The present invention relates to a heating cartridge for a thermostatic element, as
well as a thermostatic valve comprising such a cartridge.
5 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 gate pin(s) is controlled by a thermostatic element,
i.e., an element that comprises a cup containing a thermodilatable material and a piston
10 able to slide relative to the cup under the action of the thermodilatable 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 an electric cartridge into the
15 valve in order to heat the thermodilatable material, 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, the heating cartridge comprises electric heating means, such as a heating
resistance, arranged inside the aforementioned piston or a similar tube: for example, by
20 immobilizing the piston in the casing of the valve, the power supply of the resistance
causes the temperature of the thermodilatable material to increase, which, by extension of
the latter, causes the cup to slide around the piston, a sealing member for example being
supported by that cup to act on the flow of fluid through the valve. To supply electricity to
the heating means, the cartridge comprises connectors allowing the electrical connection
25 of electrical conduction wires, belonging to the heating means, and power supply
terminals that extend to the outside of the casing, where they are connected to an outside
current source. FR 2,943,148, which discloses this type of thermostatic valve and heating
cartridge, provides that the aforementioned connectors are supported by a plastic base,
which is secured to the tube by overmolding a flare of this tube, located at the end of the
30 latter opposite that submerged in the thermodilatable material. In the assembled state of
the valve, this base is received in a housing of the casing, while being pressed therein
against the casing in the axial direction of the tube, such that this base at least partially
experiences the usage stresses absorbed by the tube.
To prevent the fluid circulating in the valve from infiltrating to the base and
35 reaching the electrical connectors, the heating cartridge can be equipped with a seal, like
that proposed in FR 9,243,148. This seal is fastened to the base, while surrounding the
2
flare of the tube, and when the base is assembled to the valve casing while being
received in the aforementioned housing, the flare of the tube keeps the seal pressed
radially against the casing in the housing so as to seal the inside of the housing. This
solution yields satisfactory results, but depends on the dimensional allowances of the
5 flare: if the flare is manufactured with very large dimensional deviations, the radial bearing
of the seal in the housing risks being insufficient to preserve the sealing, in particular
when fluid circulates in the valve with pressures of several bars.
The aim of the present invention is to propose a heating cartridge with improved
sealing.
10 To that end, the invention relates to a heating cartridge for a thermostatic element,
as defined in claim 1.
The idea at the base of the invention is to provide a sort of double sealing, that is
to say, a first sealing for the inside of the housing, done by a first part of the seal that is
interposed radially between the base and the casing when the base is in the housing of
15 the casing, and a second sealing for the overmolding interface between the flare of the
tube and the base, done by a second part of the seal designed to radially grip not the flare
of the tube, but the cylindrical body of the tube from which this flare extends. These first
and second parts of the seal are provided to be separate from one another, which makes
it possible for the respective sealings that they procure to be independent from one
20 another. Additionally, compared with its flare, the tube has much smaller machining
allowances at its cylindrical body, in particular because the latter is manufactured in
rectilinear form: in this way, the sealing done by the second part of the seal is controlled,
that is to say, has a guaranteed minimal performance, including when the heating
cartridge is integrated into a valve in which pressurized fluid circulates.
25 Additional advantageous features of the heating cartridge according to the
invention are specified in the dependent claims.
The invention also relates to a thermostatic valve as defined in claim 10.
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:
30 - figure 1 is a perspective view of a heating cartridge according to the invention;
- figure 2 is an elevation view along arrow II of figure 1;
- figure 3 is a sectional view along line III-III of figure 2, showing the heating
cartridge with its seal not yet assembled to the rest of the heating cartridge;
- figure 4 is a sectional view, in the same plane as figure 3, of part of the heating
35 cartridge with its seal assembled to the rest of this heating cartridge, the latter being
associated with a casing of a valve to which the heating cartridge can be assembled;
3
- figure 5 is a view similar to figure 4, showing, on a larger scale, a detail of the
heating cartridge during assembly to the casing of the valve; and
- figure 6 is a view similar to figure 4, showing the heating cartridge assembled to
the casing of the valve.
5 Figures 1 to 6 show a heating cartridge 1 which, in figures 4 to 6, is associated
with a casing 2 of a thermostatic valve, having noted that in these figures 4 to 6, the
casing 2 is only partially shown. More generally, the aforementioned thermostatic valve is
not shown, aside from the heating cartridge 1 and the part of the casing 2 shown in the
figures, having stressed that the other specificities of this thermostatic valve are not
10 limiting with respect to the invention and are known in the field. As an example, the reader
may refer to FR 2,943,148 for a non-limiting example of such specificities for the
thermostatic valve.
