TEMPERATURE-DEPENDENT SWITCH

Abstract

A temperature-dependent switch which comprises a first and a second stationary counter contact and a temperature-dependent switching mechanism having a current transfer member. The switching mechanism, depending on its temperature, either closes the switch by pressing the current transfer member against the first and the second counter contact and thereby establishing an electrically conductive connection between the two counter contacts via the current transfer member, or opens the switch by keeping the current transfer member at a distance from the first and the second counter contact and thereby interrupting the electrically conductive connection. A closing lock is provided, which keeps the switch open when it has been opened for the first time. The closing lock comprises a spring washer which directly interacts with the current transfer member and mechanically locks the latter permanently when the switch has been opened for the first time so that the switch remains permanently open.

Claims

1. A temperature-dependent switch, comprising: a first stationary counter contact, a second stationary counter contact, and a temperature-dependent switching mechanism having a current transfer member, wherein the switching mechanism is configured to close and open the switch depending on its temperature, wherein the switching mechanism is configured to close the switch by pressing the current transfer member against the first counter contact and the second counter contact and thereby establishing an electrically conductive connection between the first counter contact and the second counter contact via the current transfer member, and to open the switch by keeping the current transfer member at a distance from the first counter contact and the second counter contact and thereby interrupting the electrically conductive connection, wherein the switch further comprises a closing lock which is configured to keep the switch open when it has been opened for the first time, wherein the closing lock comprises a spring washer which is configured to directly interact with the current transfer member and to mechanically lock the current transfer member in a permanent manner when the switch has been opened for the first time, so that the switch remains permanently open.

2. The switch according to claim 1, wherein the temperature-dependent switching mechanism comprises a temperature-dependent snap disc having a geometrical high-temperature configuration and a geometrical low-temperature configuration, and a bistable spring disc at which the current transfer member is arranged, wherein the spring disc has two geometrical configurations which are stable in a temperature-independent manner, wherein, in a first configuration of said two geometrical configurations, the spring disc is configured to press the current transfer member against the first counter contact and the second counter contact and, wherein, in a second configuration of said two geometrical configurations, the spring disc is configured to keep the current transfer member away from the first counter contact and the second counter contact.

3. The switch according to claim 2, wherein the snap disc is configured to exert a force on the spring disc such that the spring disc snaps from the first configuration to the second configuration, when the snap disc transitions from the geometrical low-temperature configuration to the geometrical high-temperature configuration.

4. The switch according to claim 3, wherein the snap disc is fixed to the current transfer member, wherein a clearance is provided in an area around an edge of the snap disc, and wherein the edge of the snap disc is configured to project at least partially into said clearance when the snap disc re-assumes its geometrical low-temperature configuration with the spring disc being in its second configuration.

5. The switch according to claim 2, wherein the snap disc and the spring disc are fixed to the current transfer member.

6. The switch according to claim 1, wherein it the switch further comprises a housing, wherein the first counter contact and the second counter contact are arranged at the housing, and wherein the switching mechanism is arranged in the housing.

7. The switch according to claim 6, wherein the housing comprises a lower part and an upper part for closing the lower part, wherein the first counter contact and the second counter contact are arranged on an inner side of the upper part.

8. The switch according to claim 2, wherein the housing comprises a lower part and an upper part for closing the lower part, wherein the first counter contact and the second counter contact are arranged on an inner side of the upper part, and wherein a clearance is provided between the snap disc and the lower part, such that the snap disc does not contact the lower part in its geometrical high-temperature configuration and in its geometrical low-temperature configuration.

9. The switch according to claim 2, wherein the snap disc is a bi- or trimetal snap disc.

10. The switch according to claim 7, wherein the spring washer is configured to interact with the current transfer member and with a spacer ring which is arranged between the upper part and the lower part.

11. The switch according to claim 10, wherein the spring washer is arranged between the spacer ring and the upper part, and wherein the spring washer comprises at least one locking member, which is configured to interact with the current transfer member.

12. The switch according to claim 11, wherein the locking member comprises a radially inwardly resilient tongue, which rests pre-stressed against an edge of the current transfer member when the switch is closed, and which braces on the current transfer member when the switch is open.

