one of the fluid channels, preferably both fluid channels each comprise at least one cross-sectional and/or directional change. Moreover, at least one section of one of the fluid channels is formed in a structure which was manufactured in a generative manufacturing method, as was described above.

[22] Preferably, a shaping of the fluid channel which damps pressure shocks is formed in at least one of the fluid channels in the structure which is manufactured in a generative manufacturing method. This is preferably that fluid channel, in which the greater pressure acts, for example given the application in a pump assembly, that fluid channel which connects the measuring element to the delivery side of the pump assembly. The shaping for damping pressure shocks preferably comprises several changes in direction of the fluid channel,

[23] Further preferably, at least one section which is situated in a structure which is manufactured in a generative manufacturing method is present in at least one of the fluid channels in the differential pressure sensor, wherein a cavitation-reducing shaping of the fluid channel, for example in the form of one or several changes in cross section or diameter or in form of an expansion space, is formed in this structure. This second fluid channel, in the differential pressure sensor is preferably that channel, in which the lower pressure acts. On using the pressure sensor in a pump assembly, this is preferably that fluid channel which connects the measuring element of the suction side of the pump assembly,

[24] According to a further preferred embodiment the fluid channel may comprise a section having a shaping which allows sedimentation protection, wherein this section is formed in at least one of the fluid channels within the structure which is manufactured in a generative manufacturing method. The shaping allowing sedimentation protection may for example be an expansion space. Forming this shape within the structure which is manufactured in a generative manufacturing method has the advantage that this manufacturing method allows formation of complex structures,

[25] According to a further preferred embodiment the fluid channel or at least one of the fluid channels may comprise a section shaped to damp pressure shocks and/or a section shaped to reduce cavitation and/or a section shaped for sedimentation or sedimentation protection, wherein these sections are arranged in series. This means there are arranged preferably at least two of the different sections (for damping pressure shocks, reducing cavitation or sedimentation) in series. Preferably the respective sections are formed within the structure manufactured in a generative manufacturing method. As mentioned before such a method allows to form a complex structure or shape of the fluid channel providing the afore-mentioned properties, i.e. to reduce pressure shocks, reduce cavitation and/or to prevent sedimentation. The respective shapes may include changes in direction, changes in cross section and/or expansion spaces of different shape. [26] According to a further possible embodiment of the invention, the pressure sensor comprises at least two fluid channels which each comprise a section, in which the at least one cross-sectional and/or directional change is situated and which is formed in a structure of the sensor body which is manufactured in a generative manufacturing method, wherein the several fluid channels preferably have a different design. Thus the fluid channels can be precisely adapted to the respective requirements. Particularly preferably, different fluid channels can be provided with different functions which are each related to a measuring element, wherein the measuring elements can be selectively activated depending on the application case of the pressure sensor, as described above.

[27] According to a further embodiment of the invention, a fluid channel for transferring a pressure to be defected to the measuring element is departing from a first side of the circuit board, extending through an opening in the circuit board to a second side of the circuit board and being connected to the measuring element at this second side of the circuit board. This design has the advantage that the measuring element which is to detect the pressure in the fluid channel, does not necessarily need to be situated at that side of the circuit board, departing from which the fluid channel extends to the pressure sensing opening. In contrast, the fluid channel can thus extend through the circuit board to its rear side, at which the measuring element is then arranged, This can permit a very compact construction of the pressure sensor. This fluid channel may be the fluid channel described before or a further fluid channel.

[28] Herein, the aforementioned fluid channel preferably extends through the opening in a direction transverse and in particular normal to a surface of the circuit board. The fluid channel can therefore extend away from the circuit board to a pressure sensing opening, for example in the manner of a sensor or measuring finger, wherein this measuring finger can be inserted info a recess in the housing of a facility or a machine, in which facility or machine the pressure is to be determined. Herein, a pressure sensing opening then lies at one end of the measuring finger, whereas the circuit board preferably lies at the opposite end and there can extend transversely to the extension direction of the fluid channel, so that a pressure sensor with an as short as possible axial construction length can be created.