As clearly shown in figures 1 to 3, the heating cartridge 1 comprises a metal tube
10 that is primarily made from a cylindrical body 11. The cylindrical body 11 is centered on
15 a longitudinal axis X-X, for example with a circular base like in the figures.
The heating cartridge 1 also comprises an electric heating resistance 20 that, as
schematically illustrated in figure 3, is arranged inside the cylindrical body 11 of the tube
10, such that a main heating body 21 of this resistance 20 occupies a terminal part 11.1 of
the cylindrical body 11, facing downward in the figures. During use, the terminal part 11.1
20 of the cylindrical body 11 of the tube 10 is submerged in a thermodilatable material
contained in a cup, not shown, of a thermostatic element, so that this thermodilatable
material is heated by the main heating body 21. The heating resistance 20 is only one
example of electric heating means that, arranged inside the terminal part 11.1 of the
cylindrical body 11 of the tube 10, make it possible to heat, through this tube made from a
25 thermally conductive material, the aforementioned thermodilatable material.
For convenience, the remainder of the description is oriented relative to the axis XX: the terms "lower", "bottom" and the like describe a direction oriented toward the
terminal part 11.1 of the cylindrical body 11, while the terms "upper", "top" and the like
describe a direction in the opposite sense. The terminal part 11.1 of the cylindrical body
30 11 thus constitutes a lower terminal part for this cylindrical body.
As clearly shown in figure 3, an upper terminal part 11.2 of the cylindrical body 11
of the tube 10 extends axially upward with a flare 12 of the tube 10. The precise geometry
of this flare 12 is not limiting inasmuch as the latter has a shape that flares outward while
moving upward. In particular, the flared shape, shown in the figures, is not the only
35 conceivable one, and for example, FR 2,943,148 discloses an alternative flared shape. In
4
practice, the flare 12 is integral with the cylindrical body 11, while for example being
obtained by stamping the upper end of the tube 10.
As clearly shown in figures 1 to 3, the heating cartridge 1 also comprises a base
30 that is secured to the tube 10 while closing off the upper end. This base 30 is made
5 from a plastic material that is molded on the flare 12 of the tube 10, as well as, if
applicable, on the upper end of the upper terminal part 11.2 of the cylindrical body 11,
while leaving most or even all of this cylindrical body free. Thus, the base 30 is secured to
the tube 10 by overmolding of the flare 12 of the latter.
As shown in figures 4 to 6, the base 30 is designed to be received in a housing 3
10 of the casing 2, which is complementary to the base, so as to assemble the heating
cartridge 1 to the casing 2. In practice, the base 30 is inserted axially upward into the
housing 3, until it bears axially against the casing in the housing, typically at ad hoc stop
shoulder(s) and/or surface(s), provided on the base and in the housing. The
corresponding developments of the base 30 are not limiting, and a detailed example of
15 these developments is provided in FR 2,943,148, to which the reader may refer.
As clearly shown in figure 3, the base 30 is passed all the way through, in the
direction of the axis X-X, by electrical conduction wires 22 coming from the main heating
body 21 of the resistance 20. These wires 22 are connected to the main heating body 21
or make up the connection terminals thereof. In all cases, the wires 22 extend lengthwise
20 from the inside of the lower terminal part 11.1 of the cylindrical body 11, to the outside of
the tube 10, while passing through the upper terminal part 11.2 of the cylindrical body 11,
then through the flare 12 at which these wires pass axially through the base 30. One
upper end of each of the wires 22 emerges from the base 30, at a dedicated region of the
base where the respective upper ends of the wires are provided to be connected to an
25 outside current source, having noted that in practice, this connection is done after the
heating cartridge 1 has been assembled to the casing 2. In the exemplary embodiment
considered in the figures, the upper ends of the wires 22 are respectively placed in open
upper cavities of the base that, when the heating cartridge 1 is assembled to the casing 2
like in figure 6, can each receive a terminal 4 for connecting to the outside current source,
30 the connection between each terminal 4 and the upper end of the corresponding wire 22
advantageously being provided by a connector 40 that is attached in the corresponding
cavity of the base 30 and then makes it possible to pinch the terminal and the upper end
of the wire against one another. Details of this exemplary embodiment are provided in FR
2,943,149. Of course, other embodiments can be considered for the electrical connection
35 supported by the base 30, between the heating resistance 20 and the aforementioned
outside current source.
