EP0749141A1 - Thermostat with probe having a SMA spring in its socket - Google Patents

Thermostat with probe having a SMA spring in its socket Download PDF

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Publication number
EP0749141A1
EP0749141A1 EP96420191A EP96420191A EP0749141A1 EP 0749141 A1 EP0749141 A1 EP 0749141A1 EP 96420191 A EP96420191 A EP 96420191A EP 96420191 A EP96420191 A EP 96420191A EP 0749141 A1 EP0749141 A1 EP 0749141A1
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EP
European Patent Office
Prior art keywords
probe
spring
thermostat
thermostat according
finger
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Granted
Application number
EP96420191A
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German (de)
French (fr)
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EP0749141B1 (en
Inventor
Jean Serigny
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Cotherm SA
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Cotherm SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/002—Thermally-actuated switches combined with protective means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/01—Details
    • H01H61/0107—Details making use of shape memory materials
    • H01H2061/0115—Shape memory alloy [SMA] actuator formed by coil spring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/323—Thermally-sensitive members making use of shape memory materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/46—Thermally-sensitive members actuated due to expansion or contraction of a solid
    • H01H37/48—Thermally-sensitive members actuated due to expansion or contraction of a solid with extensible rigid rods or tubes

Definitions

  • the present invention relates to a probe thermostat intended for example for regulating the temperature of the water contained inside an electric water heater.
  • Thermostats are thermosensitive control devices with cyclic action, intended to maintain the temperature between two particular values for normal operating conditions and in which adjustment by the user can be provided.
  • Probe thermostats are electromechanical temperature regulation systems comprising on the one hand a metal tube with high coefficient of expansion (copper, brass) inside which is placed a metal rod with low coefficient of expansion (invar) and on the other hand an electrical breaker controlling the current to be sent to the heating resistor and actuated by the differential expansion of the two metals constituting the probe.
  • the two metals forming the probe are fixed to each other at the free end of the latter by crimping or welding.
  • probe thermostats intended for electric water heaters operating under pressure include safety devices making it possible to cut off the electrical supply when the electrical switch of the probe thermostat operates abnormally.
  • standardization requires that these probe thermostats are now fitted with an effective circuit breaker for user safety.
  • thermostats of this kind which include a fuse cartridge which is mounted in series on the conductor constituting the supply phase of the heating resistor with which the electric switch of the thermostat is associated, while said fuse is immersed or not in the plastics material of the base in the immediate vicinity of the probe so as to follow the evolution of the water temperature with a minimum thermal gradient.
  • This type of thermostat has certain drawbacks with regard to the risks of thermal drift over time, due to the rise in temperature which can cause the temperature of the thermostat to overlap with the operating temperature of the latter. and therefore an untimely triggering of security.
  • the fuse cartridge has an alteration over time due to the temperature variations to which it is subjected.
  • thermostats with a fuse cartridge are not reversible because the latter melts under the effect of heat slightly higher than the maximum allowed. When the cartridge is damaged, the operator must completely change the thermostat because it is no longer in working order.
  • the thermostat according to the present invention comprises a spring made of shape memory alloy which is disposed inside a housing located in the immediate vicinity of the probe for controlling an electrical contact of the thermostat safety device placed on one supply phases of the heating resistor so as to follow the evolution of the water temperature with a minimum thermal gradient.
  • An advantage according to the invention consists in that the shape memory alloy spring is placed in a housing which communicates with that receiving the probe tube.
  • the probe thermostat comprises between the spring and the elastic and metallic blade of the safety contact or breaker an insulating pallet with a reset finger.
  • Fig. 1 is an exploded perspective view illustrating the probe thermostat provided with the shape memory alloy safety device according to the present invention.
  • Fig. 2 is a view with partial cutaway showing the installation of the safety device inside the probe thermostat.
  • Fig. 3 is a diagrammatic section representing the probe thermostat in the operating position.