[29] According to a further preferred embodiment of the invention, the circuit board annularly surrounds the opening. Herein, the circuit board can form a closed ring around the opening. However, it is also conceivable for the circuit board to extend around the opening in the manner of an open ring. Herein, the circuit board preferably extends around the opening by at least 270 degrees. The construction space which surrounds the opening can be utilised for electronic or electrical components on the circuit board due to the annular arrangement of the circuit board around the opening. The opening is preferably situated centrally in the circuit board which according to a preferred embodiment has a round outer contour.

[30] According to a further preferred embodiment of the invention, the fluid channel extending through the circuit board comprises a deflecting element at the second side of the circuit board, in which deflecting element the extension direction of fhe fluid channel changes and preferably changes by 180 degrees. I.e., the fluid channel is deflected at the second side such that it can end at a measuring element, preferably from the second side of fhe circuit board. The measuring element can therefore be subjected to pressure, even if its measuring surface is away from a first side of the circuit board, departing from which first side the fluid channel extends to the circuit board and through this to the second side. The deflection in the deflecting element is preferably effected by 180 degrees, i.e. in a U-shaped manner, wherein the measuring element is arranged laterally, i.e. in the direction of the surface of the circuit board next to the opening.

[31 ] The fluid channel extending through the circuit board can therefore comprise a deflecting element at the second side of the circuit board, in which deflecting element the extension direction of the fluid channel changes twice by 90 degree, wherein a channel section which extends parallel to the surface of the circuif board is preferably present between the two deflections. A lateral displacement of the measuring element to the opening, through which the fluid channel extends can be realised by way of this.

[32] According to a further possible embodiment of the invention, the fluid channel can comprise at least one first channel section which is situated at the first side of the circuit board, i.e. is situated essentially at the first side of the circuit board, and at least one second channel section which is situated af the second side of the circuit board, i.e. essentially at the second side of the circuit board. If the first channel section is situated essentially at the first side of the circuit board, then this means that preferably the largest part of the channel section is situated at this side of the circuit board. This correspondingly applies to the second channel section. The first and the second channel section are preferably connected to one another via a sealed interface, wherein this sealed interface is preferably situated in the region of the opening in the circuit board. This two-part design of the fluid channel permits a simple assembly, since the circuit board can thus be arranged between two components which each accommodate one of the channel sections and sealingly engage into one another in the region of the opening.

[33] Further preferably, a second channel section of the fluid channel which is situated at the second side of the circuit board is formed in a housing body which is part of an electronics housing which accommodates the circuit board. This housing body, possibly with further housing parts can therefore encompass a receiving space, in which the circuit board is arranged. Herein, the housing body is preferably designed such that it extends parallel to the circuit board to the extent that the circuit board is completely covered by the housing body at its second side. The housing body can therefore function as a cover of an electronics housing. However, it is also possible for the housing body to be arranged in the inside of the electronics housing and to be covered for example by an additional cover. In this case, the housing body can also merely serve for example for accommodating the fluid channel.

[34] Further preferably, at leas t that part of the housing body, in which the second channel section is situated, is designed as one piece. The channel section can therefore be formed directly in the inside of a solid housing body, which is particularly advantageous. This for example is possible by way of the housing body being designed as a moulded component or also as a component which is generated in a generative manufacturing method (3D printing). A channel section with a complex course, for example with the deflections which are described above, and without interfaces which are to be sealed, can also be simply formed in this manner.

[35] According to a further embodiment of the invention, the measuring element can be a differential pressure element with two measuring surfaces which are away from one another. The measuring element can therefore for example be a membrane which is subjected to pressure from both sides, wherein the differential pressure between the two sides can be determined via the deflection of the membrane. The deflection can be detected for example by way of strain gauge elements which are arranged on the membrane, or piezoelectric elements. However, it is also possible to apply two measuring elements which act independently of one another, for determining the differential pressure, A first measuring surface preferably faces the first side of the circuit board and a second measuring surface faces the second side of the circuit board. Due to the described extension of a first fluid channel through the circuit board, a pressure to be detected can therefore be brought onto the second measuring surface at the second side of the circuit board, i.e, the rear side of the circuit board, whereas the other pressure at the first side of the circuit board acts upon the first measuring surface which is situated there. The differential pressure can therefore be determined in a simple manner and the measuring element can be reliably contacted on the circuit board, The circuit board preferably comprises a hole in the region of the measuring element, so that here too, a pressure channel can extend through the circuit board and a measuring element which is arranged on one side of the circuit board can be subjected to pressure from two sides,

[36] A first fluid channel preferably ends at the second measuring surface of the measuring element which is away from the second side of the circuit board. This can be achieved by way of the aforementioned deflection in the fluid channel at the second side of the circuit board.

