Temperature-dependent switch

Abstract

A temperature-dependent switch with a housing, which comprises a cover part having an upper side and a lower part having a raised peripheral wall, the upper section of which is bent onto the upper side of the cover part and thereby holds the cover part on the lower part, wherein two contact surfaces are provided outside at the housing and a switching mechanism is arranged in the housing, wherein the switching mechanism is configured to switch, depending on its temperature, between a closed state, in which the switching mechanism establishes an electrically conductive connection between the two contact surfaces, and an open state, in which the switching mechanism interrupts the electrically conductive connection between the two contact surfaces. A sealing ring is arranged on the upper side of the cover part, which sealing ring is in sealing contact with the bent upper section of the wall.

Claims

1. A temperature-dependent switch comprising a housing, wherein the housing comprises a cover part having an upper side and a lower part having a peripheral wall, wherein a bent upper section of the peripheral wall is bent onto the upper side of the cover part and thereby holds the cover part on the lower part, wherein two contact surfaces are provided on the housing and a switching mechanism is arranged in the housing, wherein the switching mechanism is configured to switch, depending on its temperature, between a closed state, in which the switching mechanism establishes an electrically conductive connection between the two contact surfaces, and an open state, in which the switching mechanism interrupts the electrically conductive connection between the two contact surfaces, wherein a sealing ring is arranged on the upper side of the cover part, and the bent upper section of the peripheral wall penetrates into the sealing ring so that the sealing ring is in sealing contact with the bent upper section of the peripheral wall, wherein the sealing ring is connected to at least one of the upper side of the cover part or the bent upper section of the peripheral wall with a material bond.

2. The switch according to claim 1, wherein the material bond includes gluing, hot stamping, or welding.

3. The switch according to claim 1, wherein the sealing ring comprises an annular plastic ring.

4. The switch according to claim 1, wherein the upper section of the peripheral wall is pressed in a mounting area directly or indirectly onto the upper side of the cover part.

5. The switch according to claim 4, wherein a radially inner edge of the sealing ring is at a first distance from a central axis of the switch, and the mounting area is at a second distance from the central axis of the switch, said second distance being larger than the first distance.

6. The switch according to claim 1, wherein the upper section of the peripheral wall is bent by at least 90° when viewed in a cross-section.

7. The switch according to claim 1, wherein each of the lower part and the cover part comprises an electrically conductive material, and wherein an insulating foil is arranged between the cover part and the lower part.

8. The switch according to claim 7, wherein the two contact surfaces comprise a first contact surface that is arranged on the cover part and a second contact surface that is arranged on the lower part, and wherein the switching mechanism supports a movable contact member which interacts with a stationary counter contact, wherein the stationary counter contact is arranged on an inner side of the cover part and coupled to the first contact surface.

9. The switch according to claim 1, wherein the switching mechanism comprises a bi-metal member.

10. The switch according to claim 1, wherein the switching mechanism comprises a spring snap disc.

11. A temperature-dependent switch comprising a housing, wherein the housing comprises a cover part having an upper side and a lower part having a peripheral wall, wherein a bent upper section of the peripheral wall is bent towards the upper side of the cover part and thereby holds the cover part on the lower part, wherein two contact surfaces are provided on the housing and a switching mechanism is arranged in the housing, wherein the switching mechanism is configured to switch, depending on its temperature, between a closed state, in which the switching mechanism establishes an electrically conductive connection between the two contact surfaces, and an open state, in which the switching mechanism interrupts the electrically conductive connection between the two contact surfaces, wherein a sealing ring having a radially outer edge and a radially inner edge is arranged on the upper side of the cover part, the radially inner edge of the sealing ring is at a smaller distance from a central axis of the temperature-dependent switch than is the radially outer edge of the sealing ring, the bent upper section of the peripheral wall penetrates into the radially outer edge of the sealing ring and leaves the radially inner edge of the sealing ring intact so that the sealing ring is in sealing contact with the bent upper section of the peripheral wall at the radially outer edge, and wherein the sealing ring is connected to at least one of the upper side of the cover part or the bent upper section of the peripheral wall with a material bond.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic sectional view of a first embodiment of the temperature-dependent switch;

(2) FIG. 2 shows a schematic sectional view of a second embodiment of the temperature-dependent switch;

(3) FIG. 3 shows a schematic sectional view of a third embodiment of the temperature-dependent switch;

(4) FIG. 4 shows a schematic sectional view of a fourth embodiment of the temperature-dependent switch; and

(5) FIG. 5 shows a schematic sectional view of a fifth embodiment of the temperature-dependent switch.

DESCRIPTION OF PREFERRED EMBODIMENTS

(6) FIG. 1 shows schematically, not to scale and in a lateral cross section a temperature-dependent switch 10, which comprises a housing 12, which comprises an electrically conductive, pot-like lower part 14 and an electrically conductive, plate-like cover part 16.

