Mass flow sensor assembly and method of manufacturing a mass flow sensor assembly

Abstract

A mass flow sensor assembly for a mass flow controller or a mass flow meter comprises a mass flow sensor comprising a capillary tube held by a first corner support and a second corner support formed separately from each other. The capillary tube comprises a sensor portion which is located between the two corner supports, and wherein the two corner supports each have an arc-shaped groove in which the capillary tube is partially received. In addition, a method of manufacturing a mass flow sensor assembly is described.

Claims

1. A mass flow sensor assembly for a mass flow controller or a mass flow meter, comprising a mass flow sensor which comprises a capillary tube which is held by a first corner support and a second corner support formed separately from each other, wherein the capillary tube comprises a sensor portion located between the two corner supports, and the two corner supports each have an arc-shaped groove in which the capillary tube is partially received, wherein the two corner supports are spaced apart from each other so that a free space is provided between the two corner supports in which the sensor portion is located, wherein the capillary tube has at least two arcuate portions which are arranged in the arc-shaped grooves of the two corner supports, wherein the sensor portion is provided between the two arcuate portions, and wherein each of the arcuate portions of the capillary tube is in contact with the arc-shaped groove of a respective one of the two corner supports and permanently connected to the respective one of the two corner supports at an adhesive joint via an adhesive spot in the arc shaped groove.

2. The mass flow sensor assembly according to claim 1, wherein the two arcuate portions each are joined by straight legs.

3. The mass flow sensor assembly according to claim 1, wherein the mass flow sensor has a first sensor coil and a second sensor coil which are electrically insulated from each other and which are wound at least partially around the sensor portion, wherein the first sensor coil is assigned to the first corner support and the second sensor coil is assigned to the second corner support.

4. The mass flow sensor assembly according to claim 3, wherein the respective sensor coil has a first end and a second end connected to a first contact element and to a second contact element of the assigned corner support.

5. The mass flow sensor assembly according to claim 3, wherein the respective sensor coil has at least one winding which is wound around a fastening projection of the assigned corner support.

6. The mass flow sensor assembly according to claim 5, wherein the fastening projection is oriented substantially perpendicular to the sensor portion.

7. The mass flow sensor assembly according to claim 4, wherein the respective sensor coil has at least one winding which is wound around a fastening projection of the assigned corner support, wherein the fastening projection is part of the first contact element.

8. The mass flow sensor assembly according to claim 1, wherein the mass flow sensor assembly has a sensor housing in which the mass flow sensor is at least partially received.

9. The mass flow sensor assembly according to claim 8, wherein the sensor housing is configured in several parts.

10. The mass flow sensor assembly according to claim 8, wherein the sensor housing comprises two recesses in which the two corner supports are received, and a cavity which is located between the two recesses, wherein the sensor portion of the capillary tube extends through the cavity.

11. The mass flow sensor assembly according to claim 10, wherein at least one insulation is arranged in the cavity.

12. A method of manufacturing a mass flow sensor assembly, comprising the following steps: providing a first corner support and a second corner support, wherein the corner supports each have an arc-shaped groove and are spaced apart from each other so that a free space is provided between the two corner supports in which a sensor portion is located, and inserting a capillary tube into the corner supports by fitting arcuate portions of the capillary tube into the arc-shaped grooves such that the sensor portion of the capillary tube is formed between the two spaced apart corner supports and such that each of the arcuate portions of the capillary tube is in contact with the arc-shaped groove of a respective one of the two corner supports and permanently connected to the respective one of the two corner supports at an adhesive joint via an adhesive spot in the arc shaped groove.

13. The method according to claim 12, wherein the two corner supports are manufactured in a common panel.

14. The method according to claim 12, wherein a first sensor coil and a second sensor coil which are assigned to the first corner support and the second corner support, respectively, are wound around the sensor portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and properties of the claimed subject matter will become apparent from the description below and from the drawings to which reference is made and in which:

(2) FIG. 1 shows an exploded view of a mass flow sensor assembly according to the present disclosure,

(3) FIG. 2 shows a perspective view of the mass flow sensor assembly according to the present disclosure of FIG. 1,

(4) FIG. 3 shows a sectional view of the mass flow sensor assembly of FIGS. 1 and 2,

