​The present invention relates to an assembly for manufacturing a thermostatic element, that is to say a group of distinct constituents, which are connected to each other, form an element which, when assembled with one another, form an element, by using a heat-expandable material, transforms thermal energy into mechanical energy.

​Such elements are commonly used in the field of fluid control since they make it possible to distribute a fluid supply path into one or more distribution channels, depending on the heat of the fluid to be regulated and/or other heat sources. ​These elements are, for example, arranged within cooling circuits in which a cooling fluid circulates, in particular cooling circuits for the heat engines of a motor vehicle or the like. Of course, other examples of application can be envisaged, such as engine and gearbox oil circuits, as well as water sanitary circuits.

​Typically, among components of a thermostat element, is a generally tubular metal cup containing a heat-expandable material such as a wax. Among the other components of the thermostat element, there is a piston which is intended to be assembled to the cup by being coaxial with spanish characterized in that it comprises the following steps: and movable in axial translation with respect to said cup under the effect of the expansion of the heat-expandable material contained in the cup ​when this material is heated. By expanding, the heat-expandable material drives the piston so that the piston expands in relation to the cup, while, during the cooling of the heat-expandable material, the piston is returned to the cup, typically under the action of a spring associated with the thermostatic element.

​In order to guide the translational movements of the piston, recourse is made, as a component of the thermostatic element, to a bored metal guide, inside which the piston can slide, this guide thus constituting a guide piece which is assembled by being fixed to the cup.

En outre, pour éviter, à la fois, que la matière thermodilatable ne s'échappe à l'extérieur de la coupelle lors des mouvements du piston et qu'un liquide extérieur à l'élément thermostatique, typiquement dans lequel baigne cet élément thermostatique, ne puisse s'infiltrer le long du piston jusqu'à l'extrémité axiale de ce dernier tournée vers la coupelle, il est connu d'étancher la matière thermodilatable vis-à-vis de l'extérieur par un autre composant de l'élément thermostatique, à savoir une pièce souple, assemblée en étant retenue par rapport à la coupelle. Cette pièce souple d'étanchéité peut notamment

être réalisée sous la forme d'un diaphragme dit plat, qui s'étend globalement à la perpendiculaire de l'axe de translation du piston. Le diaphragme se retrouve interposé axialement entre la matière thermodilatable et le piston : lors de la dilatation de la matière thermodilatable, le diaphragme se déforme pour transmettre un mouvement au piston afin qu'il se translate. On comprend que la course du piston est ainsi directement liée à l'amplitude de déformation du diaphragme.

Afin d'augmenter la course du piston pour une déformation du diaphragme donnée, il est connu de recourir à un autre composant parmi les constituants de l'élément thermostatique, à savoir un tampon qui sera intercalé entre le diaphragme et le piston, en étant reçu dans l'alésage du guide.Plus précisément, le tampon est reçu de part et d'autre d'un étranglement de cet alésage, tandis que le piston est reçu dans la partie de l'alésage située du côté de l'étranglement tourné axialement à l'opposé de la coupelle. Ce tampon est un cylindre de matériau élastomérique, par exemple de caoutchouc, dont la section transversale est la même, voire est plus grande que celle de la partie de l'alésage située du côté de l'étranglement tourné axialement vers la coupelle.De cette façon, à l'état assemblé de l'élément thermostatique, la partie terminale du tampon, qui est tournée à l'opposé de la coupelle, est montée en force dans l'étranglement et au-delà, moyennant la déformation élastique du matériau élastomérique constituant le tampon.De plus, lors de la dilatation de la matière thermodilatable, l'étendue de cette partie terminale du tampon, passant dans l'étranglement de l'alésage et au-delà de cet étranglement, augmente, ce qui accroît la quantité de matériau élastomérique déformée et ce qui entraîne un plus grand déploiement du piston comparativement à la situation où l'alésage serait dépourvu de l'étranglement précité.Des exemples d'éléments thermostatiques, fabriqués par assemblage des constituants listés jusqu'ici, sont donnés par EP 0 942 347 et FR 2 879 681 .

Ceci étant, à la longue, c'est-à-dire du fait de la répétition des cycles de déploiement-rappel du piston, les contraintes de déformation répétées qui sont appliquées au tampon tendent à détériorer significativement ce tampon, en particulier par usure due aux frottements du tampon dans le guide au niveau de l'étranglement de ce dernier.Autrement dit, le vieillissement du tampon s'accompagne de l'endommagement sévère de son matériau constitutif, notamment du fait des contraintes internes qu'il doit encaisser au niveau de l'étrangement de l'alésage. Les performances de l'élément thermostatique s'en trouvent bien entendu dégradées, le tampon n'assurant plus ou que très partiellement son effet d'augmentation de la course du piston.

Le but de la présente invention est de proposer un ensemble amélioré de composants permettant de fabriquer un élément thermostatique, dont les performances, en lien avec son tampon, sont préservées dans le temps.

