Abstract:
Provided herein is a valve with a housing, a thermostatic element of which a first end part of a piston, which axially opposes the end submerged in a thermodilatable material contained in the body of the thermostatic element, is secured to the housing; a return spring; an electrical heating resistance arranged inside the second end part of the piston; electrical connection for feeding the resistance from outside the housing; and a check mechanism for controlling a flow of fluid circulating through the housing, in a direction leading from the first end part towards the second end part of the piston, and connected to the body of the thermostatic element such that the relative movements between the body and the piston, resulting from the dilation and contraction of the thermodilatable material, move the check mechanism in relation to the housing, between closed and open positions affecting the flow of fluid.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. National Stage application under 35 U.S.C. §371 of International Application No. PCT/EP2015/050245, filed Jan. 8, 2015, designating the U.S. and published as WO 2015/104325 A1 on Jul. 16, 2015, which claims the benefit of French Patent Application No. FR 1450151, filed Jan. 9, 2014. Any and all applications for which a foreign or a domestic priority is claimed is/are identified in the Application Data Sheet filed herewith and is/are hereby incorporated by reference in their entirety under 37 C.F.R. §1.57. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a thermostatic valve. In some embodiments, the invention relates to the thermostatic valves that are used in cooling circuits of heat engines, in particular those of motor vehicles. 
       SUMMARY 
       [0003]    The invention relates to thermostatic valves, whereof the body of the thermostatic element is fixedly secured to a sealing gate, the latter typically being mounted gripped around the body of the thermostatic element, and whereof the piston of the thermostatic element is, at its end opposite that submerged in the thermodilatable material contained in the body, securely fixed to the housing of the valve, using any appropriate means, while electrical wires or the like pass through the aforementioned end of the piston so as, from the outside of the housing, to rejoin the heating resistance. In this configuration, a stream of incoming fluid, going from the piston toward the body of the thermostatic element, necessarily causes an overpressure upstream from the sealing plug when this plug closes off the circulation of this stream of fluid through the housing of the valve, the sealing plug withstanding the overpressure under the action of a return spring associated with the thermostatic element. When, inopportunely or predictably and in certain usage cases, this overpressure reaches peaks such that the load of the spring is thwarted, the plug and the body of the thermostatic element, which is fixedly secured to the gate, are pushed by the stream of fluid, the body of the thermostatic element then descending on the piston: by friction between the body and the piston of the thermostatic element, the piston tends to be pulled jointly with the body and the gate, which causes the risk of making the fastening of the end of the piston to the housing and/or the electrical wires passing through the end of the piston fragile, or even damaging them. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The invention will be better understood upon reading the following description, provided solely as an example and done in reference to the drawings, in which  FIGS. 1 to 3  are a longitudinal sectional view of a thermostatic valve according to the invention, illustrating three different functional configurations. 
           [0005]      FIG. 1  shows an embodiment of a longitudinal sectional view of a functional configuration of a thermostatic valve according to the present invention. 
           [0006]      FIG. 2  shows an embodiment of a longitudinal sectional view of a functional configuration of a thermostatic valve according to the present invention. 
           [0007]      FIG. 3  shows an embodiment of a longitudinal sectional view of a functional configuration of a thermostatic valve according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    In many applications in the fluid field, in particular for cooling vehicle heat engines, thermostatic valves are used to distribute an incoming fluid in different circulation pathways, based on the temperature of that fluid. These valves are said to be thermostatic inasmuch as the movement of their inner seal(s) is controlled by a thermostatic element, i.e., an element that comprises a body, containing a thermodilatable material, and a piston, submerged in this thermodilatable material, the body and the piston being movable relative to one another in translation along the longitudinal axis of the piston. To distribute the fluid as a function of other parameters, in particular conditions outside the valve, such as the ambient temperature or the load of the vehicle propelled by the engine equipped with the valve, it is known to incorporate an electric heating resistance, arranged inside the piston of the thermostatic element, into the valve, to heat the thermodilatable material, which makes it possible to control the valve from the outside, independently of or in addition to the temperature of the incoming fluid, in particular using an onboard computer of the vehicle programmed appropriately. 