  • Fig. 4 is a section similar to that of FIG. 3, but showing the probe thermostat out of use due to the expansion of the safety device.
  • FIG. 1 to 4 There is shown in FIG. 1 to 4 a probe thermostat 1 comprising a plastic base 2 and a metal probe 3.
  • the probe thermostat 1 has two terminals 2 a , 2 b secured to the base 2 by which it can be installed in series on a constituent conductor one of the phases for supplying electric current to the resistor 4 of a water heater or similar device (Fig. 3).
  • the probe 3 comprises a tube 3 a with a high coefficient of expansion which is fixed to the base 2 by crimping or overmolding in the plastic material constituting said base. Inside the tube 3 a, a metal rod 3 b with a low coefficient of expansion is placed, one end of which is crimped to the tube 3 a , while the other end cooperates with an adjustment member 5.
  • the base 2 is closed by a cover 6 made of plastic material comprising an opening 6 a for access to the adjustment member 5.
  • This opening 6 a is obstructed by a patch 6 b which snaps into suitable grooves made in the cover 6.
  • the first connection terminal 2 a is connected via an elastic and metallic safety strip 2 c to a safety breaker 2 d .
  • the safety switch 2 d has another fixed blade 2 e secured to the base 2 of the thermostat 1.
  • the second connection terminal 2b is connected via a fixed blade 2f to another electrical switch 2g .
  • the latter comprises a flexible metal blade 2 h which is supported on a fork 2 i secured to the fixed blade 2 e of the safety switch 2 d .
  • the blade 2 h is in contact with an insulating lever 2 i which is located near the adjustment member 5 and which is crossed by the metal rod 3 b of the probe 3.
  • the base 2 comprises a housing 2 k which communicates with that receiving the tube 3 a of the probe 3.
  • the housing 2 k is formed below the flexible blade 2 c of the safety switch 2 u .
  • a spring 7 made of shape memory alloy.
  • the spring 7 operates as a safety device when the electric breaker 2 g is defective and / or when the water temperature becomes higher than a predetermined safety temperature.
  • a cylindrical hole 2 l is drilled in the base 2 near the housing 2 k to receive a reset finger 8 made of an insulating material such as plastic.
  • the reset finger 8 is provided with a height sufficient to come out into a hole 6 c formed in the cover 6 in the vicinity of the opening 6 a .
  • the reset finger 8 is integral in its lower part and perpendicular to its vertical axis with a horizontal pallet 8 a which is inserted between the spring 7 and the blade 2 c of the safety breaker 2 d .
  • a horizontal pallet 8 a which is inserted between the spring 7 and the blade 2 c of the safety breaker 2 d .
  • studs 8 b , 8 c and 8 d are provided at the level of the pallet 8 a allowing the angular indexing of the reset finger 8 when it is placed in the plastic base 2.
  • the spring 7 is disposed in the immediate vicinity of the probe 3 so as to follow the evolution of the water temperature with a minimum thermal gradient.
  • the probe thermostat 1 described above operates in the same way as those of the prior art. Under the effect of the heat of the water which is determined by the adjusting member 5, the rod 3 b expands and when the water temperature is reached, it moves the lever 2 j which pushes the metal blade 2 h to open the 2 g electrical breaker in order to cut off the electrical supply to the heating resistor 4. The cooling of the water causes the rod 3 b to retract to rest the 2 g breaker contacts in order to supply the again the heating resistor 4.
  • the temperature of the water transmitted to the tube 3b is then passed on by conduction to the spring 7 which expands under the effect of a heat slightly higher than the maximum allowed (Fig. 4).
  • the expansion of the spring 7 in a vertical direction in its displacement causes the pallet 8 a of the reset finger 8 making it possible to elastically deform the metal blade 2 c in order to open the safety breaker 2 d .
  • the reset finger 8 protrudes above the cover 6 due to its vertical movement indicating to the operator that the thermostat 1 is no longer in working order.
  • the elastic deformation of the blade c 2 immediately cuts the power supply 4 heating resistor avoiding a dangerous increase in temperature of the water (Fig. 4).
  • the spring 7 made of shape memory alloy has no alteration over time whatever the temperature conditions to which it is subjected, provided that these are below its transition threshold.
  • the spring 7 has a reversible deformation.
  • the operator can, by means of the reset finger 8, apply a force in opposition to cause the spring 7 in memory alloy to return to its initial configuration ( Fig. 4).
  • the thermostat 1 does not have a reset finger 8, but that there exists between the spring 7 and the blade 2 c a pad or insulating cap not shown to avoid any short circuit. In this case, the thermostat 1 is to be changed when the maximum allowed temperature is exceeded since the blade 2 c is located away from that 2 e of the safety switch 2 d . We then see that thermostat 1 is no longer in working order and that the operator must change it.