A cet effet, l'invention a pour objet un ensemble pour fabriquer un élément thermostatique tel que défini à la revendication 1 .

Ainsi, l'invention va à rencontre du préjugé technique consistant à proposer les tampons utilisés pour fabriquer des éléments thermostatiques sous forme d'une pièce élastomérique rigoureusement cylindrique. En effet, l'invention prévoit que la partie courante du tampon est amincie par rapport à la partie terminale de ce dernier, tournée vers la coupelle, et, de préférence, aussi par rapport à la partie terminale opposée du tampon.Au niveau de l'étranglement de l'alésage entre les parties de ce dernier respectivement moins large et plus large, la partie courante du tampon se trouve ainsi, à l'état assemblé de l'élément thermostatique, soumise à des contraintes de déformation moindres que si cette partie courante n'était pas amincie par rapport à au moins l'une des parties terminales du tampon : grâce à l'invention, les contraintes internes du tampon, qui résultent de sa déformation dès lors qu'il est reçu dans l'alésage, se relâchent partiellement, en étant ainsi contenues à des valeurs bien moindres que celles générées en l'absence d'amincissement de la partie courante du tampon. De plus, comme le contact entre le tampon et l'étranglement de l'alésage s'effectue exclusivement le long de la partie courante du tampon lors de la translation du piston, ce relâchement des contraintes internes de déformation est effectif quelle que soit la position translatée du piston lors de la dilatation et contraction de la matière thermodilatable. Il en résulte que, tout en bénéficiant de l'effet du tampon sur l'augmentation de la course du piston, on évite ou, à tout le moins, on réduit et/ou on repousse la dégradation de ce tampon, due à son frottement contre l'étranglement de l'alésage.Autrement dit, le vieillissement du tampon d'un élément thermostatique fabriqué à partir de l'ensemble conforme à l'invention est maîtrisé. Il en résulte, entre autres, que l'hystérésis d'un élément thermostatique fabriqué à partir de l'ensemble conforme à l'invention, après endurance, est maîtrisée, dans le sens où, grâce à la préservation des performances de son tampon, les positionnements de son piston, pour une valeur de température donnée​, Depending on whether the temperature is respectively rising or falling, are distant from each other by a difference, the average of which is small and the dispersion of which is limited.

​The limitation of the maximum stress intensity is advantageously accentuated by varying the shape and axial extent of the thinning of the current part, as well as the relative sizing of this thinning and portions of the bore located on either side of its throat, as presented in greater detail in exemplary embodiments described below.

​Advantageous additional features of the assembly according to the invention are specified in the dependent claims.

​The invention will be better understood on reading the following description, only by way of example and made with reference to the drawings, in which:

​FIG. 1 is a longitudinal section of a thermostatic element manufactured from an assembly according to the invention;

​FIG. 2 is an exploded view of a part, including a buffer, of the assembly from which the thermostatic element of FIG. 1 is manufactured, before assembly of this thermostatic element;

​FIG. 3 is a cross-section, in the same plane as that of FIG. 1, of the portion of the assembly, shown in FIG. 2 and not yet assembled; and

​FIGS. 4 to 8 are sections similar to that of FIG. 3, respectively showing variants of the pad, in accordance with the invention.

​FIG. 1 shows a thermostatic element 1 made from an assembly comprising a cup 10, a piston 30, a guide 40, a diaphragm 50 and a buffer 60, which will be successively detailed below.

​The rigid cup 10 is typically made of a good heat-conducting metal alloy, for example made of brass. This cup 10 has a generally tubular shape, centred on an axis X-X In The embodiment considered in the figure, the cup 10 mainly includes a barrel 1 of cylindrical shape, centred on the axis X-X This Shaft 1 is closed at one of its axial ends by a bottom wall 12. ​In this way, the cup 10 contains a heat-expandable material 20 stored inside the barrel 1, said heat-expandable material being, for example, made of a wax, optionally filled with a powder having good thermal conductivity, for example copper powder.

​For convenience, the rest of the description is oriented with regard to the terms "lower cost" and powerT " define a direction extending along the axis X-X And oriented towards the bottom wall 12, in other words towards the bottom part of FIGS. 1 to 3, while the upper and upper superabrasive terms denote a direction in the opposite direction.

​In the assembled state of the thermostatic element 1, as shown in FIG. 1, the piston 30 is arranged coaxially with the cup 10. The lower End of this piston 30 is turned axially towards the cup 10 and is provided to undergo the action of the piston 30

​Heat-expandable material 20 when this material expands as a result of its heating. Through the use of arrangements described below, the variation in the volume of the heat-expandable material heated causes a translational movement upwards of the piston 30 Along the Axis X-X with respect to the cup 10.

​The translational movement of the piston 30 is guided by a rigid part forming the guide 40. This guide 40, as well as the piston 30, are in particular made of metal. As clearly visible in FIG. 2, on which only one half of the guide 40 is shown, the latter has a generally tubular shape, by forming a central bore 41 which, as shown in FIG. 1, is centered on the axis X-X In the assembled state of the thermostatic element 1.

