GB2217111A

GB2217111A - A transducer

Info

Publication number: GB2217111A
Application number: GB8906485A
Authority: GB
Inventors: Giovanni Arturo De
Original assignee: Veglia Borletti SRL
Current assignee: Veglia Borletti SRL
Priority date: 1988-03-31
Filing date: 1989-03-21
Publication date: 1989-10-18
Anticipated expiration: 2009-03-21
Also published as: FR2629587A1; FR2629587B1; DE3907655A1; GB8906485D0; BR8901593A; IT214347Z2; IT8853033V0; GB2217111B; DE3907655C2

Abstract

A transducer (1) comprises a cup-shape body (4) of plastics material containing means (5) for detecting a physical quantity e.g. temperature, and a cap (6) provided with electrical connectors (7) connected to contacts (32) operable by the detection means (5). The connection between the cup-shape body (4) and the cap (6) is formed by a layer (8) of connecting material e.g. polyamide resin interposed between facing surfaces thereof. <IMAGE>

Description

A TRANSDUCER OF IMPROVED TYPE The present invention relates to a transducer of improved type.

As is known, transducers comprise a first cup-shape body in which means operable to detect a physical quantity such as, for example the temperature of a fluid, are installed, and a second body provided with electrical connectors connected to contacts operable by the said means. The first body is fitted into a cylindrical metal body provided with hook elements by which the first and the second body are joined together.

The above described transducers have several disadvantages.

In particular, such transducers are of high cost above all because of the means for fixing the said first and second body together. Moreover, such fixing does not ensure the seal within the cup-shape body so that it is also necessary to instal sealing washers with associated housing seats.

The object of the present invention is that of providing a transducer having a system for fixing the two bodies thereof together, which will be simple to produce and which ensures that they are sealed together.

Further objections and advantages of the present invention will become evident during the course of the following description.

According to the present invention there is provided a transducer characterised by the fact that it comprises: - a cup-shape body made of plastics material and housing means for detecting a physical quantity: - a cap inade of plastics material and provided with electrical connectors connected to respective contacts operable by the said means; and - a layer of connecting material interposed between facing surfaces of the said cup-shape body and of the said cap.

For a better understanding of the present invention a preferred embodiment is now described, purely by way of non-liritative example, with reference to the attached drawings, in which: - Figure 1 is a section through a transducer formed according to the principles of the present invention; - Figures 2 and 3 are partial views of the transducer of Figure 1 with a component installed in a different manner; and - Figures 4 and 5 are partially sectioned views of the transducer of Figure 1 respectively before and after assembly onto a support wall.

As illustrated in Figure 1, a transducer, represented here as a thermometer switch, known as a temperature switch for short, is indicated with the reference numeral 1. The transducer 1 is mounted in a through hole 2 formed in a wall 3 of a body (not illustrated) such as, for example, a collection tank for the coolant liquid of a vehicle engine.

The transducer 1 comprises a cup-shape body 4, made of plastics material, housiny means 5 for detecting the physical quantity, in this case represented by the value of the temperature of the liquid which flows over this body 4. A part of this latter in fact extends through the hole 2 into the interior of the said container. The transducer 1 further includes a cap 6 made of plastics material and provided with an electrical attachment having two connectors 7 formed as blade-like pins.

Between the facing surfaces of the body 4 and the cap 6 there is interposed an annular layer 8 of connecting material preferably made of a polyamide resin fused by electromagnetic induction.

With reference to Figure 1, the body 4 has a base wall 11, a cylindrical side wall 12, and an annular flange 13 which extends from the free end of the wall 12. In particular, the flange 13 lies outside the tank and upon assembly engages against the wall 3. On the inner part of the flange 13 are formed two annular steps 14 and 15 the step 14 of which is at a higher level and of greater length than the length of the step 15.

The cap 6 comprises a cylindrical portion 16 upwardly from which extends a substantially elliptical hollow portion 17 and within which are housed connectors 7.

Downwardly from the portion 16 extends an annular flange 18 which in use comes into contact with the flange 13 of the body 4. A first annular projection 21 extends axially downwardly from the inner part of the flange 8, from which extends a second annular projection 22 of smaller thickness in such a way as to define externally a step 23. In use, the projection 22 engages against the step 15, whilst the step 23 rests on the step 14. The step 23 has a narrower width than that of the step 14 so that, in correspondence with this, between the flanges 13 and 18 there is created an annular groove 24 within which the said layer 8 is deposited which, upon fusing, forms the connection between the body 4 and the cap 6.

With reference to Figure 1, the means 5 comprise a heat sensitive membrane, resting on the bottom wall ii of the body 4 and cooperating with a vertical push rod 26 acting to translate axially along a cylindrical guide body 27 having an upper annular flange 28 on which the projection 22 of the body 6 acts. In particular, the peripheral edge of the flange 28 is situated between the projection 22 and an annular shoulder 31 formed on the inner surface of the side wall 12 of the body 4. In the cap 6, in correspondence with the flange 18, there is defined a chamber delimited internally by the upper surface of the flange 28. The connectors 7 are connected to two contacts 32 which are located in the said chamber, one of which is supported by a resilient blade 33 on which the push rod 26 acts.