Landscapes

  • Thermally Actuated Switches (AREA)
  • Control Of Resistance Heating (AREA)

Abstract

The thermostat (1) includes a plastic base (2) and a metal probe (3). Two contacts (2a,b) fixed on the base connect the thermostat in series with the power supply of an immersion electrical heater (4). Conductor blades link each of the two contacts to a safety breaker. The probe includes a metal tube (3a) housing a rod (3b) cooperating with an adjustment device (5). A lid (6) covers the thermostat. The base is provided with a recess (2k) which houses a spring (7) made of a shape memory alloy. A cylindrical hole (2l) is provided in the base to receive a reset finger (8) which is made of an insulating material.

Description

La présente invention a trait à un thermostat à sonde destiné par exemple à la régulation de la température de l'eau contenue à l'intérieur d'un chauffe-eau électrique.The present invention relates to a probe thermostat intended for example for regulating the temperature of the water contained inside an electric water heater.

Les thermostats sont des dispositifs de commande thermosensible à action cyclique, destinés à maintenir la température entre deux valeurs particulières pour des conditions de fonctionnement normal et dans lesquelles un réglage par l'utilisateur peut être prévu.Thermostats are thermosensitive control devices with cyclic action, intended to maintain the temperature between two particular values for normal operating conditions and in which adjustment by the user can be provided.

Les thermostats à sonde sont des systèmes électromécaniques de régulation de la température comprenant d'une part un tube métallique à fort coefficient de dilatation (cuivre, laiton) à l'intérieur duquel est placée une tige de métal à faible coefficient de dilatation (invar) et d'autre part un rupteur électrique commandant le courant à envoyer dans la résistance de chauffage et actionné grâce à la dilatation différentielle des deux métaux constituant la sonde. Les deux métaux formant la sonde sont fixés l'un à l'autre à l'extrémité libre de cette dernière par sertissage ou soudage.Probe thermostats are electromechanical temperature regulation systems comprising on the one hand a metal tube with high coefficient of expansion (copper, brass) inside which is placed a metal rod with low coefficient of expansion (invar) and on the other hand an electrical breaker controlling the current to be sent to the heating resistor and actuated by the differential expansion of the two metals constituting the probe. The two metals forming the probe are fixed to each other at the free end of the latter by crimping or welding.

Les thermostats à sonde connus destinés aux chauffe-eau électriques fonctionnant sous pression, comportent des dispositifs de sécurité permettant de couper l'alimentation électrique lorsque le rupteur électrique du thermostat à sonde fonctionne anormalement. De plus, la normalisation impose que ces thermostats à sonde soient désormais munis d'un coupe-circuit efficace pour la sécurité des utilisateurs.Known probe thermostats intended for electric water heaters operating under pressure include safety devices making it possible to cut off the electrical supply when the electrical switch of the probe thermostat operates abnormally. In addition, standardization requires that these probe thermostats are now fitted with an effective circuit breaker for user safety.

On connait des thermostats de ce genre qui comprennent une cartouche fusible qui est montée en série sur le conducteur constituant la phase d'alimentation de la résistance de chauffage à laquelle est associé le rupteur électrique du thermostat, tandis que ledit fusible est immergé ou non dans la matière plastique du socle à proximité immédiate de la sonde de façon à suivre l'évolution de la température de l'eau avec un gradiant thermique minimal.There are known thermostats of this kind which include a fuse cartridge which is mounted in series on the conductor constituting the supply phase of the heating resistor with which the electric switch of the thermostat is associated, while said fuse is immersed or not in the plastics material of the base in the immediate vicinity of the probe so as to follow the evolution of the water temperature with a minimum thermal gradient.

Ce type de thermostat comporte certains inconvénients en ce qui concerne les risques d'une dérive thermique au cours du temps, du fait de l'élévation de la température qui peut entraîner un recoupement de la température du thermostat avec la température de fonctionnement de ce dernier et donc un déclenchement intempestif de la sécurité.This type of thermostat has certain drawbacks with regard to the risks of thermal drift over time, due to the rise in temperature which can cause the temperature of the thermostat to overlap with the operating temperature of the latter. and therefore an untimely triggering of security.

En outre, la cartouche fusible présente une altération dans le temps du fait des variations de température auxquelles elle est soumise.In addition, the fuse cartridge has an alteration over time due to the temperature variations to which it is subjected.

De plus, on constate que les thermostats à cartouche fusible ne sont pas réversibles car cette dernière fond sous l'effet d'une chaleur légérement supérieure à celle maximale admise. Lorsque la cartouche est détériorée, l'opérateur doit changer intégralement le thermostat car celui-ci n'est plus en état de fonctionner.In addition, it can be seen that thermostats with a fuse cartridge are not reversible because the latter melts under the effect of heat slightly higher than the maximum allowed. When the cartridge is damaged, the operator must completely change the thermostat because it is no longer in working order.

