TEMPERATURE-DEPENDENT SWITCHING MECHANISM, TEMPERATURE-DEPENDENT SWITCH, AND METHOD OF MANUFACTURING THE SAME

Abstract

A temperature-dependent switching mechanism for a temperature-dependent switch, having: a temperature-dependent bimetal snap-action disc having a first through hole; a temperature independent snap-action spring disc having a second through hole; and an electrically conductive contact member including a main body that passes through the first through hole and the second through hole. The contact member includes a support shoulder projecting radially from the main body, a first locking element projecting radially from the main body and arranged on a first side of the support shoulder, and a second locking element projecting radially from the main body and arranged on a second side of the support shoulder opposite the first side. The temperature-dependent bimetal snap-action disc and the snap-action spring disc are arranged between the locking elements and the support shoulder and are each held captive, but with clearance, by these on the main body of the contact member.

Claims

1. A temperature-dependent switching mechanism for a temperature-dependent switch, having: a temperature-dependent bimetal snap-action disc comprising a first through hole; a temperature-independent snap-action spring disc comprising a second through hole; and an electrically conductive contact member comprising a main body that passes through the first through hole and the second through hole; wherein the electrically conductive contact member comprises a support shoulder projecting radially from the main body, a first locking element projecting radially from the main body and being arranged on a first side of the support shoulder, and a second locking element projecting radially from the main body and being arranged on a second side of the support shoulder opposite the first side, wherein the temperature-dependent bimetal snap-action disc is arranged between the first locking element and the support shoulder and is held captive, but with clearance, on the main body of the electrically conductive contact member by the first locking element and the support shoulder, wherein the temperature-independent snap-action spring disc is arranged between the second locking element and the support shoulder and is held captive, but with clearance, on the main body of the electrically conductive contact member by the second locking element and the support shoulder, and wherein the electrically conductive contact member is integrally formed and the main body is integrally connected to the support shoulder, the first locking element and the second locking element.

2. The temperature-dependent switching mechanism according to claim 1, wherein the first locking element comprises at least one first retaining claw projecting radially from the main body, or a first collar projecting radially from the main body and surrounding a circumference of the main body, and wherein the second locking element comprises at least one second retaining claw projecting radially from the main body, or a second collar projecting radially from the main body and surrounding the circumference of the main body.

3. The temperature-dependent switching mechanism according to claim 1, wherein a first distance between an upper side of the electrically conductive contact member arranged on the first side of the support shoulder and a lower side of the electrically conductive contact member arranged on the second side of the support shoulder is larger than a second distance between the first locking element and the second locking element.

4. The temperature-dependent switching mechanism according to claim 1, wherein the bimetal snap-action disc is held on the main body with larger clearance than the snap-action spring disc.

5. The temperature-dependent switching mechanism according to claim 1, wherein the switching mechanism is rotationally symmetrical about a longitudinal axis of the electrically conductive contact member.

6. The temperature-dependent switching mechanism according to claim 1, wherein the first through hole is arranged centrally in the bimetal snap-action disc, and wherein the second through hole is arranged centrally in the snap-action spring disc.

7. The temperature-dependent switching mechanism according to claim 1, wherein the bimetal snap-action disc and the snap-action spring disc are each circular disc-shaped.

8. The temperature-dependent switching mechanism according to claim 1, wherein the snap-action spring disc is bistable having two temperature-independent stable geometric configurations, and wherein the bimetal snap-action disc is bistable having two temperature-dependent stable geometric configurations.

9. The temperature-dependent switching mechanism according to claim 1, having a switching mechanism housing which holds the bimetal snap-action disc, the snap-action spring disc and the electrically conductive contact member captive, but with clearance.

10. The temperature-dependent switching mechanism according to claim 9, wherein the switching mechanism housing surrounds the bimetal snap-action disc and the snap-action spring disc from a first housing side, a second housing side opposite the first housing side, and a housing peripheral side extending between and transverse to the first and second housing sides, the first housing side having an opening through which the electrically conductive contact member is accessible from outside the switching mechanism housing.

11. The temperature-dependent switching mechanism according to claim 10, wherein a diameter of the opening is smaller than a diameter of the bimetal snap-action disc measured parallel thereto.

12. The temperature-dependent switching mechanism according to claim 9, wherein the switching mechanism housing is integrally formed and comprises an electrically conductive material.