         [0009]    Document WO-A-2005/078255 discloses a thermostatic valve incorporating a thermal safety function. In this valve, a gate, the movements of which are normally controlled by the moving part of the thermostatic element, is movable relative to this part when the temperature of the fluid to be regulated is too high, owing to the deterioration of an interface made from a eutectic alloy, inserted between the plug and a part fixedly attached on the moving part of the thermostatic element. 
         [0010]    The aim of the present invention is to propose a thermostatic valve of the aforementioned type that is improved inasmuch as it is protected from overpressure peaks upstream from its sealing gate. 
         [0011]    To that end, the invention relates to a thermostatic valve, including:
       a housing,   a thermostatic element that comprises both a body, containing a thermodilatable material, and a piston, which piston is thermally conductive, extends lengthwise along an axis, includes a first terminal part that is fixedly secured to the housing, and also includes a second terminal part that is axially opposite the first terminal part and that is submerged in the thermodilatable material, such that the body and the piston are movable relative to one another along the axis, moving away from one another under the action of an expansion of the thermodilatable material,   a return spring that is suitable for bringing the body and the piston of the thermostatic element closer to one another during a contraction of the thermodilatable material,   a heating electric resistance, which is arranged inside the second terminal part of the piston of the thermostatic element,   an electric conductor, which is suitable for supplying electricity to the resistance from outside the housing and that extends from the resistance to the outside of the piston, via the first terminal part of the piston, and   a plug:
           that is suitable for controlling a fluid flow circulating, through the housing, in a direction oriented from the first terminal part to the second terminal part of the piston,   that is connected to the body of the thermostatic element such that the relative movement between the body and the piston of the thermostatic element, resulting from the expansion and contraction of the thermodilatable material, move the plug relative to the housing between a closing off position with respect to the fluid flow and an open position with respect to the fluid flow, and   that is mounted on the body of the thermostatic element movably along the axis such that, as long as the pressure of the fluid flow upstream from the plug is below a predetermined threshold value, the plug is stationary relative to that body under the action of the return spring, whereas when the pressure of the fluid flow upstream from the plug exceeds the threshold value, the plug moves axially along the body while supporting the action of the return spring.   
               
 
         [0021]    One of the ideas at the base of the invention is to challenge the traditional assembly of the sealing plug on the body of the thermostatic element, this traditional assembly typically being a tight fitting of the plug around this body, which has the well-known advantages of substantially limiting the passage leak at the contact interface between the plug and the body of the thermostatic element, as well as reducing the vibrations of the thermostatic element “cold”, i.e., when its piston is more pushed into the body than the side at which the deployment of the piston relative to the body begins to drive the movement of the plug relative to the housing of the valve. Thus, contrary to this technical prejudice regarding the fixed assembly of the plug on the body of the thermostatic element, the invention proposes to leave the plug movable, in the longitudinal axis of the piston of the thermostatic element, on the body of the thermostatic element, this mobility, typically translational, nevertheless being implemented only in case of overpressure peaks upstream from the gate. Thus, when the pressure upstream from the plug remains below a predetermined threshold value, the fixed connection between the plug and the body of the thermostatic element is maintained under the action of the return spring associated with the thermostatic element, the load of this spring opposing the pressure of the fluid upstream from the gate. When the pressure upstream from the plug increases until it overcomes the load of the return spring, only the plug is pushed axially back in the direction of the fluid stream, while sliding around the body of the thermostatic element, which in turn remains stationary relative to the housing and therefore does not cause any stress, in particular traction, on the piston of the thermostatic element. The securing between the piston and the housing, irrespective of the embodiment of this securing, is thus not made fragile. The thermostatic valve according to the invention has a simple design, avoiding the addition of a specific overpressure spring, since the deballasting of the overpressure peaks is obtained by moving the “primary” regulating gate. The bulk and manufacturing cost of the thermostatic valve according to the invention are substantially identical to those of a thermostatic valve of the prior art. In particular, according to one embodiment of the invention, no specific arrangement of the body of the thermostatic element is necessary: in other words, the invention may be implemented with a pre-existing thermostatic element. According to another embodiment, the sliding contact interface between the plug and the body of the thermostatic element is made tight, subject to specific arrangements, which will be described in more detail below. 