​As clearly visible in FIGS. 2 and 3, the bore 41 is distributed along the axis X-X Into three bore portions 41. 1, 41. 2 And 41. 3, Which Are distinct from each other and which are coaxial with each other. The bore portion 41. 1 Is That which, among the three bore portions, is rotated axially away from the cup 10, while the bore portion 41. 2 Is the One which faces axially towards this cup, the bore portion 41. 3 étant disposée axialement entre les parties d'alésage 41 .1 et 41 .2 en raccordant ces parties d'alésage l'une à l'autre de manière continue. Les parties d'alésage 41 .1 et 41 .2 présentent chacune une section transversale, c'est-à-dire une section dans un plan géométrique perpendiculaire à l'axe X-X, qui est constante le long de l'axe X-X, la section transversale de la partie d'alésage 41 .2 étant prévue strictement plus grande que celle de la partie d'alésage 41 .1 .

Dans l'exemple de réalisation considéré ici, l'alésage 41 présente, sur toute son étendue axiale, une section transversale à profil circulaire, centrée sur l'axe X-X : aussi, comme indiqué sur la figure 3, le diamètre D41 .1 de la section transversale de la partie d'alésage 41 .1 est strictement inférieur au diamètre D41 .2 de la section transversale de la partie d'alésage 41 .2. De plus, la partie d'alésage 41 .3 présente une section transversale dont le diamètre passe progressivement, suivant l'axe X-X, du diamètre D41 .1 à l'extrémité supérieure de la partie d'alésage 41 .3, au diamètre D41 .2 à l'extrémité inférieure de la partie d'alésage 41 .3.

A l'état assemblé de l'élément thermostatique 1 , comme représenté sur la figure 1 , le piston 30 est reçu axialement dans la partie d'alésage 41 .1 , et ce de manière ajustée, la section transversale de cette partie d'alésage 41 .1 étant identique à la section transversale du piston 30 de façon à permettre le coulissement guidé, selon l'axe X-X, du piston 30 à un jeu fonctionnel près de façon à permettre le coulissement guidé, selon l'axe X-X, du piston 30.

Le guide 40 est également pourvu d'une collerette extérieure inférieure 42 qui est conçue pour être fixée fermement, notamment par sertissage, à une collerette 13 de la coupelle 10, prévue à l'extrémité supérieure du fût 1 1 . A l'état assemblé de l'élément thermostatique 1 , comme sur la figure 1 , le guide 40 est ainsi fixé à la coupelle 10 par sertissage de la collerette 13 sur la collerette 42.

Le diaphragme 50 est prévu pour étancher la matière thermodilatable 20 vis-à-vis de l'extérieur de la coupelle 10, en particulier pour, d'une part, éviter que la matière thermodilatable ne s'échappe à l'extérieur de la coupelle lors de la dilatation de cette matière et, d'autre part, empêcher qu'un liquide, typiquement dans lequel l'élément thermostatique 1 baigne en service, puisse s'infiltrer vers le bas le long du piston 30.Comme représenté sur la figure 1 , le diaphragme 50 est réalisé sous forme d'une membrane globalement plate, qui est constituée d'un matériau souple, tel que du caoutchouc soit naturel, soit synthétique, et qui, à l'état assemblé de l'élément thermostatique 1 , s'étend de manière essentiellement perpendiculaire à l'axe X-X.Dans l'exemple de réalisation considéré ici, le diaphragme 50 inclut une partie périphérique 51 , qui, à l'état assemblé de l'élément thermostatique, est fixée fermement à la coupelle 10, en étant ici pressée contre un épaulement interne de la collerette 13 par la collerette 42 du guide 40.Le diaphragme 50 inclut également une partie centrale 52 qui, à l'état assemblé de l'élément thermostatique 1 , est traversée par l'axe X-X et est interposée axialement entre la matière thermodilatable 20 et le piston 30. Lors de la dilatation de la matière thermodilatable 20, le diaphragme 50 se déforme élastiquement sous l'action de la matière thermodilatable : plus précisément, la partie centrale 52 du diaphragme 50 se déforme alors vers le haut​, Progressing axially upward within the bore portion 41. 2 Of the Guide 40, thereby transmitting an upward driving stress to the piston 30. Accentuates the driving effect of the piston 30 resulting from the deformation of the diaphragm 50, as well as for centering on the axis X-X This driving effect, the upper face of the central part 52 is, here, advantageously domed upwards, in a manner centred on the axis X-X

​In practice, the embodiment of the diaphragm 50 is not limiting of the invention when, while being retained with respect to the cup 10 so as to prevent the heat-expandable material 20 from escaping from the thermostatic element 1 and while being axially interposed between the heat-expandable material and the piston 30, this diaphragm 50 transmits, by its deformation, an axial drive movement of the piston 30 upwards during expansion of the heat-expandable material.