[37] Furthermore, a second fluid channel is preferably present in the pressure sensor, said second fluid channel ending at the first measuring surface of the measuring element, i.e. the measuring surface which faces in the direction of the first side of the circuit board. This second fluid channel, preferably departing from the first side of the circuit board, extends to a pressure sensing opening which is preferably situated distanced to a pressure sensing opening of the first fluid channel. Both pressure sensing openings can be situated for example in a measuring finger in a distanced manner, wherein the measuring finger extends in or through two measuring spaces, in which the two pressures are to be sensed, [38] The second fluid channel and at least a first channel section of the first fluid channel are therefore preferably arranged in a common sensor body which is preferably designed of one part. This simplifies the construction and permits a very compact construction of the pressure sensor. The fluid channels can be formed in the sensor body in different manners. Thus for example it is possible to form one or both fluid channels on manufacture of the sensor body, for example in a moulding method or in a generative manufacturing method. It is alternatively possible to incorporate one or both fluid channels or only sections of the fluid channels into the sensor body at a later stage by way of machining the sensor body, for example by way of material-removing machining or also thermal machining, e.g, by way of laser beam. The formation of the fluid channels or of the channel sections of the fluid channels in a single-part and in particular single-piece sensor body has the advantage that few as possible interfaces which are to be sealed arise.

[39] The circuit board is preferably situated between a housing body of the electronics housing and the sensor body. The housing body of the electronics housing, as described above, can herein be a housing part of the electronic housing which terminates this to be outside, or however a housing body which is situated in the inside of the electronics housing and forms one or more fluid channels or channel sections of fluid channels there. The housing body and the sensor body are preferably shaped such that when they are put together, they enclose a receiving space, in which the circuit board is arranged. Herein, the circuit board is preferably fixed between the housing body and the sensor body. Further preferably, measuring element receivers which are formed in the sensor body and/or the housing body and at which the described fluid channels end, on assembly come into sealing contact with the measuring elements or with sealing surfaces which surround the measuring elements. The necessary seals are therefore preferably also brought into contact by way of the fixation of the circuit board between the housing body and the sensor body.

[40] Apart from the described pressure sensor, a pump assembly which comprises such a pressure sensor as has been described above is also the subject-matter of the invention. This pressure sensor is preferably a differential pressure sensor which is arranged between the suction side and the delivery side of the pump assembly, so that the differentia! pressure across the pump can be detected. The fluid channels can herein preferably be designed in the manner described above, in order to minimise pressure shocks upon the measuring element and/or undesirable cavitation occurrences.

[41] The invention is hereinafter described by way of the example and by way of the attached figures. In these are shown in:

Fig, 1 a sectioned view of a multi-stage centrifugal pump assembly according to the invention, Fig. 2 a sectioned view of a base and foot casing of a multi- staged centrifugal pump assembly with a pressure sensor which is arranged therein,

Fig, 3 a perspective exploded view of a pressure sensor according to the invention,

Fig. 4 a perspective exploded view of the pressure sensor according to Fig.3 with a view onto the electronics housing, Fig. 5 A a partly transparent view of a housing body of the pressure sensor according to Fig. 3 and 4, Fig. 5B a sectioned view of the housing body according to Fig. 5A,

Fig. 6 a sectioned view of the pressure sensor according to Fig. 3 and 4,

Fig. 7 a first alternative embodiment example for fluid channels in a pressure sensor,

Fig. 8 a second alternative embodiment example for an arrangement of fluid channels in a pressure sensor,

Fig. 9 a third alternative embodiment example for the arrangement of fluid channels in a pressure sensor.

Fig. 10 a fourth alternative embodiment example for the arrangement of fluid channels in a pressure sensor.

Fig. 1 1 a sectioned view of a further embodiment example of a fluid channel in a pressure sensor according to the invention and

Fig. 12 a schematic sectioned view of a further embodiment example of a fluid channel in a pressure sensor according to the invention.

