ADJUSTABLE PRESSURE SENSOR DEVICE, ESPECIALLY FOR HOUSEHOLD APPLIANCES.

Description

DESCRIPTION of the industrial utility model entitled: "Adjustable pressure sensor device, especially for household appliances" By: ELBI INTERNATIONAL SpA, Italian nationality na, Corso Principe Oddone 18, 1-10100 Turin Designated Inventors: Michele FARANO, Angelo MUNE-RETTO Filed: July 28, 2003 JQ 2 0Q3U 000 122] * * * DESCRIPTION The present invention relates to a pressure sensing device, particularly for household appliances. More specifically, the invention concerns a pressure sensing device of the type comprising a support body in which a membrane is mounted so as to define a variable volume chamber to which a fluid pressure is supplied in use; and a plurality of electrical switches mounted in the body and coupled to the membrane, in such a way that the latter is capable of causing its switching when the pressure in said chamber exceeds JACOBACCI corresponding different threshold values ​​which are predetermined by means of associated calibration means including for each switch a respective spring whose compression is variable by means of a corresponding contrast organ whose position with respect to the body is adjustable. The purpose of the present invention is to create a pressure sensing device of the type defined above, which allows the pressure threshold values ​​operationally associated with the aforementioned electrical switches to be changed quickly and easily. This and other purposes are achieved according to the invention with a pressure sensing device of the type specified above, characterized in that said contrasting organs are rigidly connected to the ends of corresponding wings of an interconnecting structure, preferably integral with them; said interconnecting structure being movable with respect to the body in a guide structure which comprises a plurality of laterally slotted tubular guide formations, each for the guidance of a corresponding counter-member JAGO CC P ERS .pA sto, and an intermediate guide formation designed to slide a median portion of the interconnecting structure; to said median portion of the interconnection structure being associated elastic pushing means tending to push the interconnecting structure away from the body, and snap-action positioning means, suitable for retaining, against the action of said elastic means, the interconnecting structure selectively in one of a plurality of relative positions with respect to the body, in each of which said electrical switches are associated with different respective pressure threshold values. Further features and advantages of the invention will appear from the detailed description that follows, given purely by way of non-limiting example, with reference to the attached drawings, in which: Figure 1 is a perspective view of a pressure sensing device according to the invention; Figure 2 is a partial perspective view showing a detail of the device according to Figure 1, indicated by the arrow II in that fi- JACOBACC1 & PARTNERS figure ; Figure 3 is a sectional view along line III-III of Figure 1; Figure 4 is a partial exploded perspective view, showing some parts of the device according to the previous figures; Figure 5 is a sectional view along line VV of Figure 1; and Figure 6 is a sectional view similar to that shown in Figure 5, and shows a variant embodiment. In figures 1 to 3, the number 1 indicates a pressure sensor device according to the invention. This device 1 comprises a supporting body or casing 2, which in the illustrated embodiment is formed by a half-shell 3, essentially in the shape of a cup, and by an associated lid 4. The lid 4 is snap-fitted to an edge 3a surrounding the mouth or opening of the half-shell 3, and the periphery of an elastic membrane 5, for example made of elastomeric material, is clamped between them (figure 3). The membrane 5 defines, together with the lid 4, a variable volume chamber 6 to which JAGOBACCI PARTNERS SA In use, fluid pressure is supplied through an inlet connection 7. In the embodiment illustrated by way of example, this connection 7 extends radially from the cover 4. In a manner known per se, and as shown in Figure 3, the membrane 5 rests on a rigid element 8 that is essentially planar, for example made of plastic material. This element is coupled, by means of tip-like formations, to a plurality of transmission organs, only one of which is visible in Figure 3, where it is generally indicated by the reference numeral 9. In the embodiment illustrated by way of non-limiting example, the pressure sensing device 1 is of the so-called two-level type, i.e. capable of operationally providing signals when the pressure in the chamber 6 exceeds a first and a second predetermined threshold value, respectively. Correspondingly, in the body 2 of the device 1 there are two intermediate transmission elements 9 of the type indicated above and further described below. Each intermediate transmission element 9 has a branch 9a pivoted at 10 in the half-shell 3, on the opposite side to the cover 4 with respect to the membrane 5, and at least one further branch 9b, opposite to the previous one, and presenting a tip 9c engaged in a cap 11 of essentially conical shape. On the opposite side of the cover 4 with respect to the transmission elements 9, in the half-shell 3 (two) electrical switches are mounted, each of which is indicated overall with 12 (only one of them is visible in figure 3). In a manner known per se, each switch 12 comprises a plate 13, preferably of metallic material, in particular of the type described for example in German patent 28 19 795 or of the type according to Italian patent no. 1,219,392, to which reference is made for further details. The plate 13 of each switch has an elongated shape, and its ends have movable contact members, indicated by 15 and 16, capable of cooperating with respective pairs of fixed contacts 17, 18 and 19, 20, fixed to the half-shell 3. The transmission elements 9 associated with each commutator 12 with the respective pin formation 9c and the associated conical element 11 are capable of acting on the commutator plate 13. J COBACCI & PARTNERS corresponding tors, as the fluid pressure in the variable volume chamber 6 varies. When the pressure in this chamber exceeds a predetermined threshold value, the membrane, via an intermediate transmission element 9, is susceptible to cause the snap switching of the plate 13 of a switch 12, and this occurs in particular when the pressure exerted by the The associated tip 9c on the plate 13 overcomes the elastic reaction of a calibration spring 21. The compression of each spring 21, as see for example in figure 5 or 6, is variable by means of an associated contrast member 22, mounted in a translatable manner in a tubular formation 23 which extends externally from the bottom wall of the half-shell 3 of the device. In the embodiment illustrated by way of example, as already mentioned above, the