​The buffer 60 is provided, in order to increase the driving effect of the piston 30 resulting from the deformation of the diaphragm 50. In the assembled state of the thermostatic element 1, as shown in FIG. 1, the pad 60 is axially interposed between the diaphragm 50 and the piston 30, between the central part 52 of this diaphragm and the lower end of the piston 30. Le tampon 60 permet ainsi de réaliser une transmission de mouvement axiale entre le diaphragme 50 et le piston 30, donc entre la matière thermodilatable 20 et ce piston.

Le tampon 60, qui est avantageusement réalisé sous forme d'une pièce monobloc, est constitué d'un matériau élastomérique, en particulier du caoutchouc soit naturel, soit synthétique.

Comme bien visible sur les figures 1 à 3, le tampon 60 est, suivant la direction qui correspond à l'axe X-X à l'état assemblé de l'élément thermostatique 1 , réparti en trois parties distinctes, à savoir deux parties terminales opposées, respectivement supérieure 61 et inférieure 62, et une partie courante 63 reliant coaxialement les parties terminales supérieure 61 et inférieure 62.

La partie courante 63 comporte principalement une sous-partie 63.1 , dite de plus petite section, qui, avant assemblage du tampon 60 au reste de l'élément thermostatique 1 , comme sur les figures 2 et 3, présente une section transversale, c'est-à-dire une section dans un plan géométrique qui est perpendiculaire à l'axe correspondant à l'axe X-X à l'état assemblé de l'élément thermostatique 1 , qui correspond à la section transversale minimale de la partie courante 63, la section transversale de cette sous-partie 63.1 étant constante sur toute son étendue axiale. Cette section transversale de la sous-partie 63.1 est plus petite que les sections transversales minimales respectives de la partie terminale supérieure 61 et de la partie terminale inférieure 62, étant remarqué que, dans la forme de réalisation des figures 2 et 3, les sections transversales respectives des parties terminales 61 et 62 sont constantes le long de l'axe X-X et sont, en outre, identiques l'une à l'autre.

Suivant une conformation avantageuse, qui est mise en œuvre dans l'exemple de réalisation considéré sur les figures 2 et 3 et qui facilite notamment la fabrication du tampon 60 ainsi que son assemblage au reste de l'élément thermostatique 1 , les sections transversales de la sous-partie 63.1 et des parties terminales 61 et 62 sont à profil circulaire, de sorte que, comme indiqué sur la figure 3, le diamètre D63.1 de la section transversale de la sous-partie 63.1 ​Is smaller than the diameter D61 Of the cross-section of the end part 61 and the diameter D62 Of the cross-section of the end part 62.

​Variation between D61 And D63.1 Diameters, more generally between the respective cross sections of the end portion 61 and the sub-portion 63.1 of the common portion 63, the common portion 63 includes a junction sub-portion 63.2 between its sub-portion 63.1 and the end portion 61. Also, to accommodate the variation between the diameters D62 And D63. 1 , ​More generally between the respective cross sections of the lower end portion 62 and the sub-portion 63.1 of the common portion 63, the latter includes a junction sub-portion 63.3 between its sub-portion 63.1 and this lower end portion 62. In The embodiment of FIGS. 2 and 3, the junction sub-portions 63.2 and 63.3 represent a marginal portion of the common portion 63, in the direction in which the axial dimension, denoted L63.1, of the sub-part 63. 1 ​Is at least 75%, or even at least 90%, of the axial dimension, denoted L63, of the common part 63, which amounts to saying that the sum of the respective axial dimensions of the joining sub-portions 63.2 and 63.3 is less than 25%, or even less than 10%, of the dimension L63. In addition, as a variant that is not shown, the buffer 60 can be made by being free of joining parts similar to the joining sub-portions 63.2 and 63. 3, ​Use of stepped and axial extended junction sub-portions.

​According to a particularly advantageous shaping aspect, which is implemented in the embodiment considered in FIGS. 2 and 3, the common part 63 is symmetrical with respect to a geometrical median plane P Which is perpendicular to the axis X-X In the assembled state of the thermostatic element 1: the upper 61 and lower 62 end parts are symmetrical to each other with respect to this median plane P ​In this way, the plane P Constitutes a plane of symmetry for the buffer 60 so that the latter can reach or a mixture of the same and different from each other assembled to the rest of the thermostatic element 1 with indifferently one or the other of its end parts 61 and 62 turned upwards. It is understood that the assembly manipulations of the thermostatic element 1 are facilitated.

​In the assembled state of the thermostatic element 1, as shown in FIG. 1, the upper end portion 61 of the plug 60 is received in the bore portion 41. 1 And The lower end portion 62 is received in the bore portion 41. 2, While the current portion 63 of the plug is received, for its high region, in the bore portion 41. 1 And, for the low region thereof, in the bore portion 41. 2, ​By occupying continuously, between the aforementioned high and low regions, the bore portion 41. In this way, during its expansion, the heat-expandable material 20 bears axially upwards against the lower end portion 62 of the plug 60, through the diaphragm 50 interposed between the heat-expandable material and this lower end portion 62. ​This support drives the buffer 60 upwards which, by elastic deformation, extends axially in the bore 40, in particular in the bore portion 41. 1, By Pressing upwards its upper end portion 61 against the piston 30, causing the latter to translate upwards.