5
Furthermore, the heating cartridge 1 also comprises a seal 50 that, in the
assembled state of the heating cartridge, is fastened to the base 30, as shown in figures 1
and 2. As described in detail below, the seal 50 includes two separate parts, namely an
upper part 51 and a lower part 52, which perform different respective functions: the upper
5 part 51 makes it possible both to fasten the seal 50 to the base 30 and to seal the inside
of the housing 3 of the casing 2 when the base 30 is received in this housing, while the
lower part 52 makes it possible to seal the overmolding interface between the flare 12 of
the tube 10 and the base 30.
Although they are separate in particular from a functional perspective, the upper 51
10 and lower 52 parts of the seal 50 are advantageously made in one piece, like in the
exemplary embodiment considered in the figures. In other words, the upper 51 and lower
52 parts are then integral with one another, the seal 50 being a molded seal, molded in
one piece.
In the exemplary embodiment considered in the figures, and as more particularly
15 shown in figure 3, the lower part 52 of the seal 50 comprises both a crown 53, centered on
a geometric axis that is aligned with the axis X-X when the seal 50 is fastened to the base
30, and a discoid wall 54, which extends transversely, or generally perpendicular, with
respect to the axis X-X and which couples the crown 53 to the upper part 51 of the seal
50. In the assembled state of the heating cartridge 1, that is to say, when the seal 50 is
20 fastened to the base 30 like in figures 1, 2 and 4 to 6, the crown 53 grips the upper
terminal part 11.2 of the cylindrical body 11 of the tube 10, while being pressed radially
against this upper terminal part 11.2 by the discoid wall 54. More generally, it will be
understood that the lower part 52 of the seal 50 is designed to be pressed radially not
against the flare 12 of the tube 10, which is overmolded by the base 30, but directly
25 against the cylindrical body 11 of this tube 10, below the base 30: in this way, the lower
part 52 of the seal 50 seals the part of the tube 10 placed above this lower part 52, with
respect to what is located below this lower part 52. The lower part 52 thus in particular
seals the overmolding interface between the flare 12 of the tube 10 and the base 30, as
clearly shown in figure 4.
30 To further improve the sealing procured by the lower part 52 of the seal 50, the
crown 53 is advantageously toroidal.
Additionally, the discoid wall 54 is advantageously provided with stiffening ribs 55,
clearly shown in figure 2, which extend lengthwise substantially radially with respect to the
axis X-X and which reinforce the pressing effect of the crown 53 on the tube 10, procured
35 by the discoid wall 54. It will be noted that at least some of the stiffening ribs 54 are wisely
provided protruding from the lower face of the discoid wall 54, that is to say, from the face
6
of this discoid wall that is turned axially away from the base 30, like in the exemplary
embodiment considered in the figures: in this way, these stiffening ribs 55 form reliefs on
the lower side of the seal 50 facilitating the gripping and handling of the latter, both by an
ad hoc tool and manually by a human operator.
5 In the exemplary embodiment considered in the figures, the upper part 51 of the
seal 50 includes a tubular wall 56 centered on a geometric axis that, when the seal 50 is
fastened to the base 30, finds itself aligned with the axis X-X. As clearly shown in figure 3,
the lower axial end of the wall 56 couples the upper 51 and lower 52 parts of the seal 50
to one another, in particular couples the rest of the tubular wall 56 to the discoid wall 54.
10 On its lower face, the tubular wall 56 is provided both with a tongue 57 and an inner bead
58, the latter being located axially between the tongue 57 and the lower axial end of the
tubular wall 56. In the exemplary embodiment considered here, the tongue 57 and the
inner bead 58 each run over the entire inner periphery of the tubular wall 56, having noted
that in a variant that is not shown, one and/or the other can run discontinuously. In all
15 cases, the tongue 57 and the inner bead 58 each protrude from the inner face of the
tubular wall 56, in other words protrude radially toward the axis X-X. Furthermore, the
tubular wall 56 is provided, on its outer face, with three outer beads, namely an upper
outer bead 59, an intermediate outer bead 60 and a lower outer bead 61. In the exemplary
embodiment considered in the figures, the outer beads 59, 60 and 61 run continuously
20 over the entire outer periphery of the tubular wall 56, with the understanding that in a
variant, one or several of them may only run discontinuously. In all cases, each of the
outer beads 59, 60 and 61 is provided protruding from the outer face of the tubular wall
56, that is to say, protruding radially outward relative to the axis X-X. The tongue 57, the
inner bead 58 and the outer beads 59, 60 and 61 have other functional features, which will
25 be disclosed hereinafter, in particular in light of figures 4 to 6.
