HEATING ASSEMBLY FOR A THERMOSTATIC VALVE
AND CORRESPONDING PRODUCTION METHOD, AND A
THERMOSTATIC VALVE COMPRISING SUCH AN ASSEMBLY
The present invention relates to a heating assembly for a thermostatic valve, as
5 well as a method for manufacturing such a heating assembly. It also relates to a
thermostatic vaive 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
10 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 iatter expands.
To distribute the fluid as a function of other parameters, in particular conditions
15 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 vaive, 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 appropriateiy. In
20 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 iatter, 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.
25 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
30 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
35 wires is changed, typically depending on the position, on the case, of the aforementioned
connecting pads.
2
EPA-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
5 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
10 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
15 easy to adapt to various heating assembly geometries.
To that end, the invention relates to a heating assembly for a fluid control
thermostatic valve, as defined in claim 1.
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.
20 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
25 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
30 invention makes it possible to modify the arrangement of the wires before molding to
adapt to various geometries of heating assemblies.
Other advantageous features of the heating assembly according to the invention
are specified in dependent claims 2 to 8.
The invention also relates to a fluid control thermostatic valve, as defined in claim
35 9.
3
The invention further relates to a method for manufacturing a heating assembly for
a fluid control thermostatic valve, as defined in claim 10.
The method according to the invention makes it possible to manufacture a heating
assembly as defined above.
5 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:
- figure 1 is a longitudinal cross-section of a thermostatic valve according to the
invention;
- figures 2 and 3 are perspective, cross-sectional quarter views of the vaive of
10 figure 1;
-figure 4 is an enlarged view of the circled detail IV in figure 1;
- figures 5 and 6 are cross-sections along lines V-V and VI-VI of figure 1,
respectively; and
- figure 7 is a perspective view, showing a subassembly to be overmolded,
15 belonging to the valve of figure 1 and comprising a thermally conductive tube positioned in
a framework so as to be inserted into a mold for producing the housing of the vaive.
Figures 1 to 6 show a thermostatic valve comprising a housing 1 made from
plastic, in which a fluid is designed to flow, in a manner regulated by the other
components of the valve, in particular oil or a coolant liquid when the valve belongs to a
20 cooling circuit for a heat engine.
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 figure 1.
During use, the aforementioned fluid flows through the body 11, between its two
longitudinal ends, while being regulated, here at one of said ends, by a closure disk 2
25 centered on the axis X-X and transiatable along the axis: when this closure member is
pressed tightly against a seat 12 delimited by the aforementioned end of the body 11, as
shown in figure 1, the flow of the fluid is interrupted, whereas when the closure member 2
is separated from the seat 12, the fluid can flow freely around the ciosure member and
thus enter or leave the body 11.
30 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 orthoradialiy surrounding the body 11, while being made
in a single piece with that body.
In order to control the movement of the ciosure member 2, the thermostatic valve
35 comprises a thermostatic element 4 comprising, in a manner well known in the fieid, a cup
41 on the one hand, which contains a thermally expandable material, not shown in figures,
4
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
5 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 piastic 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 figures 2 and 3
and as specified in more detail below. Thus, during use, the piston 42 is stationary relative
10 to the housing 1, while the cup 41 and the closure member 2 that it supports are movable
aiong the axis X-X relative to the housing, under the effect of the thermally expandable
material when the latter expands, or when that material contracts, under the opposite
effect of a returns spring 5 interposed between the closure member 2 and a stirrup 3
which, during use, is fixedly connected to two tabs 15 integral with the flange 13. In a
15 manner known in itself, these movements are guided aiong the piston 42, typically by a
guide part secured to the cup 41.
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.
20 The thermostatic valve comprises an electric heating resistance 61 which, as
shown in dotted lines in figure 1, is arranged inside the piston 42, made to that end in the
form of a metal tube, here with a circular base, such that said resistance 61 occupies the
lower terminai part 43 of the piston 42, i.e., its terminal part plunged in the cup 41, so that
the resistance 62 can heat the thermally expandable material contained in that cup.
25 In its upper terminal part 44, the piston 42 is configured with an outwardly flared
free end 45: as clearly shown In figure 4, this flared end 45 is made up of a stepped wall
46, globally fitted into a plane perpendicular to the axis X-X, and a horn-shaped wali 47,
connecting, while gradually narrowing, the inner end of the stepped wall 46 to the upper
end of the rest of the terminal part 44. Advantageously, the stepped wall 46 and the horn-
30 shaped wall 47 here form a single piece with the rest of the terminal part 44, while in
particular being obtained by stamping the free end 45. As an alternative that is not shown,
the stepped wali 46 can be extended or even replaced by a wall with a raised shape, for
example cylindrical, centered on the axis X-X.