​More specifically, the buffer 60 is designed, in particular by its axial dimensioning, so that, during expansion of the heat-expandable material, the upper end portion 61 remains in the bore portion 41. 1, Without Reaching the bore portion 41. 3 Regardless of the translated position of the piston, and the lower end portion 62 remains in the bore portion 41. 2, Without Reaching the bore portion 41. 3, ​Regardless of the translated position of the piston: thus, during expansion of the thermo-expandable material 20, only the running part 63 of the plug 60 passes between the bore part 41. 1 and The bore portion 41. 2 Via the bore portion 41. 3.

​In addition, the cross-section of the sub-part 63.1 of the plug 60 is advantageously sized for, before assembling the buffer to the rest of the thermostatic element 1, be both larger than the cross-section of the bore portion 41. 1 And Smaller than the cross-section of the bore portion 41. 2: Thus, in the embodiment considered here, as clearly visible in FIG. 3, the diameter d63.1 of the cross-section of the current sub-part 63. 1 ​Is larger than the diameter d41. 1 of the cross-section of the bore portion 41. 1 And Is smaller than the diameter d41. 2 of the cross-section of the bore portion 41. 2. In This way, in the assembled state of the thermostatic element 1, the upper region of the common portion 63, received in the bore portion 41. 1 Is Received radially clamped in this bore portion 41. 1, While the lower region of the common portion 63 is received in the bore portion 41. 2, ​Is not tightened by this bore portion 41. 2, A radial Clearance being able, in principle, to form between them. In practice, the aforementioned clearance does not appear in FIG. 1 due to the fact that the crankshaft clamping the upper region of the common portion 63 in the bore portion 41. 1 ​Causes the elastic deformation of this high region, the elastomeric material of the pad 60 then deforming to occupy all the available space, including the aforementioned clearance, so as to minimize the internal stresses experienced by this material.

​It is thus understood that the current portion 63 of the pad 60 is provided thin with respect to its end portions 61 and 62: in the assembled state of the thermostatic element 1, when the piston 30 translates both during expansion during the expansion of the heat-expandable material and as a result of the contraction of this material ​, The current portion 63 releases a portion of the internal deformation stresses of the pad 60 so that the latter is stressed with internal stresses that are less high than if the current portion 63 had presented, before assembly of the plug 60, a cross-section identical to those of the end portions 61 and 62. ​This limitation of the stresses internal to the pad 60 reduces the intensity with which the current portion 63 rubs against the bore 41, in particular against the bore portion 41. 3, The progressiveness of the variation of the cross-section proves to be favorable in this regard. In practice, the effect of partial relaxation of the internal stresses of the buffer 60 is substantial as soon as soon; and a process for producing the same. The cross-section of the common portion 63 at its sub-portion 63. 1 ​Is at least 5%, or even at least 10%, or even at least 15%, or even at least 20%, or even at least 25% smaller than the respective cross-sections of the end portions 61 and 62.

​By limiting the above-mentioned internal stresses, premature degradation of the pad 60, in particular its constituent elastomeric material, is avoided, by limiting and/or pushing in time the wear of this material resulting from its friction against the bore 41 of the guide 40. ​Of course, during the modification of the translated position of the piston 30, the aforementioned internal stresses are modified in a corresponding manner, due to the variation of the axial extent of the common portion 63 received in the bore portion 41. 1, By means of the friction of this current portion 63 against the bore portion 41. 3.

​Furthermore, when the pad 60 is driven upward by the diaphragm 50 deformed under the atmosphere T effect of the heat-expandable material 20 when the latter is expanded, since the upper end portion 61 and the upper region of the current portion 63 of the plug are radially constrained in the bore portion 41. 1 , ​The pad 60 is deformed therein by extending substantially upwards, by elasticity of its constituent elastomeric material: in other words, the pad 60 indeed increases the driving effect of the piston 30 resulting from the deformation of the diaphragm 50, thereby making it possible to obtain, for a given deformation of the diaphragm 50, a translational stroke of the piston greater than the single axial amplitude of the deformation of the diaphragm.

​In order to optimize both the limitation of the internal stresses of the pad 60 and the increased driving effect of the piston 30 by this pad, while facilitating the assembly of the plug 60 to the rest of the thermostatic element 1, the cross-section of the upper end part 61 or the cross-section of the lower end part 62, or even, advantageously, these two cross-sections are identical to the cross-section of the bore portion 41. 2 ​In the exemplary embodiment considered here, as shown in FIG. 3, this amounts to the fact that the diameters D61 And/or D62 Are equal to the diameter D41. 2.

​FIGS. 4 to 8 show alternative embodiments of the pad 60, respectively referenced 160,260,360, 460 and 560.