(5) FIG. 4 shows a top view of a panel for the manufacture of the corner supports of the mass flow sensor assembly according to the present disclosure,

(6) FIG. 5 shows a detailed view of FIG. 4 showing two corner supports,

(7) FIG. 6 shows the corner supports of FIG. 5 in a subsequent manufacturing step,

(8) FIG. 7 shows the representation of FIG. 6 rotated by 180°,

(9) FIG. 8 shows the detail of FIGS. 6 and 7 in a perspective view in a later manufacturing step,

(10) FIG. 9 shows a detail of FIG. 8,

(11) FIG. 10 shows a perspective view of the mass flow sensor assembly to be manufactured at a later point in time of manufacture,

(12) FIG. 11 shows a perspective view of the manufactured mass flow sensor assembly according to FIG. 2 at a later point in time,

(13) FIG. 12 shows a sectional view of the manufactured mass flow sensor assembly according to FIG. 11, and

(14) FIG. 13 shows a detailed view of FIG. 12.

DETAILED DESCRIPTION

(15) FIG. 1 shows an exploded view of a mass flow sensor assembly 10 which can be used in a mass flow controller (MFC) or mass flow meter (MFM).

(16) In the embodiment shown, the mass flow sensor assembly 10 comprises a sensor housing 12 which in the present case is configured in two pieces and comprises a base part 14 and a cover 16, which may also be referred to as the housing lid.

(17) In addition, the mass flow sensor assembly 10 comprises a circuit board 18 which is coupled to the sensor housing 12 in the assembled state, as shown in FIG. 2 which shows the mass flow sensor assembly 10 in the assembled state.

(18) The circuit board 18 can be at least partially inserted into the sensor housing 12 or placed onto the sensor housing 12 and can be fastened to the sensor housing 12 in a mechanically detachable by a fastening means 20 such as a screw, as clearly shown in FIG. 2.

(19) In addition, the mass flow sensor assembly 10 comprises a mass flow sensor 22 which, in the assembled state, is at least partially, and in particular largely, received within the sensor housing 12, as clearly shown in FIG. 2.

(20) The mass flow sensor 22 comprises two corner supports 24, 26 and a capillary tube 28, which is supported or held by the two corner supports 24, 26.

(21) The capillary tube 28 comprises a first leg 30, an adjoining arcuate portion 32, an adjoining sensor portion 34, an adjoining arcuate portion 36 and a second leg 38, which branches off from the second arcuate portion 36, as is particularly clear from FIG. 3, which shows a representation rotated by 180°.

(22) The two arcuate portions 32, 36 substantially correspond to a 90° bend, so that the capillary tube 28 generally has a U-shape, the two free ends of the capillary tube 28 being assigned to the legs 30, 38.

(23) Furthermore, the mass flow sensor 22 comprises a first sensor coil 40 and a second sensor coil 42, both of which are wound around the sensor portion 34 of the capillary tube 28. The two sensor coils 40, 42 are electrically insulated from each other. In addition, a gap 44 is provided between the two sensor coils 40, 42. In other words, the individual windings of the sensor coils 40, 42 do not overlap in the area of the gap 44.

(24) The sensor coils 40, 42 are each assigned to one of the two corner supports 24, 26.

(25) The two sensor coils 40, 42 are each made of a wire wound around the capillary tube 28 in the area of the sensor portion 34. The respective wire therefore has two open ends which must be electrically contacted.

(26) In particular, each of the two sensor coils 40, 42 has its two ends in electrical contact with the corner support 24, 26.

(27) For this purpose, the respective corner support 24, 26 has a first contact element 46, 48 and a second contact element 50, 52, respectively, at which the two ends of the sensor coils 40, 42 are connected both mechanically and electrically, for example via a soldered joint.

(28) In the embodiment shown, the first contact elements 46, 48 of the two corner supports 24, 26 are each assigned to fastening projections 54, 56 of the corner supports 24, 26.

(29) Specifically, the sensor coils 40, 42 are each wound with at least one winding around the corresponding fastening projection 54, 56 of the respective corner support 24, 26, so that a mechanical fixing of the sensor coils 40, 42 with respect to the capillary tube 28 is possible.

(30) The first contact elements 46, 48 extend from the fastening projections 54, 56 to a distal end of the respective corner support 24, 26, towards which the second contact element 50, 52 also extends.

