Abstract:
A thermostat assembly including a flow blocking sleeve and a seat between which is defined a flow passage through which a fluid can flow and wherein the sleeve has an end opposing a bearing surface of the seat which extends perpendicular to an axis of the sleeve, and wherein the sleeve and the seat are movable relative to one another by movement of a piston of a thermostatic member to thereby control flow through the flow passage which is radial to the axis and wherein a gasket is crimped within a housing formed between a lateral wall adjacent the end of the sleeve and a ring so as to be secured to be normally engaged with the bearing surface to prevent flow through the flow passage unless the passage is opened by separation of the gasket from the bearing surface by movement of the piston in response to the thermostatic member being activated.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a thermostatic fluid flow regulating assembly comprising, by way of the flow-obstructing part, a sleeve whose movements are controlled by a thermostatic element influenced by the temperature of the moving fluid. 
     2. Brief Description of the Related Art 
     This kind of thermostatic assembly is used in valves generally employed in cooling circuits used in heat engines of large cylinder capacity, such as those used in lorries and certain motor vehicles, where the fluid flow rates necessary for their operation are higher than those found in heat engines of smaller cylindrical capacity, in which the thermostatic valves are of the shutter type. 
     The reason for the use of a sleeve is that it generally enables the use of a so-called balanced flow obstructor, that is to say an obstructor where the pressure differential between the two sides of the walls of the sleeve is approximately zero in the direction in which the obstructor is moved by the thermostatic element. This direction corresponds in practice to the axial direction of the sleeve. In contrast to this, in a shutter-type thermostatic valve, the shutter is in a plane perpendicular to the direction in which the shutter is moved by the thermostatic element, which means that the pressure differential between the two sides of the shutter in this direction reaches high values, especially when the fluid flow is interrupted by the shutter. The energy required to lift the shutter off its seat in this condition is often very great, and is greater the higher the flow rate of the fluid to be regulated. 
     The invention is concerned more particularly with thermostatically controlled sleeves used in combination with a flat bearing seat on an axial end of the sleeve, which is generally in the shape of a flat annular edge. An example of this kind of sleeve is given in EP-A-1 486 843. A fluid flowing radially with respect to the axis of the sleeve can then be regulated by the relative gap between the end of the sleeve and the seat. In particular, when the end of the sleeve is pressed against the seat, this fluid flow is theoretically zero. In practice, however, the sleeve/seat contact allows a certain amount of radial leakage due to the metal/metal nature of this contact. To limit these leaks, it is known practice to overmould the flat seat with rubber. This improves the leaktightness of the contact between the sleeve and the seat. This solution is technically reliable because it is based on technical teaching relating to the overmoulding of the shutters referred to earlier. However, this overmoulding is expensive and often difficult to make compatible, from the technical point of view, with the seat environment, depending in particular on the integration of the thermostatic regulation assembly into a valve housing of a specific geometry. As a result, leaks through the contact between the sleeve and the seat have hitherto very often been tolerated. 
     U.S. Pat. No. 4,022,377 discloses another example of a thermostatically controlled obstructing sleeve. To improve the regulation of the flow of a fluid between the end of the sleeve and a flat metal seat, a metal insert whose outer face is generally a frustum of a cone is attached to the end of the sleeve and bears against and moves progressively away from the seat, depending on the movements of the sleeve. In this way, fluid admitted between the frustoconical face of the insert and the seat increases in a progressive and controlled manner as the sleeve lifts off the seat. However, because of the rigidity of this insert, which is typically hardened steel, the insert/seat contact when the sleeve is supposed to close the seat leaks in the same way as described above. In the long term, these leaks also tend to increase during burring and/or indentation of the seat by the action of the insert, unless this seat is made of harder, tougher metal, but this increases the cost and does no more than stabilize leakage at a non-zero level. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a thermostatic sleeve assembly that has a better seal between the end of the sleeve and its bearing seat and yet is easier to manufacture and install in a large number of valve housings, especially pre-existing valve housings. 
     To this end, the subject of the invention is a thermostatic fluid flow regulating assembly as defined herein and as shown in the drawings. 
     The idea on which the invention is based is to attach a gasket, such as a cut gasket or a moulded gasket, to the end of the sleeve, essentially in the axis of this sleeve, so that the gasket forms a flat leaktight contact with the seat when it is desired to interrupt the flow of fluid. The advantage of this is that, owing to the structure of the thermostatic assembly according to the invention, the movements of the sleeve, controlled by the thermostatic element, are perpendicular to the bearing surface defined by the seat. Consequently, by making the separate gasket at least partially axially continuous with the body of the sleeve, this gasket is efficiently compressed in the axial direction of the sleeve between the latter and the seat when in the fluid flow obstructing position. A highly leaktight peripheral line is thus obtained. 