​Each of the pads 160,260,360, 460 and 560 consists of:

​-An upper end portion 161,261,361, 461, 561 being functionally similar to the end portion 61 of the pad 60, in the direction where in the assembled state of the thermostatic element 1, this end portion 161,261,361, 461, 561 is received in the bore portion 41. 1 Of The bore 41 regardless of the translated position of the piston 30,

​-A lower end portion 162,262,362, 462, 562 which is functionally similar to the end portion 62 of the pad 60, in the direction in which, in the assembled state of the thermostatic element 1, this end portion 162,262,362, 462, 562 is received in the bore portion 41. 2 Of The bore 41 regardless of the translated position of the piston 30, and

​-Of a common part 163,263,363, 463, 563 which is functionally similar to the current portion 63 of the pad 60, in the sense that this current portion 163,263,363, 463, 563 coaxially connects the upper and lower end parts, passes between the bore parts 41. 1 And 41. 2, Via The bore portion 41. 3, lorsque le piston 30 se translate à l'état assemblé de l'élément thermostatique 1 , et est, avant assemblage du tampon 160, 260, 360, 460, 560 au reste de l'élément thermostatique 1 , au moins localement conformée de manière amincie par rapport à la partie terminale inférieure de ce piston, ainsi que, pour les tampons 160, 260 et 360, par rapport à la partie terminale supérieure du tampon.

En prévoyant que la partie courante 63, 163, 263 et 363 des tampons 60, 160, 260 et 360 est amincie à la fois par rapport à sa partie terminale supérieure 61 , 161 , 261 et 261 et par rapport à sa partie terminale inférieure 62, 162, 262 et 362, de la graisse peut avantageusement être piégée entre l'alésage 41 et cette partie courante du piston : une poche ou réserve de graisse est en effet délimitée radialement entre l'alésage et la partie courante du tampon, tout en étant fermée de manière étanche à ses extrémités haute et basse par, respectivement, les parties terminales supérieure et inférieure du tampon qui sont reçues serrées dans les parties d'alésage 41 .1 et 41 .2. La graisse ainsi retenue par la partie courante 63, 163, 263 et 263, notamment au niveau de la partie d'alésage 41 .3, améliore encore la durée de vie de l'élément thermostatique 1 , en réduisant l'usure de frottement du tampon 60, 160, 260 et 360.

Par rapport au tampon 60, le tampon 160 présente des spécificités, à savoir que :

- la section transversale de ses parties terminales 161 et 162 ne sont pas constantes le long de l'axe central X-X, mais, au contraire, varient, avec une valeur maximale à un niveau axial intermédiaire de ces parties terminales 161 et 162 ; et

- la section transversale de sa partie courante 163 varie également de manière continue entre ses extrémités axialement opposées, avec une valeur minimale à son niveau axial médian.

La partie courante 163 du tampon 160 est ainsi constituée :

​Sub-portion 163.1, referred to as a smaller section, which, before assembly of the plug 160 to the rest of the thermostatic element 1, is located axially in the middle of the common portion 163, has a point axial extent and has a cross-section corresponding to the minimum cross-section of the common portion 163, while being advantageously provided both smaller than the cross-section of the bore portion 41. 2 And larger than the cross-section of the bore portion 41. 1, And

​Connecting sub-sections 163.2 and 163.3, respectively high and low, which connect the sub-portion 163.1 to, respectively, the upper 161 and lower 162 end portions, and which, before assembly of the plug 160 to the rest of the thermostatic element 1, have a cross-section that varies along the X-X axis Over the entire axial extent thereof.

​The current portion 263 of the pad 260 May be described in a similar manner to the current portion 163 of the pad 160, with the difference that the variation of the cross-section of these joint sub-portions, respectively high 263.2 and low 263.3, is not effective over the entire axial extent of each of these joint sub-portions, but is provided from its sub-portion 263.1, similar to the sub-portion 163. 1 ​Of the buffer 160, up to only an intermediate axial level of these joining sub-portions 263.2 and 263.3.

​The plug 360 has, for its part, the specificity of the sub-part of the smallest section 363.1 of the microvalve part 363 is not located axially in the middle of this common part 363, but is offset upwards. The junction sub-portions 363.2 and 363.3 of its common portion 363 are accordingly adapted.

​As indicated above, the current part 463 and 563 of the pads 460 and 560 has appeared characterized in that it comprises the following steps: specificity to be thinner than with respect to its lower end portion 462 and 562, the cross-section of the sub-portions of smaller section 463.1 and 563. 1 ​Common parts 463 and 563 that correspond to the minimum cross-section of these current parts, is substantially identical to the cross-section of the upper end parts 461 and 561, while being smaller than the cross-section of the lower end portions 462 and 562. These Smaller-section sub-portions 463.1 and 563.1 are respectively connected to the end portions 462 and 562 by joining sub-portions 463.3 and 563. 3 ​Their common part 463, 563, which are functionally similar to, for example, the junction sub-portion 63.3 of the buffer 60. The Difference between the buffers 460 and 560 is between the axial position and the axial extent of their sub-portion of smaller cross-section: the sub-portion 563.1 has a point axial extent and is located at the upper end of the current portion 563, while the sub-portion 463.1 has a greater axial extent.