13. A temperature-dependent switch comprising: a temperature-dependent switching mechanism; and a switch housing surrounding the switching mechanism and comprising a first electrical terminal and a second electrical terminal; wherein the temperature-dependent switching mechanism comprises: a temperature-dependent bimetal snap-action disc comprising a first through hole; a temperature-independent snap-action spring disc comprising a second through hole; and an electrically conductive contact member comprising a main body that passes through the first through hole and the second through hole; wherein the electrically conductive contact member comprises a support shoulder projecting radially from the main body, a first locking element projecting radially from the main body and being arranged on a first side of the support shoulder, and a second locking element projecting radially from the main body and being arranged on a second side of the support shoulder opposite the first side, wherein the temperature-dependent bimetal snap-action disc is arranged between the first locking element and the support shoulder and is held captive, but with clearance, on the main body of the electrically conductive contact member by the first locking element and the support shoulder, wherein the temperature-independent snap-action spring disc is arranged between the second locking element and the support shoulder and is held captive, but with clearance, on the main body of the electrically conductive contact member by the second locking element and the support shoulder, wherein the electrically conductive contact member is integrally formed and the main body is integrally connected to the support shoulder, the first locking element and the second locking element, and wherein the switching mechanism is configured to establish an electrical connection between the first electrical terminal and the second electrical terminal below a response temperature of the bimetal snap-action disc and to interrupt the electrical connection upon exceeding the response temperature.

14. A method of manufacturing a temperature-dependent switching mechanism comprising: providing a temperature-dependent bimetal snap-action disc comprising a first through hole; providing a temperature-independent snap-action spring disc comprising a second through hole; providing an electrically conductive contact member comprising a main body and a support shoulder projecting radially from the main body; passing the main body through the first through hole so that the bimetal snap-action disc is arranged on a first side of the support shoulder; passing the main body through the second through hole so that the snap-action spring disc is arranged on a second side of the support shoulder opposite the first side; forming a first portion of the main body arranged on the first side of the support shoulder to create a first locking element such that the temperature-dependent bimetal snap-action disc is arranged between the first locking element and the support shoulder and is held captive, but with clearance, to the main body of the electrically conductive contact member by the first locking element and the support shoulder; and forming a second portion of the main body arranged on the second side of the support shoulder to create a second locking element such that the temperature-independent snap-action spring disc is arranged between the second locking element and the support shoulder and is held captive, but with clearance, to the main body of the electrically conductive contact member by the second locking element and the support shoulder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] FIG. 1 a schematic sectional view of the temperature-dependent switching mechanism according to a first embodiment;

[0080] FIG. 2 a schematic sectional view of the temperature-dependent switching mechanism according to a second embodiment;

[0081] FIG. 3 a schematic sectional view of the temperature-dependent switching mechanism according to a third embodiment;

[0082] FIG. 4 a schematic sectional view of the temperature-dependent switching mechanism according to a fourth embodiment;

[0083] FIG. 5 a schematic sectional view of an embodiment of the temperature-dependent switch in its low-temperature position;

[0084] FIG. 6 a schematic sectional view of the embodiment of the temperature-dependent switch shown in FIG. 5 in its high-temperature position; and

[0085] FIG. 7 a schematic illustration for explaining a manufacturing step in the production of the switching mechanism in accordance with the second embodiment shown in FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0086] FIGS. 1-4 show various embodiments of the switching mechanism, each in a schematic sectional view. In each case, the switching mechanism is designated in its entirety with the reference numeral 10.

[0087] The switching mechanism 10 is a temperature-dependent switching mechanism. As explained in more detail below, the switching mechanism 10 switches between a low-temperature position and a high-temperature position depending on the temperature. In FIGS. 1-4, the low-temperature position of the switching mechanism 10 is shown in each case.

[0088] The switch unit 10 has a three-part design. It comprises a temperature-dependent bimetal snap-action disc 12, a temperature-independent snap-action spring disc 14 and a contact member 16. The bimetallic snap-action disc 12 and the snap-action spring disc 14 are held captive on the contact member, but with clearance. The switching mechanism 10 can thus be prefabricated as a semi-finished product and then installed as a com-plete unit in a corresponding switch, such as that shown in FIGS. 5 and 6. Since the two snap-action discs 12, 14 are held captive on the contact member 16, an unintentional detachment of the two snap-action discs 12, 14 from the contact member 16 is prevented.

[0089] The two snap-action discs 12, 14 are preferably circular disc-shaped, wherein each comprises a centrally arranged through hole 18, 20. The through hole 18 arranged centrally in the bimetal snap-action disc 12 is referred to as the first through hole. The through hole 20 arranged in the snap-action spring disc 14 is referred to as the second through hole.