     The gasket is by nature, of course, a flexible gasket, that is a gasket which deforms elastically when compressed or crushed. This gasket thus efficiently fills the positioning gap between the end of the sleeve and the seat and creates a complete seal all the way around its line of contact, pressing onto the seat when the sleeve is sufficiently close to the seat. In practice, the gasket is advantageously a rubber gasket, in elastomer, for example. 
     The use of a separate gasket is economical because the gasket used is readily commercially available. Moreover, since this gasket is attached to the end of the sleeve, the bearing seat for this end requires no modification, and thus causes no corresponding stress on the valve housing in which the thermostatic assembly according to the invention is fitted. Also, since the separate gasket is located in the axis of the sleeve, its presence can be designed, according to the invention, to minimize the disturbance to the flow of a fluid passing axially through the sleeve. In other words, with the invention, the gasket can be attached in such a way as to reduce to a minimum the head losses associated with the presence of the sleeve. 
     An embodiment which is practical to produce is specified in the following description of the invention. 
     Also, forms of the invention which are both technically and economically satisfactory are described in the following description of the invention. 
     One simple and effective embodiment of the invention is specified in the following description of the invention. 
     Other advantageous features of the assembly according to the invention, taken in isolation or in any technically possible combination, are set out in the following description of the invention. 
     The invention also relates to a method for manufacturing a thermostatic fluid flow regulating assembly as defined herein. 
     The method according to the invention can be used in particular to manufacture a thermostatic assembly as defined above. 
     One advantageous implementation of this method is specified herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be understood more clearly on reading the following description, which is given purely by way of example with reference to the drawings, in which: 
         FIG. 1  is a diagrammatic side view, with partial cutaway, of a thermostatic assembly in accordance with the invention; 
         FIG. 2  is an enlarged view of detail II circled in  FIG. 1 ; 
         FIG. 3  is a view similar to  FIG. 2 , illustrating the thermostatic assembly of  FIGS. 1 and 2  in a different state of operation from that illustrated in those two figures; and 
         FIG. 4  is a view similar to  FIG. 2 , illustrating a variant of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 3  show a thermostatic assembly comprising a sleeve  10 , a seat  20  and a thermostatic element  30 . This thermostatic assembly is suitable for regulating a flow of fluid through this assembly, with an incoming fluid supply F 1  and two outgoing fluid discharges F 2  and F 3 , as explained in detail below. 
     The sleeve  10  comprises an uninterrupted tubular main body  11  with a circular base and its centre on a longitudinal axis X-X. At one of its axial ends, marked  12 , corresponding to its bottom end in the figures, the body  11  is freely open, while at its other end the body  11  is occupied by an end wall  13  across the axis X-X. This end wall  13  is interrupted so that the incoming fluid F 1  admitted into the body  11  through its end  12  is discharged through its end wall  13  to form the outgoing fluid F 2 . In practice, the end wall  13  may for example consist of metal spokes extending within the sleeve at an angle to the X-X axis from the top end of the body  11  and formed integrally with this body. 
     The end wall  13  is connected in its centre, through which the X-X axis passes, to a block  14 , to which the inner ends of the spokes forming the end wall  13  are fixed, in particular. The block  14  forms an axial stop for a piston  31  which belongs to the thermostatic element  30  and whose centre is on the X-X axis. The piston  31  is able to move relative to a cup  32  belonging to the element  30 , which contains a thermodilatable material, such as a wax, the change in volume of which causes the piston to move translationally along the X-X axis. The cup  32  is heat-sensitive, in the sense that, as the temperature of the incoming fluid F 1  in which this cup is immersed rises, the wax inside it expands and causes a translational movement of the piston  31  which in turn moves the sleeve  10  with a corresponding translational movement. A spring (not shown) inserted appropriately between on the one hand the sleeve  10 , or a part fixed to this sleeve, and on the other hand the cup  32 , or a part fixed to this cup, moves the sleeve back translationally as the temperature of the incoming fluid F 1  falls, thus allowing the piston  31  to retract inside the cup. 
     The movements of the sleeve  10  thus controlled by the thermostatic element  30  regulate the passage of the incoming fluid F 1  between the bottom end  12  of the sleeve and the seat  20 , to form the outgoing fluid F 3  ( FIG. 3 ). For this purpose, the seat  20  comprises a main annular body  21  whose centre is on the X-X axis and which is fixed to the cup  32  by, for example, a rigid stirrup  22 . This stirrup is perforated, in the appropriate direction for the incoming fluid F 1  to be able to flow through the stirrup, in the direction of the X-X axis, and thus enter the body  11  of the sleeve  10 , after passing axially through the body  21 . 