C'est à ces inconvénients qu'entend plus particulièrement remédier la présente invention.It is these drawbacks that the present invention intends to remedy more particularly.

Le thermostat suivant la présente invention comporte un ressort réalisé en alliage à mémoire de forme qui est disposé à l'intérieur d'un logement situé à proximité immédiate de la sonde pour commander un contact électrique du dispositif de sécurité du thermostat placé sur l'une des phases d'alimentation de la résistance de chauffage de façon à suivre l'évolution de la température de l'eau avec un gradient thermique minimal.The thermostat according to the present invention comprises a spring made of shape memory alloy which is disposed inside a housing located in the immediate vicinity of the probe for controlling an electrical contact of the thermostat safety device placed on one supply phases of the heating resistor so as to follow the evolution of the water temperature with a minimum thermal gradient.

Un avantage selon l'invention consiste en ce que le ressort en alliage à mémoire de forme est placé dans un logement qui communique avec celui recevant le tube de la sonde.An advantage according to the invention consists in that the shape memory alloy spring is placed in a housing which communicates with that receiving the probe tube.

Un autre avantage selon l'invention consiste en ce que le thermostat à sonde comprend entre le ressort et la lame élastique et métallique du contact ou rupteur de sécurité une palette isolante d'un doigt de réarmement.Another advantage according to the invention consists in that the probe thermostat comprises between the spring and the elastic and metallic blade of the safety contact or breaker an insulating pallet with a reset finger.

Le dessin annexé, donné titre d'exemple, permettra de mieux comprendre l'invention, les caractéristiques qu'elle présente et les avantages qu'elle est susceptible de procurer :The appended drawing, given by way of example, will allow a better understanding of the invention, the characteristics which it presents and the advantages which it is capable of providing:

Fig. 1 est une vue en perspective éclatée illustrant le thermostat à sonde pourvu du dispositif de sécurité en alliage à mémoire de forme suivant la présente invention.Fig. 1 is an exploded perspective view illustrating the probe thermostat provided with the shape memory alloy safety device according to the present invention.

Fig. 2 est une vue avec arrachement partiel montrant la mise en place du dispositif de sécurité à l'intérieur du thermostat à sonde.Fig. 2 is a view with partial cutaway showing the installation of the safety device inside the probe thermostat.

Fig. 3 est une coupe schématique représentant le thermostat à sonde en position de fonctionnement.Fig. 3 is a diagrammatic section representing the probe thermostat in the operating position.

Fig. 4 est une coupe semblable à celle de Fig. 3, mais illustrant le thermostat à sonde hors usage du fait de la dilatation du dispositif de sécurité.Fig. 4 is a section similar to that of FIG. 3, but showing the probe thermostat out of use due to the expansion of the safety device.

On a représenté en Fig. 1 à 4 un thermostat à sonde 1 comportant un socle 2 en matière plastique et une sonde métallique 3. Le thermostat à sonde 1 comporte deux bornes 2a, 2b solidaires du socle 2 grâce auxquelles il peut être installé en série sur un conducteur constituant l'une des phases d'alimentation en courant électrique de la résistance 4 d'un chauffe-eau ou appareil analogue (Fig. 3).There is shown in FIG. 1 to 4 a probe thermostat 1 comprising a plastic base 2 and a metal probe 3. The probe thermostat 1 has two terminals 2 a , 2 b secured to the base 2 by which it can be installed in series on a constituent conductor one of the phases for supplying electric current to the resistor 4 of a water heater or similar device (Fig. 3).

La sonde 3 comporte un tube 3a à fort coefficient de dilatation qui est fixé au socle 2 par sertissage ou surmoulage dans la matière plastique constituant ledit socle. A l'intérieur du tube 3a est placée une tige de métal 3b à faible coefficient de dilatation dont l'une des extrémités est sertie au tube 3a, tandis que l'autre extrémité coopère avec un organe de réglage 5.The probe 3 comprises a tube 3 a with a high coefficient of expansion which is fixed to the base 2 by crimping or overmolding in the plastic material constituting said base. Inside the tube 3 a, a metal rod 3 b with a low coefficient of expansion is placed, one end of which is crimped to the tube 3 a , while the other end cooperates with an adjustment member 5.