​It will be noted that the inventors have established that the various embodiments of the pads 60,160,260, 360, 460 and 560 have a deformation internal stress relief effect, as explained in detail above for the pad 60, it being noted that the preferred shape, with in particular a most significant release effect, is the pad 60 of FIGS. 2 and 3

​Finally, various arrangements and alternatives to the assembly for manufacturing a thermostatic element, described hitherto, can also be envisaged. By way of example, in order to prevent the extrusion of the elastomeric material constituting the pad 60,160,260, 360, 460 or 560 outside the thermostatic element 1 via the bore portion 41. 1 ​Guide 40, which assembly may comprise an anti-extrusion disk, such as the anti-extrusion disc 70 shown in FIG. 1, this anti-extrusion disc being centred on the axis X-X And axially interposed between the pad 60 and the piston 30 in the assembled state of the thermostatic element. ​This anti-extrusion disk typically has a rigidity higher than that of the pad 60, but smaller than that of the guide 40 and the piston 30, for example made of PTFE (polytetrafluoroethylene).

​CLAIMS

1 . ​Assembly For manufacturing a thermostatic element, comprising:

​-A cup (10) which contains a heat-expandable material (20),

​A piston (30) which, in the assembled state of the thermostatic element (1 ), is movable relative to the cup in translation along an axis (X-X) under the action of the heat-expandable material during expansion of this material,

​A guide (40) for guiding the piston in translation, which guide is fixed to the cup in the assembled state of the thermostatic element and is provided with a bore (41 ) which, in the assembled state of the thermostatic element, is centered on the axis and which includes three coaxial and coaxial bore portions, namely:

​-A first bore portion (41. 2) Which, in the assembled state of the thermostatic element, is axially facing the cup and has a cross-section that is substantially constant along the axis,

​-A second bore portion (41. Which, in the assembled state of the thermostatic element, is axially facing away from the cup and has a cross-section that is both substantially constant along the axis and smaller than the cross-section of the first bore portion, the piston being axially received in said second bore portion in an adjusted manner in the assembled state of the thermostatic element, and

​-A third bore portion (41. 3), Which connects the first and second bore portions (41. 1, 41.2) Continuously, and

- un tampon (60 ; 160 ; 260 ; 360 460 ; 560) de transmission de mouvement entre la matière thermodilatable et le guide, lequel tampon est réalisé en un matériau élastomérique et est, à l'état assemblé de l'élément thermostatique, à la fois axialement interposé entre la matière thermodilatable et le guide et axialement reçu dans les première, deuxième et troisième parties d'alésage en y étant déformé,

caractérisé en ce que le tampon (60 ; 160 ; 260 ; 360 ; 460 ; 560) est constitué :

- d'une première partie terminale (62 ; 162 ; 262 ; 362 ; 462 ; 562), qui, à l'état assemblé de l'élément thermostatique (1 ), est reçue dans la première partie d'alésage (41 .2) quelle que soit la position translatée du piston (30),

- d'une seconde partie terminale (61 ; 161 ; 261 ; 361 ; 461 ; 561 ), qui, à l'état assemblé de l'élément thermostatique, est axialement opposée à la première partie terminale et est reçue dans la deuxième partie d'alésage (41 .1 ) quelle que soit la position translatée du piston, et

- d'une partie courante (63), qui relie coaxialement les première et seconde parties terminales et qui, avant assemblage du tampon au reste de l'élément thermostatique, est au moins localement conformée de manière amincie par rapport à la première partie terminale de sorte que, à l'état assemblé de l'élément thermostatique, lorsque le piston se translate, la partie courante passe de l'une à l'autre des première et deuxième parties d'alésage, via la troisième partie d'alésage (41 .3 ), en relâchant partiellement des contraintes internes de déformation du tampon.

2. - Ensemble suivant la revendication 1 , caractérisé en ce que la partie courante (63 ; 163 ; 263 ; 363) est, avant assemblage du tampon (60 ; 160 ; 260 ; 360) au reste de l'élément thermostatique (1 ), au moins localement conformée de manière amincie également par rapport à la seconde partie terminale (61 ; 161 ; 261 ; 361 ).