     The body  21  forms a peripheral edge  23  situated axially in front of the end  12  of the sleeve  10 . As  FIGS. 2 and 3  clearly show, this edge  23  defines, on its sleeve  10 -facing side, a planar surface  24  extending in a plane perpendicular to the X-X axis. This surface  24  thus forms a bearing surface for the end  12  of the sleeve  10 , so that, depending on the axial gap between this surface and that end, the sleeve closes to a greater or lesser extent the radial passage for the fluid F 1  to flow out and form the fluid F 3 . 
     A gasket  40  is attached to the end  12  of the sleeve  10 . In the example considered, this gasket  40  is an annular body  41  made of rubber, whose centre is on the X-X axis and which has an essentially rectangular cross section. The body  41  thus has, on the one hand, a top face  42  and bottom face  43  opposite each other, the former turned towards the sleeve  10  and the latter towards the seat  20 , and on the other end an outer face  44  and inner face  45 , also opposite each other, the former turned away from and the latter towards the X-X axis. 
     The gasket  40  is partially housed in a peripheral housing  15  defined by the end  12  of the sleeve  10 . This housing forms a sort of shoulder on the inside of the body  11  of the sleeve. Thus, in a radial direction relative to the X-X axis, the housing  15  is open to the inside of the body  11  and closed to the outside by a peripheral outer wall  16  that is part of the same material as the body  11 , thus forming an integral part of the end  12 . Advantageously, the outer face  16 A of the wall  16  is, at least in its upper part connected to the body  11 , cylindrical and of axis X-X and has the same diameter as the outer face  11 A of the body  11 , so that these faces  16 A and  11 A are cylindrically continuous with each other. In this way the presence of the housing  15  and of the gasket  40  housed in this housing do not create any outward projections at the end  12  of the sleeve  10 . In other words, the dimensions of this end  12 , on its outward side, are not modified by the presence of the housing  15  and gasket  40 . The sleeve  10  can therefore be fitted in place of a pre-existing sleeve that does not have the gasket  40 . 
     In the direction of the X-X axis, the housing  15  is open in the downward direction and closed at the top by an end wall  17  that is part of the same material as the body  11  of the sleeve. This wall  17  thus forms an integral part of the end  12  of the body  11 . 
     The gasket  40  is fixed in the housing  15  partly by the wall  16 , which, particularly at its bottom end, is bent in, that is it is inclined so as to converge downwards in the direction of the X-X axis. The bent part of the wall  16  therefore squeezes the outer face  44  of the gasket  40 , penetrating into this face by flexible deformation of the gasket. To absorb the deformation stresses on the body  41  and thus grip the gasket  40  securely in the housing  15 , the top face  42  and inner face  45  of the gasket are covered by a separate ring  50 . This ring is made of a mechanically strong material to withstand the holding forces on the gasket  40 , besides the deformations due to the high temperatures of the regulated fluid. 
     For this purpose, the ring  50  has a cross section in the shape of an inverted L. The ring  50  thus has a planar top wall  51  extending in a plane perpendicular to the X-X axis when the ring is fitted to the sleeve. At the inward edge of the wall  51 , an annular lateral wall  52  extends downwards in a direction parallel to the X-X axis. When the ring  50  is assembled to the housing  15 , the wall  51  is axially interposed between the top face  42  of the gasket  40  and the end wall  17  of the housing  15 , while the outer wall  16  and the wall  52  grip the gasket radially between themselves, covering the outer face  44  and inner face  45 , respectively, of the gasket. The bottom face  43  of the gasket remains exposed, extending down beyond the axial level of the bottom edges of the walls  16  and  52 . 
     To assemble the gasket  40  to the end  12  of the sleeve  10 , this end is first shaped to define the housing  15  in it, typically by machining or stamping the lower end of the body  11 . At the end of this shaping step, the wall  16  is as shown in broken lines in  FIG. 2 , that is to say it is cylindrical. 
     The ring  50  is then fitted to this end  12  by inserting it from the bottom into and coaxially with this sleeve, until the outer edge of the wall  51  meets the end wall  17  axially. Simultaneously with the ring  50 , or after the latter is fitted, the gasket  40  is fitted to the end  12 , with its top face  42  covered by the wall  51 , while its outer  44  and inner  45  faces are covered by the walls  16  and  52 , respectively. The wall  16 , chiefly its lower end, is then crimped to grip the gasket, that is to say the wall  16  is bent towards the X-X axis, preferably all the way around its periphery, until it is as shown in solid lines in the figures. In practice, the wall  16  is crimped using a rolling or punching type tool which, as indicated by the arrow S in  FIG. 2 , applies a radial force directed towards the X-X axis, relative positioning and movements of this tool and sleeve  10  being selected as appropriate. 
