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WO2014188374A1 - Capteur de pression, procédé d'assemblage et appareil électroménager pourvu de ce capteur - Google Patents

Capteur de pression, procédé d'assemblage et appareil électroménager pourvu de ce capteur Download PDF

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Publication number
WO2014188374A1
WO2014188374A1 PCT/IB2014/061631 IB2014061631W WO2014188374A1 WO 2014188374 A1 WO2014188374 A1 WO 2014188374A1 IB 2014061631 W IB2014061631 W IB 2014061631W WO 2014188374 A1 WO2014188374 A1 WO 2014188374A1
Authority
WO
WIPO (PCT)
Prior art keywords
membrane
conductive
sensor
conductive membrane
detection unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2014/061631
Other languages
English (en)
Inventor
Renzo MARCANZIN
Leila MOSCATO
Luigi Salerno
Gabriele SORRENTINO
Salvatore TOMARCHIO
Giovanni Cerizza
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eliwell Controls SRL
Original Assignee
Eliwell Controls SRL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from IT000068A external-priority patent/ITUD20130068A1/it
Priority claimed from IT000069A external-priority patent/ITUD20130069A1/it
Priority claimed from IT000070A external-priority patent/ITUD20130070A1/it
Application filed by Eliwell Controls SRL filed Critical Eliwell Controls SRL
Publication of WO2014188374A1 publication Critical patent/WO2014188374A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
    • G01L19/0627—Protection against aggressive medium in general
    • G01L19/0654—Protection against aggressive medium in general against moisture or humidity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
    • G01L19/0627—Protection against aggressive medium in general
    • G01L19/0645—Protection against aggressive medium in general using isolation membranes, specially adapted for protection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/14—Housings
    • G01L19/148—Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/12—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in capacitance, i.e. electric circuits therefor

Definitions

  • the present invention concerns a digital pressure sensor of the capacitive type, suitable for application in domestic appliances, such as for example, but not only, washing machines or dishwashers, in order to detect pressure values with the purpose of conditioning the activation of pre-determinate functions and cycles of the electric appliance.
  • the invention also concerns the method to assemble the digital pressure sensor and a domestic appliance provided with the sensor.
  • Capacitive sensors are known, which are normally provided with a flexible conductive membrane kept by a spacer at a determinate distance from a conductive plate connected to a printed circuit, or PCB (Printed Circuit Board).
  • PCB printed Circuit Board
  • Capacitive sensors can be used in various fields in the state of the art, to measure different quantities, such as for example pressure, displacements, chemical composition, electric or magnetic field, acceleration, level or composition of a fluid.
  • the sensors can also be of micrometric sizes and have very high sensitivity and resolution, and operate with variations in capacity even in the order of 5 aF.
  • MEMS Micro Electro-mechanical Systems
  • capacitive sensors provide them to be used as high- resolution proximity sensors.
  • the present Applicant does not know of capacitive pressure sensors used in the field of domestic appliances.
  • one or more pressure sensors are used in order to detect particular and defined values of a pressure and to determine the activation or de-activation of a particular function or functioning cycle of the appliance, based on the commands of an electronic or electro-mechanical programmer.
  • pressure sensors comprise for example pressure switches of the electro-mechanical type, which can be activated when the pressure reaches a predetermined level.
  • known pressure switches have the further disadvantage that they are not very versatile, since they are generally calibrated only to detect a predetermined pressure and do not perform any measuring of the quantity.
  • Another problem is to satisfy different requirements in terms of output signal with the same sensor, in order to be able to install the same sensor, possibly modifying only its programming, in applications that manage different output signals.
  • Such deformations can be due to tensions inside the pressure sensor that can occur due to the effect of different heat dilation of its components.
  • Known sensors also have the problem of limited resolution due to the fact that the compressibility of the dielectric present between the plates of the capacitor may be such as to contrast, and therefore limit, the deformation of the flexible conductive membrane. Consequently, the capacity variations inside the sensor are also reduced, and hence the resolution of the sensor itself.
