The present invention relates to a heating assembly for a thermostatic valve, as well as a method for manufacturing such a heating assembly. It also relates to a thermostatic valve comprising one such heating assembly.
In many applications in the fluids field, in particular for cooling vehicle heat engines, thermostatic valves are used to distribute a fluid entering various circulation channels, based on the temperature of that fluid. These valves are said to be thermostatic because the movement of their inner closure member(s) is controlled by a thermostatic element, i.e., an element that comprises a cup containing a thermally expanding material and a piston able to slide relative to the cup under the action of the thermally expanding material when the latter expands.
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 electric heating of the thermally expandable material into the valve, which makes it possible to control the valve from outside it, independently of or in addition to the temperature of the incoming fluid, in particular using an onboard computer in the vehicle programmed appropriately. In practice, a heating resistance is arranged inside the aforementioned piston or a similar tube: for example, by immobilizing the piston in the moving case of the valve, the power supply of the resistance causes the temperature of the thermally expanding material to increase, which, by extension of the latter, causes the cup to slide around the piston, a closure member being supported by that cup to act on the flow of fluid through the valve.
To provide electricity to the heating resistance, one possibility, known from DE-A-103 03 133, consists of the electrically conductive wires, which extend from the resistance to the outside of the aforementioned tube while passing through a terminal part of the latter, and the free ends of which are electrically connected to connecting steps to be connected to an external current source, being directly coated with the plastic material of the housing during molding of the latter around the aforementioned terminal part of the tube. However, this solution is delicate to manufacture, since during molding of the case, the plastic material injected so as to overmold the terminal part of the tube tends to pull, or even pull out, the electrical wires, unless sophisticated and therefore expensive injection molds are used, which furthermore need to be modified when the arrangement of the wires is changed, typically depending on the position, on the case, of the aforementioned connecting pads.
EP-A-0,853,267 proposes overmolding both the terminal part of a heating tube, similar to what is mentioned above, and the electrical wires that leave that tube, with a plastic coating material, so as to form a module, which is next attached in a single piece to the rest of the thermostatic valve, by screwing a thread formed by that plastic material in a complementary tapping, formed by the housing of the valve. The implementation of this solution has the same drawbacks as above, during the injection of the aforementioned plastic coating material.
WO-A-2011/010051 mentions a possible pre-injection of plastic around electrical wires similar to those mentioned thus far, but only at the end of those wires, at which they are electrically connected to connecting studs. This pre-injection is followed by an injection of plastic to form the housing of the valve, then coating all of the rest of the wires, extending outside the tube, as well as the terminal part of the tube.
The aim of the present invention is to propose a heating assembly in which molding of the overmolded housing is simple and cost-effective to perform, while being easy to adapt to various heating assembly geometries.
To that end, the invention relates to a heating assembly for a fluid control thermostatic valve, comprising:
a tube, being thermally conductive, having a longitudinal central axis and being able to be plunged in a thermally expandable material of a thermostatic element of the valve,
an electric heating resistance, which is positioned inside the tube and from which electrically conducting wires extend outside the tube,
a single-piece housing made from a plastic material, through which the fluid flows and which is secured by overmolding to a terminal longitudinal part of the tube, and
a framework for supporting the conductive wires outside the tube, the framework being separate from the housing, the tube being secured to the framework by overmolding.
The framework is suitable, before molding of the housing, for being fixedly attached to the terminal longitudinal part of the tube and for supporting the conductive wires outside the tube, those conductive wires being outwardly assembled on the framework. The frame work is also suitable, during molding of the housing, for keeping the conductive wires in place while the plastic material of the housing coats those conductive wires, the framework and the terminal longitudinal part of the tube.
One of the ideas at the base of the invention is to keep the electrical wires leaving the tube in place, at least during the injection of plastic material to overmold the housing. The invention is thus based on the presence of a framework for supporting the wires outside the tube, which is placed before molding the housing, while being fixedly attached to the terminal part of the tube, for example by cooperating with that terminal part through complementary shapes. During the molding of the housing, the framework keeps the wires in place outside the tube, thus protecting them from any excess stress applied by the injected plastic material. This framework, jointly with the wires and the terminal part of the tube, is then coated by the injected plastic material. Owing to the invention, the overmolding of the housing may be done simply and quickly, using a standard mold and in an automated manner, without running the risk of damaging the wires and/or separating them from their pre-molding position. Advantageously, the framework according to the invention makes it possible to modify the arrangement of the wires before molding to adapt to various geometries of heating assemblies.