(31) This distal end of the respective corner support 24, 26 protrudes from the sensor housing 12, so that it can be contacted by the circuit board 18 when the mass flow sensor 22 is received in the sensor housing 12, as clearly shown in FIG. 2.

(32) To this end, the circuit board 18 has first electrical contacts 58, 60 and second electrical contacts 62, 64 which cooperate with the corresponding first contact element 46, 48 and the second contact element 50, 52, respectively, of the corner supports 24, 26 to ensure the electrical contacting of the mass flow sensor 22 with the circuit board 18.

(33) The electrical connection may also be established by means of a soldered joint, which at the same time enables a mechanical fixing.

(34) It is also clear from FIG. 1 that the mass flow sensor 22 can be received in the sensor housing 12, in particular in the base part 14, as recesses 66, 68 are provided for this purpose, in which the two corner supports 24, 26 of the mass flow sensor 22 can be received.

(35) The recesses 66, 68 are assigned to openings 70, 72 of the sensor housing 12, in particular of the base part 14, into which sleeves 74, 76 are inserted, as explained below with reference to FIGS. 4 to 13.

(36) A cavity 78 is provided between the two recesses 66, 68 and is assigned to the sensor portion 34 of the capillary tube 28 when the mass flow sensor 22 has been inserted into the sensor housing 12.

(37) In addition, two insulations 80, 82 are provided in the cavity 78 in the assembled state, which thermally insulate the mass flow sensor 22, in particular thermally encapsulate the sensor portion 34 of the capillary tube 28.

(38) After insertion of the mass flow sensor 22 into the sensor housing 12, the cover 16 is connected to the base part 14 via a fastening means 84, such that the mass flow sensor 22 is received in the sensor housing 12 so as to be protected from external influences.

(39) The space created between the cover 16 and the base part 12 and in which the mass flow sensor 22 is received, is completely filled with a casting compound 86, for example, so that the mass flow sensor 22 is received in the sensor housing 12 in a protected manner. The fillable space includes, for example, the recesses 66, 68 and excludes the cavity 78, in which the mass flow sensor 22 is located, with the insulations 80, 82.

(40) FIG. 3 which shows a sectional view of FIG. 2, also shows that the free ends of the U-shaped capillary tube 28, i.e. the ends of the capillary tube 28 assigned to the legs 30, 38 are assigned to the two sleeves 74, 76, which have been inserted into the openings 70, 72.

(41) Furthermore, it can be seen from FIG. 3 that the two corner supports 24, 26 each have an arc-shaped groove 88, 90, in which the capillary tube 28 is received via its two arcuate portions 32, 36.

(42) The arc-shaped grooves 88, 90 therefore also have a bend of about 90° in order to guide the capillary tube 28 accordingly.

(43) The two corner supports 24, 26, in particular the arc-shaped grooves 88, 90 of the corner supports 24, 26, are therefore each assigned exclusively to one of the two arcuate portions 32, 36 of the capillary tube 28.

(44) In other words, the two corner supports 24, 26 are each assigned to different portions of the capillary tube 28, namely to the two arcuate portions 32, 36 of the capillary tube 28. These are the portions of the capillary tube 28 which adjoin the respective ends of the sensor portion 34.

(45) Therefore, the two corner supports 24, 26 do not abut each other. The two corner supports 24, 26 do not contact each other, either. Rather, the two corner supports 24, 26 are spaced apart from each other.

(46) In addition, FIG. 3 clearly shows that the two corner supports 24, 26 and the capillary tube 28 are in a common plane, in particular in a common sectional plane of the mass flow sensor assembly 10.

(47) Furthermore, FIG. 3 shows that the two contact elements 46-52 of the corner supports 24, 26 extend to a distal end which is opposite to the free ends of the capillary tube 28.

(48) It will be explained below with reference to FIGS. 4 to 13 how the mass flow sensor assembly 10 shown in FIGS. 1 to 3 is manufactured.

(49) In a first step, a panel 92 shown in FIG. 4 is provided, which comprises a plurality of corner supports 24, 26, which are each substantially arranged in pairs, mirrored to each other about an axis of symmetry S.