  • One purpose of the present invention is to obtain a digital pressure sensor that is not bulky, is reliable, inexpensive and able to measure with great accuracy a pressure in a domestic appliance, to allow the automatic management of a plurality of functioning programs.
  • Another purpose of the present invention is to perfect a completely automated method to make a digital pressure sensor that allows large scale production of the digital sensor, allowing to contain the production costs.
  • Another purpose of the invention is to obtain a capacitive sensor that supplies an extremely precise measurement irrespective of the heat stresses to which it is subjected.
  • Another purpose of the present invention is to obtain a digital pressure sensor that is able to measure the pressure in a domestic appliance with maximized resolution and independent of the compressibility of the dielectric comprised between the plates of the capacitor thus made.
  • the Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
  • a digital pressure sensor comprises at least a pressure detection unit and is configured to measure at least a pressure in a domestic appliance
  • the digital pressure sensor is the capacitive type and the detection unit comprises at least a printed circuit provided on its surface with a conductive plate, and a conductive membrane positioned parallel to and distanced from the conductive plate. Moreover, in substantial correspondence to the conductive plate, the conductive membrane has a deformable zone. In particular, the conductive membrane and the conductive plate define the plates of a variable capacity capacitor.
  • the innovative advantage is obtained, in this specific application, of being able to measure said pressure by means of a sensor of the capacitive and digital type, which is compact, reliable, sensitive and high resolution, and also without mechanical elements in movement which could create hysteresis, are difficult to assemble and calibrate, and are not very reliable and sensitive.
  • the domestic appliance comprises a command and control unit and the printed circuit integrates a micro-controller configured to detect variations in capacity between the conductive membrane and the conductive plate.
  • the micro-controller is connected to the command and control unit in order to transmit a signal relating to said variations in capacity.
  • the digital pressure sensor is integrated in a programmable card of the command and control unit, and the printed circuit is an integrating part of the programmable card. In this way the other advantage is obtained of reducing the bulk of the digital pressure sensor and consequently optimizing the productive steps or the functioning cycles of the domestic appliance, which can provide a simultaneous embodiment of the command and control unit and the digital pressure sensor.
  • the detection unit consists of three overlapping layers defined by an insulating membrane, the conductive membrane and the printed circuit, and is made in such a way that the conductive membrane is interposed between the insulating membrane and the printed circuit.
  • the insulating membrane is provided with attachment means configured to connect to both the conductive membrane and to the printed circuit.
  • the conductive membrane and the printed circuit lie on reciprocally parallel respective lying planes and have respective perimeter edges free from mechanical constraints.
  • the detection unit is inserted inside a container provided with at least a first part, and the insulating membrane is interposed between the first part and an attachment ring positioned around the conductive membrane and the printed circuit.
  • the attachment ring is configured to press a peripheral connection edge of the insulating membrane against the first part, so that conductive membrane and printed circuit are positioned in the container at least without any lateral contact with it.
  • the capacitor defined by the conductive membrane and by the conductive plate of the printed circuit is substantially suspended in the container, and therefore both the conductive membrane and the printed circuit are free from deformations on its lying plane, without being subjected to constraints with respect to its external perimeter, because of the effect of heat stresses.
  • the digital pressure sensor also comprises at least an exit aperture which puts the interspace between the conductive plate and the conductive membrane in communication with the environment outside the sensor, so that the flection of the deformable zone, due to a pressure applied on the conductive membrane, causes part of the dielectric material to exit from the pressure detection unit.
  • the present invention also has the advantage of making this resolution independent of the compressibility of the dielectric material. Consequently, the digital pressure sensor can supply a response even to minimum variations in pressure.
  • the at least one exit aperture is made through, through the conductive plate and the printed circuit.
  • At least part of said at least one exit aperture is made through in one part of the container.