         [0022]    According to additional advantageous features of the thermostatic valve according to the invention:
       The plug is mounted on the body of the thermostatic element such that, while the resistance is substantially inactive:
           as long as the pressure from the fluid flow upstream from the plug is below the threshold value, the plug occupies, relative to the housing, its closing off position and is fixedly maintained in a position relative to the body of the thermostatic element under the action of the return spring, while   when the pressure from the fluid flow upstream from the plug exceeds the threshold value, the plug leaves its closing off position relative to the housing, moving along the body of the thermostatic element.   
           The plug is mounted coaxially in sliding adjustment around the body of the thermostatic element.   The body of the thermostatic element is provided with a bearing zone, against which the plug is axially pressed by the return spring when the pressure from the fluid flow upstream from the plug is below the threshold value, and from which the plug moves axially away when the pressure from the fluid flow upstream from the plug is above the threshold value.   The body of the thermostatic element includes a hub for storing the thermodilatable material, which, in the direction opposite the direction of the fluid flow, is extended by a collar of the body, the hub and the collar being connected to one another by a shoulder that protrudes from the hub toward the outside of the latter and defines the bearing zone.   The thermostatic valve further includes a sealing gasket inserted between the plug and the body of the thermostatic element so as to substantially seal the contact between them.   The sealing gasket is a toroid.   The sealing gasket is inserted substantially radially to the axis between the plug and the body of the thermostatic element.   The body of the thermostatic element is provided with a bearing zone, against which the plug is axially pressed by the return spring when the pressure from the fluid flow upstream from the plug is below the threshold value, and from which the plug moves axially away when the pressure from the fluid flow upstream from the plug is above the threshold value; the body of the thermostatic element includes a hub for storing the thermodilatable material, which, in the direction opposite the direction of the fluid flow, is extended by a collar of the body, the hub and the collar being connected to one another by a shoulder that protrudes from the hub toward the outside of the latter and defines the bearing zone; and the collar of the body of the thermostatic element is provided with a peripheral groove for receiving the sealing gasket.   The thermostatic valve has no sealing pieces added between the plug and the body of the thermostatic element.       
 
         [0034]      FIGS. 1 to 3  show a thermostatic valve  1  intended to regulate the circulation of the fluid, in particular a coolant liquid circulating within a cooling circuit of a heat engine. 
         [0035]    The valve  1  includes a housing  10 , which is for example made from a plastic or metal alloy material, and which is designed to keep the other components of the valve  1  assembled to one another, while allowing the fluid the possibility of circulating through the housing  10 , while forming a stream of fluid F regulated by the other components of the valve  1 . 
         [0036]    The housing  10  includes a tubular body  12 , which is centered on a geometric axis X-X in the direction of which the stream of fluid F flows when the latter crosses inwardly through the tubular body  12 , as shown in the figures. This circulation of the stream of fluid F is oriented in the direction where the stream of fluid F crosses inwardly through the tubular body  12  of the housing  10  in a predetermined direction, i.e., from top to bottom in the figures. 
         [0037]    The valve  1  also includes a thermostatic element  20  that is centered on the axis X-X. More specifically, the thermostatic element  20  includes a body  22 , centered on the axis X-X and containing a thermodilatable material such as a wax. The thermostatic element  20  also comprises a piston  24 , the longitudinal geometric axis of which is aligned on the axis X-X within the valve  1 . A terminal axial part  24 . 1  of the piston  24 , which corresponds to the downstream terminal part of said piston in the direction of the fluid stream F, is submerged in a thermodilatable material contained in the body  22 . In the assembled state, the body  22  and the piston  24  are movable relative to one another in translation along the axis X-X: under the effect of the expansion of the thermodilatable material contained in the body  22 , the piston  24  deploys outside the body, while, during a contraction of the thermodilatable material, the piston retracts inside the body under the return effect of a compression spring  30  that is functionally inserted between the body of the thermostatic element and the housing  10 . In the example embodiments considered in the figures, the spring  30  is substantially centered on the axis X-X and its end turn  31 , opposite its end turn  32  acting on the body  22  of the thermostatic element, in other words, its end turn  31  downstream in the direction of the fluid stream bears on a rigid framework  33  that is secured to a downstream part  14  of the housing  10  by arrangements known in themselves and therefore not outlined here. 