Since the above-mentioned tank contains liquid a seal must be formed in correspondence with the hole 2 by installing a suitable sealing ring 34. In Figure 1 the sealing ring 34 is housed in an annular seat 35 formed around the hole 2 in the outer face of the wall 3. In this way the sealing ring 34 is compressed by the lower face of the flange 13. In Figure 2 the sealing ring 34 is housed in an annular seat 36 formed at the upper end of the hole 2 so that it is compressed both by the flange 13 and by the side wall 12 of the body 4. In Figure 3 the sealing ring 34 is housed in an annular seat 37 formed around the hole 2 in an intermediate region thereof. In this case the sealing ring 34 is compressed by the side wall 12 of the body 4.

With reference to Figures 4 and 5, the transducer 1, after having been assembled, is engaged in the hole 2 of the wall 3 with a connector of the bayonet type. To provide a connection of this type two axial grooves in diametrically opposite positions are formed on the outer surface of the wall 12 of the body 4, from each of which extends a semi-annular groove 42 engaged, upon connection, by a corresponding tooth 43 formed in the hole 2. The body 4 is inserted into the hole 2 by making the respective teeth 43 traverse the axial grooves 41, and then rotated until the tooth 43 engages the groove 42. Along this is formed a ridge 44 which resists involuntary disengagement of the tooth 43. The mounting of the transducer 1 into the hole 2 is achieved by an operating arm of an automatic machine which engages the portion 17 in correspondence with two external parallel slots 45 formed in the flange 18 (Figure 5).

In use, after having installed the means 5 within the body 4, the layer 8 is deposited onto the step 14. Then the cap 6 is mounted onto the body 4 and by electromagnetic induction the layer 8 is fused; upon cooling this forms a welded connection between the body 4 and the cap 6. This welding causes an hermetic seal and connection such that it is not necessary to provide sealing rings.

From what has been explained above the advantages achieved by the present invention will be evident.

In particular, there is provided a simple, hermetic and resistant fixing system between the body 4 and the cap 6, both formed by moulding plastics material and therefore of low cost. This moreover allows the body 4 on which various types of cap 6 are to be fitted depending on the type of electrical attachments used by the various motor vehicle manufacturers, to be made with standardised dimensions.

Finally, it is clear that the transducer 1 described and illustrated here can have modifications and variations introduced thereto without by this departing from the protective ambit of the present invention.

In particular the layer 8 can be interposed between two counterposed flat faces of the body 4 and the cap 6.

Alternatively the layer 8 can be deposited on a recess formed in a flange and then a welding achieved on a flat face on a recess. The means for detecting a physical quantity and the type of coupling to the wall 3 may be different from those illustrated.

Claims

1. A transducer characterised by the fact that it comprises: - a cup-shape body made of plastics material and housing means adapted to detect a physical quantity; - a cap made of plastics material and provided with electrical connectors connected to associated contacts operable by the said means ; and - a layer of coni.ecting material interposed between facing surfaces of the cup-shape body and the said cap 2. A transducer according to Claim 1, characterised by the fact that the said layer is made of pclyam.,ide resin fused by electromagnetic induction in such a Way as to cause an hermetic welding between the said cup-shape body and the cap 3.A transducer according to Claim 1 or Claim 2, characterised by the fact that an annular groove is defined between and along the said facing surfaces, along which groove the said layer is deposited.

4. A transducer according to Claim 3, characterised by the fact that the said cup-shape body comprises a cylindrical side wall from a free edge of which extends a first annular flange having an internal step , and in that the said cap has a cylindrical portion upwardly from which extends a hollow portion within which the ends of the said connectors are situated and downwardly from which extends a second annular flange which engages on the said first flange and from which extends an annular projection cooperating with the said step ; the said annular groove being defined in correspondence with the said step between this and the said annular projection 5.A transducer according to at least one of the preceding Claims, characterised by the fact that it includes means for connecting it into a hole of a wall of a support body; the said cup-shape body extending through the said hole into the interior of the said support body.

6. A transducer according to Claim 5, characterised by the fact that between the said cup-shape body and the said wall a sealing ring is installed in correspondence with the said hole 7. A transducer according to Claims 5 and 6 when dependent on Claim 4, characterised by the fact that the said sealing ring is housed in an annular seat formed in the outer face of the said wall so that the said sealing ring is compressed in the said seat by the said first flange 8. A transducer according to Claims 5 and 6 when dependent on Claim 4, characterised by the fact that the said sealing ring is housed in an annular seat formed at the upper end of the hole so that the said sealing ring is compressed in the said seat by the said first flange and by the said side wall.

5. A transducer according to Claims 5 and 6 when dependent on Claim 4, characterised by the fact that the said sealing ring is housed in an annular seat formed in an intermediate region of the said hole so that the said sealing ring is compressed by the said side wall 10. A transducer according to Claim 5 when dependent c Claim 4, characterised by the fact that in the said annular flange of the said cap are formed slots constituting gripping regions for an operating arm of an automatic machine adapted to effect assembly of the said transducer into the said hole 11. A transducer according to any preceding Claim, characterised by the fact that it is constituted by a thermometer switch and that the said support body is a coolant liquid collection tank of a motor vehicle engine.

12. A transducer as described and illustrated with reference to the attached drawings.