pressure sensing device is of the two-level type, and comprises correspondingly two electrical switches 12, with associated transmission elements 9 which couple them mechanically to the membrane 5. Associated with the snap-on plates 13 of these switches 12 are respective variable compression springs 21, and corresponding respective contrast organs 22 which can be moved with respect to the body 3, and whose position with respect to this body can be adjusted in the manner which will be described below. In figures 1, 2 and 4, the contrast members of the springs 21 associated with the two electric switches are indicated by 22a and 22b respectively, and the corresponding tubular guide formations of the body 3 are indicated by 23a and 23b. As can be seen in particular in figure 4, the contrast members 22a and 22b associated with the threshold calibration springs of the two electric switches are rigidly connected to the ends of corresponding wings 24a and 24b of an interconnection structure generally indicated by 24. Preferably, this structure 24 is made entirely in one piece with the contrast members 22a and 22b, and in the version illustrated has a general configuration that is essentially T-shaped. The tubular guide formations 23a and 23b of the body 3 are provided with respective lateral slots, through which the wings 24a and 24b of the interconnecting structure 24 extend in a sliding manner. JACOBACC & AR N RS The 24 interconnection structure is convenient It mainly features, at the top, in its intermediate portion 24c, a rectilinear raised formation 25, which engages in a guided manner in a corresponding guide formation 26, which is integral with the half-shell 3 of the body of the device and has a shape like an inverted channel. The sliding fit between the projection formation 25 of the interconnecting structure 24 and the corresponding guide 26 reliably and safely prevents the structure 24 from being subjected to transverse oscillations during operation. With reference to figure 4, the interconnecting structure 24 has a central lower branch or extension 27, which extends essentially in a plane orthogonal to the plane common to the wings 24a and 24b. At the lower end the branch 27 carries a counter formation 28 which engages one end of a helical spring 29, the other end of which (figures 2 and 3) reacts against the body of the device. The helical spring 29 tends to push the interconnecting structure 24 away from the half-shell 3 of the body 2 of the device. As can be seen better in Figures 1 to 3, a support structure, generally indicated by 30, is connected to the external face of the bottom wall of the half-shell 3. This structure has an essentially U-shaped cross-section, with two overlapping and facing plate-like portions 31 and 32. This structure extends below the tubular guide formations 23a, 23b, and in the upper plate-like portion 31 it has a slot through which the branch 27 of the interconnecting structure 24 described above can slide. A shaft 33 is rotatably mounted between the plate-shaped portions 31 and 32 of the support structure 30. Connected to the upper end of this shaft, protruding above the plate-shaped portion 31, is a cam member 34 which rotates around an axis which, for the observer of the figures, is substantially vertical. On the side facing the interconnecting structure 24, the cam member 34 has a plurality of notches or notches, indicated by 35 and 36 in figures 1 and 4. These notches are directed essentially in a radial direction, relative to the axis of rotation of the shaft 33 of the cam member 34, JACOBACC & PARTNERS and have different respective extensions. With reference to figure 4, in the illustrated embodiment the notch or notch 35 has a more pronounced radial extension than the notch or notch 36. The cam member 34 cooperates operatively with the interconnecting structure 24, and in particular with the external edge 27a (figure 4) of its branch 27. In particular, when the branch 27 is engaged in the notch 35 of the cam member 34 (figure 1), the interconnecting structure 24 and the associated contrast members 22a and 22b are arranged, under the action of the contrast spring 29, in a first operating position, in which said members 22a and 22b, cooperating with the corresponding springs 21 inside the device, associate to the corresponding electrical switches 12 respective first pressure threshold values ​​in the chamber 6, in correspondence with which said switches switch. By rotating the shaft 33, the cam member 34 can be snapped into a second operating condition, not illustrated in the drawings, in which the branch 27 of the interconnecting structure 24 engages in the notch 36. In J CO OC PARTNERS S.pA under this condition, since the notch 36 is radially less extended and its bottom is further from the axis of the shaft 33, the structure 24 and the associated contrast members 22a and 22b assume, under the action of the spring 29, a second operating position, which corresponds to a state of greater compression of the springs 21 associated with the electric switches 12. Correspondingly, other pressure threshold values ​​in the chamber 6 are associated with these switches, at which they switch into operation. Evidently, it is possible to provide the cam member 34 with three or more different notches, having a different radial extension, which correspond to correspondingly different settings of the threshold pressures at which the switchings of the switches 12 of the pressure sensing device intervene. The free end portion 33a of the shaft 33 can be conveniently connected to a manually operated member, such as a knob, accessible from the outside of the household appliance, to allow the user to set the desired pressure thresholds to be associated with the device switches, e.g. JACOBACC TNERS pA more depending on the expected wash load for a washing machine. Figures 5 and 6 show two different coupling methods between a generic contrast member 22 and the cap 11 of the corresponding intermediate transmission element 9, via the spring 21 placed between them. In figure 5 the spring 21 acts directly on the corresponding conical cap 11, while in the variant according to figure 6 the spring 21 acts on the cap 11 indirectly, that is, through an intermediate member 40 shaped essentially like a cup and preferably provided with an external collar 40a capable of cooperating with an annular gap formation 50 of the half-shell 3 to limit the maximum displacement to which the cap 11 and the associated intermediate transmission element 9 are subject. Naturally, without prejudice to the principle of the invention, the embodiments and details of the construction may be varied widely with respect to what has been described and illustrated purely by way of non-limiting example, the invention extending to all the embodiments which achieve equal utility thanks to the same innovative concepts. JAC08A r 'C' & PARTNERS S.A JACOBACCI & PARTNERS SpA television