According to other advantageous features of the heating assembly according to the invention:
the framework is made in a single piece;
the framework has an elongated overall shape, which extends lengthwise, at least for a part thereof turned toward the tube, in a transverse or substantially radial direction with respect to the axis;
an end part of the framework, turned toward the tube, is configured to surround and fasten itself, in particular by cooperating through complementary shapes, to a free, outwardly flared end of the terminal longitudinal part of the tube;
between an end part of the framework turned opposite the tube and a running part of the framework, the framework includes a flexible zone, in particular thinner, suitable for being deformed so as to adjust the relative positioning between that end part and the rest of the framework before molding the housing;
in an end part of the framework turned opposite the tube, the framework has through holes for complementary reception of electrical connecting studs that are respectively electrically connected to the conductive wires before molding of the housing;
a running part of the framework, which connects end parts thereof turned toward and opposite the tube, respectively, to each other, delimits a longitudinal trough for receiving the conductive wires, in which the wires run lengthwise between the end parts of the framework and which is provided with means for keeping those conductive wires in place before molding the housing;
the heating assembly further comprises a single sealing gasket, which is an O-ring or a four-lobed seal, which is both inserted radially between the housing and the tube and arranged axially against an end part of the framework, turned toward the tube.
The invention also relates to a fluid control thermostatic valve, comprising:
a heating assembly as defined above,
a valve housing consisting at least partially of the housing of the heating assembly,
a closure member for regulating the flow of a fluid through the valve housing, and
a thermostatic element, comprising a stationary part fixedly connected to the valve housing, and a moving part that bears the closure member and is movable relative to the stationary part under the expansion action of a thermally expanding material in which the tube of the heating assembly is plunged.
The invention further relates to a method for manufacturing a heating assembly for a fluid control thermostatic valve, wherein a tube is provided, that is thermally conductive, has a longitudinal central axis and is suitable for being plunged in a thermally expanding material of a thermostatic element of the valve and in which an electrical heating resistance is positioned from which electrically conductive wires extend outside the tube. A framework, on which the conductive wires outside the tube are outwardly assembled so as to support those conductive wires, is fixedly attached to a terminal longitudinal part of the tube. Then a single-piece housing, that is made from a plastic material and through which a fluid is intended to flow, is secured simultaneously to the terminal longitudinal part of the tube, the framework and the conductive wires outside the tube, by coating the terminal longitudinal part of the tube, the framework and the conductive wires outside the tube, those conductive wires being kept in place by the framework during molding of the plastic material.
The method according to the invention makes it possible to manufacture a heating assembly as defined above.
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:
The housing 1 comprises a tubular single-piece main body 11, here with a globally rectilinear shape centered around an axis X-X belonging to the cutting plane of
In practice, various embodiments can be considered regarding the body 11 and the closure member 2, without limiting the invention. Advantageously, the housing 1 comprises an annular flange 13 orthoradially surrounding the body 11, while being made in a single piece with that body.
In order to control the movement of the closure member 2, the thermostatic valve comprises a thermostatic element 4 comprising, in a manner well known in the field, a cup 41 on the one hand, which contains a thermally expandable material, not shown in figures, and around which the closure member 2 is securely fastened, for example by fitting, and a piston 42 on the other hand, which is partially plunged in the cup 41 and translatable along its central longitudinal axis under the action of the expansion of the thermally expandable material contained in that cup. The thermostatic element is arranged across from the housing 1 such that on the one hand, its piston 42 is substantially centered on the axis X-X, and on the other hand, that piston is fixedly connected to the body 11, here at a plastic arm 14 that is a single piece with the body 11 and that extends, through the inside of the body 11, from a portion of that body 11, as clearly shown in
For convenience, the rest of the description is oriented relative to the axis X-X: the terms “lower” and “bottom” describe an axial direction oriented toward the cup 41 of the thermostatic element 4, while the terms “upper” and “top” describe an opposite direction.