13. The switch according to claim 10, wherein the spring washer is arranged on the current transfer member and comprises at least one locking member, which is configured to interact with the spacer ring.

14. The switch according to claim 13, wherein the locking member comprises a radially outwardly resilient tongue, which rests pre-stressed against an inner surface of the spacer ring when the switch is closed, and which braces on a recess in the spacer ring when the switch is open.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0084] FIG. 1 shows a schematic side view of a switch in the closed state;

[0085] FIG. 2 shows a representation as FIG. 1, but in the closed state of the switch, wherein a clearance is provided here for the edge of the snap disc;

[0086] FIG. 3 shows a first embodiment of a spring washer used as a closing lock, wherein the top part shows a top view with tongues lying in the ring plane, and the bottom part shows a sectional view with tongues that are bent upwards and inwardly resilient;

[0087] FIG. 4 shows a second embodiment of a spring washer used as a closing lock, wherein the top part shows a top view with tongues lying in the ring plane, and the bottom part shows a sectional view with tongues that are bent upwards and inwardly resilient;

[0088] FIG. 5 shows an enlarged view of section I of FIG. 1, but with the spring washer according to FIG. 3;

[0089] FIG. 6 shows a representation as in FIG. 5, but with the switch open;

[0090] FIG. 7 shows an enlarged view of section I of FIG. 1, but with the spring washer according to FIG. 4; and

[0091] FIG. 8 shows a representation as in FIG. 5, but with the switch open.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0092] FIG. 1 shows a schematic, sectioned side view of a switch 10 which is realized in a rotationally symmetrical manner in top view and preferably comprises a circular form.

[0093] The switch 10 comprises a housing 11 in which a temperature-dependent switching mechanism 12 is provided.

[0094] The housing 11 includes a pot-like lower part 14 which is produced from electrically conducting material and a flat, insulating upper part 15 which is held on the lower part 14 by means of a bent-over edge 16. For reasons of clarity, the bent-over edge 16 is not shown solidly right across the upper part 15.

[0095] A spacer ring 17, which holds the upper part 15 at a spacing from the lower part 14, is provided between the upper part 15 and the lower part 14.

[0096] The upper part 15 comprises an inner surface 18 on which a first stationary counter contact 19 and a second stationary counter contact 21 are provided. The counter contacts 19 and 21 are realized as rivets which extend through the upper part 15 and end on the outside in heads 22 or 23 which serve for the external connection of the switch.

[0097] The switching mechanism 12 further includes a current transfer member 24 which, in the shown embodiment, is a contact disc, the upper side 25 of which is coated in an electrically conducting manner so that in the case of the system shown in FIG. 1 it ensures an electrically conducting connection between the two counter contacts 19 and 21 at the counter contacts 19 and 21.

[0098] As usual, the components consisting of solid material, here the spacer ring 17 and the contact disc 24, are not hatched, although they are also shown cut.

[0099] The current transfer member 24 is connected via a rivet 26, which is also to be seen as part of the contact member, to a bistable spring disc 27 and a bistable snap disc 28.

[0100] The spring disc 27 comprises two temperature-independent configurations, the first configuration of which is shown in FIG. 1 (closed switch 10) and the second configuration in FIG. 2 (open switch 10).

[0101] The snap disc 28 comprises two temperature-dependent configurations, namely its low-temperature configuration which is shown in FIG. 1 (closed switch 10) and its high-temperature configuration which is shown in FIG. 2 (open switch 10).

[0102] A circumferential shoulder 29, on which the spacer ring 17 rests, is provided in the inside of the lower part 14. The spring disc 27 is clamped by way of its edge 31 between the shoulder 29 and the spacer ring 17, whilst it rests by way of its center 32 on a shoulder 33 on the rivet 26. The spring disc 27 is consequently clamped at its center 32 between the current transfer member 24 and the shoulder 33.

[0103] Another shoulder 34, on which the snap disc 28 rests by way of its center 35, can be seen in FIG. 1 further below and further radially outside on the rivet 26.

[0104] The center 35 rests freely on the shoulder 34. The snap disc 28 also rests freely, i.e. without mechanical stress, on an inner bottom 37 of the lower part 14 by way of its edge 36.

[0105] According to FIG. 1, the inner surface 37 is designed as a wedge-shaped support shoulder 38 which ascends radially outwardly and serves as a support surface for the edge 36.