[42] In a sectioned view, Fig. 1 shows a multi-stage centrifugal pump assembly as an example for a pump assembly according to the invention, in which a pressure sensor according to the invention is applied. The shown pump assembly comprises a foot casing or base casing 2, on which an inlet branch (nozzle or stub) 4 and an outlet branch 6 are formed. In this embodiment example, three pump stages which are each formed from an impeller 8 and intermediately lying diffusers 10 are attached onto the base casing 2. The impellers 8 are arranged on a common shaft 12 which is connected to a drive motor 16 which here is only shown schematically, via a coupling 14. The individual pump stages are situated in an inner tubular casing 18 which is surrounded at a distance by an outer casing 20 which is likewise designed in a tubular manner. An annular channel 22 which serves as a delivery channel and connects the outlet side of the pump stages to the outlet or delivery branch 6 in the base casing 2 is therefore formed between the casings 18 and 20. As is shown in Fig. 2, a pressure sensor 24 is arranged in the base casing 2. The pressure sensor 24 is inserted through an opening 26 in the outer casing wall of the base casing 2. Lying opposite this opening 26, the pressure sensor 24 projects into an opening 28 in a wall of the suction channel 30 which is formed in the inside of the basis housing 2. The pressure sensor 24 therefore extends through an annular space 32. The annular space 32 connects onto the annular channel 22 in the base casing 2 and creates the connection to the delivery branch 6. The pressure sensor 24 can detect the delivery-side pressure in the annular space 32 as well as the suction-side pressure in the suction channel 30 and thus the differential pressure between the inlet side and the outlet side of the pump assembly, due to the arrangement of the pressure sensor 24 in such a manner.

[43] The construction of the pressure sensor is described in more detail by way of Fig. 3 to 5. The pressure sensor 24 consists of a sensor body 34 and an electronics housing 36. The electronics housing 36 comprises a housing body 38 and a cover 40 which closes this. The sensor body 34 and the electronics housing 36 together form a sensor housing which contains all essential components of the pressure sensor.

[44] The sensor body 34 is formed from two sections 42 and 44. The first section 42 of the sensor body forms a sensor finger which, as is shown in Fig. 2, extends through the annular space 32 into the opening 28. The connecting second section 44 of the sensor body is adjacent to the electronics housing 36. The second section 44 together with the housing body 38 encloses a receiving space 46, in which a circuit board 48 with the actual measuring electronics of the pressure sensor is arranged.

[45] The first section of the sensor body 42 and the second section of the sensor body 44 are connected to one another in a connection plane 50 which is represented in Fig. 6. Herein, concerning the pressure sensor which is shown here, the first section 42 is firstly provided as a premanufactured component, for example as a component which is manufactured from round steel in a material-removing manner, in the manufacturing process. In contrast, the second section 44 is formed onto the premanufactured component which forms the first section 42, in a generative or additive manufacturing method, which is to say by way of so-called 3D printing. This means that the second section 44 has been generated directly on the first section 42 which is premanufactured, in an additive manner. Herein, a welding of both components takes place at the connection plane 50, so that these are formed in a single-part manner as a result. In the shown example, both parts are manufactured of the same material, preferably rust-free stainless steel,

[46] A first fluid channel 52 runs through the complete sensor body 34 in the longitudinal direction Y of this body. Herein, the first fluid channel 52 comprises a first channel section 52a and a second channel section 52b. The first channel section 52a extends in the sensor body 34, An extension of this channel section which is likewise part of the first fluid channel 52 extends as a second channel section 52b in the housing body 38. The first fluid channel 52 can be formed in the first section 42 of the sensor body 34 for example with a drilling method. The first fluid channel 52 is formed in the generatively manufactured structure in a direct manner in the second section of the sensor body 44, [47] The circuit board 48 in its centre comprises an opening 54 in the form of a central hole. This serves for the first fluid channel 52 being able to extend through the circuit board 48, Herein, the first section 52a of the fluid channel 52 is situated essentially, which is to say for its greater part, at a first distal end 58 of the circuit board 48. The first side 56 faces the free or distal end of the sensor body 34, whereas the opposite second side 58 of the circuit board faces the housing body 38. A seated interface 80, at which the first channel section 52a is connected to the second channel section 52b is formed between the sensor body 34 and the housing body 38.