(7) In the lower part 14, which is circular in a plan view, an inner circumferential shoulder 18 is provided, on which the cover part 16 that closes the lower part 14 rests with an insulating foil 20 interposed therebetween.

(8) The cover part 16 comprises a circumferential wall 22 which separates an upper side 24 from an inner side 26. The insulating foil 20 extends along the inner side 26 and along the circumferential wall 22 and reaches with its upper edge up to the upper side 24.

(9) The lower part 14 comprises a cylindrical circumferential, raised wall 28, the upper section 30 of which is bent or flanged onto the upper side 24 of the cover part 16. In this way, the cover part 16 is held on the lower part 14 with the interposed insulating foil 20.

(10) The insulating foil 20 provides an electrical insulation of the cover part 16 against the lower part 14. Although the insulating foil 20 also provides a mechanical sealing that prevents liquids or contaminants from entering the inside of the housing from the outside. However, a sealing ring 32 is provided as additional mechanical sealing, which sealing ring is in sealing contact with the bent upper section 30 of the wall 28. This sealing ring 32 is arranged on the upper side 24 of the cover part 16.

(11) In the first embodiment shown in FIG. 1, the sealing ring 32 is clamped between the upper section 30 of the wall 28 and the upper side 24 of the cover part 16. During the manufacture of the temperature-dependent switch 10, the sealing ring 32 is preferably placed on the upper side 24 of the cover part 16 before the upper section 30 of the wall 28 is bent or flanged inwards. The sealing ring 32 is then clamped between the wall 28 and the cover part 16 by bending or flanging the upper section 30 of the wall 28. The above manufacturing steps may be fully automated.

(12) The sealing ring 32 may additionally be glued to the cover part 16. The sealing ring 32 may also be glued to the bent upper section 30 of the wall 28. This gluing can also be carried out fully automatically, for example by applying a suitable adhesive to the upper and lower sides of the sealing ring 32 before it is arranged on the cover part 16 and clamped between the cover part 16 and the bent upper section 30 of wall 28.

(13) However, not only for reasons of improving the sealing effect of the sealing ring 32, but also from a manufacturing point of view, it is preferred to create a material bond between the sealing ring 32, the upper side 24 of the cover part 16 and/or the bent upper section 30 of the wall 28 by means of a welded joint produced by ultrasonic welding. This welded joint produced by ultrasonic welding may also be produced after the upper section 30 of the wall 28 has already been bent or flanged and the sealing ring 32 has been clamped underneath.

(14) Alternatively, a material bond between the above-mentioned components 32, 16, 30 may also be created by hot stamping.

(15) However, depending on the clamping force generated by the bent or flanged upper section 30 of the wall 28, it may be sufficient to simply arrange the sealing ring 32 on the cover part 16 and clamp it between the upper section 30 and the upper side 24.

(16) In the herein shown embodiment, the sealing ring 32 is a plastic O-ring. In general, however, other circular plastic rings may be used in the same or a similar way, for example with a triangular, rectangular, square, oval or complexly shaped cross-section.

(17) In the housing 12 of the switch 10, which is formed by the lower part 14 and the cover part 16, a temperature-dependent switching mechanism 34 is arranged, which comprises a spring snap disc 36, which centrally supports a movable contact member 38, on which a freely inserted bi-metal snap disc 40 sits.

(18) The spring snap disc 36 is supported on a bottom 42 on the inside of the lower part 14, while the movable contact member 38 is in contact with a stationary counter contact 46 through a central opening 44 in the insulating foil 20, wherein the stationary counter contact 46 is arranged on the inner side 26 of the cover part 16.

(19) Two contact surfaces 48, 50 are used as the external connection of the switch 10 of FIG. 1. A first contact surface 48 is formed in a central area of the upper side 24 of the cover part 16. A second contact surface 50 is formed on the bent upper section 30 of wall the 28. However, a contact surface, which is formed on the circumferential outer wall 52 of the housing or on the lower side 54 of the lower part 14, may also be used as a second contact surface 50.

(20) The lower side 54 of the lower part 14 is preferably configured to be flat. Via this lower side 54 the switch 10 can be thermally coupled to a device to be protected.

(21) In this way, the temperature-dependent switching mechanism 34 establishes in the low-temperature position shown in FIG. 1 an electrically conductive connection between the two outer contact surfaces 48, 50, wherein the operating current flows via the stationary counter contact 46, the movable contact member 38, the spring snap disc 36 and the lower part 14.

