Thermostatic valve

A thermostatic valve includes a hollow body, two openings opening into the body and being hydraulically connected by a pass section, and a shut-off component arranged partially in the pass section and having a thermostatic actuator, a return component, a valve capable of opening the first opening when actuated by the thermostatic actuator and of closing the first opening when returned by the return component. The thermostatic actuator includes a cylinder containing an expansion material and a stem defining an axial direction. A relative movement between the cylinder and the stem along the axial direction occurs under the action of the expansion material. The stem bears at an ends against an abutment element, which is movable under the action of movement component in the direction of the cylinder to allow the opening of the first opening when the temperature of the expansion material is below the threshold temperature.

TECHNICAL FIELD

The present disclosure concerns the field of thermostatic valves. A thermostatic valve is typically used in the field of automatic thermal regulation for fluid circuits (gas, water, oil, etc.).

BACKGROUND

In a known manner, a thermostatic valve comprises a closed hollow body pierced with a first opening and a second opening and comprising a plug separating the two openings in a sealed manner. The plug is sensitive to the temperature of the fluid so as to open above a threshold temperature and to close below said threshold temperature.

An illustrative application in the automotive field is the making of water inlet casings (convergent) or water outlet casings (divergent).

The plug of a thermostatic valve typically comprises a thermostatic actuator, such as a wax capsule, and a flap actuated by the thermostatic actuator. A wax capsule comprises a cylinder filled with a temperature-sensitive wax. The wax repels a rod under the effect of a significant change in volume accompanying a change in solid/liquid phase, occurring at a threshold temperature. Such a thermostatic actuator automatically controls the opening stroke of the flap from a threshold temperature or a start-of-opening temperature. The closure of the flap is ensured by a biasing means, such as a spring, antagonist to the thermostatic actuator. The valve advantageously has a through section adapted to the passage of the nominal (maximum) flow rate provided for the thermostatic valve.

Although relatively powerful and inexpensive, wax capsule thermostats have a certain number of drawbacks. One of their major drawbacks is their reactivity at a single threshold temperature. Yet, depending on a method of operating the engine, it is sometimes beneficial to be able to open the flap of the thermostatic valve at a temperature below the change of state temperature of the wax. To overcome this drawback, it has been proposed in the prior art to add an electric heater intended to heat the wax. However, this type of electric heater does not make it possible to anticipate the opening of the thermostat below 20° C. of the threshold temperature, which is not always sufficient to ensure optimal operation of the engine. Moreover, the time between the moment when the wax is heated and the moment when the valve opens is generally long, which may be a problem, especially in the case where a rapid opening of the valve is necessary.

SUMMARY

To overcome the aforementioned problems of wax capsule thermostats, systems of electric spool valves have been developed in order to control the circulation of the heat transfer fluid in all conditions. These valves operate based on the principle of one or more spool(s) enabling the opening or the closure of radial windows, each dedicated to a branch of circulation. These valves thus make it possible to pilot the flow rate of the heat transfer fluid according to the temperature, but also according to other parameters, such as the load applied to the engine, the temperature of the intake air, or that of the cylinder head. Nonetheless, these valves require the installation of sensors in order to control the operating parameters and a control unit in order to manage the displacement of the spools. Furthermore, to ensure a good seal between the spool(s) and each branch of circulation, rigorous geometric and dimensional control is necessary. These valves therefore have a prohibitive cost that reserves them for high-end use. Moreover, due to the use of an electric actuator, these pilot-operated valves have a substantial size that prevents their installation on some types of vehicles.

Hence, the disclosure aims at providing a thermostatic valve making it possible to overcome the drawbacks of wax capsule thermostats while being of reduced cost and size.

To this end, according to a first aspect, the disclosure provides a thermostatic valve comprising a hollow body, a first opening and a second opening leading into the body and hydraulically connected by a through section and a plug disposed at least partially in the through section and comprising a thermostatic actuator, a biasing means, a flap capable of opening the first opening when actuated by the thermostatic actuator and of closing the first opening when biased by the biasing means, wherein the thermostatic actuator comprises a cylinder containing an expansion material, the volume of which increases beyond a threshold temperature, and a rod defining an axial direction, a relative displacement between the cylinder and the rod along the axial direction might occur under the action of the expansion material, characterized in that the rod bears at one of its ends against an abutment element, said abutment element being displaceable under the action of displacement means towards the cylinder so as to enable the opening of the first opening when the temperature of the expansion material is lower than the threshold temperature, said displacement means being at least partially disposed inside the through section.