     Crimping the wall  16  deforms the material of the body  41  of the gasket  40  so that the latter is trapped, with its faces  42  and  44  pressed against the walls  51  and  52  of the ring  50 . 
     Once the gasket  40  is thus secured and immobilized on the end  12  of the sleeve  10 , the sleeve  10 , the seat  20  and the thermostatic element  30  are assembled together. 
     In operation, when the thermostatic element  30  and its associated return spring move the sleeve  10  translationally towards the seat  20 , in other words when the end  12  moves from the position shown in  FIG. 3  to that shown in  FIG. 2 , the gasket  40  is moved with it along a straight translational movement parallel to the X-X axis, in such a way that its bottom face  43  is pressed against the surface  24  of the edge  23 . The contact between the face  43  and the surface  24  is thus a plane/plane contact, which is a highly efficient way of creating a seal. Also, this contact is firm, in the sense that the force which moves and compresses the gasket  40  against the edge  23  is transmitted parallel to the X-X axis to every point on the outer part of the gasket  40 , that is the peripheral part of this gasket extending axially beneath the end wall  17 , through the outer part of the wall  51 . In other words, a substantial part of the gasket  40  is axially in line with the inner peripheral part of the body  11  of the sleeve  10  and is thus firmly pushed down at right angles to the surface  24 . The rest of the gasket, i.e. its inner peripheral part, is also pressed firmly against the surface  24  by the ring  50 , primarily the inner part of its wall  51 , through which the forces of movement and compression against the edge  23  are efficiently transmitted. 
     The quality of the seal created by the plane/plane contact between the gasket  40  and the surface  24  is such that the thermostatic assembly incorporating the sleeve  10  can be used to regulate a fluid flow in the opposite direction to that considered in  FIG. 1 . On this point, it will be observed that the directions of flow of the fluids indicated thus far are illustrative only, and the thermostatic assembly can be fitted equally well to a valve with one inlet and two outlets, or to a valve with two inlets and one outlet, or even to other valves in which a fluid flow radial to the X-X axis is to be regulated by the interaction between the end  12  of the sleeve and the seat  20 . Similarly, the kinematic relations between the thermostatic element  30  and the sleeve  10 /seat  30  pair can be reversed, thus connecting the sleeve to the cup  32 , and the seat to the piston  31 . 
     Various arrangements and variants of the thermostatic assembly and its method of manufacture described above may also be envisaged. As an example,  FIG. 4  shows a “symmetrical” variant of the embodiment shown in  FIGS. 1 to 3 , in the sense that the gasket  40 ′ of this variant is fitted not to the inside but to the outside of the end  12  of the sleeve  10 . For this purpose this end  12  defines a housing  15 ′ which is open both outwards and downwards, but closed towards the inside by an inner wall  16 ′, and upwards by an end wall  17 ′, these walls  16 ′ and  17 ′ forming integral parts of the end  12  of the body  11  of the sleeve, having been produced by appropriate shaping of the end  12 . A ring  50 ′ “symmetrical” to the ring  50  is fitted to assemble the gasket  40 ′ to the housing  15 ′: the gasket  40 ′ is jammed or trapped by crimping, by bending the wall  16 ′ outwards so that it penetrates into the inner face  45 ′ of the gasket and thus deforms the latter until the top face  42 ′ and outer face  44 ′ are pressed against the top wall  51 ′ and side wall  52 ′, respectively, of the ring  50 ′. 
     The variant shown, in  FIG. 4  has the advantage over the embodiment shown in  FIGS. 1 to 3  of not having any part that projects inwards at the end  12  of the sleeve  10 . The inner face  16 ′B of the wall  16 ′ is cylindrically continuous with the inner wall  11 B of the body  11  of the sleeve. Consequently the decision as to which of the two embodiments illustrated should be chosen is connected to the question of the inward or outward space requirement at the end  12  of the sleeve  10 . 
     In practice, the wall  16  is easier to crimp than the wall  16 ′, as the tooling required to bend this wall  16  is easier to control from the outside of the sleeve  10 . 
     Another variant which is not shown is to trap the gasket  40  or  40 ′ by bending the side wall  52  or  52 ′ of the ring  50  or  50 ′ towards the wall  16  or  16 ′, either instead of in addition to the bending of the wall  16  or  16 ′.