WO2013107843A2

WO2013107843A2 - Thermostatic element

Info

Publication number: WO2013107843A2
Application number: PCT/EP2013/050898
Authority: WO
Inventors: Guillaume GAUTIER GRAINDORGE; Thierry Maraux
Original assignee: Vernet
Priority date: 2012-01-19
Filing date: 2013-01-18
Publication date: 2013-07-25
Also published as: WO2013107843A3; FR2986045B1; FR2986045A1

Abstract

This thermostatic element (1) comprises: a thermally conducting cup (10) containing a thermally expanding substance (20); a piston (30) able to move in translation along its axis (X-X) under the action of the thermally expanding substance; a guide piece (40) for guiding the piston, which guide piece is secured fixedly to the cup; a seal (50) interposed radially between the piston and the guide piece, being housed in a groove (45) delimited in the axial end face (41A), the opposite face to the cup, of the guide piece; and an axial retention piece (60) for the axial retention of the seal in the groove, which piece is mounted around the piston, is fixed to the guide piece and/or the cup and has an annular body (61), mounted more or less coaxially and as a close fit around the piston (30), axially covering the groove (45) in order to retain the seal (50) therein. According to the invention, the annular body (61) of the retaining piece (60) bears means (63) of attachment to the guide piece (40) and/or to the cup (10), these means of attachment comprising branches (63) each extending from the annular body (61) and distributed about this annular body, their respective free ends (64) collaborating with the guide piece (40) and/or with the cup (10).

Description

THERMOSTATIC ELEMENT

The present invention relates to a thermostatic element, that is to say an element which, by using a thermally expandable material, converts a heat energy into a mechanical energy.

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

Typically, a thermostatic element comprises a metal cup of generally tubular shape and containing a thermally expandable material such as a wax. The element also comprises a piston coaxial with the cup and displaceable in translation relative to this cup under the effect of the expansion of the thermodilatable material contained in the cup, when the material is heated. By expanding, the thermally expandable material partly expels the piston, so that the latter deploys on the outside of the cup while, during the cooling of the thermally expandable material, the piston can be retracted inside the cup , generally under the action of a return spring associated with the thermostatic element. To guide the translational movement of the piston, the thermostatic element comprises a bored metal part, within which the piston slides, this guide piece being firmly secured to the cup.

In addition, to prevent the fluid, in which baths the thermostatic element, can not infiltrate the element along the piston, it is known to report a flexible sleeve, forming a sealing bellows, which is fixed the piston and the guide piece, covering the outlet of the latter on the outside. This being so, setting up such a headline remains a complex operation and therefore expensive to implement. In addition, its sealing performance is limited, especially when the fluid in which bathes the thermostatic element is under high pressure.

US Pat. No. 4,095,470, on which the preamble of claim 1 is based, proposed to use a seal to seal a thermostatic element with respect to the outside, this seal being attached around the piston of the thermostatic element, while being received in a groove dug in the outer end face of the guide piece of this thermostatic element. To retain the seal in this groove, US-A-4,095,470 teaches to use a washer-like piece: this washer is fixed to the guide piece by tongues, located at the outlet of the groove and obtained by local deformation of the material of the guide piece. Thus, the assembly of this thermostatic element proves tedious and expensive, except to run the risk of a failure of the fixing of the aforementioned washer.

The object of the present invention is to improve the existing thermostatic elements, by reinforcing and facilitating the retention of their sealing seal vis-à-vis the outside.

For this purpose, the invention relates to a thermostatic element, as defined in claim 1.

Additional advantageous features of the thermostatic element according to the invention are specified in the dependent claims.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the drawings in which:

- Figure 1 is a perspective view of a thermostatic element according to the invention;

FIG. 2 is a longitudinal section of the thermostatic element of FIG. 1;

FIGS. 3 and 4 are exploded perspective views of the thermostatic element of FIG. 1, at different respective viewing angles; and

- Figure 5 is a longitudinal section of the thermostatic element of Figure 1, considered in its exploded configuration of Figures 3 and 4.

In Figures 1 to 5 there is shown a thermostatic element 1 having a thermally conductive cup 10 typically made of a metal alloy good conductor of heat, for example brass. This cup 10 has a generally tubular shape, centered on an axis X-X. In the embodiment considered in the figures, the cup 10 includes a main cylinder 1 1 of cylindrical shape, circular base centered on the axis X-X. This barrel 1 1 is closed at one of its axial ends by a bottom wall 12. In this way, the cup 10 contains a thermodilatable material 20 stored inside the barrel January 1. This thermally expandable material is for example made of a wax, optionally filled with a powder having a good thermal conductivity, for example a copper powder.