In order to electrically connect the heating resistance 61 and external current
35 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
5
terminal part 44 of the latter, in which the wires 62 emerge upwardly, as clearly shown in
figure 2 and figure 7, in which several components of the thermostatic valve have been
omitted for greater clarity related to the following considerations. The respective parts of
the wires 62 outside the piston 42 extend from the terminal part 44 of the latter to the
5 connecting studs 63, to which the wires 62 are respectively electrically connected and the
free ends 64 of which, i.e., those turned opposite the wires 62, are accessible outside the
housing 1 to be connected to the aforementioned external current source. It will be noted
that, for visibility reasons, only one of the studs 63 is shown in figures 2 and 3. In practice,
the respective ends 65 of the studs 63, opposite their end 64, are respectively connected
10 to the ends of the wires 62, opposite the heating resistance 61, by any appropriate means,
for example by welding, crimping or brazing. The stud ends 64 are left stripped,
advantageously remotely surrounded by a base 16 for connecting to the external current
source, that base 16 advantageously being made in a single piece with the body 11 of the
housing 1.
15 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 figures 2 to 7, the thermostatic valve further comprises a
framework 7 designed to support the wires 62 outside the piston 42, that framework 7
being separate from the housing 1, inasmuch as, as shown in figure 7, that framework 7 is
20 made in the form of one or more parts, in the case at hand a single part, which are not
integral with the housing 1.
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
25 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
30 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 figure 4. Furthermore, in its upper end part, the
35 tubular body 71.1 is provided with hooks 71.3, of which there are three in the example
embodiment considered here and which are suitable for clipping to the piston end 45,
6
while cooperating with respective portions of the stepped wall 46 of the piston end 45 so
as to axially upwardly block that stepped wall 46 and thereby maintaining that stepped
wall and the horn-shaped wall 47 bearing axially downward against the rim 71.2 of the end
part 71 of the framework 7.
5 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 ailowing 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.
10 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
15 which trough those wires run lengthwise between the opposite end parts 71 and 73 of the
framework 7. Furthermore, as clearly shown in figure 5, the trough 72.1 is provided with at
least one raised portion 72.2 that is configured, by itself or jointly with the rest of the
trough 72.1, to keep the wires 62 inside the trough 72.1 and thus participate in keeping
those wires in place outside the piston 42. Thus, for the example embodiment considered
20 in the figures, the trough 72.1 is provided with several of these raised portions 72.2, which
are distributed in the longitudinal direction of the framework 7, and at each of which each
wire 62 is transversely jammed between the raised portion and the bottom of the trough
72.1.
Of course, embodiments other than the trough 72.1 andlor the raised portions 72.2
25 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
30 as shown in figure 6, this end part 73 is provided with through holes 73.1, in each of which
one of the studs 63 is received, in a complementary manner so as to connect the studs 63
and the framework 7 to each other.
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
35 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
7
downwardly, while the running part 72 and the opposite end part 71 are only upwardly
open, as shown by comparing figures 2 and 3. Thus, in figure 3, a downwardly through
window, delimited by the end part 73 and upwardly emerging on the connecting zone
between the studs 63 and the wires 62, is referenced 73.2.
5 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
10 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
15 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
20 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 I. 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
25 assembled to one another to form an assembly as shown in figure 7. Then, secondly, the
housing 1 is molded, more specifically overrnolded, around that preassembled assembly.
In practice, this means that the aforementioned preassembled assembiy is positioned
inside a molding mold, inside which the plastic material is injected so as simultaneously to
coat the upper terminal part 44 of the piston 42, the framework 7 and the conductive wires
30 62. More specifically, at the terminal part 44 of the piston 42, the plastic material coats the
flared end 45 of the terminal part 44 of the piston 42, as well as the end part 71 of the
framework 7: the plastic then spreads inside the piston part 44, covers the upper face of
the stepped wall 46, and coats the entire end part 71 of the framework 7, advantageously
except for the inner periphery of the lower face of the rim 71.2 of that end part 71, as
35 clearly shown in figures 1, 3 and 4. Likewise, the plastic material coats the entire running
part 72 of the framework 7, in particular by spreading on the wires 62 running over that
8
running part 72, inside the trough 72.1. During the injection of the plastic material, the
aforementioned wires are kept in place inside the trough 72.1, ensuring that they are
reliably coated, without risking pulling them, or even pulling them out.
It will be understood that the plastic material that overmolds the upper terminal part
5 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 figures 1 to 3, in particular
coating the electrical connections between the studs 63 and the wires 62.
10 Advantageously, beyond the end part 73, moving away from the axis X-X, the
overmolding is done so as to form the connecting base 16 around the free end 64 of the
studs 63. Of course, as an alternative that is not shown, before molding the housing 1, the
flexible zone 74 of the framework 7 can be deformed so as to modify the relative
positioning of the end part 73 with respect to the rest of the framework 7, to adapt to other
15 positional geometries of the studs 63 within the thermostatic valve: the overmolding of the
housing I then freezes the deformation of the flexible zone 74, by coating.