[0106] If the temperature of the snap disc 28 then increases, its edge 36 in FIG. 1 is lifted upward such that the snap disc 28 snaps from its convex position shown in FIG. 1 into its concave position shown in FIG. 2 in which its edge 36 is supported against the inside of the switch 10, in this case against the spring disc 27, as can be seen in FIG. 2.

[0107] When transitioning from its low-temperature configuration in FIG. 1 into its high-temperature configuration in FIG. 2, the snap disc 28 is therefore supported by way of its edge 36 against the spring disc 27, pressing by way of its center 35 onto the shoulder 34 of the rivet 26 and, as a result, pressing the current transfer member 24 away from the stationary counter contacts 19 and 21 against the force of the spring disc 27.

[0108] As a result of said movement, the rivet 26 is settled on the inner bottom 37 of the lower part 14, while at the same time the spring disc 27 snaps from its first configuration shown in FIG. 1 to its likewise stable second geometric configuration shown in FIG. 2.

[0109] While the spring disc 27 holds the current transfer member 24 in abutment with the counter contacts 19 and 21 in its first configuration according to FIG. 1 when switch 10 is closed, it holds the current transfer member 24 at a distance from the counter contacts 19 and 21 in its second configuration according to FIG. 2 when switch 10 is open.

[0110] While switch 10 is shown in FIG. 1 in its closed state, it is situated in FIG. 2 in its open state.

[0111] If the temperature of the device to be protected and consequently the temperature of the switch 10 cools down again then, the snap disc 28 snaps from its high-temperature configuration according to FIG. 2 back again into its low-temperature configuration, which it had already assumed in FIG. 1.

[0112] The snap disc 28 is again in its low-temperature configuration to which it has cooled down as a result of the cooling of the device to be protected. The edge 36 of the snap disc 28 will move downwards, so that it comes to rest on the support shoulder 38 provided at switch 10 in FIG. 1.

[0113] The snap disc 28 will therefore push the spring disc 27 back into its first configuration when transitioning into its low-temperature configuration.

[0114] In the embodiment in FIG. 2, however, a circumferential clearance 40 is provided below the edge 36 of the snap disc 28, which is provided in an edge area 41 of the inner base 37.

[0115] When the snap disc 28 of switch 10 is again in its low-temperature configuration according to FIG. 2, it has moved with its edge 36 into the clearance 40. The snap disc 28 of the switch 10 according to FIG. 2 is therefore not able to push up the spring disc 27 at its center 32.

[0116] The switch 10 of FIG. 2 therefore remains open even if the snap disc 28 has moved back to its low-temperature configuration. However, vibrations may cause the switch 10 of FIG. 2 to close again, which is undesirable with one-time switches.

[0117] A closing lock 39 is provided, which is arranged in the area indicated by circles I and II in FIGS. 1 and 2. For the sake of clarity, embodiments of the locking devices 39 are not shown in FIGS. 1 and 2 but in FIGS. 3 to 8.

[0118] The task of the closing locks 39 is to mechanically lock the temperature-dependent switching mechanism 12 permanently in a switch 10 that it has been opened once, so that the switch 10 cannot close again even if the snap disc 28 cools down again.

[0119] While at the switch 10 of FIG. 1 the closing locks 39 must permanently absorb the closing pressure exerted by the cooled down snap disc 28, this closing pressure is missing at switch 10 of FIG. 2, because the edge 36 of the snap disc 28 does not find a support shoulder 38 here, but is located in the clearance 40.

[0120] The closing locks 39 each comprise a spring washer 43, 51, as shown schematically and not to scale in FIG. 3 in a first embodiment and in FIG. 4 in a second embodiment.

[0121] The spring washer 43 is shown in a top view in the upper part of FIG. 3. It comprises an annular surface 44, with the inside 45 of which three resilient tongues 46 are integrally formed. The spring washer 43 is punched out of spring steel and is initially provided as shown in the upper part of FIG. 3, namely with tongues 46 lying in the ring plane.

[0122] The tongues 46 are then bent upwards by approx. 85, as shown in the sectional side view in the lower part of FIG. 3. If the tongues 46 are now bent further outwards during assembly, they spring radially inwards in the direction of the arrow 47.