[0090] The two snap-action discs 12, 14 are imposed on the contact member 16 from opposite sides with their respective through hole 18, 20. Thus, the contact member 16 penetrates both snap-action discs 12, 14 at a central point. The contact member 16 comprises a main body 22, which is preferably solid and comprises an electrically conductive material. This main body 22 passes through the two through holes 18, 20.

[0091] Approximately in the middle, i.e. at about half the height, the contact member 16 comprise a support shoulder 24 projecting radially from the main body 22. The two snap-action discs 12, 14 rest against this support shoulder 24 from opposite sides. The bimetal snap-action disc 12 is arranged on a first side of the support shoulder 24, which forms the upper side in FIGS. 1-4. The snap-action spring disc 14 is arranged on a second side of the support shoulder 24 opposite the first side, which forms the lower side in FIG. 1-4.

[0092] Furthermore, locking elements 26, 28 are formed on the contact member 16, by means of which the two snap discs 12, 14 are held on the contact member 16. The two locking elements 26, 28 project radially from the main body 22 of the contact member 16. The first locking element 26 is arranged on the first side of the support shoulder 24. The second locking element 28 is arranged on the opposite second side of the support shoulder 24.

[0093] The bimetal snap-action disc 12 is arranged between the first locking element 26 and the support shoulder 24, and is held captive but with clearance on the main body 22 of the contact member 16 between the first locking element 26 and the support shoulder 24 due to the radial projection of the first locking element 26 and the support shoulder 24.

[0094] The snap-action spring disc 14 is arranged between the second locking element 28 and the support shoulder 24, and is held captive but with clearance on the main body 22 of the contact member 16 between the second locking element 28 and the support shoulder 24 due to the radial projection of the second locking element 28 and the support shoulder 24.

[0095] The contact member 16 is formed in one piece together with the support shoulder 24 and the two locking elements 26, 28. In other words, the support shoulder 24 and the two locking elements 26, 28 are formed integrally with the main body 22 of the contact member 16.

[0096] In the first embodiment shown in FIG. 1, the two locking elements 26, 28 are each configured as a circumferential collar formed by a circumferential cut notch 30 and 32, respectively. The circumferential collar forming the first locking element 26 projects radially upwardly at an angle from the main body 22 of the contact member 16. The collar forming the second locking element 28 projects obliquely downward radially from the main body 22 of the contact member 16.

[0097] Both collars can be formed into the contact member 16 relatively easily by forming a circumferential cut notch 30 or 32. The cut notches 30, 32 are formed into the contact member 16 after the two snap-action discs 12, 14 have been slipped over the main body 22 of the contact member 16 with their through holes 18, 20.

[0098] In the second embodiment shown in FIG. 2, the locking elements 26, 28 each comprise at least one retaining claw 34 or 36. Both locking elements 26, 28 can have either a radially circumferential retaining claw 34, 36 extending over the entire circumference of the contact member. Such circumferential retaining claws then form very similar locking elements to the collars shown in FIG. 1.

[0099] Alternatively, it is possible for both locking elements 26, 28 to each comprise a plurality of such retaining claws 34, 36, which are circumferentially spaced from one another on the contact member 16. Intermediate spaces then exist between these individual, circumferentially distributed retaining claws.

[0100] Regardless of whether the two retaining claws 34, 36 each extend contin-uously over the entire circumference of the contact member or have several claw elements distributed over the circumference, the retaining claws 34, 36 are preferably manufactured by forming or beading correspondingly preformed claw elements. Part of this manufacturing process is shown schematically in FIG. 7.

[0101] FIG. 7 shows in particular the flanging of the lower retaining claw 36, which later forms the second locking element 28, which serves to fasten the snap-action spring disc 14 to the contact member 16. In the initial state, the preformed retaining claws 34, 36 protrude upward and downward, respectively, from the main body 22 in the axial direction. They are flanged by a suitable press plunger 38. This press plunger 38 has at its radially outer end a circumferentially arranged bevel 40, with which the press plunger 38 contacts the retaining claw 36 during the forming process. A counter-holder 42 acting as a counterpart to the press plunger 38 presses from the opposite side onto the support shoulder 24 of the contact member 16. The retaining claw 36 is thus bent or flanged by the press plunger 38. This is indicated in FIG. 7 by the arrows 44. During this process, the snap-action spring disc 14 preferably rests on a radially circumferential bearing surface 46.