(22) If the temperature of the bi-metal snap disc 40 of the switch 10 shown in FIG. 1 increases, via the thermal contact on the lower side 54 to the device to be protected, above its response temperature, it snaps over from the convex position shown in FIG. 1 to its concave position in which it lifts the movable contact member 38 from the stationary contact 46 against the force of the spring snap disc 36, thus opening the electrical circuit.

(23) FIG. 2 shows a second embodiment of the switch 10, wherein the same reference numerals are used as before for identical components and design features.

(24) In contrast to the first embodiment shown in FIG. 1, the upper section 30 of the wall 28 here penetrates at least partially into sealing ring 32. Preferably, the upper section 30 of the wall 28 circumferentially penetrates into the sealing ring 32 with its free, frontal edge 56 along the entire outer circumference. A penetration depth of at least 10% of the diameter of sealing ring 32 is preferred.

(25) In the embodiment shown in FIG. 2, the upper section 30 of the wall 28 penetrates into the sealing ring 32 laterally from outside. However, it is also possible that the upper section 30 of the wall 28 penetrates into sealing ring 32 from above. To do this, the upper section 30 of the wall 28 would only have to be flanged slightly further than shown in FIG. 2, for example by a total of 180°.

(26) Since the circumferential edge 56 of the wall 28 penetrates into sealing ring 32, the sealing effect of the sealing ring 32 can be further improved, as an additional mechanical barrier is created.

(27) In the embodiment shown in FIG. 2, the sealing ring 32 is still pressed onto the upper side 24 of the cover part 16 by the bent or flanged upper section 30 of the wall 28. In this way the sealing ring 32 also seals the interface between the lower side of the sealing ring 32 and the upper side 24 of the cover part 16.

(28) Even with an arrangement of the sealing ring 32 as shown in FIG. 2, it is preferred that the sealing ring 32 is connected to the upper side 24 of the cover part 16 and/or the upper section 30 of the wall 28 by means of a material bond. As already mentioned above, this may be done by gluing, hot stamping or welding the above-mentioned components using ultrasound.

(29) FIG. 3 shows a third embodiment of the switch 10. In this embodiment, the upper section 30 of the wall 28 is flanged by 180° or at least approximately 180° so that its cross-section essentially corresponds to the shape of an upside down U. The frontal edge 56 of the flanged upper section 30 of the wall 28 presses vertically or almost vertically onto the upper side 24 of the cover part 16 with the interposed insulating foil 20.

(30) The area in which the edge 56 presses from above onto the cover part 16 with the interposed insulating foil 20 is referred to in the present case as mounting area 58. This mounting area 58 is a circumferential circular line or a annular surface, where the mechanical pressure is transferred from the wall 28 of the lower part 14 to the cover part 16.

(31) In order to prevent a short circuit between the lower part 14 and the cover part 16 in this area, the insulating foil 20 is, according to this embodiment, pulled slightly further upwards and folded over onto the upper side 24 of the cover part 16.

(32) If the lower part 14 or the cover part 16 is made of an insulating material, the flanged upper section 30 of the wall 28 may also press directly (without the interposed insulating foil 20) with its edge 56 onto the upper side 24 of the cover part 16.

(33) It also goes without saying that the insulating foil 20 may also be continued further, up to under the sealing ring 32, if the lower part 14 and the cover part 16 are made of an electrically conductive material.

(34) In the embodiment shown in FIG. 3, the sealing ring 32 is applied from radially inside to the flanged upper section 30 of the wall 28. A radially inner edge 62 of the sealing ring 32 is therefore at a smaller distance from the centrally arranged central axis 60 of the switch 10 than the mounting area 58.

(35) On the opposite side, the sealing ring 32 abuts with its radially outer edge or edge area 64 an outer side 66 of the flanged upper section 30 of the wall 28, which, as can be seen from FIG. 3, faces the centrally arranged central axis 60 of the switch 10.

(36) Here too, the sealing ring 32 is preferably connected to the outer side 66 of the flanged upper section 30 of the wall 28 by means of a material bond in order to improve its sealing effect. Likewise, the sealing ring 32 is preferably also connected to the upper side 24 of the cover part 16 by means of a material bond. The material-locking connection of the sealing ring 32 with the outer side 66 of the wall 28 and the upper side 24 of the cover part 16 creates several mechanical barriers which prevent impurities from penetrating into the inside of the switch. In order to get into the switch interior, impurities would first have to pass the sealing ring 32 to reach the mounting area 58, which is almost impossible due to the material connection between sealing ring 32 and the outer side 66 and the upper side 24. In addition, a further mechanical barrier is provided in the mounting area 58, since the edge 56 of the flanged upper section 30 of the wall 28 presses on the insulating foil 20 here or even penetrates into it partially. The same applies if the edge 56 presses directly on the upper side 24 of the cover part 16 (without the interposed insulating foil 20).