[48] As is shown in section in Fig. 5B, the second channel section 52b, departing from the interface 60, extends in the housing body 38 in a manner angled twice by 90° in a U-shaped course to a measuring element receiver 62. The measuring element receiver 62 is situated radially offset to the interface 60 which is arranged centrally. The housing body 38 with the channel section 52b is preferably likewise manufactured in a generative or additive manufacturing method in particular of metal such as for example rust-free stainless steel.

[49] The measuring element receiver 62 comes to bear on a first measuring element 64, The measuring element 64 is arranged on the circuit board 48, wherein the circuit board 48 comprises an opening, through which the measuring element receiver 82 comes to bear on the measuring element 84 which is arranged on the first side 56 of the circuit board. The channel section 52b of the fluid channel 52 therefore ends at a second measuring surface 66 of the measuring element 64. The measuring element 64 is a differential pressure measuring element. A second fluid channel 70 which is likewise formed in the sensor body 34 is situated on the first measuring surface 68 which is situated at the first side 56 of the circuit board 48, The second fluid channel 70 connects a measuring element receiver 72 which lies opposite the first measuring surface 68 of the measuring element 64, to a pressure sensing opening 74, The pressure sensing opening 74 is situated distanced to the distal end of the sensor body 34 in the region of the second section 44, In the axial direction Y, the pressure sensing opening 74 is therefore distanced to the pressure sensing opening 76 which is situated at the distal end and at which the first fluid channel 52 runs out. When it is inserted into the base casing 2 as is shown in Fig. 2, the pressure sensor 24 can therefore detect the pressure in the suction channel 30 at the distal end via the pressure sensing opening 76, The pressure sensing opening 74 is simultaneously open to the annular space 32, in order to detect the outlet pressure of the pump assembly,

[50] The second fluid channel 70 in the second section 44 of the sensor body 43 comprises a complex, multi-angled and, resulting from this, meandering course. Reflection surfaces which reflect pressure waves are created by the sectionally angled and zigzag-shaped course, A pressure wave which enters into the pressure sensing opening 74 cannot therefore reach the measuring surface 68 on the measuring element 64 in an unhindered manner. In contrast, a damping takes place, said damping protecting the measuring element 64 from damage. Furthermore, a cross- sectional widening in the form of a cylindrical expansion space 78 which likewise serves for damping for the reduction of cavitation given occurring vacuums is provided in the course of the fluid channel 70, In the embodiment example which is shown here, furthermore yet a flushing (purging) connection 80 which in particular is provided for the venting and can possibly be closed in operation branches from the second fluid channel 70, Apart from the expansion space 78, the second fluid channel 70 yet comprises an annular expansion space 82 which can likewise serve for damping occurring pressure fluctuations and for avoiding cavitation. The contour of the second fluid channel 70, second fluid channel in this embodiment example being assigned to the delivery side of the pump assembly, in its course and its contour can be very flexibly adapted for the second section 44 by way of the selected generative manufacturing method, since complicated geometries can be formed without further ado. The first fluid channel 52 could also be provided with direction changes and/or cross-sectional changes in this manner,

[51 ] As a generative manufacturing method, the selective laser sintering or a similar method can likewise be applied. Additionally to the mentioned fluid channels, in this example o free space 84 is formed in the second section 44 of the sensor body 34, in order to save material and to shorten the manufacturing time. The manufacturing time is likewise shortened by way of the described hybrid construction with the pre manufactured first section 42, since this can be conventionally premanufactured. However, it is alternatively conceivable to also manufacture the first section 42 in a generative manufacturing method and for example to post-machine it, for example to grind or polish it on the outer periphery, before the attachment of the second section 44, in order to minimise the flow resistance in the annular space 32,.