[0102] The bimetal snap-action disc 12 is mounted and fixed in the same way. For this purpose, the contact member 16 together with the snap-action spring disc 14 attached to it is turned through 180 about an axis aligned orthogonally to the sheet plane and the bimetal snap-action disc is slipped over the main body 22 of the contact member 16 so that it is arranged on the opposite side of the support shoulder 24 compared to the snap-action spring disc 14. The retaining claw 34 can then be bent radially outwardly by means of the same press plunger 38, so that it too is ultimately secured to the contact member 16.

[0103] The main body 22 of the contact member 16 is preferably convexly shaped at its upper side 48. The contact member 16 is preferably configured such that a distance d.sub.1 between the upper side 48 and the lower side 50 of the contact member 16 is larger than a distance d 2 between the first locking element 26 and the second locking element 28.

[0104] Preferably, at least the upper side 48 of the contact member 16 protrudes upwards with respect to the first locking element 26. This is particularly advantageous because the upper side 48 of the contact member 16 comes into contact with a corresponding counter contact and the locking elements 26, 28 do not cause a collision with the counter contact.

[0105] Furthermore, it is advantageous for the function of the switching mechanism 10 if the bimetal snap-action disc 12 is held on the contact member 16 with larger clearance than the snap-action spring disc 14. This guarantees sufficiently free movement of the bimetal snap-action disc 12. At the same time, the slightly smaller clearance between the snap-action spring disc 14 and the contact member 16 guarantees the best possible electrical contact between these two components.

[0106] FIGS. 3 and 4 show further embodiments of the switching mechanism 10. The configuration of the bimetallic snap-action disc 12, the snap-action spring disc 14 and the contact member 16 is identical to the embodiment shown in FIG. 1. In addition thereto, the switching mechanism 10 according to the embodiments shown in FIGS. 3 and 4 comprises a switching mechanism housing 52. In this switching mechanism housing 52, the unit consisting of the bimetal snap-action disc 12, the spring snap-action disc 14 and the contact member 16 is held captive but with clearance.

[0107] The switching mechanism housing 52 surrounds the bimetal snap-action disc 12 and the snap-action spring disc 14 at least partially from a first housing side 54, a second housing side 56 opposite the first housing side 54, and a housing peripheral side 58 extending between and transverse to the first and second housing sides 54, 56. An opening is provided in the switching mechanism housing 52 on the first housing side 54, through which the contact member 16 is accessible from outside the switching mechanism housing 52.

[0108] A diameter D.sub.1 of the opening 60 is smaller than a diameter D.sub.2 of the bimetal snap-action disc 12 measured parallel thereto. Thus, although the contact member 16 is accessible from the outside through the opening 60, the bimetal snap-action disc 12 cannot detach from the switching mechanism housing 52.

[0109] The switching mechanism housing 52 is preferably formed in one piece and consists of an electrically conductive material, for example metal. The switching mechanism 10 is preferably rotationally symmetrical about a longitudinal axis 62 of the contact member 16, both including and excluding the switching mechanism housing 52.

[0110] The two embodiments of the switching mechanism 10 shown in FIGS. 3 and 4 differ essentially in the shape of the switching mechanism housing 52. While the bottom 64 arranged on the second housing side 56 in the embodiment shown in FIG. 4 has in section an arcuate configuration and forms a kind of convex dome, the bottom 64 in the embodiment shown in FIG. 3 has an essentially plate-like configuration and has a cup-like bulge 66 in a central section.

[0111] Of course, other shapes of the switching mechanism housing 52 are possible. However, it is important that the contact member 16 can move downward within the switching mechanism housing 52 when the snap-action discs 12, 14 snap over from the position shown in FIGS. 3 and 4. The reason for this can be seen, in particular, from the following explanations of the function of the temperature-dependent switch shown in FIGS. 5 and 6.

[0112] In FIGS. 5 and 6, an embodiment of a temperature-dependent switch in which the switching mechanism 10 can be used is shown in each case in a schematic sectional view. The switch is denoted therein in its entirety with the reference numeral 100.

[0113] FIG. 5 shows the low temperature position of switch 100. FIG. 6 shows the high temperature position of switch 100.

[0114] According to the embodiment shown in FIGS. 5 and 6, the switch 100 comprises a switch housing 68 which functions as an outer housing for the switching mechanism 10. The switching mechanism 10 is inserted into the switch housing 68 together with its switching mechanism housing 52. The switching mechanism 10 corre-sponds to the embodiment shown in FIG. 3. However, it is understood that the switching mechanism shown in FIG. 4 can also be inserted into the switch housing 68 of the switch 100 in an equivalent form. Likewise, a switching mechanism 10 without a switching mechanism housing 52, as shown in FIGS. 1 and 2, for example, can also be inserted into the switch housing 68 of the switch 100 without changing the basic function of the switch 100.