The thermostatic valve comprises an electric heating resistance 61 which, as shown in dotted lines in
In its upper terminal part 44, the piston 42 is configured with an outwardly flared free end 45: as clearly shown in
In order to electrically connect the heating resistance 61 and external current source, two electrically conductive wires 62 are connected to that resistance 61 and extend from the latter to the outside of the piston 42, while passing through the upper terminal part 44 of the latter, in which the wires 62 emerge upwardly, as clearly shown in
According to the invention, the portion of the conductive wires 62 outside the piston 42 is not embedded alone in the plastic material making up the housing 1. On the contrary, as clearly shown in
This framework 7 has an elongated overall shape that extends lengthwise in a direction transverse to the axis X-X, or a substantially radial direction, as in the example considered in the figures. Thus, the framework 7 includes, in its longitudinal direction, an end part 71 turned toward the axis X-X, a running part 72 and an end part 73, opposite its end part 71.
The end part 71 of the frame 7 is designed to be fixedly attached to the upper terminal part 44 of the tube 42 independently of the other components of the thermostatic valve, in particular for molding of the housing 1. In the example embodiment considered in the figures, this end part 71 comprises a globally tubular body 71.1, which is suitable for being arranged all around the flared end 45 of the upper terminal part 44 of the piston 42 and which has, at its lower axial end, a stepped rim 71.2, turned toward the axis X-X and forming an axial downward bearing for the stepped wall 46 and the horn-shaped wall 47 of that piston end 45, as clearly shown in
Of course, forms other than those described above can be considered for the end part 71 of the framework 7, as long as that end part 71 has arrangements allowing it to be fixedly connected to the upper terminal part 44 of the piston 42 before molding of the housing 1, if applicable by adapting to geometries other than that of the flared end 45 shown in the figures.
The running part 72 of the framework 7 is designed so as, before molding of the housing 1, to allow the part of the conductive wires 62 outside the piston 42 to be outwardly attached on that running part 72 and thus to be kept in place relative to the framework 7. In the example embodiment considered in the figures, this running part 72 delimits, on its upper face, a trough 72.1 for receiving wires 62 outside the piston 42, in which trough those wires run lengthwise between the opposite end parts 71 and 73 of the framework 7. Furthermore, as clearly shown in
Of course, embodiments other than the trough 72.1 and/or the raised portions 72.2 can be considered as long as they consist of arrangements, in particular but not exclusively in terms of shape, of the running part 72 seeking to keep the wires in place outwardly attached on the framework 7 and running along that running part 72.
The end part 73 of the framework 7 is advantageously designed to fixedly receive the connecting studs 63. Thus, in the example embodiment considered in the figures and as shown in
Optionally and advantageously, the end part 73 is more openworked than the rest of the framework 7, so as to facilitate access to the electrical connection zone between the ends 65 of the studs 63 and the conductive wires 62: thus, in the example embodiment considered in the figures, the end part 73 is openworked both upwardly and downwardly, while the running part 72 and the opposite end part 71 are only upwardly open, as shown by comparing
Furthermore, independently of the immediately preceding considerations, the framework 7 advantageously includes a flexible zone 74 connecting its running part 72 and the end part 73 to each other. In the example embodiment considered in the figures, this flexible zone 74 consists of two parallel strands of material, which each connect the end 73 and running 72 parts to each other and which have respective cross-sections, the sum of which is significantly smaller than the minimum cross-section of the parts 72 and 73. In other words, and more generally, the flexible zone 74 is thinner compared to the rest of the framework 7. It will be understood that, owing to its flexibility, the zone 74 is easily deformable relative to the rest of the framework 7, such that said flexible zone 74 makes it possible to adjust the relative position between the end part 73 and the running part 72. In particular, as an example, the end part 73 can, subject to deformation of the flexible zone 74, extend in an inclined direction relative to the longitudinal direction of the running part 72.