         [0038]    In the assembled state of the valve  1 , the piston  24  of the thermostatic element  20  is fixedly secured to the housing  10 . More specifically, in a manner known in itself, the upstream terminal part  24 . 2  of this piston  24  is permanently fixed to an upstream part  16  of the housing  10 , arranged across the axis X-X. In practice, various embodiments can be considered regarding the permanent securing of the terminal part  24 . 2  of the piston  24  to the housing part  16 : this securing can be done by fitting, or by overmolding, or by the addition of a mechanical maintaining system, etc. In all cases, it will be understood that, when the thermodilatable material of the body  22  of the thermostatic element  20  expands, contracts, respectively, the piston  24  is kept immobile relative to the housing  10 , due to the fastening of the upstream terminal part  24 . 2  to that housing, while the body  22  moves away from, comes closer to, respectively, the piston  24  relative to the housing  10 , translated along the axis X-X in the direction of the fluid stream F, in the opposite direction, respectively. 
         [0039]    The valve  1  further includes a heating electric resistance  40 , as well as electrical wires  50  supplying electricity to the resistance  40  from outside the housing  10 , these wires connecting the resistance  40  to a current source, outside the valve  1 , not shown. In a manner known in itself, the resistance  40  is arranged inside the downstream terminal part  24 . 2  of the piston  24  of the thermostatic element  20 , so that this resistance can heat the thermodilatable material contained in the body  22  of the thermostatic element. To that end, the piston  24  is made, at least regarding its downstream terminal part  24 . 1 , from a thermally conductive material, typically metal. In practice, various other embodiments can be considered regarding the heating resistance  40 , this resistance being symbolized, in  FIG. 1 , by a zigzag line, this diagrammatic illustration not limiting the present invention. Likewise, the embodiment of the wires  50  does not limit the invention, inasmuch as these wires can be made by any electric conductor, connecting the resistance  40  to the aforementioned outside current source, having nevertheless noted that, irrespective of their embodiment, these wires  50  extend, from the resistance  50  to the outside of the housing  10 , passing through the upstream terminal part  24 . 2  of the piston  24  and thus at least partially crossing through the upstream part  16  of the housing  10 , as diagrammatically indicated in  FIG. 1 . 
         [0040]    The valve  1  further includes a sealing plug  60  having a tubular global shape which, in the assembled state of the valve  1 , is substantially centered on the axis X-X. 
         [0041]    In its peripheral part  62  turned radially opposite the axis X-X, the plug  60  defines a peripheral surface  62 A which, during use, is provided to cooperate with a seat  12 A inwardly defined by the tubular body  12  of the housing  10 : in the assembled state of the valve  1 , when the surface  62 A is pressed in tight contact against the seat  12 A, the plug  60  prohibits the circulation of the fluid between the plug and the body  12  of the housing  10 , closing off the passage for the fluid stream F through the housing  10  and keeping that fluid stream F only on the upstream side of the plug  60 , as in the configuration shown in  FIG. 1 , while, when the surface  62 A is separated from the seat  12 A, the fluid stream F flows, from upstream from the plug  60 , between said plug and the tubular body  12  of the housing  10 , thus crossing through the housing, as shown in  FIGS. 2 and 3 . 
         [0042]    In practice, the tight contact surface  62 A and/or the seat  12 A can be made directly by the peripheral part  62  of the plug  60  and/or the tubular body  12  of the housing  10 , respectively, or on the contrary, the peripheral part  62  of the plug  60  and/or the body  12  of the housing  10  can, to that end, be provided with a tight fitting, for example attached by overmolding. 