For convenience, the remainder of the description will be oriented by considering that the terms "lower" and "bottom" denote a direction extending along the axis XX and oriented towards the bottom wall 12, in other words towards the lower part of the figures. 1 to 5, while the terms "superior" and "high" designate a direction in the opposite direction. The thermostatic element 1 also comprises a piston 30 arranged coaxially with the cup 10. The lower end portion of this piston 30 is housed inside the barrel 11 to undergo the action of the thermally expandable material 20 when this material expands as a result of its heating. By means of arrangements known per se, which are not shown and which will not be detailed here above, the variation of the volume of the heated thermosetting material causes a translational movement upwards of the piston 30 along the axis XX by relative to the cup 10.

The translational movement of the piston 30 is guided by a rigid piece 40 belonging to the thermostatic element 1, which is in particular made of metal. This guide piece 40 includes a tubular body 41 whose central bore 42 is centered on this axis. Cross-sectional to the axis XX, the bore 42 has a substantially fitted profile on the outer profile of the piston 30 so that the piston is axially received and guided in the bore 42. The guide piece 40 also comprises a collar ring 43, which is centered on the axis XX and which extends radially outwardly projecting from the lower portion 44 of the tubular body 41. This collar 43 is adapted to be secured rigidly, in particular by crimping, to a collar 13 of the cup 10, provided at the upper end of the barrel 1 1.

In practice, in particular for reasons which will appear later, the cup 10, the thermally expandable material 20, the piston 30 and the guide piece 40 together form a pre-assembled assembly, as shown in FIGS. 3 to 5.

In order to seal the upper outlet of the bore 42 vis-à-vis the outside, in particular to limit or even prevent pressurized fluid, in which the thermostatic element 1 bathes in service, can s infiltrating along the piston 30 inside the bore 42, the thermostatic element 1 comprises a seal 50 which, as in the embodiment considered in the figures, advantageously consists of an O-ring. This seal 50 is mounted co-axially around the piston 30, being internally adjusted to the outer diameter of this piston. In the assembled state of the thermostatic element 1, as clearly visible in FIG. 2, this seal 50 is thus radially interposed between the piston 30 and the guide piece 40, more precisely between the cylindrical outer wall of the piston 30 and the radial bottom wall 45.1 of a groove 45 delimited in the upper axial end face 41 A of the tubular body 41 of the guide piece 40. The establishment of this seal is easy since it consists of to engage it around the piston and then bring it axially closer to the guide piece, until the housing in the aforementioned groove, preferably by engaging it in a radially constrained manner as explained in more detail later. The groove 45 is thus located in the region of the upper outlet of the central bore 42 of the guide piece 40, this groove 45 opening, on the one hand, upwards on the upper axial end face 41A of the tubular body 41 and, on the other hand, radially inwards in the bore 42, as clearly visible in FIGS. 3 and 5. In the embodiment considered in the figures, the groove 45 presents, in cross-section, a overall profile in "L", which amounts to saying that the groove 45 is delimited, radially, by the radial bottom wall 45.1 of substantially cylindrical shape with a circular base centered on the axis XX and, axially, by a bottom wall axial 45.2 which connects the lower end of the radial bottom wall 45.1 to the central bore 42 of the tubular body 41, extending in a plane substantially perpendicular to the axis XX. This "L" profile of the groove 45 has the advantage of being easy to produce, in particular by machining the tubular body 41. That being said, as variants not shown, the groove 45 may have other transverse profiles, as long as the groove is shaped to receive axially downwardly the seal 50 and thus arrange the latter radially interposed between the piston 30 and the upper part 46 of the tubular body 41, that is to say the part of the latter delimiting upward the upper axial end face 41 A of the tubular body 41.

In the assembled configuration of the thermostatic element 1 and when the latter is in use, it is understood that, in view of the presence of the seal 50 radially interposed between the piston 30 and the guide piece 40, this seal forms two peripheral sealing lines, respectively with the outer wall of the piston 30 and with the radial bottom wall 45.1 of the groove 45, these two sealing lines limiting, or preventing the fact that fluid, which bathes the thermostatic element 1, can reach the inside of the bore 42, in particular during the translational movements of the piston 30 with respect to the guide piece 40. The sealing performance is remarkable, even in the case where the fluid in which the element is under strong pressure.