Le socle 2 est fermé par un couvercle 6 en matière plastique comportant une ouverture 6a pour l'accès à l'organe de réglage 5. Cette ouverture 6a est obstruée par une pastille 6b qui vient s'encliqueter dans des rainures adéquates ménagées dans le couvercle 6.The base 2 is closed by a cover 6 made of plastic material comprising an opening 6 a for access to the adjustment member 5. This opening 6 a is obstructed by a patch 6 b which snaps into suitable grooves made in the cover 6.

La première borne de connexion 2a est reliée par l'intermédiaire d'une lamelle élastique et métallique de sécurité 2c à un rupteur de sécurité 2d. Le rupteur de sécurité 2d comporte une autre lame fixe 2e solidaire du socle 2 du thermostat 1.The first connection terminal 2 a is connected via an elastic and metallic safety strip 2 c to a safety breaker 2 d . The safety switch 2 d has another fixed blade 2 e secured to the base 2 of the thermostat 1.

La seconde borne de connexion 2b est reliée par l'intérmédiaire d'une lame fixe 2f à un autre rupteur électrique 2g. Ce dernier comporte une lame flexible et métallique 2h qui est en appui sur une fourche 2i solidaire de la lame fixe 2e du rupteur de sécurité 2d. La lame 2h est en contact avec un levier isolant 2i qui se trouve à proximité de l'organe de réglage 5 et qui est traversé par la tige métallique 3b de la sonde 3.The second connection terminal 2b is connected via a fixed blade 2f to another electrical switch 2g . The latter comprises a flexible metal blade 2 h which is supported on a fork 2 i secured to the fixed blade 2 e of the safety switch 2 d . The blade 2 h is in contact with an insulating lever 2 i which is located near the adjustment member 5 and which is crossed by the metal rod 3 b of the probe 3.

Le socle 2 comporte un logement 2k qui communique avec celui recevant le tube 3a de la sonde 3. Le logement 2k est ménagé en dessous de la lame flexible 2c du rupteur de sécurité 2u. A l'intérieur du logement 2k est introduit un ressort 7 réalisé en alliage à mémoire de forme.The base 2 comprises a housing 2 k which communicates with that receiving the tube 3 a of the probe 3. The housing 2 k is formed below the flexible blade 2 c of the safety switch 2 u . Inside the housing 2 k is introduced a spring 7 made of shape memory alloy.

Le ressort 7 fonctionne comme un dispositif de sécurité lorsque le rupteur éléctrique 2g est défectueux et/ou lorsque la température de l'eau devient supérieure à une température de sécurité pré-déterminée.The spring 7 operates as a safety device when the electric breaker 2 g is defective and / or when the water temperature becomes higher than a predetermined safety temperature.

Un trou cylindrique 2l est percé dans le socle 2 à proximité du logement 2k pour recevoir un doigt de réarmement 8 réalisé en une matière isolante telle que du plastique. Le doigt de réarmement 8 est prévu d'une hauteur suffisante pour venir déboucher dans un trou 6c ménagé dans le couvercle 6 au voisinage de l'ouverture 6a.A cylindrical hole 2 l is drilled in the base 2 near the housing 2 k to receive a reset finger 8 made of an insulating material such as plastic. The reset finger 8 is provided with a height sufficient to come out into a hole 6 c formed in the cover 6 in the vicinity of the opening 6 a .

Le doigt de réarmement 8 est solidaire dans sa partie inférieure et perpendiculairement à son axe vertical d'une palette horizontale 8a qui vient s'intercaler entre le ressort 7 et la lame 2c du rupteur de sécurité 2d. Au niveau de la palette 8a sont prévus des tétons 8b, 8c et 8d permettant l'indexation angulaire du doigt de réarmement 8 lors de sa mise en place dans le socle en matière plastique 2.The reset finger 8 is integral in its lower part and perpendicular to its vertical axis with a horizontal pallet 8 a which is inserted between the spring 7 and the blade 2 c of the safety breaker 2 d . At the level of the pallet 8 a are provided studs 8 b , 8 c and 8 d allowing the angular indexing of the reset finger 8 when it is placed in the plastic base 2.

On observe que le ressort 7 est disposé à proximité immédiate de la sonde 3 de façon à suivre l'évolution de la température de l'eau avec un gradient thermique minimal.It is observed that the spring 7 is disposed in the immediate vicinity of the probe 3 so as to follow the evolution of the water temperature with a minimum thermal gradient.