  • the container is formed by a lid and a closing body connected to each other; the part of the container in which the at least one exit aperture is made is a zone of the lid which acts as spacer element, or it is the closing body.
  • the at least one exit aperture is configured to define an exit path of the dielectric, for example air, substantially parallel to the direction of application of the pressure on the conductive membrane.
  • the at least one exit aperture is configured to define an exit path of the dielectric, for example air, that is incident or orthogonal to the direction of application of the pressure on the conductive membrane.
  • the present invention also concerns a method to assemble a digital pressure sensor comprising at least a pressure detection unit configured to detect a pressure in a domestic appliance. The method provides to assemble the detection unit comprising at least a conductive membrane and an insulating membrane and a printed circuit provided with a conductive plate, to insert the detection unit in a first part, for example a containing body, of a container, and to connect the detection unit to said first part, and to close the container by attaching a second part, for example a closing body, to the first part.
  • Forms of embodiment of the method provide that, before closing the container, an attachment ring is inserted in the first part of the container, after the insertion of the detection unit, so that the attachment ring is in contact with a peripheral edge of the insulating membrane included in the pressure detector.
  • the attachment ring is clamped on one of the parts of the container and is configured to press the insulating membrane against it in order to determine an insulating effect for the digital pressure sensor.
  • the insulating membrane is used to insulate the conductive membrane with respect to the outside of the digital sensor.
  • the method provides to connect the insulating membrane, conductive membrane and conductive plate with respect to each other so that the conductive membrane and the conductive plate are essentially suspended to the insulating membrane, to insert the detection unit in a first part, for example a containing body, of a container, and to connect the detection unit to the first part so that the conductive membrane and conductive plate are without lateral constraints with respect to the walls of the container, and to close the container by attaching a second part, for example a closing body, to the first part.
  • a first part for example a containing body
  • the present invention also comprises a domestic appliance provided with a capacitive digital pressure sensor made as described above.
  • FIG. 1 is a schematic representation of a washing machine provided with a digital pressure sensor according to the invention
  • - fig. 2 is a schematic view in section of a form of embodiment of the digital pressure sensor in fig. 1;
  • FIG. 3 is a schematic representation of a washing machine provided with a digital pressure sensor according to another form of embodiment
  • - fig. 4 is a three-dimensional and exploded view of a detail of another form of embodiment of the pressure sensor in fig. 2;
  • FIG. 5 is a exploded view of another form of embodiment
  • - figs. 6a and 6b are, respectively, a view in section of one form of embodiment of the pressure sensor in fig. 1 and an enlarged view of a detail of fig. 6a;
  • figs. 7 and 8 are schematic views in section of other forms of embodiment of the digital pressure sensor in fig. 1 ;
  • - fig. 9 is a schematic representation of the method to assemble the digital pressure sensor according to the invention.
  • - fig. 10 is a variant of fig. 9.
  • a digital pressure sensor is indicated in its entirety by the reference number 10 and is shown schematically, assembled in a domestic appliance, such as for example a washing machine 11.
  • washing machine 1 The present description is referred by way of example to a washing machine 1 1, but can easily be adapted to any domestic appliance in which it is necessary to measure one or more internal pressures.
  • Fig. 1 is used to describe by way of example a washing machine 1 1 of the known type and its corresponding functioning.
  • the washing machine 1 1 is provided with at least a drum 12 in which the garments to be washed are contained and with an electric motor 13 configured to supply the desired rotatory motion to the drum 12.
  • the digital pressure sensor 10 is connected to the drum 12 through a measuring pipe 18 that allows it to measure the pressure of the water contained in the drum 12 in an indirect way.
  • the measuring causes some steps of the washing cycle, which depend on the amount of water in the drum 12, to start and/or stop.
  • the washing cycles are managed by a command and control unit 19 to which the digital pressure sensor 10, the electric motor 13, the electrovalve 15 and the discharge pump 16 are connected, for example by means of electric feed and signal transmission cables.