         [0043]    In its peripheral part  64  turned radially toward the axis X-X, the plug  60  is assembled on the body  22  of the thermostatic element  20 . More specifically, in the example embodiment considered in the figures, this peripheral part  64  of the plug  60  has a stepped annular shape, which is centered on the axis X-X and which includes, successively in the direction of the axis X-X, an upstream ring  64 . 1  and a downstream ring  64 . 2 , connected to one another by a shoulder  64 . 3  protruding from the downstream ring  64 . 2  toward the outside of the latter. This peripheral part  64  of the plug  60  is mounted on the body  22  of the thermostatic element movably along the axis X-X: the downstream ring  64 . 2  of the plug  60  is mounted coaxially and in sliding adjustment around a hub  22 . 1  of the body  22 , containing the thermodilatable material of that body, and the upstream ring  64 . 1  inwardly receives a complementary collar  22 . 2  of the body  22 , said collar  22 . 2  extending, in the direction opposite the direction of the stream of fluid F, the hub  22 . 1  of that body. The hub  22 . 1  and the collar  22 . 2  of the body  22  of the thermostatic element  20  are connected to one another by a shoulder  22 . 3 , which protrudes from the hub  22 . 1  toward the outside of the latter and defines a zone  22 . 3 A against which the shoulders  64 . 3  of the plug  60  can be pressed axially in the direction opposite the direction of the fluid stream F. 
         [0044]    In the assembled state of the valve  1 , the spring  30  acts on the plug  60 , in return for the bearing of its upstream end turn  32  on the downstream side of the plug  60 , so as to axially press by bearing, in the direction opposite that of the fluid stream F, the shoulder  64 . 3  of the plug  60  against the shoulder  22 . 3  of the body  22 , more specifically against the bearing zone  22 . 3 A of the latter. In other words, more generally, as long as the action of the spring  30  on the plug  60  is not supported by the plug itself, this plug  60  is stationary relative to the body  22  of the thermostatic element  20 , here by axial bearing against the bearing zone  22 . 3 A of this body  22 : as long as the spring  30  keeps the plug  60  fixedly in position relative to the body  22  of the thermostatic element, the relative movements between the body and the piston  24  of the thermostatic element command corresponding movements of the plug  60  relative to the housing  10 , the plug then being movable, by driving of the body  22  relative to the piston  24  and therefore relative to the housing  10  to which this piston is fixedly secured, between a closing off position, which is shown in  FIG. 1  and in which the surface  62 A of the plug  60  is tightly bearing against the seat  12 A of the housing  10 , and an open position, which is shown in  FIG. 2  and in which the surface  62 A is separated from the seat  12 A. Of course, inasmuch as, when the plug  60  is in its sealing position of  FIG. 1 , the fluid stream F is kept upstream from the plug  60 , without reaching the hub  22 . 1  of the body of the thermostatic element, the heating of the thermodilatable material contained in the hub  22 . 1 , necessary for the expansion of this material and therefore the separation of the body  22  relative to the piston  24  of the thermostatic element, is to be controlled by the activation of the heating resistance  40 . 
         [0045]    Furthermore, irrespective of the position of each body  22  of the thermostatic element  20  relative to the housing  10 , including its position of  FIG. 1  corresponding to the sealing position for the plug  60 , the plug  60  remains free to slide axially along the body  22  of the thermostatic element  20  in the direction of the fluid stream F. This sliding occurs when the pressure from the fluid stream F, upstream from the gate, is above a predetermined threshold value, depending on the load of the spring  30 : indeed, when the pressure from the fluid stream F upstream from the plug  60  exceeds the aforementioned threshold value so as to support the action of the spring  30  on the gate, the latter moves axially along the body  22  under the action of this pressure from the fluid stream F, here by sliding of its downstream ring  64 . 2  around the hub  22 . 1  of the body of the thermostatic element. Thus, in case of overpressure peaks on the upstream side of the plug  60 , the latter goes, for example, from its sealing position of  FIG. 1  to the deballasting position of  FIG. 3 , in which its surface  62 A is separated from the seat  12 A to allow the passage of the fluid stream F in the downstream direction of the gate, without moving the body  22  of the thermostatic element  20  relative to the housing. It is therefore understood that the valve  1  is protected from overpressure peaks upstream from the gate. 