[52] If the housing body 38 is attached onto the sensor body 34, then the measuring element receivers 62 and 72 lie opposite one another such that the measuring element 64 is clamped between them in a sealing manner and can therefore be subjected to pressure from both sides for the differential pressure measurement. A second measuring element 86 which is envisaged for detecting the ambient pressure is also arranged on the circuit board 48. For this, a third fluid channel 88 is formed in the housing body 38, as is shown in Fig. 5A. The fluid channel 88, departing from a measuring element receiver 90, extends to an opening 92 in the cover 40. The third fluid channel 88 herein runs in an arched manner, so that it is not possible to insert a straight object through the opening 92 and through the complete third fluid channel 88 up to the measuring element receiver 90. The measuring element 88 is protected from damage by way of this. The third fluid channel 88 brings the ambient pressure to the measuring element 86. For this, the measuring element receiver 90 which engages through an opening in the circuit board 48 bears on a measuring surface of the measuring element 88. The measuring element 88 is likewise arranged at the first side of the circuit board 48. The circuit board 48 comprises a recess in the form of a radially extending slot 94, in order to achieve a force decoupling between the measuring elements 84 and 86, This slot extends from the outer periphery in the radial direction up to the opening 54. The slot 94 permits a certain deformability of the circuit board 48. Apart from the described measuring elements 84 and 88, the circuit board 48 carries further electronic components for measured value detection and for evaluation, and creates the connection to a connection plug 98 of the pressure sensor.

[53] A described, the generative manufacture of the structure, in which the fluid channels are formed, permits different courses or geometries of the fluid channels, in order to achieve different damping characteristics. Further possible geometries for such fluid channels in a pressure sensor are described by way of Fig, 7 to 1 1.

[54] Concerning the embodiment example according to Fig. 7, there is a pressure sensing opening 98, departing from which a fluid channel runs to a valve device 100, via which the connection can be selectively switched to a fluid channel 102 or a fluid channel 104. The valve device 100 can likewise be co-formed in the generatively manufactured structure, wherein preferably the movable valve element is also coformed in an integral manner. The fluid channel 102 runs in a relatively direct manner with three bendings to a first measuring element receiver 108. The second fluid channel 104 has a more complex geometry with three expansion spaces 108 and several bendings. The fluid channel 104 runs out again into the other fluid channel 102 in front of the measuring element receiver 106. The fluid channel 102 or the fluid channel 104 can be selectively used for connection to the measuring element receiver 106 by way of switching-over the valve device 100. The sensor can therefore be adapted to different applications cases.

[55] A further possible embodiment is shown in Fig. 8. A pressure sensing opening 98, onto which a common channel section 1 10 connects is likewise provided there. Three channel sections 1 12 branch away from this common channel section 1 10, to three measuring element receivers 1 14. The three channel sections 1 12 comprise different geometries with different bendings and differently shaped expansion spaces. With this embodiment example, all three measuring element receivers 1 14 are permanently in connection with the pressure sensing opening 98 via the three channel sections 1 12. Such a sensor can be adapted to different application purposes by way of one of three measuring elements which bear on the measuring element receivers 1 14 being selectively activated and the other two for example not being used. A purely electronic adaptation to different application possibilities can be achieved by this.

[56] Fig. 9 shows an embodiment example similar to the embodiment example in Fig. 7, with the difference that no valve element 100 is provided, but the fluid channel 104 ends at the second pressure sensing opening 1 16. Furthermore, the fluid channel 104 ends at its own measuring element receiver 1 18. Here too, two measuring elements can therefore also be arranged on the measuring element receivers 106 and 1 18 and an adaption of the sensor can be achieved by way of activation of the respective measuring element, so that the fluid channel 102 or the fluid channel 104 can be selectively used for the pressure transmission. Such a sensor could also be used for differential pressure measurement, by way of the pressure sensing openings 98 and 1 16 being placed at different locations of an assembly, as has been described above by way of Fig. 2. The measuring element receivers 108 and 1 18 would then both be used, or, similarly to the first embodiment example, brought into contact with two sides of a differential pressure measuring element, for such a differential pressure measurement.

[57] A fourth possible embodiment example for a fluid channel is shown in Fig. 10. There, the fluid channel corresponds essentially to the fluid channel 104 according to Fig. 9, Here, the fluid channel 104 branches to two measuring element receivers 1 18 at the end which is away from the pressure sensing opening 1 16, so that the pressure in the fluid channel 104 can simultaneously act upon two measuring elements, of which for example one measuring element is used for differential pressure measurement and the other for an absolute pressure measurement.