(50) A total of ten pairs of corner supports 24, 26 are shown in the embodiment shown in FIG. 4, each pair comprising a first corner support 24 and a second corner support 26, each pair being adapted to be used by one mass flow sensor assembly 10.

(51) The two corner supports 24, 26 are oriented to each other in the panel 92 such that the arc-shaped grooves 88, 90 thereof have their corresponding ends facing each other; see in particular FIG. 5. This orientation already corresponds to the orientation in the finished state of the mass flow sensor assembly 10, in particular of the mass flow sensor 22.

(52) In other words, the two corner supports 24, 26 are provided already correctly oriented to each other on the panel 92, as a result of which the degree of automation can be increased and thus the manufacturing costs can be reduced.

(53) Basically, the panel 92 has a number of corner supports 24, 26, which are arranged next to each other or one below the other. The respective corner supports 24, 26 can be produced by milling or etching.

(54) Furthermore, the panel 92 includes separating edges 94, which ensure that the individual corner supports 24, 26 can be easily separated from the panel 92. This can be carried out by manual breaking, by milling them free or by punching.

(55) Apart from the separating edges 94, the respective corner supports 24, 26 do not have any connection to the panel 92.

(56) Subsequently, a capillary tube 28 already configured in a U-shape is inserted into one pair of the corner supports 24, 26, i.e. into two corner supports 24, 26 arranged in a mirror-inverted manner, wherein the arcuate portions 32, 36 of the capillary tube 28 are fitted into the arc-shaped grooves 88, 90 of the corner supports 24, 26, as shown in FIG. 6.

(57) Subsequently, the capillary tube 28 can be permanently connected to the two corner supports 24, 26, for example by means of an adhesive joint 96, which has also been provided in the corresponding corner support 24, 26, in particular in the form of a depression. The adhesive joint 96 can be produced by milling or etching.

(58) In this respect, the capillary tube 28 can be permanently mechanically connected to the corresponding corner support 24, 26 at the adhesive joint 96 via an adhesive spot.

(59) In FIG. 6, the adhesive point is only shown for the first corner support 24, so that the depression in the second corner support 26 is still visible.

(60) After the coupling of the capillary tube 28 to the two corner supports 24, 26, the two corner supports 24, 26 can be separated from the panel 92 via the separating edges 94, which is already shown in FIG. 6.

(61) Two corner supports 24, 26 which are formed separately from each other and are only connected to each other via the capillary tube 28 are thus produced.

(62) FIG. 7 shows the corresponding intermediate state of the mass flow sensor 22 rotated by 180° with respect to FIG. 6, so that the respective contact elements 46-52 can be seen.

(63) In other words, the contact elements 46-52 are located on the sides of the corner supports 24, 26 opposite to the arc-shaped grooves 88, 90. In an alternative embodiment, the contact elements 46-52 can also be located on the same side of the respective arc-shaped groove 88, 90 or in the corner supports 24, 26.

(64) FIG. 7 clearly shows that the respective first contact element 46, 48 extends from the respective fastening projection 54, 56 to the distal end of the corner support 24, 26, in particular in a U-shape, which protrudes from the sensor housing 12.

(65) After the two corner supports 24, 26 with the inserted capillary tube 28 have been separated from the panel 92, a first wire and a second wire are wound around the capillary tube 28 in the area of the sensor portion 34 to form the first sensor coil 40 and the second sensor coil 42, which is shown schematically in FIG. 8.

(66) To this end, the corresponding wire is (temporarily) connected to the assigned corner support 24, 26 via a free end of the wire.

(67) The rest of the wire is then wound around the capillary tube 28, in particular the sensor portion 34, until the corresponding sensor coil 40, 42 has been wound in the desired manner.

(68) The other free end of the wire is then connected to one of the two contact elements 46-52 of the corresponding corner support 24, 26, via a soldered connection, for example. In particular, the still free end of the wire is connected to the corresponding second contact element 50, 52 of the corresponding corner support 24, 26.

(69) Subsequently, the first wire end, which was previously only temporarily coupled to the corner support 24, 26, can also be permanently connected thereto, for example also via a soldered connection.

(70) However, it may also be provided that the first wire end has already been permanently connected to the corner support 24, 26, in particular to the corresponding contact element 46-52, preferably to the first contact element 46, 48.