         [0046]    Advantageously, the valve assembly  1  is provided so that, cold, i.e., when the heating resistance  40  is inactive or not active enough to cause a non-negligible extension of the thermodilatable material, the spring  30  acts on the plug  60  so as on the one hand to press its surface  62 A bearing tightly against the seat  12 A of the housing  10  and press, by bearing, its shoulder  64 . 3  against the zone  22 . 3 A of the body  22  of the thermostatic element: in this way, while the pressure from the fluid stream F upstream from the plug  60  is below the aforementioned threshold value, the plug  60  occupies its sealing position relative to the housing  10  when the valve is cold and the plug moves away from this sealing position to allow the passage of the fluid stream F toward the downstream direction of the plug once the resistance  40  is activated, without the beginning of the separation of the body  22  with respect to the piston  24 , resulting from the expansion of the thermodilatable material, having to make up a residual axial play between the shoulders  22 . 3  and  64 . 3 . 
         [0047]    According to one optional arrangement, which is implemented in the embodiment considered in the figures, the valve  1  also includes a sealing gasket  70  that is inserted between the plug  60  and the body  22  of the thermostatic element  20  so as to seal the contact between the plug and the body of the thermostatic element, at least as long as the pressure from the fluid stream F upstream from the plug  60  is below the aforementioned threshold value. In this way, in all of the usage configurations of the valve  1 , or at the very least, as long as the plug  60  is stationary relative to the body  22  of thermostatic element  20 , the fluid stream F is prevented from flowing downstream from the plug by passing between the plug and the body  22  of the thermostatic element, to within a leakage allowance. Advantageously, this sealing gasket  70  is a toroid. Furthermore, so as not to cause an axial position shift between the plug  60  and the body  22  of the thermostatic element  20 , this sealing gasket is advantageously inserted exclusively radially between the plug and the body of the thermostatic element: thus, in the example embodiment considered in the figures, this seal  70  is received in a peripheral groove  22 . 4  hollowed in the outer face of the collar  22 . 2  of the body  22 , found radially inserted between the bottom of this groove  22 . 4  and the upstream ring  64 . 1  of the plug  60 . 
         [0048]    In all cases, the presence of the sealing gasket  70 , inserted between the plug  60  and the body  22  of the thermostatic element  20 , damps and/or reacts the vibrations and small surging movements of the body  22  of the thermostatic element  20 , in particular relative to the piston  24  when the thermostatic element is cold. 
         [0049]    According to another embodiment, which is not shown in the figures, the sealing gasket  70  described above may be omitted: generally, in this alternative embodiment that is not shown, the valve  1  has no sealing means added between the plug  60  and the body  22  of the thermostatic element  20 . It will be understood that, in this case, the sealing threshold at the assembly interface between the plug  60  and the body  22  of the thermostatic element  20  is not severe, since a fluid leak downstream from the plug  60  is tolerated irrespective of the position of the plug relative to the housing, including in its sealing position of  FIG. 1 . The interest of this alternative embodiment lies in being able to use, as thermostatic element  20 , a pre-existing thermostatic element, since no development of its body  22  is necessary for the mobile assembly of the plug  60  around this body  22 : indeed, many pre-existing thermostatic elements include a shoulder similar to the shoulder  22 . 3  shown in the figures, connecting a hub of said pre-existing thermostatic element, similar to the hub  22 . 1  shown in the figures, to a collar that corresponds to the collar  22 . 2  shown in the figures, with the difference that it does not include the groove  22 . 4 . 
         [0050]    Various arrangements and alternatives of the valve  1  may also be considered. For example, in a manner known itself, the body  22  may be extended on the side opposite the piston  24 , by a rod movably bearing a sealing member other than the plug  60 , in order to control the regulation of the circulation of the fluid supplying the valve in a channel other than that regulated by the gate, in particular to perform a bypass function within a cooling circuit of an engine.