[0123] The spring washer 51 is shown in a top view in the upper part of FIG. 4. It comprises an annular surface 52, with the outside 53 of which three resilient tongues 54 are integrally formed. The spring washer 51 is punched out of spring steel and is initially provided as shown in the upper part of FIG. 4, namely with tongues 54 lying in the ring plane.

[0124] The tongues 54 are then bent upwards by approx. 85, as shown in the sectional side view in the lower part of FIG. 4. If the tongues 54 are now bent further inwards during assembly, they spring radially outwards in the direction of the arrow 55.

[0125] FIG. 5 shows an enlarged view of the detail I of the closed switch 10, which detail is marked in FIG. 1. The spring washer 43 from FIG. 3 rests with its annular surface 44 on top of the spacer ring 17 and is clamped between the spacer ring 17 and the upper part 15 and thus fixed. The tongues 46 are located in a gap 57 between the spacer ring 17 and a radially outwardly directed edge 58 of the current transfer member 24.

[0126] The tongues 46 were bent radially outwards during assembly and extend at almost 90 to the annular surface 44, so that they are spring preloaded radially inwards and lie against the edge 58, as indicated by the arrow 47.

[0127] For this assembly, if necessary, an expanding tool is used with which the tongues 46 are pressed into the lower part 14 and radially outwards onto the spacer ring 17, but without bending them, while inserting the spring washer 43.

[0128] If the switch 10 is now opened, the current transfer member moves downwards in FIG. 5 and assumes the position shown in FIG. 6. FIG. 6 shows an enlarged view of the detail of the opened switch 10 which is indicated by I in FIG. 2.

[0129] During this movement of the current transfer member 24, the tongues 46 are released from its edge 58, move radially inwards and thus pass over the current transfer member 24, which they mechanically lock by contact with its upper side 59 in a permanent manner. In the area where the tongues 46 rest on the upper side 59, the upper side 59 is preferably not electrically conductive.

[0130] The current transfer member 24 is thus prevented from moving upwards again into abutment with the two counter contacts 19, 21, even if the switching mechanism 12 cools down again and the spring disc 27 is snapped back to its first configuration.

[0131] FIG. 7 shows an enlarged view of the detail I of the closed switch 10, which detail is marked in FIG. 1. The spring washer 51 from FIG. 4 rests with its annular surface 52 on the upper side 59 of the current transfer member 24 and is suitably fixed there, for example by gluing or soldering. In the area where the spring washer 51 rests on the upper side 59, the upper side 59 is preferably not electrically conductive.

[0132] The tongues 54 rest against a radially inwardly facing inner surface 61 of the spacer ring 17. The tongues 54 have been bent radially inwards during assembly by contact with the spacer ring 24 and extend at almost 90 to the annular surface 52, so that they lie against the inner face 61 in a radially outward, spring preloaded manner.

[0133] The assembly is carried out in such a way that first the switching mechanism 12 is inserted into the lower part 14 and then the spacer ring 17. Then the spring washer is inserted into the spacer ring 17 until it rests on the upper side 59 of the current transfer member 24. Then the spring washer 51 is fixed to the upper side 59.

[0134] If the switch 10 is now opened, the current transfer member moves together with the spring washer 51 downwards in FIG. 7 and assumes the position shown in FIG. 8. FIG. 8 shows an enlarged view of the detail of the closed switch 10 which is indicated by I in FIG. 2.

[0135] During this movement of the current transfer member 24, the tongues 54 are released from the inner surface 61, move radially outwards and enter the recess 62 in the spacer ring 17, which is located below the inner surface 61 and is set back radially outwards.

[0136] In this way, the current transfer member 24 is mechanically locked in a permanent manner by the contact of the tongues 54 in the recess 62. The current transfer member 24 is thus prevented from moving upwards again into abutment with the two counter contacts 19, 21, even if the switching mechanism 12 cools down again and the spring disc 27 is snapped back to its first configuration.

[0137] The spring washer 51 can also be attached to the current transfer member 24 by means of clamps 63, which are arranged on the spring washer 51 and embrace the current transfer member 24. This type of fixing is done when inserting the spring washer 51 and saves subsequent fixing by gluing or soldering.

[0138] 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.

[0139] 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.