  • the command and control unit 19 can include a memorization module 20, in which programs containing all the operations connected to the execution of each of the steps of the washing cycles can be memorized, and an electronic processor 21, configured to execute such programs.
  • the memorization module 20 and the electronic processor 21 can both be integrated into a programmable card, or motherboard 22.
  • command and control unit 19 can also include a user interface 23, by means of which a user can select the desired washing cycle and the desired functions of the washing machine 1 1, or control the progress of the cycle.
  • the digital pressure sensor 10 measures the pressure of the water contained in the drum 12, which causes some steps in the washing cycle to start and stop, for example the start of the filling of the drum 12 at the beginning of the cycle, the stop of said filling and the start of the washing step, the start of the partial discharge step and the subsequent further filling of the drum 12 during the washing cycle and the start of the spinning step.
  • the digital pressure sensor 10 sends a signal relating to the pressure of the water in the drum 12 to the command and control unit 19.
  • the electronic processor 21 processes the signal in order to obtain the value of the pressure and to compare it to a threshold value contained in the program to be executed and memorized in the memorization module 20. Based on this comparison, the command and control unit 19 selectively commands the electrovalve 15, to open or close.
  • the digital pressure sensor 10 can be configured to send the signal corresponding to the pressure measurement to the command and control unit 19 continuously, in order to optimize and accelerate the response times of the command and control unit 19.
  • the digital pressure sensor 10 is provided with great precision and sensitivity, to render the washing conditions of each washing cycle repeatable and to optimize consumption, in particular of water.
  • a greater resolution of the digital pressure sensor 10 can also make it possible to increase the washing programs of a washing machine 1 1 , further contributing to its optimization and rendering the washing machine 1 1 versatile and flexible, meeting the different needs of the user.
  • fig. 2 is used to describe preferential forms of embodiment of a digital pressure sensor 10, in which it is the capacitive type.
  • the digital pressure sensor 10 comprises a container 24, in this case with a box-like shape defined by a first part, or lid 25, and by a second part, or closing body 26, said parts 25, 26 being attached to each other, for example by means of gluing, welding or joining means.
  • a printed circuit or PCB 27 rests, on one surface of which a conductive plate 28 is made, which can also be a few microns thick, for example if defined by a metal coating of the PCB 27 surface itself, or by part of it.
  • the lid 25 can be provided, in example forms of embodiments, with housing seatings 29 in which peripheral ends of the PCB 27 can be housed, in order to keep the latter firmly in position after the assembly of the container 24.
  • one or more attachment compartments 30 can be made in the lid 25, able to contain at least a peripheral part of a conductive membrane 31 for the attachment of the latter to the lid 25.
  • the portion of the lid 25 comprised between the attachment compartments 30 and the PCB 27 acts as a spacer element or spacer, between the conductive membrane 31 and the conductive plate 28.
  • a spacer separate from the lid 25 is provided, contained therein and bearing said attachment compartments 30 for the conductive membrane 31.
  • the aforementioned attachment provides that the conductive membrane 31 is located parallel to the conductive plate 28 and at a determinate distance from it, so that conductive membrane 31 and conductive plate 28 define the plates of a capacitor, when a desired difference in potential is set between them.
  • the distance between the conductive membrane 31 and the conductive plate 28 define an interspace I which can even be a few hundredths of a millimeter, in order to obtain a desired value of sensitivity of the digital pressure sensor 10 that can be also extremely low.
  • the shape of the conductive membrane 31 is defined by a peripheral zone 32, or attachment zone, with a greater thickness than a central zone 33, deformable under flection, which defines the sensitive element of the digital pressure sensor 10.
  • the conductive membrane 31 is in fact configured to bend if subjected to a pressure (arrows in fig. 2) applied in its central zone 33, thus increasing the capacity of the capacitor formed by the conductive membrane 31 and the conductive plate 28.