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
20 the configuration shown in figures 1 to 6.
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
25 shown in figures 1, 3 and 4. As an alternative that is not shown, the O-ring 8 has a fourlobed
shape.
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
30 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
35 thermostatic valve described thus far may also be considered. For example:
9
- 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 eiement;
5 andlor
- 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
10 material of which is heated by the heating resistance belonging to the heating assembly,
may consist of two separate parts; in that case, generaily, the tube of the heating
assembly extends through the bottom of the cup of the thermostatic eiement, opposite the
piston of that element.

CLAIMS
1.- A heating assembly for a fluid control thermostatic valve, comprising:
- a tube (42), being thermally conductive, having a longitudinal central axis (X-X)
and being able to be plunged in a thermally expandable material of a thermostatic element
5 (4) of the valve,
- an electric heating resistance (61), which is positioned inside the tube and from
which electrically conducting wires (62) extend outside the tube, and
- a single-piece housing (1) made from a plastic material, through which the fluid
flows and which is secured by overmolding to a terminal longitudinal part (44) of the tube,
10 characterized in that the heating assembly further comprises a framework (7) for
supporting the conductive wires (62) outside the tube (42), the framework being separate
from the housing (I), the tube being secured to the framework by overmolding, the
framework being suitable, before molding of the housing, for being fixedly attached to the
terminal longitudinal part (44) of the tube and for supporting the conductive wires (62)
15 outside the tube, those conductive wires being outwardly assembled on the framework,
and the frame work being 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.
2.- The heating assembly according to claim 1, characterized in that the framework
20 (7) is made in a single piece.
3.- The heating element according to one of claims 1 to 2, characterized in that the
framework (7) has an elongated overall shape, which extends lengthwise, at least for a
part (71, 72) thereof turned toward the tube (42), in a transverse or substantially radial
direction with respect to the axis (X-X).
25 4. The heating assembly according to claim 3, characterized in that an end part
(71) of the framework (7), turned toward the tube (42), is configured to surround and
fasten itself, in particular by cooperating through complementary shapes, to a free,
outwardly flared end (45) of the terminal longitudinal part (44) of the tube (42).
5.- The heating assembly according to one of claims 3 and 4, characterized in that
30 between an end part (73) of the framework (7) turned opposite the tube (42) and a running
part (72) of the framework, the framework includes a flexible zone (74), in particular
thinner, suitable for being deformed so as to adjust the relative positioning between that
end part (73) and the rest (71, 72) of the framework before molding the housing (1).
6.- The heating assembly according to one of claims 3 to 5, characterized in that in
35 an end part (73) of the framework turned opposite the tube (42), the framework (7) has
through holes (73.1) for complementary reception of electrical connecting studs (63) that
11
are respectively electrically connected to the conductive wires (62) before molding of the
housing (1).
7.- The heating assembly according to any one of claims 3 to 6, characterized in
that a running part (72) of the framework (7), which connects end parts (71, 73) thereof
5 turned toward and opposite the tube (42), respectively, to each other, delimits a
longitudinal trough (72.1) for receiving the conductive wires (62), in which the wires run
lengthwise between the end parts of the framework and which is provided with means
(72.2) for keeping those conductive wires in place before molding the housing (1).
8.- The heating assembly according to any one of claims 3 to 7, characterized in
10 that the heating assembly further comprises a single sealing gasket (8), which is an O-ring
or a four-lobed seal, which is both inserted radially between the housing (1) and the tube
(42) and arranged axially against an end part (71) of the framework (7), turned toward the
tube.
9.- A fluid control thermostatic valve, comprising:
15 - a heating assembly according to any one of the preceding claims,
- a valve housing (1) consisting at least partially of the housing of the heating
assembly,
- a closure member (2) for regulating the flow of a fluid through the valve housing
(I), and
20 - a thermostatic element (4), comprising a stationary part (42) fixedly connected to
the valve housing (I), and a moving part (41) 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 (42) of the heating assembly is plunged.
10.- A method for manufacturing a heating assembly for a fluid control thermostatic
25 valve,
in which a tube (42) is provided, that is thermally conductive, has a longitudinal
centrai axis (X-X) and is suitable for being plunged in a thermally expanding material of a
thermostatic element (4) of the valve and in which an electrical heating resistance (61) is
positioned from which electrically conductive wires (62) extend outside the tube,
30 characterized in that a framework (7), on which the conductive wires (62) outside
the tube are outwardly assembled so as to support those conductive wires, is fixedly
attached to a terminal longitudinal part (44) of the tube (42),
then a single-piece housing (I), that is made from a plastic material and through
which a fluid is intended to flow, is secured simultaneously to the terminal longitudinal part
35 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
12
tube, those conductive wires being kept in place by the framework during molding of the
plastic material.