In light of the preceding explanations, it will be understood that the framework 7 is a part making it possible to support the conductive wires 62, for the part of the latter outside the piston 42, said part being designed to cooperate with the piston, the wires 62 and the connecting studs 63 before molding of the housing 1. Furthermore, according to one manufacturing example of the thermostatic valve, the aforementioned components, in other words the piston 42, inwardly equipped with the heating resistance 61 from which the conductive wires 62 extend, the framework 7 and the connecting studs 63 are assembled to one another to form an assembly as shown in
It will be understood that the plastic material that overmolds the upper terminal part 44 of the piston 42 and the framework 7 and is arranged inside the body 11, molded jointly with the rest of the housing 1, forms the aforementioned arm 14.
Of course, the overmolding of the housing 1 around the framework 7 is also done around the end part 73 of that framework, as clearly shown in
At the end of molding of the housing 1, the latter is secured to the aforementioned preassembled assembly, by overmolding of the upper terminal part 44 of the piston 42, the framework 7 and the conductive wires 62 outside the piston 42. The valve 1 is then in the configuration shown in
Advantageously, the manufacture of the thermostatic valve ends by attaching a single O-ring 8, which is arranged coaxially around the piston 42, radially interposed between the piston and a part 17 across from the arm 14 of the housing 1, and situated axially upwardly bearing against the rim 71.2 of the end part 71 of the frame 7, as clearly shown in
When the thermostatic valve is in use, the piston 42 is pressed against the transverse arm 14 under the action of the thermostatic element 4 and the return spring 5: the corresponding axial stresses are transmitted through the upper face of the stepped wall 46. The first radial dimension of the space guarantees a reliable force transmission, without damaging the arm 14, and more generally, the housing 1. Furthermore, the seal 8 makes the inside of the piston 42 tight with respect to the fluid flowing in the body 11 of the housing 1.
Various arrangements and alternatives to the heating assembly and the thermostatic valve described thus far may also be considered. For example:
in the embodiment described thus far, the single-piece housing 1, which is attached by overmolding, constitutes the entire external housing of the illustrated valve; alternatively, this single-piece housing may correspond only to part of the valve housing, while in particular being provided to be assembled to another ad hoc housing element; and/or
in the example embodiment considered in the figures, the tube of the heating cartridge, in which the heating resistance 61 is arranged, constitutes the piston 42 of the thermostatic element 4; for other thermostatic valve construction forms, this tube of the heating cartridge and the piston of the thermostatic element, the thermally expandable material of which is heated by the heating resistance belonging to the heating assembly, may consist of two separate parts; in that case, generally, the tube of the heating assembly extends through the bottom of the cup of the thermostatic element, opposite the piston of that element.
Number | Date | Country | Kind |
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12 62081 | Dec 2012 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/076525 | 12/13/2013 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2014/090986 | 6/19/2014 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3719795 | Bolomier | Mar 1973 | A |
3747627 | Christie | Jul 1973 | A |
4153326 | Frantz | May 1979 | A |
4931625 | Marlinski | Jun 1990 | A |
5170752 | Binversie | Dec 1992 | A |
7275697 | Roman | Oct 2007 | B2 |
7520446 | Maraux | Apr 2009 | B2 |
7878868 | Mech | Feb 2011 | B2 |
8217319 | Pottie | Jul 2012 | B2 |
8453943 | Pottie et al. | Jun 2013 | B2 |
20020070367 | Friesenhahn | Jun 2002 | A1 |
20100230504 | Pottie | Sep 2010 | A1 |
20130140296 | Mas | Jun 2013 | A1 |
Number | Date | Country |
---|---|---|
203 08 941 | Oct 2003 | DE |
0 853 267 | Jul 1998 | EP |
1 545 158 | Jun 2005 | EP |
WO 2011010051 | Jan 2011 | WO |
WO 2012013896 | Feb 2012 | WO |
WO 2012013897 | Feb 2012 | WO |
Entry |
---|
Preliminary Search Report in corresponding French Application No. 1262081, dated Aug. 8, 2013. |
Number | Date | Country | |
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20150323090 A1 | Nov 2015 | US |