(37) In the fourth embodiment shown in FIG. 4, the upper section 30 of the wall 28 is flanged to an inverted U in the same or at least similar manner as in the third embodiment shown in FIG. 3. The sealing ring 32, in contrast to this, is now, however, arranged radially further outwards and abuts the flanged upper section 30 of the wall 28 from the inside on an inner side 68, which faces away from the centrally arranged central axis 60 and is opposite the outer side 66.

(38) Thus, the sealing ring 32 here abuts with its radially inner edge 62 the inner side 68 of the flanged upper section 30 of the wall 28. Accordingly, the radially inner edge 62 of the sealing ring 32 is at a larger distance from the centrally arranged central axis 60 of the switch 10 than the mounting area 58, in which the edge 56 of the flanged upper section 30 of the wall 28 presses onto the cover part 16 with the interposed insulating foil 20.

(39) Also in this embodiment, the sealing ring 32 is preferably connected to the inner side 68 of the flanged upper section 30 of the wall 28 by means of a material bond. The sealing ring 32 is also preferably connected to the upper side 24 of the cover part by means of a material bond, either directly or indirectly with the insulating foil 20 interposed therebetween.

(40) Also in this embodiment, it is possible that the flanged upper section 30 of the wall 28 presses with its edge 56 directly onto the upper side 24 of the cover part 16, provided that no electrical insulation is required between the lower part 14 and the cover part 16. In such a case, it is preferred that also the sealing ring 32 is directly arranged on the upper side 24 of the cover part 16 and is connected to it by means of a material bond.

(41) FIG. 5 shows a fifth embodiment of the switch 10. The arrangement of the sealing ring 32 is at least equal or similar to the arrangement of the sealing ring 32 as described above with regard to the first embodiment shown in FIG. 1. The sealing ring 32 is clamped between the bent upper section 30 of the wall 28 and the upper side 24 of the cover part 16.

(42) However, the fifth embodiment shown in FIG. 5 differs from the embodiments shown in FIGS. 1 to 4 in the way the switching mechanism 34 and the housing 12 are designed. For the sake of simplicity, the previously used reference numerals were also used in FIG. 5 for identical or equivalent components.

(43) The housing 12 here comprises a pot-shaped lower part 14 made of electrically conductive material. The cover part 16 of the housing 12 is in the embodiment shown in FIG. 5, however, made of insulating material or PTC material. An insulation by means of an insulating foil, as used in the embodiments shown in FIGS. 1 to 4, is therefore not necessary here.

(44) A spacer ring 74 is provided between the cover part 16 and the lower part 14, which spacer ring 74 keeps the cover part 16 at a distance from the lower part 14.

(45) Two stationary counter contacts 46, 47 are provided on the cover part 16. The counter contacts 46 and 47 are configured as rivets, which extend through the cover part 16 and end outside in the heads 48, 50, which serve as contact surfaces for the external connection of the switch 10.

(46) The switching mechanism 34 comprises a current transfer member 70 as a contact element, which current transfer member 70 is designed as a contact plate or contact bridge, the upper side 76 of which is coated in an electrically conductive manner, so that the current transfer member 70, in the closed position of the switch 10 shown in FIG. 5, rests against the counter contacts 46, 47 and provides an electrically conductive connection between the two counter contacts 46, 47.

(47) The current transfer member 70 is connected to a bistable spring snap disc 36 and a bistable bi-metal snap disc 40 via a rivet 72, which is also to be regarded as part of the contact element.

(48) A circumferential shoulder 18 is again provide inside the lower part 14, on which circumferential shoulder 18 the spacer ring 74 rests. Between the shoulder 18 and the spacer ring 74 the spring snap disc 36 is clamped with its edge 78 while it rests with its center 80 on a shoulder 82 on the rivet 72. At its center 80 the spring snap disc 36 is thus clamped between the current transfer member 70 and the shoulder 82.

(49) In FIG. 5 further downwards and radially further outwards, a shoulder 84 is provided on the rivet 72, on which the bi-metal snap disc 40 rests with its center 86. The center 86 of the bi-metal snap disc 40 rests freely on the shoulder 84. The edge 88 of the bi-metal snap disc 40 rests freely on the inner bottom 42 of the lower part 14.

(50) The switching operation of the switch 10 shown in FIG. 5 is carried in a similar way as with the embodiments of the switch 10 shown in FIGS. 1 to 4 by snapping the bi-metal snap disc 40 from its low temperature position (shown in FIG. 5) to its high temperature position or vice versa. If the bi-metal snap disc 40 snaps over into its high temperature position (not shown here), the current transfer member 70 is lifted downwards from the two stationary contacts 46, 47 in FIG. 5, thus interrupting the electrical circuit and preventing the device to be protected from heating up further.

(51) It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

(52) As used in this specification and claims, the terms “for example,” “e.g.,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.