  • the lid 25 in correspondence to the central zone 33 of the conductive membrane 31, the lid 25 is provided with an aperture 35 communicating with the measuring pipe 18 and with the function of transmitting the pressure of the water contained in the drum 12 to the central zone 33 of the conductive membrane 31, deforming it.
  • This increase in capacity like other possible reductions in capacity which occur, for example, following the increase in said pressure, are detected by a micro-controller 34, for example a microchip.
  • the microcontroller 34 is integrated in the PCB 27.
  • the PCB 27 and the conductive membrane 31 define a pressure detection unit 36.
  • the detection unit 36 is contained in the container 24, which determines an at least partial insulation thereof with regard to the outside of the digital pressure sensor 10.
  • the microcontroller 34 is configured to process the measurement of the capacity variations and supply an output signal to the command and control unit 19 with which it is electronically connected.
  • the digital pressure sensor 10 as described heretofore can be used for example to advantageously measure pressures comprised between 0 and 5,000 Pa, with a resolution of about 8 Pa.
  • microcontroller 34 can be configured to detect variations in capacity even in the order of 0.05 pF.
  • the components of the digital pressure sensor 10 can be miniaturized, it is possible that the overall volumetric bulk of the digital pressure sensor 10 can also be only 40 mm x 40 mm x 20 mm.
  • This solution gives the advantage of reducing the internal bulk of the washing machine 11 and the advantage of simplifying the production process thereof, thus reducing the number of independent components.
  • the digital pressure sensor 10 can be made in the same production cycle as the command and control unit 19.
  • Figs. 4 and 5 are used to describe forms of embodiment of a digital pressure sensor 10 in which the detection unit 36 also includes an insulating membrane 37, used to insulate the conductive membrane 31 with respect to the outside and to prevent its direct contact with the air coming from the measuring pipe 18. This insulation can be functional both to prevent external disturbances to the pressure measurement and to preserve the conductive membrane 31 and the PCB 27 from damage or wear.
  • the insulating membrane 37 can have the function of a second insulation for the digital pressure sensor 10, guaranteeing, in this way, that the latter belongs to the category of electrical devices in class 2 (or class II).
  • the insulating membrane 37 is made of a flexible polymeric material, such as for example rubber or other material which can combine the properties of flexibility and impermeability at least to water and air and insulation.
  • Fig. 4 shows an exploded view of the detection unit 36, consisting of three overlapping layers defined by the insulating membrane 37, the conductive membrane 31 and the PCB 27.
  • the insulating membrane 37 is provided with a plan bulk greater than that of the conductive membrane 31 and the PCB 27 and has a peripheral connection edge 38 and a central flexible zone 39, protruding with respect to the peripheral connection edge 38 and connected to it.
  • the flexible zone 39 in this specific case, is provided with attachment pegs 40, jutting out with respect to the flexible zone 39 and having a stem 41 and a free end 42 with a bigger size than the stem 41.
  • the attachment pegs 40 have the function of attaching the conductive membrane 31 and the PCB 27 to the insulating membrane 37. This attachment is achieved by inserting the attachment pegs 40 in first through holes 43 made in the peripheral zone 32 of the conductive membrane 31 and in second through holes 44, made in the PCB 27.
  • the first 43 and second 44 through holes constitute connection means complementary to the connection means of the insulating membrane 37.
  • the first and the second through holes 43, 44 can have a diameter smaller than the width of the free end 42 and are at least equal in number to that of the attachment pegs 40.
  • the assembly of the detection unit 36 first of all provides to align the attachment pegs 40 axially with the first through holes 43 and with the second through holes 44, and then to deform the free end 42 of the attachment pegs 40 in order to force it to pass through the first and second through holes 43, 44. Subsequently, the release of this deformation can allow a stable attachment between the three components of the detection unit 36, since the greater size of the free end 42 compared to the through holes 43, 44 prevents the attachment pegs 40 from coming out.