Le thermostat à sonde 1 décrit précédement fonctionne de la même manière que ceux de l'art antérieur. Sous l'effet de la chaleur de l'eau qui est déterminée par l'organe de réglage 5, la tige 3b se dilate et lorsque la température de l'eau est atteinte, elle déplace le levier 2j qui pousse la lame métallique 2h pour ouvrir le rupteur électrique 2g en vue de couper l'alimentation électrique de la résistance de chauffage 4. Le refroidissement de l'eau fait rétracter la tige 3b pour remettre en appui les contacts du rupteur 2g afin d'alimenter à nouveau la résistance de chauffage 4.The probe thermostat 1 described above operates in the same way as those of the prior art. Under the effect of the heat of the water which is determined by the adjusting member 5, the rod 3 b expands and when the water temperature is reached, it moves the lever 2 j which pushes the metal blade 2 h to open the 2 g electrical breaker in order to cut off the electrical supply to the heating resistor 4. The cooling of the water causes the rod 3 b to retract to rest the 2 g breaker contacts in order to supply the again the heating resistor 4.

Il arrive que les contacts du rupteur électrique 2g restent collés, entraînant une augmentation dangereuse de la température de l'eau à l'intérieur du chauffe-eau.It happens that the contacts of the 2 g electric breaker remain stuck, causing a dangerous increase in the temperature of the water inside the water heater.

La température de l'eau transmise au tube 3b est ensuite répercutée par conduction au ressort 7 qui se dilate sous l'effet d'une chaleur légérement supérieure à celle maximale admise (Fig. 4). La dilatation du ressort 7 dans une direction verticale entraîne dans son déplacement la palette 8a du doigt de réarmement 8 permettant de déformer élastiquement la lame métallique 2c pour ouvrir le rupteur de sécurité 2d. Lors de la dilatation du ressort 7, on constate que le doigt de réarmement 8 dépasse au-dessus du couvercle 6 du fait de son déplacement vertical indiquant à l'opérateur que le thermostat 1 n'est plus en état de fonctionner. La déformation élastique de la lame 2c coupe immédiatement l'alimentation éléctrique de la résistance de chauffage 4 évitant une augmentation dangereuse de la température de l'eau (Fig. 4).The temperature of the water transmitted to the tube 3b is then passed on by conduction to the spring 7 which expands under the effect of a heat slightly higher than the maximum allowed (Fig. 4). The expansion of the spring 7 in a vertical direction in its displacement causes the pallet 8 a of the reset finger 8 making it possible to elastically deform the metal blade 2 c in order to open the safety breaker 2 d . During the expansion of the spring 7, it is noted that the reset finger 8 protrudes above the cover 6 due to its vertical movement indicating to the operator that the thermostat 1 is no longer in working order. The elastic deformation of the blade c 2 immediately cuts the power supply 4 heating resistor avoiding a dangerous increase in temperature of the water (Fig. 4).

Il suffit alors à l'opérateur d'appuyer sur le doigt de réarmement 8 pour contraindre le ressort 7 dans sa position initiale afin que la lame 2c vienne en contact avec la lame fixe 2e du rupteur de sécurité 2d pour permettre le passage du courant et alimenter à nouveau la résistance de chauffage 4 du chauffe-eau.The operator then just needs to press the reset finger 8 to force the spring 7 into its initial position so that the blade 2 c comes into contact with the fixed blade 2 e of the safety switch 2 d to allow passage of current and supply heating resistor 4 of the water heater again.

On observe que le ressort 7 réalisé en alliage à mémoire de forme ne présente aucune altération dans le temps quelles que soient les conditions de température auxquelles il est soumis, pourvu que celles-ci soient inférieures à son seuil de transition. Le ressort 7 présente une déformation réversible. Ainsi, lorsque la température est redescendue en dessous du seuil de transition, l'opérateur peut, par l'intermédiaire du doigt de réarmement 8, appliquer une force en opposition pour faire retrouver au ressort 7 en alliage à mémoire de forme sa configuration initiale (Fig. 4).It is observed that the spring 7 made of shape memory alloy has no alteration over time whatever the temperature conditions to which it is subjected, provided that these are below its transition threshold. The spring 7 has a reversible deformation. Thus, when the temperature has dropped below the transition threshold, the operator can, by means of the reset finger 8, apply a force in opposition to cause the spring 7 in memory alloy to return to its initial configuration ( Fig. 4).