[58] Common to all four embodiment examples according to Fig. 7 to 10 is the fact that apart from differently shaped direction changes, differently shaped expansion spaces 108 can also be applied, wherein these for example can be designed annularly as with the expansion space 82 in Figure 6 or cylindrically as with the expansion space 78 in Fig. 6.

[59] In the examples according to figures 7, 9 and 10 three different shaped structures or expansion spaces 108, namely 108a, 108b and 108c are arranged in series inside the fluid channel. The first structure 108a forms an area for sedimentation protection in form of an expansion spave, the second section 108b forms an area for water hammer protection having several changes in direction of extension of the fluid channel and the third section 108c forms an area for cavitation protection having changes in cross sectional size or diameter, respectively. These three sections 108 are formed with additional changes in direction of the fluid channel therein and between the aforementioned three sections. [60] Fig. 1 1 shows a further geometry of a fluid channel 120 which can be formed by a generative manufacturing method. This fluid channel 120 in its inside comprises projections 122 which effect a meandering course of the free passage of the flow channel 120. A damping of pressure waves or pressure impulses can also be achieved by way of such a channel course.

[61 ] Fig. 12 shows a further embodiment example of a fluid channel, as can be applied in the previously described pressure sensor. Thus Fig. 12 shows a variant of the embodiment of the first fluid channel 52 in the sensor body 34. Fig. 12 shows the first section 42' of a pressure sensor as is shown in section in Fig. 6. In this embodiment example, in contrast to the embodiment in Fig. 6, the channel section 52' a of the first fluid channel 52 comprises two expansion spaces 108'. These spaces each form an additional fluid volume, which is advantageous, in order to prevent cavitation in the region of the measuring element 64 given the occurrence of vacuums. It is to be understood that such channel characteristics which serve for preventing cavifafion, in the case of the first fluid channel 52 can also be formed in the second fluid channel 52b. Otherwise, if is to be understood that all described fluid channels with regard to their geometric fashion can be designed in an arbitrary combination of the previously described design possibilities, in order, adapted to the different application purposes, to reduce pressure impulses or wafer hammers and/or the occurrence of cavitation.

List of reference numerals

2 base housing

4 intet branch

6 outlet branch

8 impellers

10 diffuser

12 shaft

14 coupling

16 drive motor

18 inner housing

20 outer housing

22 channel

24 pressure sensor

26 opening

28 opening

30 suction channel

32 annular space

34 sensor body

36 electronics housing

38 housing body

40 cover

42, 42' first section of sensor body

44 second section of sensor body 46 receiving space

48 circuit board

50 connection plane

52 first fluid channel

52a, 52' a first channel section

52b second channel section

54 recess

58 first side of circuit board 58 second side of circuit board

60 interface

62 measuring element receiver

64 measuring element

66 second measuring surface

68 first measuring surface

70 second fluid channel

72 measuring element receiver

74, 76 pressure sensing opening

78 expansion space

80 flushing connection

82 expansion space

84 free space

86 measuring element

88 third fluid channel

90 measuring element receiver 92 opening

94 slot

96 connection plug

98 pressure sensing opening

100 valve device

102, 104 fluid channels

106 measuring element receiver

108, 108’, 108a, 108 b, 108c expansion spaces

1 10 1 12 channel sections

1 14 measuring element receiver

1 16 pressure sensing opening

1 18 measuring element receiver

120 fluid channels

122 projections

Y longitudinal axis of sensor

X rotation axis of the pump assembly

Claims

1 . A pressure sensor with at least one measuring element (64) and with at least one fluid channel (70) which is arranged in a sensor body (34) and which connects a pressure sensing opening (74) to the measuring element (64), characterised in that

the fluid channel (70) comprises at least one cross-sectional and/or directional change, and

that at least one section of the fluid channel (70), in which channel the at least one cross-sectional and/or directional change is situated, is formed in a structure (44} of the sensor body (34) which is manufactured in a generative manufacturing method.

2. A pressure sensor according to claim 1 , characterised in that the fluid channel (70) is connected to a measuring element receiver (72) receiving the measuring element (64), wherein the measuring element receiver (72) is formed in said structure (44) manufactured in a generative manufacturing method.