  • the assembly as described above allows to stack or overlap, in correspondence to each other inside the detection unit 36, the flexible zone 39 of the insulating membrane 37, the central zone 33 of the conductive membrane 31 and the conductive plate 28.
  • the flexible zone 39 and the central zone 33 are located in reciprocal contact, so that they are solidly mobile.
  • the entity of the flectional deformation of the central zone 33 of the conductive membrane 31 depends, as is known, on the compressibility of the dielectric material present in the interspace I (figs. 7 and 8).
  • the digital pressure sensor 10 includes one or more exit apertures 57 configured to put the interspace I in communication with the outside.
  • exit apertures 57 can be provided, in the case where it is deemed to be necessary.
  • the exit aperture 57 can be defined by a through hole, a through slot, or a through groove with any shape depending on requirements.
  • the exit aperture 57 in this case, is configured to define an exit path of the dielectric that is essentially parallel to the direction of application of the pressure P on the conductive membrane 31.
  • the aperture 57 is defined by a first portion 57a made through in the conductive plate 28, a second portion 57b made through in the PCB 27 and a third portion 57c made through in the closing body 26 of the container 24.
  • the exit aperture 57 as described above can consist of only the first portion 57a and the second portion 57b, provided that their overlapping puts the interspace I into communication with the outside of the digital pressure sensor 10.
  • Fig. 8 can be used to describe forms of embodiment in which at least one exit aperture 157, in this case a plurality of exit apertures 157, is made in a through manner transversely in the portion of lid 25 which acts as a spacer between the conductive membrane 31 and the PCB 27.
  • the exit apertures 157 are configured to define an exit path of the dielectric that is incident with respect to the direction of application of the pressure P on the conductive membrane 31.
  • the exit path can be substantially orthogonal to the direction of application of the pressure P on the conductive membrane 31, that is, parallel to the latter and to the conductive plate 28.
  • the digital pressure sensor 10 in the forms of embodiment described above, can be used for example to measure pressures comprised between 0 and 5,000 Pa.
  • the digital pressure sensor equipped with exit apertures 57, 157 can reach a resolution of about 8 Pa, corresponding to about 0.8 mm of water column.
  • the microcontroller 34 can be configured to detect variations in capacity even in the order of 0.05 pF.
  • the containing body 25 is made in a single body with the measuring pipe 18.
  • the containing body 25 includes perimeter walls 45 in which fixed joint seatings 46 are made, which in this specific case are through, but they can also be blind, internal or external.
  • the fixed joint seatings 46 can be disposed on one or more rows. Furthermore, the fixed joint seatings 46 can affect all or only some of the perimeter walls 45.
  • the containing body 25 also includes a plurality of spacing protuberances 47, which protrude toward the inside of the containing body 25 and surround the aperture 35 that feeds the air from the measuring pipe 18.
  • the spacing protuberances 47 are configured to enter into contact with the flexible zone 39 of the insulating membrane 37 and keep it distanced from the containing body 25. In this way, a chamber 48 (fig. 6a) is created in which the air coming from the measuring pipe 18 is distributed to exert a uniform pressure on the flexible zone 39 of the insulating membrane 37. This pressure causes the flexible zone 39 to bend and consequently also the central zone 33 of the conductive membrane 31 to which it is connected. In this way, reducing the distance between the conductive membrane 31 and the conductive plate 28, and therefore increasing the capacity of the capacitor of which they represent the plates, the digital pressure sensor 10 is able to measure the pressure of the water contained in the drum 12, as described for the previous forms of embodiment.
  • Figs. 6a and 6b also show an attachment ring 49, with sizes mating to those of the peripheral connection edge 38 of the insulating membrane 37 and configured to be inserted in the containing body 25.
  • the attachment ring 49 can be made of an insulating material, for example a polymer material such as rubber or other plastic material, or a composite, or other materials impermeable to air and water.