Advantageously, to enhance the performance of the aforementioned sealing lines, the seal 50 is interposed between the piston 30 and the guide piece 40 being radially constrained. In other words, this seal 50 is radially crushed between the piston 30 and the guide piece 40. This is also the case in the embodiment considered in the figures: indeed, the cross section of the seal 50 on the FIG. 2 is oblong, with a radial dimension denoted d in FIG. 2, which is strictly smaller than the radial dimension, denoted D in FIG. 5, corresponding to the diameter of the circular section of the seal 50 when the latter is at rest, c that is to say not yet assembled to the rest of the thermostatic element 1. In practice, to thereby constrain the seal 50 to move from its radial dimension D to its radial dimension d, several possibilities of relative arrangement between the seal 50, the piston 30 and the groove 45 of the guide piece 40 are conceivable, it being understood that a preferred solution, illustrated by the figures, in particular FIG. 5, consists in providing that, on the one hand, the inside diameter δ 50 of the seal 50 at rest is substantially equal to the outside diameter δ 30 of the piston 30, which facilitates the assembly of the seal 50 about the piston 30 and the axial drive of this seal along the piston to join the groove 45, and, secondly, the outer diameter Δ50 of the seal 50 at rest is strictly greater than the maximum diameter Δ45 of the groove 45, that is to say strictly greater than the maximum diameter of the radial bottom wall 45.1 of this groove, which induces the radial crushing of the seal 50 when the latter is put in place, in force, to the inside the groove 45, the corresponding crushing ratio of the seal 50 being predetermined as a function of the difference between the outer diameter Δ50 of the seal and the maximum diameter Δ45 of the groove.

In practice, the seal 50 is made of a material capable of producing a sealing effect vis-à-vis the piston 30 and the guide piece 40, this material is typically an elastomer, both natural and synthetic .

The thermostatic element 1 further comprises a part 60 dedicated to the axial retention of the seal 50 inside the groove 45. Indeed, in the absence of this retaining piece 60, it is understood that when translational movements of the piston 30 relative to the guide piece 40 when the thermostatic element 1 is in use, the seal 50 could be driven axially with the piston and then out of the groove 45. In the embodiment shown in the figures, the retaining piece 60 comprises an annular body 61, whose central bore 62 is centered on the axis XX and which, in the assembled state of the thermostatic element 1, is mounted co-axially around the piston 30. As clearly visible in Figure 2, the bore 62 of the annular body 61 has a profile substantially fitted to the outer profile of the piston 30 to a functional clearance, so that the piston 30 is axially received in bore 6 2, with a relative adjustment less strict than that between the piston and the guide piece 40. This is because the annular body 61 of the retaining piece 60 does not have the main function of guiding the piston 30 in translation according to the axis XX, this translational guiding function being devolved on the guide piece 40, but the annular body 61 of the retaining piece 60 is designed to axially cover the groove 45 sufficiently wide to retain the seal 50 inside this gorge. To do this, the inner periphery of the lower face of the annular body 61 forms an upward stop for the seal 50. Advantageously, to prevent any axial displacement of the seal 50 inside the groove 45, the annular body 61 of the retaining piece 60 is immobilized with respect to the guide piece 40 at an axial level such as the distance axial axis between the lower face of this annular body 61 and the axial bottom wall 45.2 is less than or equal to the maximum axial dimension of the seal 50 when the latter is in place in the groove 45.

In the assembled state of the thermostatic element 1, the retaining piece 60 is immobilized relative to the guide piece 40, being fixedly attached to the latter, directly or indirectly. For this purpose, the retaining piece 60 has branches 63, each extending from the annular body 61, projecting from the outer periphery of this annular body 61, and which are distributed around the periphery of this body 61, advantageously regular. In the embodiment considered here, these branches 63 are four in number. Each branch 63 has, opposite the annular body 61, a free end 64 which, on its side facing the X-X axis, has a shoulder surface 64A facing upwards. Each of these stepped surfaces 64A is designed to bear axially upward against a downwardly facing peripheral flange 47, which is delimited by the guide piece 40, more precisely in the connection zone between the upper part 46 of this last and an intermediate portion 48 of the tubular body 41 of this piece 40, connecting to each other the lower 44 and high portions 46 thereof. Thus, in the assembled state of the thermostatic element 1, the free ends 64 of the branches 63 fix the retaining piece 60 to the guide piece 40, by retaining the retaining piece 60 axially upwards by cooperation between their surface. shoulder 64A and the flange 47 of the intermediate portion 48 of the body 41, being recalled that, at the same time, the retaining piece 60 is held axially downwardly relative to the guide piece 40, by support of its annular body 61 against the upper part 46 of the body 41 of the guide piece 40, and either directly or, as in the example considered in the figures, with axial interposition of the seal 50.