As clearly shown in figure 4, the tongue 57 makes it possible to fasten the seal 50
to the base 30, while being engaged in a peripheral groove 31 of the base 30. In practice,
the structural flexibility of the tongue 57, in particular its resilient deformation capability
with respect to the tubular wall 56, is used to allow the tongue 57 to be folded down
30 against the inner face of the tubular wall 56 when the base 30 begins to be inserted inside
this tubular wall 56, then to allow the tongue 57 to be deployed, by resilient return, with
respect to the tubular wall 56 and to penetrate inside the peripheral groove 31 once the
axial insertion of the base 31 inside the tubular wall 56 brings the tongue 57 and the
peripheral groove 31 to substantially the same level along the axis X-X. In other words,
35 during the assembly of the seal 50 to the base 30, the tongue 57 deforms resiliently
relative to the rest of the seal 50, until being clipped to the inside of the peripheral groove
7
31, as clearly shown in comparison with figures 3 and 4. Once the tongue 57 is engaged
in the peripheral groove 31 and the seal 50 is thus fastened to the base 30, but as long as
this base 30 is not inserted into the housing 3 of the casing 2, it will be noted that the
tongue 57 does not touch the radial bottom of the peripheral groove 31, as clearly shown
5 in figure 4: in other words, the end of the tongue 57, turned radially toward the axis X-X, is
then radially distant from the bottom of the peripheral groove 31, subject to ad hoc
dimensioning of the peripheral groove 31. In figure 4, reference L1 denotes the radial
expanse of the tongue 57, which is then effectively engaged inside the peripheral groove
31.
10 During the assembly of the heating cartridge 1 with the casing 2, more specifically
during the upward axial insertion of the base 30 inside the housing 3 of this casing,
indicated by arrow F in figures 4 and 5, the peripheral wall of the housing 3 interferes
axially with the outer face of the tubular wall 56, as shown in figures 5 and 6.
In particular, when the seal 50 begins to be inserted inside the housing 3, the
15 peripheral wall of the latter interferes axially with the upper outer bead 59 of the upper part
51, as shown schematically in figure 5: under the effect of this interference, the upper
outer bead 59 radially contracts, around the base 30, the tubular wall 56, in particular the
upper end part of this tubular wall 56. This radial contraction of the tubular wall 56 drives
the engagement of the tongue 57 more deeply inside the peripheral groove 31, which
20 amounts to saying that the radial end of the tongue 57, turned toward the axis X-X,
radially approaches the bottom of the peripheral groove 31, as shown in figure 5: the
tongue 57 is then engaged in the peripheral groove 31 with a greater radial expanse L2
than the expanse L1. In this way, the seal 50 is effectively kept in position relative to the
base, in particular avoiding any risk of untimely disengagement of the seal with respect to
25 the base during the assembly between the heating cartridge 1 and the casing 2.
Additionally, as the axial insertion of the base 30 inside the housing 3 of the casing
2 continues, the peripheral wall of the housing 3 interferes with the rest of the outer face of
the tubular wall 56, in particular interferes with the intermediate outer bead 60, then with
the lower outer bead 61. As the peripheral wall of the housing 3 interferes with these
30 beads 60, then 61, each of the latter radially contracts the tubular wall 56 around the base
30. This progressive radial contraction of the tubular wall 56 causes the inner bead 58 to
cooperate firmly with the periphery of the base, advantageously by pressing axially
against an ad hoc stop, referenced 32, of this base 30, thus making it possible to reinforce
the maintenance of the seal on the base during the insertion of the latter inside the
35 housing 3. At the lower terminal part of the tubular wall 56, the radial contraction of the
latter is advantageously transmitted to the lower part 52 of the seal 50, through the
8
flexibility of the seal, which tends to accentuate the radial bearing of this part 52 against
the cylindrical body 11 of the tube 10.