Claims

CLAIMS 1. Adjustable pressure sensing device (1), particularly for household appliances, comprising a support body (2; 3, 4) in which a membrane (5) is mounted so as to define a variable volume chamber (6) to which a fluid pressure is supplied in use; and a plurality of electrical switches (12) mounted in the body (2; 3, 4) and coupled to the membrane (5), in such a way that the latter (5) is able to cause its switching when the pressure in said chamber (6) exceeds corresponding different threshold values, predetermined by means of associated calibration means (21-36) including for each switch (12) a respective spring (21) whose compression is variable by means of a corresponding contrast organ (22; 22a, 22b) whose position with respect to the body (2; 3, 4) is adjustable; the device being characterized by the fact that said contrast organs (22a, 22b) are rigidly connected to the ends of corresponding wings (24a, 24b) of an interconnection structure TNERS sion (24), preferably integral with them; said interconnecting structure (24) being translatable with respect to the body (2; 3, 4) in a guiding structure (23; 23a, 23b; 26) which comprises a plurality of tubular guiding formations (23a, 23b), laterally slit, each for guiding a corresponding contrasting organ (22a, 22b), and an intermediate guiding formation (26) suitable for slidingly guiding a median portion (24c; 25) of the interconnecting structure (24); to said middle portion (24c; 25) of the interconnecting structure (24) being associated elastic means (29) tending to cause a relative displacement between the interconnecting structure (24) and the body (2; 3, 4), and snap-action positioning means (33-36), suitable for retaining, against the action of said elastic means (29), the interconnection structure (24) selectively in one of a multiplicity of relative positions with respect to the body (2; 3, 4), in each of which the aforementioned electrical switches (12) are associated with different respective pressure threshold values.

2. Pressure sensor device according to the claim 1, wherein said interconnection structure has a general T-shape, with a central branch (27) operatively cooperating with a cam member (26) integral with a rotating shaft (33); said cam member having a plurality of seats (35, 36), angularly spaced around the axis of said shaft (33) and having different radial extensions, such that when said central branch (27) of the interconnection structure (24) engages in one of such seats (35, 36), the interconnection structure (24) under the action of said elastic means (29) is placed in a different operative position relative to the body (2; 3, 4) of the device (1).

3. Pressure sensing device, particularly for household appliances, substantially as described and illustrated, and for the purposes specified. JACOBACCI & PARTNERS S.p.A.