More generally, it is understood that the branches 63 belong to or even constitute means belonging to the retaining piece 60 and making it possible, simply, reliably and economically, to fix the annular body 61 to the guide piece 40, in particular by complementarity of forms between the free end 64 of these branch 63 and a corresponding corresponding region of the tubular body 41 of the guide member 40, and advantageously without the need for additional fasteners.

In practice, various possibilities can be envisaged as regards the mechanical cooperation between the branches 63 and the guide piece 40 with a view to fix to it. Thus, in the embodiment considered in the figures, each branch 63 is designed, from an initial rest configuration, illustrated in FIGS. 3 to 5, to be elastically deformed outwards with respect to the annular body. 61, until the radial spacing between the axis XX and its free end 64 is equal to or greater than the maximum outside radius of the upper portion 46 of the tubular body 41 of the guide piece 40. It is thus understood that, in the deformed configuration of the branches 63, the retaining piece 60, engaged around the piston 30, is able to be driven axially downwards to position the shouldered surfaces 64A of their free end 64 at the axial level of the rim 47 of the guide piece 40: while relaxing the elastic deformation of the branches 63, they find, by elastic return, their initial configuration of rest, which leads the shouldered surfaces 64A to cling to the rim 47, as described above.

Advantageously, rather than causing elastic branches to deform branches 63 by means of an ad hoc tool, this elastic deformation can be controlled by a ramping effect between the free ends 64 of these branches and the axial end face. upper 41A of the tubular body 41: thus, as in the example shown in the figures, the outer peripheral portion of this end face 41A is advantageously made in the form of a truncated cone, centered on the axis XX and diverging in the direction of the cup 10, this truncated cone thereby forming a ramp surface 41 B against which the free ends 64 of the branches 63 bear and slide to control the elastic deformation of the branches, by means of the axial drive downwards of the retaining piece 60 around the piston 30. In other words, with the implementation of an elementary assembly operation, namely the axial drive of the piece of retained 60 around the piston 30 in the direction of the cup 10, the retaining piece 60 is able to attach itself to the guide piece 40, in some way by elastic clipping.

According to a variant, not shown, of bringing the branches 63 into contact with the guide piece 40 for attachment to the latter of the retaining piece 60, the branches have, at rest, a radial spacing, with respect to the XX axis, greater than the maximum radial dimension of an upper part of the body 41 of the guide piece 40 and, after engaging the retaining piece around the piston and once the free ends of these branches are positioned at axial direction of a predetermined corresponding region of the body 41 of the guide piece 40, these free ends and the aforementioned dedicated region are crimped, by plastic deformation of the branches 63 relative to the annular body 61. In all cases, it is understood that the retaining piece 60 can be made of various semi-rigid materials, including both metallic and plastic nature.

Note that, in the embodiments described so far, the seal 50 is a mechanically distinct part of the retaining piece 60, as clearly visible in Figures 3 to 5: thus, the seal 50 is able to to be attached to the remainder of the thermostatic element 1 independently of the retaining piece 60, it being understood that, in practice, the seal is first placed in the groove, as described above, before the retaining piece 60 is manipulated and put in place until it is fixed to the guide piece 40. Of course, the operation of setting up this seal 50 and that of placing this retaining piece 60 can be made substantially simultaneously, the retaining piece 60 may also be used to participate in the establishment of the seal 50. As an alternative not shown, rather than the seal and the retaining piece are two removable components one for each To the other, this seal and retainer may be provided in the form of a one-piece assembly, which is manipulated integrally to be attached and placed on the rest of the housing. thermostatic element 1: thus, in this case, the seal and the retaining piece are either preassembled permanently or, preferably, integral with each other, more precisely come from molding, the seal being especially overmolded on the retaining piece so that all in one piece they form is bi-material type, in particular bi-plastic.