In consideration of the above explanations, it will be understood that more
generally, the upper part 51 of the seal 50 is pressed radially against the casing 2 in the
5 housing 3 of the latter when the base 30 is received in this housing, so as to seal the
inside of the housing 3, independently of the sealing procured by the lower part 52 of the
seal 50. Additionally, advantageous developments of the upper part 51 of the seal 50,
such as the tongue 57 and/or the inner bead 58 and/or the outer beads 59, 60 and 61,
facilitate and secure the assembly of the heating cartridge 1 with the casing 2.
10 Of course, various developments and variants of the cartridge 1 and the valve
including the latter, described thus far, can also be considered.
9
CLAIMS
1.- A heating cartridge (1) for a thermostatic element, including:
- a tube (10), which is thermally conductive and which is suitable for being
5 immersed in a thermodilatable material of the thermostatic element, the tube comprising a
cylindrical body (11), centered on a longitudinal axis (X-X) and extending axially with a
flare (12),
- electric heating means (20) arranged inside the cylindrical body (11),
- a base (30) made of a plastic material, which base:
10 - is secured to the tube (10) by overmolding of the flare (12) of the tube,
- supports an electric connection between the electric heating means (20)
and an external current source, and
- is suitable for being received in a housing (3) of a casing (2), and
- a seal (50), which is attached to the base (30) and which includes a first part
15 (51) which, when the base is received in the housing (3) of the casing (2), is pressed
radially against the casing in the housing so as to seal inside of the housing,
characterized in that the seal (50) also includes a second part (52), which is
separate from the first part (51) of the seal and which is pressed radially against the
cylindrical body (11) of the tube (10) so as to seal an overmolding interface between the
20 flare (12) of the tube and the base (30).
2.- The heating cartridge according to claim 1, characterized in that the first (51)
and second (52) parts of the seal (50) are made in one piece.
25 3.- The heating cartridge according to one of claims 1 or 2, characterized in that
the second part (52) of the seal (50) comprises a crown (53), which grips the cylindrical
body (11) of the tube (10) and which is coupled to the first part (51) of the seal by a
discoid wall (54) of the second part of the seal, this discoid wall extending transversely to
the longitudinal axis (X-X) and being designed to press the crown radially against the
30 cylindrical body of the tube.
4.- The heating cartridge according to claim 3, characterized in that the crown
(53) is toroidal.
10
5.- The heating cartridge according to one of the claims 3 or 4, characterized in
that the discoid wall (54) is provided with stiffening ribs (55) that extend lengthwise
substantially radially to the longitudinal axis (X-X).
5 6.- The heating cartridge according to claim 5, characterized in that at least some
of the stiffening ribs (55) protrude from a face of the discoid wall (54), which is turned
axially away from the base (30).
7.- The heating cartridge according to any one of the preceding claims,
10 characterized in the first part (51) of the seal (50) includes a tubular wall (56), which is
substantially centered on the longitudinal axis (X-X) and has an axial end that couples the
first part of the seal to the second part (52) of the seal, and in that the tubular wall (56) is
provided, on an inner face thereof, with a tongue (57) that is engaged in a peripheral
groove (31) of the base (30) to fasten the seal to the base, the peripheral groove being
15 provided such that a first radial expanse (L1) of the tongue (57) engages therein as long
as the base (30) is not inserted into the housing (3) of the casing (2) and such that a
second radial expanse (L2) of the tongue, greater than the first radial expanse (L1),
engages therein when the base is inserted in the housing of the casing.
20 8.- The heating cartridge according to claim 7, characterized in that the tubular
wall (56) is also provided, on a lower face thereof, with an inner bead (58), which is
located axially between the tongue (57) and said axial end of the tubular wall, and which is
pressed axially against a stop (32) of the base (30) so as to keep the seal (50) fastened to
the base when the base is inserted axially into the housing (3) of the casing (2).
25
9.- The heating cartridge according to one of claims 7 or 8, characterized in that
the tubular wall (56) is provided, on an outer face thereof, with at least one outer bead or
several outer beads (59, 60, 61), distributed along the longitudinal axis (X-X), this outer
bead or each of these outer beads being suitable for radially contracting the tubular wall
30 around the base (30) when the base is axially inserted into the housing (3) of the casing
(2).
10.- A thermostatic valve, including:
- a thermostatic element, comprising a heating cartridge, according to any one of
35 the preceding claims, and a cup containing a thermodilatable material in which the tube
(10) of the heating cartridge is immersed, and
11
- a casing (2) delimiting a housing (3) in which the base (30) of the heating
cartridge (1) is received.