  • the assembly of the detection unit 36 provides to position the attachment ring 49 in correspondence to the peripheral connection edge 38 of the insulating membrane 37 before the attachment pegs 40 are inserted in the through holes 43, 44.
  • the attachment ring 49 is disposed around the PCB 27 and the conductive membrane 31.
  • the attachment ring 49 can be provided peripherally with a plurality of attachment fins 50a, protruding laterally therefrom along part or all of its perimeter, as shown for example in fig. 9.
  • the attachment fins 50a can be the same number or fewer than the first fixed joint seatings 46a made, for example, in the containing body 25, and are shaped to each be inserted in a corresponding first fixed joint seating 46a.
  • the closing body 26 of the digital pressure sensor 10 can include attachment fins 50b, equal in a number or fewer than those of the fixed joint seatings 46, or to that of second fixed joint seatings 46b made in the containing body 25, and shaped to each be inserted in a corresponding fixed joint seating 46 or 46b.
  • the closing body 26 can also include one or more closing tongues 51 (figs. 9 and 10), in this case two, each configured to be inserted in a closing cavity 52 made in the containing body 25. In this way, as indicated in fig. 9, the container 24 of the digital pressure sensor 10 is obtained.
  • both the PCB 27 and the conductive membrane 31 have a smaller plan bulk than that of the attachment ring 49 and can be surrounded by it and comprised inside it.
  • a perimeter separation space can be determined, comprised between the PCB 27, the conductive membrane 31 and the attachment ring 49, in order to obtain the advantage of releasing the capacitor defined by the conductive plate 28 of the PCB 27 and by the conductive membrane 31 from the container 24.
  • the conductive membrane 31 and the PCB 27 are thus achieved substantially suspended inside the container 24 and have respective perimeter edges 131 and 127 free from mechanical constraints, so that they can dilate thermally at least on the respective lying planes PI and P2, independently from the containing body 25.
  • the independence of this dilation allows to avoid the onset of residual tensions due to the fact that the PCB 27, the conductive membrane 31 and the containing body 25 can be made of different materials from each other, for example metal and plastic materials respectively, and therefore having different dilation coefficients.
  • fig 6a shows by way of example a disposition of the components of the digital pressure sensor 10, in which the containing body 25 faces upward, but other forms of embodiment can provide dispositions rotated by any angle whatsoever with respect to this, all falling within the field of the present invention.
  • the containing body 25 is located in the lower part of the digital pressure sensor 10.
  • the assembly method first of all provides that the detection unit 36 is assembled (on the left in fig. 9), consisting in this case of the PCB 27, the conductive membrane 31, the insulating membrane 37 and the attachment ring 49.
  • the detection unit 36 is inserted in the containing body 25 so that the peripheral connection edge 38 and the flexible zone 39 of the insulating membrane 37 respectively rest on the containing body 25 and on the spacer protuberances 47.
  • attachment fins 50a of the attachment ring 49 (if present, not in the solutions in fig. 9) and the first fixed joint seatings 46a made in the containing body 25 are coupled.
  • the closing body 26 is inserted in the containing body 25 and attached to it by introducing both the attachment fins 50b into the corresponding fixed joint seatings 46 and the closing tongues 51 into the corresponding closing cavities 52.
  • the attachment fins 50b are inserted in the second fixed joint seatings 46b. In this way, the digital pressure sensor 10 is achieved as shown at the top on the right in fig. 9.
  • Forms of embodiment of the method described above can provide, where the measuring pipe 18 is not integrated in the containing body 25, a final step of connecting the measuring pipe 18 to the containing body 25.
  • Forms of embodiment of the method described above can provide that one or all the operations cited above are automated, which advantageously allows to reduce production costs of the digital pressure sensor 10, making it suitable for use even on a large scale in the field of domestic appliances, for example for measuring the pressure in washing machines.