Various arrangements and variants to the thermostatic element 1 described so far are also possible. As examples:

- The number of attachment legs 63 of the retaining piece 60 is not limited to four, but may alternatively not shown, be greater than four or two or three;

- As a variant not shown, the fixing means of the annular body 61 to the guide member 40 may include, in addition to the branches 63, other embodiments of these branches; thus, by way of example, these fixing means may include a tapping of the retaining piece, designed to be screwed and tightened on a complementary thread of the guide piece;

- Instead of being fixed to the guide piece 40, the branches 63 and, more generally, the aforementioned fixing means may be provided to attach to the cup 10; thus, by way of example, rather than clipping to the rim 47 of the guide piece 40, the branches 63 may be designed to snap to the cup 10, in particular to its shouldered zone connecting the collar 13 to the barrel 1 1 ; the use of the cup 10 as a support for fixing the retaining piece 60 may be of particular interest in the case of thermostatic elements whose guide piece 40 is short axially, which limits the space available to provide a region, such as the flange 47, dedicated maintaining the retainer 60; and or

- Optionally, the piston 30 may be internally provided with an electric heating resistor for heating the thermally degradable material 30 from the inside, the electricity supply conductors of this resistor extending from the end of the piston. opposite to that dipped in the cup 10.

Claims

Thermostatic element (1), comprising:

a thermoconductive cup (10), which contains a thermally-expandable material (20),

- a piston (30) displaceable in translation along its axis (X-X), relative to the cup (10), under the action of the thermally expandable material (20) during the expansion of this material, and

a piece (40) for guiding the piston in translation, which is fixedly secured to the cup,

- a seal (50) vis-à-vis the outside, which is interposed radially between the piston (30) and the guide piece (40), being received in a groove (45) delimited in the axial end face (41 A), opposite to the cup (10), of the guide piece, and

- a piece (60) for axial retention of the seal (50) in the groove, which is mounted around the piston (30), which is fixed to the guide piece (40) and / or the cup (10). ) and which comprises an annular body (61), mounted substantially co-axially and fitted around the piston (30), axially covering the groove (45) to retain the seal (50) therein,

characterized in that the annular body (61) of the retaining piece (60) carries means (63) for attachment to the guide piece (40) and / or the cup (10), these fastening means comprising branches (63), each extending from the annular body (61), which are distributed around this annular body and whose respective free ends (64) cooperate with the guide piece (40) and / or with the cup (10).

2. Thermostatic element according to claim 1, characterized in that the seal (50) is radially crushed between the piston (30) and the guide piece (40).

3. - Thermostatic element according to claim 2, characterized in that the seal (50) has at rest:

an inside diameter (δ50) substantially equal to the outside diameter (δ30) of the piston (30), and

an outer diameter (Δ50) strictly greater than the maximum diameter (Δ45) of the groove (45).

4. - Thermostatic element according to any one of the preceding claims, characterized in that the seal (50) is an O-ring.

5. - Thermostatic element according to any one of the preceding claims, characterized in that the legs (63) are distributed around the annular body (61) regularly.

6. - Thermostatic element according to any one of the preceding claims, characterized in that the respective free ends (64) of the branches

(63) are adapted to cooperate by complementarity of shapes with a dedicated region (47) of the guide piece (40) and / or with a dedicated region of the cup (10).

7 - thermostatic element according to claim 6, characterized in that the free end (64) of each leg (63) has a shoulder surface (64A) adapted to bear axially against a peripheral rim (47) of the piece of guide (40) or against a shouldered zone connecting one to another a barrel (1 1) and a flange (13) of the cup (10).

8. - Thermostatic element according to any one of the preceding claims, characterized in that the legs (63) are elastically deformable relative to the annular body (61) and are adapted when the annular body is engaged around the piston (30) and brought axially close to the groove (45) until covering said groove, to be successively stressed in elastic deformation and then at least partially released so that the respective free ends (64) of these branches engage with the guide piece ( 40) and / or the cup (10) by elastic return of the branches.

9. - Thermostatic element according to claim 8, characterized in that the guide piece (40) defines, on its axial end face (41 A) opposite the cup (10), a ramp surface (41 B). against which the respective free ends (64) of the legs (63) abut and slide to control the elastic deformation of the branches.

10. - thermostatic element according to any one of claims 1 to 7, characterized in that the respective free ends (64) of the legs (63) are adapted to cooperate by crimping with the guide piece (40) and / or with the cup (10), by plastic deformation of the branches relative to the annular body (61).

1 1 .- Thermostatic element according to any one of the preceding claims, characterized in that the fixing means consist of the branches (63).

12.- thermostatic element according to any one of the preceding claims, characterized in that the seal (50) and the retaining piece (60) are separate parts, which are able to be reported to the rest of the thermostatic element (1) independently of one another.

13. - Thermostatic element according to any one of claims 1 to 1 1, characterized in that the seal and the retaining piece form an assembly in one piece relative to the rest of the thermostatic element (1 ).

14. - thermostatic element according to claim 13, characterized in that the seal is molded with the retaining piece.

15. - Thermostatic element according to claim 14, characterized in that the seal is overmolded on the retaining piece.