(71) The two wires forming the two sensor coils 40, 42 can be wound around the capillary tube 28 in the area of the sensor portion 34 either simultaneously or one after the other.

(72) Finally, the two sensor coils 40, 42 are formed in an identical way, wherein the two sensor coils 40, 42 are insulated from each other, as the windings of their wires do not overlap. In other words, the gap 44 between the two sensor coils 40, 42 is created upon winding of the sensor coils 40, 42.

(73) After the two sensor coils 40, 42 have been wound, the assigned wire can be coupled to the capillary tube 28 by an inter-material bond and/or with a frictional fit in order to avoid a subsequent slipping of the respective sensor coil 40, 42.

(74) This can be ensured in a simple manner by means of an adhesive connection.

(75) FIGS. 8 and 9 also show that the respective sensor coil 40, 42 has been wound with at least one winding around the assigned fastening projection 54, 56 of the respective corner support 24, 26. This can also be used to obtain a mechanical fixing of the corresponding sensor coil 40, 42.

(76) As already explained, the corresponding fastening projection 54, 56 can be part of the first contact element 46, 48 of the corresponding corner support 24, 26, as also shown in FIG. 7, so that via the fastening projection 54, 56, an electrical contacting of the respective sensor coil 40, 42 can be made in addition to the mechanical fastening.

(77) The mass flow sensor 22 is now manufactured and can be inserted into the sensor housing 12, as shown in FIG. 10.

(78) For this purpose, the two sleeves 74, 76 are first inserted, in particular pressed into the openings 70, 72, into bores, for example.

(79) The base part 14 of the sensor housing 12 can be made of aluminum, which improves the thermal conductivity. Alternatively, the base part 14 can be made of copper or another thermally conductive material.

(80) The first insulation 80 is then inserted into the cavity 78.

(81) The mass flow sensor 22 is then inserted into the sensor housing 12, in particular into the base part 14, by inserting the two corner supports 24, 26 into the assigned recesses 66, 68. The capillary tube 28 is then inserted via its ends into the sleeves 74, 76. The sensor portion 34 of the capillary tube 28 runs through the cavity 78, which has already been covered on one side by the first insulation 80.

(82) Then the second insulation 82 is inserted to embed or thermally encapsulate the capillary tube 28, in particular the sensor portion 34, in a thermally insulating manner. This effectively shields the mass flow sensor 22 against environmental influences.

(83) Then the cover 16 is placed thereon and connected to the base part 14 via the fastening means 84.

(84) Alternatively, the second insulation 82 can also be inserted into the cover 16 first, so that the second insulation 82 surrounds the capillary tube 28, in particular the sensor portion 34, when the cover 16 is put thereon.

(85) After the mass flow sensor 22 has been inserted into the sensor housing 12, the capillary tube 28 is still coupled to the sleeves 74, 76 in an extraction-proof manner.

(86) To this end, a plunger 98 is used, which pushes the capillary tube 28 back into the corresponding sleeve 74, 76 until the capillary tube 28 only slightly protrudes at the sleeve 74, 76. This is shown in FIGS. 11 to 13.

(87) Here the plunger 98 is used after the coupling of the circuit board 18 to the sensor housing 12. However, this can also be carried out before, as will be explained below.

(88) The ends of the capillary tube 28 are formed by means of the plunger 98, in particular flanged.

(89) Then the respective sleeve 74, 76 is pressed with the corresponding end of the capillary tube 28, wherein the capillary tube 28 is then welded to the respective sleeve 74, 76 via its ends. For this purpose, a laser can be used which carries out a (pendulum) rotary motion.

(90) After the permanent coupling of the capillary tube 28 to the sleeves 74, 76, the mass flow sensor 22, which is received in the housing 12, can be encapsulated with the casting compound 86, so that the mass flow sensor 22 is received in the sensor housing 12 so as to be protected against external influences.

(91) Then the circuit board 18 is first fastened to the sensor housing 12, in particular by means of the fastening means 20.

(92) The distal ends of the respective corner supports 24, 26, which protrude from the sensor housing 12, can then be mechanically and electrically coupled to the electrical contacts 58-64 of the circuit board 18, for example via a soldered connection.

(93) The mass flow sensor assembly 10 is thus manufactured.