  • the conductive membrane 31 has a central zone 33 with through apertures 53, with the function of making the structure lighter and increasing its deformability.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

L'invention concerne un capteur de pression comprenant une unité de détection (36) destinée à détecter une pression dans un appareil électroménager (11). Ledit capteur est de type capacitif et l'unité de détection (36) comporte un circuit imprimé (27) formé sur sa surface avec une plaque conductrice (28), une membrane conductrice (31) disposée parallèle à la plaque conductrice (28) et à distance de celle-ci et comportant une zone déformable (33) en correspondance avec la plaque conductrice (28). La membrane conductrice (31) et la plaque conductrice (28) définissent les plaques d'un condensateur à capacité variable.
PCT/IB2014/061631 2013-05-22 2014-05-22 Capteur de pression, procédé d'assemblage et appareil électroménager pourvu de ce capteur Ceased WO2014188374A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
ITUD2013A000070 2013-05-22
ITUD2013A000069 2013-05-22
ITUD2013A000068 2013-05-22
IT000068A ITUD20130068A1 (it) 2013-05-22 2013-05-22 Sensore digitale di pressione, procedimento di assemblaggio ed elettrodomestico provvisto di detto sensore digitale di pressione
IT000069A ITUD20130069A1 (it) 2013-05-22 2013-05-22 Sensore digitale di pressione per un elettrodomestico ed elettrodomestico provvisto di detto sensore digitale di pressione
IT000070A ITUD20130070A1 (it) 2013-05-22 2013-05-22 Sensore digitale di pressione per un elettrodomestico, procedimento di assemblaggio ed elettrodomestico provvisto di detto sensore digitale di pressione

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WO2014188374A1 true WO2014188374A1 (fr) 2014-11-27

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PCT/IB2014/061631 Ceased WO2014188374A1 (fr) 2013-05-22 2014-05-22 Capteur de pression, procédé d'assemblage et appareil électroménager pourvu de ce capteur

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WO (1) WO2014188374A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106768608A (zh) * 2016-12-21 2017-05-31 安徽天利粮油集团股份有限公司 烘干机压力监视装置
CN109073542A (zh) * 2016-03-31 2018-12-21 皇家飞利浦有限公司 用于实时抗结垢和生物结垢监测的集成式系统

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880009A (en) * 1973-05-24 1975-04-29 Bunker Ramo Pressure transducer
JPH09280987A (ja) * 1996-04-10 1997-10-31 Fuji Electric Co Ltd 静電容量型圧力センサ
WO2005019785A2 (fr) * 2003-08-11 2005-03-03 Analog Devices, Inc. Capteur capacitif
CN201637532U (zh) * 2009-12-30 2010-11-17 中山市创源电子有限公司 电容性压力传感器以及包括该传感器的压力检测装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880009A (en) * 1973-05-24 1975-04-29 Bunker Ramo Pressure transducer
JPH09280987A (ja) * 1996-04-10 1997-10-31 Fuji Electric Co Ltd 静電容量型圧力センサ
WO2005019785A2 (fr) * 2003-08-11 2005-03-03 Analog Devices, Inc. Capteur capacitif
CN201637532U (zh) * 2009-12-30 2010-11-17 中山市创源电子有限公司 电容性压力传感器以及包括该传感器的压力检测装置

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109073542A (zh) * 2016-03-31 2018-12-21 皇家飞利浦有限公司 用于实时抗结垢和生物结垢监测的集成式系统
CN109073542B (zh) * 2016-03-31 2022-04-05 皇家飞利浦有限公司 用于实时抗结垢和生物结垢监测的集成式系统
CN106768608A (zh) * 2016-12-21 2017-05-31 安徽天利粮油集团股份有限公司 烘干机压力监视装置
CN106768608B (zh) * 2016-12-21 2024-04-05 安徽天利粮油集团股份有限公司 烘干机压力监视装置

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