On peut prévoir que le thermostat 1 ne comporte pas de doigt de réarmement 8, mais qu'il existe entre le ressort 7 et la lame 2c une pastille ou capuchon isolant non représenté pour éviter tout court-circuit. Dans ce cas, le thermostat 1 est à changer lorsque la température maximale admise est dépassée puisque la lame 2c se trouve éloignée de celle 2e du rupteur de sécurité 2d. On constate alors que le thermostat 1 n'est plus en état de fonctionner et que l'opérateur doit le changer.It can be provided that the thermostat 1 does not have a reset finger 8, but that there exists between the spring 7 and the blade 2 c a pad or insulating cap not shown to avoid any short circuit. In this case, the thermostat 1 is to be changed when the maximum allowed temperature is exceeded since the blade 2 c is located away from that 2 e of the safety switch 2 d . We then see that thermostat 1 is no longer in working order and that the operator must change it.

Claims (8)

Thermostat à sonde du genre comprenant un système électromécanique de régulation de la température pourvu d'une sonde constituée d'un tube métallique à fort coefficient de dilatation à l'intérieur duquel est placée une tige de métal à faible coefficient de dilatation et d'un rupteur de sécurité commandant le courant électrique employé dans la résistance de chauffage, caractérisé en ce qu'il comprend un ressort (7) réalisé en alliage à mémoire de forme qui est disposé à l'intérieur d'un logement (24) qui est situé à proximité immédiate de la sonde (3) pour commander le rupteur de sécurité (2d) placé sur l'une des phases d'alimentation de la résistance de chauffage (4) de façon à suivre l'évolution de la température de l'eau avec un gradiant thermique minimal.Probe thermostat of the kind comprising an electromechanical temperature regulation system provided with a probe constituted by a metal tube with high coefficient of expansion inside which is placed a metal rod with low coefficient of expansion and a safety switch controlling the electric current used in the heating resistor, characterized in that it comprises a spring (7) made of shape memory alloy which is arranged inside a housing (24) which is located in the immediate vicinity of the probe (3) to control the safety switch (2 d ) placed on one of the supply phases of the heating resistor (4) so as to follow the evolution of the temperature of the water with a minimum thermal gradient. Thermostat à sonde suivant la revendication 1, caractérisé en ce que le logement (2k) recevant le ressort (7) communique avec celui recevant le tube (3a) de la sonde (3).Probe thermostat according to claim 1, characterized in that the housing (2 k ) receiving the spring (7) communicates with that receiving the tube (3 a ) of the probe (3). Thermostat à sonde suivant la revendication 1, caractérisé en ce qu'entre le ressort (7) et la lame élastique et métallique (2c) du rupteur de sécurité (2d) est disposée une palette isolante (8a) d'un doigt de réarmement (8).Probe thermostat according to claim 1, characterized in that between the spring (7) and the elastic and metallic blade (2 c ) of the safety switch (2 d ) is arranged an insulating pallet (8 a ) with a finger reset (8). Thermostat à sonde suivant la revendication 1, caractérisé en ce que le ressort (7) est prévu pour se dilater sous l'effet d'une chaleur légérement supérieure à celle maximale admise.Probe thermostat according to claim 1, characterized in that the spring (7) is designed to expand under the effect of a heat slightly higher than the maximum allowed. Thermostat à sonde suivant la revendication 3, caractérisé en ce que le doigt de réarmement (8) est guidé à l'intérieur d'un trou (2l) disposé à proximité du logement (2k) dans lequel est placé le ressort (7)Probe thermostat according to claim 3, characterized in that the reset finger (8) is guided inside a hole (2 l ) disposed near the housing (2 k ) in which the spring (7) is placed ) Thermostat à sonde suivant la revendication 3, caractérisé en ce que le doigt de réarmement (8) comporte une palette horizontale (8a) disposée dans la partie inférieure et perpendiculairement à son axe verticaleProbe thermostat according to claim 3, characterized in that the reset finger (8) has a horizontal pallet (8 a ) arranged in the lower part and perpendicular to its vertical axis Thermostat suivant la revendication 3, caractérisé en ce qu'au niveau de la palette (8a) du doigt de réarmement (8) sont prévus des tétons horizontaux (8b, 8c et 8d) permettant l'indexation angulaire dudit doigt à l'intérieur du socle (2).Thermostat according to claim 3, characterized in that at the level of the pallet (8 a ) of the reset finger (8) are provided horizontal pins (8 b , 8 c and 8 d ) allowing the angular indexing of said finger to inside the base (2). Thermostat suivant la revendication 1, caractérisé en ce qu'entre le ressort (7) et la lame élastique (2c) du rupteur de sécurité (2d) est disposée une pastille ou un capuchon isolant pour éviter tout court-circuit.Thermostat according to claim 1, characterized in that between the spring (7) and the elastic blade (2 c ) of the safety switch (2 d ) is disposed a pad or an insulating cap to avoid any short circuit.
EP19960420191 1995-06-12 1996-06-03 Thermostat with probe having a SMA spring in its socket Expired - Lifetime EP0749141B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9507169 1995-06-12
FR9507169A FR2735278B1 (en) 1995-06-12 1995-06-12 PROBE THERMOSTAT COMPRISING A SHAPE MEMORY ALLOY SPRING IN THE BASE