[0115] The switch housing 68 includes a pot-like lower part 70 and a lid part 72 held to the lower part 70 by a folded or flanged edge 74.

[0116] In the embodiment shown in FIGS. 5 and 6, both the lower part 70 and the lid part 72 are formed from an electrically conductive material, preferably metal. An insulating foil 76 is arranged between the lower part 70 and the lid part 72. The insulating foil 76 provides electrical insulation of the lower part 70 with respect to the lid part 72. Likewise, the insulating foil 76 provides a mechanical seal that prevents liquids or contami-nants from entering the interior of the housing from the outside.

[0117] Since the lower part 70 and the lid part 72 in this embodiment are each made of electrically conductive material, thermal contact to an electrical device to be protected can be established via their outer surfaces. The outer surfaces also serve as the external electrical connection of the switch 100. For example, the outer surface 71 of the lid part 72 may serve as the first electrical terminal and the outer surface 73 of the lower part 70 may serve as the second electrical terminal.

[0118] A further insulation layer 78 may be arranged on the outside of the lid part 72, as shown in FIGS. 5 and 6.

[0119] The switching mechanism 10 is arranged clamped between the lower part and the lid part 72. A spacer ring 80, against which the switching mechanism housing 52 rests circumferentially, is used to position the switching mechanism 10. It is particularly important that the contact member 16 is aligned with respect to a counter contact 82, which is arranged on the inside of the cover part 72. This counter contact 82 is also referred to herein as the first stationary contact. The inner side 75 of the lower part 70 serves as the second stationary contact.

[0120] In the position shown in FIG. 5, the switch 100 is in its low-temperature position, in which the temperature-independent snap-action spring disc 14 is in its first configuration and the temperature-dependent bimetal snap-action disc 12 is in its low-temperature configuration. The snap-action spring disc 14 thereby presses the contact member 16 against the counter contact 82, and the switch 100 is thus in its closed position in which an electrically conductive connection is established between the first stationary contact 82 and the second stationary contact 75 via the contact member 16 and the snap-action spring disc 14. Contact pressure between the contact member 16 and the first stationary contact 82 is provided by the snap-action spring disc 14. In contrast, the bimetal snap-action disc 12 is virtually force-free in this state.

[0121] If the temperature of the device to be protected and thus the temperature of the switch 100, as well as the bimetal snap-action disc 12 arranged therein, now increases to the switching temperature of the bimetal snap-action disc 12, or above this switching temperature, the latter snaps over from its convex low-temperature configuration shown in FIG. 5 to its concave high-temperature configuration shown in FIG. 6. During this snapping over, the outer edge of the bimetal snap-action disc 12 bears against the first housing side 54 of the switch housing 52. With its center, the bimetal snap-action disc 12 pulls the movable contact member 16 downward and lifts the movable contact member 16 away from the first stationary contact 82. This simultaneously causes the snap-action spring disc 14 to flex downward at its center, causing the snap-action spring disc 14 to snap over from its first stable geometric configuration shown in FIG. 5 to its second stable geometric configuration shown in FIG. 6. FIG. 6 shows the high-temperature position of switch 100, in which it is open. The circuit is thus interrupted.

[0122] Unless the switching mechanism 10 includes a switching mechanism housing 52, in the high temperature position of the switching mechanism 100, the bimetal snap-action disc 12 supports against the lid part 72 with the insulating foil 76 interposed.

[0123] When the device to be protected and thus the switch 100 including the bimetal snap-action disc 12 then cool down again, the bimetal snap-action disc 12 snaps back into its low-temperature position when the reset temperature is reached, which is also referred to as the snap-back temperature, as shown in FIG. 5, for example. Thus, a reversible switching behavior can be realized.

[0124] Of course, it is also possible for a switch once it has been snapped over to the high-temperature position to be prevented from switching back by means of a corresponding locking mechanism. A large number of such locking mechanisms, which are used in particular for one-time switches where switchback is to be prevented, are already known from the prior art.

[0125] Finally, it should be noted that the switching mechanism 10, as shown for example in FIGS. 1-4 in various embodiments, can also be used in other types of switches of temperature-dependent switches. FIGS. 5 and 6 show only one possible design of a temperature-dependent switch in which the switching mechanism 10 can be used.