3. A pressure sensor according to claim 1 , characterised in that the structure which is manufactured in a generative manufacturing method is manufactured of plastic or metal, in particular rust-free stainless steel.

4. A pressure sensor according to one of the preceding claims, characterised in that at least the structure (44) which is manufactured in the generative manufacturing method and which forms the section of the fluid channel (70) is of one piece,

5. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (70) comprises several direction changes and in particular a zigzag and/or meandering course, within the structure (44) which is manufactured in a generative manufacturing method.

6. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (70} comprises several direction changes in at least two different planes, within the structure (44) which is manufactured in a generative manufacturing method.

7. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (70) within the structure (44) which is manufactured in a generative manufacturing method has a shape which effects at least one reflection of a pressure wave, said pressure wave entering through the pressure sensing opening into the fluid channel,

8. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (70) within the structure (44) which is manufactured in a generative manufacturing method comprises at least one, preferably several changes in cross section and/or expansions spaces (78, 82}.

9. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (70} within the structure (44) which is manufactured in a generative manufacturing method comprises several direction changes and/or at least one change in cross section and/or at least one expansion space (78, 82) arranged in series.

10. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (TOO, 1 12) within the structure which is manufactured in a generative manufacturing method comprises at least one branching, wherein the fluid channel (1 10, 1 12) preferably branches to several measuring elements

1 1. A pressure sensor according to one of the preceding claims, characterised by several fluid channels (52, 70) which are formed in a sensor body (34) and which connect one or more pressure sensing openings (74, 76) each to a measuring element (64) and of which at least one section is formed in a structure (44) which is manufactured in an generative manufacturing method.

12. A pressure sensor according to one of the preceding claims, characterised in that the fluid channel (102, 104) within the structure which is manufactured in a generative manufacturing method comprises at least one valve ( 100) which is preferably likewise manufactured in a generative manufacturing method.

13 A pressure sensor according to one of the preceding claims, characterised in that a further section of the fluid channel (52) is formed in a component (42), to which the structure (44) which is generated in a generative manufacturing method is connected by way of the generative manufacturing procedure.

14. A pressure sensor according to one of the preceding claims, characterised in that it is designed as a differential pressure sensor, concerning which a first fluid channel (70) is connected to a first side of a differential pressure measuring element (64) and a second fluid channel (52) is connected to a second side of the differential pressure measuring element (64).

15. A pressure sensor according to one of the preceding claims, characterised in that a shaping of the fluid channel (70) which damps pressure shocks is formed in at least one of the fluid channels (70) in the structure (44) which is manufactured in a generative manufacturing method,

16. A pressure sensor according to one of the preceding claims, characterised in that a shaping of the fluid channel (70) which reduces cavitation is formed in at least one of the fluid channels (70) in the structure which is manufactured in a generative manufacturing method.

17. A pressure sensor according to one of the preceding claims, characterised in that a shaping of the fluid channel (70) which allows sedimentation protection is formed in at least one of the fluid channels (70) in the structure (44) which is manufactured in a generative manufacturing method,

18. A pressure sensor according to the claims 15 to 17, characterised in that the fluid channel (70) comprises a section shaped to damp pressure shocks and/or a section shaped to reduce cavitation and/or a section shaped for sedimentation protection, wherein these sections are arranged in series,

19 . A pressure sensor according to one of the preceding claims, characterised by at least two fluid channels ( 112) which each comprise at least one section, in which the at least one cross- sectional and/or directional change is situated and which is formed in a structure of the sensor body which is manufactured in a generative manufacturing method, wherein the several fluid channels (112) preferably have o different design.

20. A pressure sensor according to one of the preceding claims, characterised in that the measuring element (64) is arranged on a circuit board (48) and connected to at least one first fluid channel (52), wherein this fluid channel (52), departing from a first side (56) of the circuit board (48), extends through an opening (54) in the circuit board (48) to a second side (58) of the circuit board (48) and is connected to the measuring element (64) at this second side (58) of the circuit board (48).

21 . A pump assembly, characterised in that it comprises a pressure sensor according to one of the preceding claims, wherein the pressure sensor is preferably designed as a differential pressure sensor which is arranged between the suction side and the delivery side of the pump assembly.