Publications (2)

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EP0749141A1 true EP0749141A1 (en) 1996-12-18
EP0749141B1 EP0749141B1 (en) 1998-12-16

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Application Number Title Priority Date Filing Date
EP19960420191 Expired - Lifetime EP0749141B1 (en) 1995-06-12 1996-06-03 Thermostat with probe having a SMA spring in its socket

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EP (1) EP0749141B1 (en)
DE (1) DE69601146T2 (en)
FR (1) FR2735278B1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003038849A1 (en) * 2001-10-29 2003-05-08 Thermowatt S.P.A. Safety thermo-protector designed in particular for electric water boilers
FR2870985A1 (en) * 2004-05-26 2005-12-02 Cotherm Sa REGULATION THERMOSTAT WITH RETENTION DEVICE
US20140090565A1 (en) * 2012-10-02 2014-04-03 Klub Manufacturing Corp. Buffer Structure of Portafilter
CN104051188A (en) * 2014-07-07 2014-09-17 佛山市通宝华龙控制器有限公司 Short-circuited prevention power failure resetting type snap action thermostat
IT202200014128A1 (en) 2022-07-04 2024-01-04 Termoregolatori Campini Corel S P A Rod thermostat with safety

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2172749A (en) * 1985-03-18 1986-09-24 Cotherm Sa Thermostat
US4679023A (en) * 1986-08-14 1987-07-07 Honeywell Inc. Over-temperature control for a thermostat
GB2204450A (en) * 1987-05-07 1988-11-09 Strix Ltd Hydraulic power assisted vehicle steering system
US4885560A (en) * 1988-09-21 1989-12-05 Masahiko Niino Thermal relay

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2172749A (en) * 1985-03-18 1986-09-24 Cotherm Sa Thermostat
US4679023A (en) * 1986-08-14 1987-07-07 Honeywell Inc. Over-temperature control for a thermostat
GB2204450A (en) * 1987-05-07 1988-11-09 Strix Ltd Hydraulic power assisted vehicle steering system
US4885560A (en) * 1988-09-21 1989-12-05 Masahiko Niino Thermal relay

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003038849A1 (en) * 2001-10-29 2003-05-08 Thermowatt S.P.A. Safety thermo-protector designed in particular for electric water boilers
FR2870985A1 (en) * 2004-05-26 2005-12-02 Cotherm Sa REGULATION THERMOSTAT WITH RETENTION DEVICE
WO2005119720A1 (en) * 2004-05-26 2005-12-15 Cotherm Control thermostat provided with a holding device
US20140090565A1 (en) * 2012-10-02 2014-04-03 Klub Manufacturing Corp. Buffer Structure of Portafilter
CN104051188A (en) * 2014-07-07 2014-09-17 佛山市通宝华龙控制器有限公司 Short-circuited prevention power failure resetting type snap action thermostat
CN104051188B (en) * 2014-07-07 2015-06-17 佛山市通宝华龙控制器有限公司 Short-circuited prevention power failure resetting type snap action thermostat
IT202200014128A1 (en) 2022-07-04 2024-01-04 Termoregolatori Campini Corel S P A Rod thermostat with safety
EP4303903A1 (en) 2022-07-04 2024-01-10 Termoregolatori Campini Corel S.p.A. Rod thermostat with safety

Also Published As

Publication number Publication date
DE69601146T2 (en) 1999-07-01
FR2735278A1 (en) 1996-12-13
EP0749141B1 (en) 1998-12-16
DE69601146D1 (en) 1999-01-28
FR2735278B1 (en) 1997-08-29

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