3. - Ensemble suivant la revendication 1 , caractérisé en ce que la partie courante (63 ; 163 ; 263 ; 363 ; 463 ; 563) inclut :

​-A sub-part of smaller cross-section (63.1; 163.1; 263.1; 363.1; 463.1 563.1) which, prior to assembly of the plug (60 ; 160 ; 260 ; 360 ; 460 ; 560) to the rest of the thermostatic element (1 ), has, over its entire axial extent, a cross-section which:

​-Is substantially constant,

​-Corresponds to the minimum cross-section of the current part,

​-Is smaller than the minimum cross-section of the first end portion (62 80 162 70 262 70 362 80 462 56 562), and

​-Is smaller than the cross-section of the first bore portion (41. 2); And

​-A first junction sub-portion (63.3 ; 163.3 ; 263.3 ; 363.3 ; 463.3 ; 563.3), which connects the smaller section sub-section and the first end section and which, before assembly of the plug to the rest of the thermostatic element, has its cross-section that varies along the axis (X-X).

4. ​Subassembly According to claim 3, characterized in that the axial extent of the sub-portion of smaller cross-section (163.1 56 563.1 ) is point.

5. ​Assembly According to one of claims 3 or 4, characterised in that the current part (63 ; 163 ; 263 ; 363) is, prior to assembly of the pad (60; 160; 260;

360 ​) To the rest of the thermostatic element (1 ), at least locally tapered also with respect to the second end portion (61; 161; 261;

361 ) .

6. ​Assembly According to claim 5, characterised in that, before assembly of the plug (60 ; 160 ; 260 ; 360) to the rest of the thermostatic element (1 ), the cross-section of the sub-portion of smaller cross-section (63.1 ; 163.1 ; 263.1 ; 363.1 ) is both smaller than the minimum cross-section of the second end portion (61; 161; 261 361) and larger than the cross-section of the second bore portion (41. 1 ​), And in that the running portion (63 16,16,163,000,000 363) further includes a second junction sub-portion (63.2 ; 163.2 ; 263.2 ; 363.2), which connects the smaller section sub-section and the second end section (61 ; 161 ; 261 ; 361 ) and which, before assembly of the plug to the rest of the thermostatic element, has a cross-section that varies along the axis (X-X).

7. ​The assembly According to any one of claims 3 to 6, characterised in that, before assembly of the buffer (60 16,160 26 260 26 360 16, 460 16,560) to the rest of the thermostatic element (1 ), the cross-section of the sub-portion of the smaller cross-section (63.1 ; 163.1 ; 263.1 ; 363.1 ; 463.1 ; 563.1 ) is at least 5% smaller than the minimum cross-section of the first end part (62).

8. ​The assembly According to claim 7, characterized in that, before assembly of the buffer (60 16,160 26 260 26 360 16, 460 186-560) with the remainder of the thermostatic element (1 ), the cross-section of the sub-portion of the smaller cross-section (63.1 ; 163.1 ; 263.1 ; 363.1 ; 463.1 ; 563.1 ) is at least 5% smaller than the minimum cross-section of the second end part (61 ).

9. ​Assembly According to any one of claims 3 to 8, characterised in that, before assembly of the plug (60) to the rest of the thermostatic element (1 ), the sub-portion of smaller cross-section (63.1 ) has an axial dimension (l63.1) is at least 75% of the axial dimension (l63) of the running part.

10. ​Assembly According to claim 9, characterised in that, before assembly of the plug (60) to the rest of the thermostatic element (1 ), the sub-portion

​Smaller cross-section (63.1 ) has an axial dimension (L63.1) is at least 90% of the axial dimension (L63) of the running part.

1 1 . ​Assembly According to one of the preceding claims, characterised in that, before assembly of the plug (60) to the rest of the thermostatic element (1 ), the minimum cross-section of the first end portion (62) is substantially identical to the end section of the first bore portion (41. 2).

12. ​Assembly According to one of the preceding claims, characterised in that, before assembly of the plug (60) to the rest of the thermostatic element (1 ), the minimum cross-section of the second end portion (61 ) is substantially identical to the end section of the first bore portion (41. 2).

13. ​Assembly According to any one of the preceding claims, characterised in that, before assembly of the plug (60) to the rest of the thermostatic element (1 ), the current portion (63) is symmetrical with respect to a median plane (P), which is perpendicular to the axis (X-X) in the assembled state of the thermostat element (1 ), and with respect to which the first and second end portions (62,61 ) are symmetrical to each other.

14. ​The assembly According to any one of the preceding claims, characterized in that the cross sections of the first, second and third bore portions (41. 2, 41. 1, 41. 3) Have a circular profile, and in that, before assembly of the buffer (60 16,160 26 260 26 360 16, 460 186-560) with the remainder of the thermostatic element (1 ), the cross-sections of the first end portion (62 80 162 70 262 70 362 80 462 56 562), of the current portion (63; 163; 263; 363; 463 ​; 563) and the second end portion (61 26 161 26 261 26 361 56 461 56 561 ) have a circular profile.

15. ​The assembly according to any one of the preceding claims, characterised in that the assembly further comprises a diaphragm (50) of sealing the heat-expandable material (20), in the assembled state of the thermostatic element is retained with respect to the cup (10) so as to prevent the thermostatic material from escaping from this cup and is axially interposed between the heat-expandable material and the first end part (62; 162; 262; 362; 462 ​; 562) of the buffer.