Thus configured, the disclosure allows opening and closing the flap, independently of the temperature of the fluid circulating in the valve. Moreover, due to the partial positioning of the displacement means in the through section, the valve has a size substantially equivalent to that of a conventional thermostatic valve, equipped with a thermostatic actuator for example of the wax capsule type.

According to other features, the thermostatic valve of the disclosure includes one or more of the following optional features considered alone or according to any possible combination:the displacement means are capable of displacing the abutment element along the axial direction defined by the rod.the abutment element comprises a hollow cylindrical ring having at least one groove on its outer boundary, said groove defining a tapped portion, and a central hub connected to said ring by means of radial fins, said central hub being aligned with the rod and in contact therewith, and in that the displacement means comprise an electric actuator capable of displacing the central hub in rotation about an axis parallel to the axial direction and at least one raised protrusion formed on the inner boundary of the body, said protrusion defining a threaded portion into which is screwed the tapped portion of the ring such that the rotational displacement of the central hub causes the displacement along the axial direction of the abutment element.the abutment element comprises a hollow cylindrical ring and a central hub connected to said ring by means of radial fins, said central hub being aligned with the rod and in contact therewith, and in that the abutment element is slidingly mounted in the body, so that it is locked in rotation but may move in the axial direction, said abutment element being screwed into a connecting element or, conversely, said connecting element being screwed in the abutment element, the connecting element being able to move in rotation around an axis parallel to the axial direction under the action of an electric actuator, the rotational displacement of the connecting element ensuring the axial displacement of the abutment element.the abutment element comprises four radial fins angularly spaced from each other.a bore formed at one of the ends of the central hub is sized to receive one end of the rod which protrudes from the cylinder.the threshold temperature is comprised between 20° C. and 115° C.the expansion material is wax.the thermostatic valve comprises sealing means capable of preventing a fluid circulation between the through section and an outer compartment partially accommodating the displacement means.the sealing means comprise an O-ring gasket disposed at least partially around a connecting element positioned between the through section and the outer compartment and subjected to a rotational movement around an axis parallel to the axial direction under the action of the displacement means. The use of such a rotating connecting element, which may not be displaced axially, makes it possible to obtain a proper sealing between the through section and the outer compartment by means of a simple O-ring gasket.the biasing means is a compression spring exerting an axial thrust against a cage at least partially surrounding the cylinder of the thermostatic actuator and resting against the flap, the cage moving along the axial direction under the combined action the thrust exerted by the compression spring and the counter thrust exerted by the flap during its displacement.

According to another aspect, the disclosure provides a fluid inlet or fluid outlet casing, for thermostatic regulation of a fluid circuit, comprising such a thermostatic valve.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG.1represents a cooling fluid outlet or inlet casing20, the cooling fluid being in general glycol water. In the particular case of a fluid outlet casing, the casing20makes it possible to manage the circulation of the fluid from the engine to the radiator. Thus, depending on the temperature of the cooling fluid, the casing20directs or not the cooling fluid to the radiator in order to maintain the operating optimum temperature of the engine. The casing20has one or more inlets through which fluid may enter and one or more outlets through which fluid may exit. As represented inFIGS.2and3, the casing20also has a circular opening23at its periphery, said opening23allowing a thermostatic valve10to be partially introduced inside the casing20, then fastened to said casing20, for example by means of a bayonet-type connection. Depending on the intended use and the engine equipping the vehicle, it will thus be possible to modify the circuit of the cooling fluid inside the casing20by simply modifying the thermostatic valve10. The casing20may thus be used for relatively different uses and loads, which require specific controls of the coolant flow rate. In particular, the thermostatic valve10may be available in several versions: with a conventional thermostat (uncontrolled), a thermostat with heater (controlled) or with an electric actuator.

In the particular embodiment represented inFIGS.1to3, the casing20comprises a frame21. The frame21has a partition26separating two chambers24,25, respectively a chamber24for the intake of the cooling fluid from the engine, the fluid entering the casing20through an inlet conduit22, and a chamber25for the return to a cooling fluid manifold, the fluid leaving the casing20through an outlet conduit22′. The partition26has an opening extended by a conduit27allowing the two chambers24,25to communicate with each other.

The casing20also incorporates a thermostatic valve10. The valve10comprises a body1having a substantially cylindrical first portion11which is aligned with the opening23and which is fastened thereto, in particular by a bayonet-type connection, and a second substantially cylindrical portion12which is disposed obliquely with respect to the first portion. The body1forms a closed cavity except for a first opening2, defined by the first portion11, and a second opening3, defined by the second portion12, which lead into the body1and allow a fluid entry and/or output. In the case of a fluid outlet casing, the second opening3could for example allow a cooling fluid to be output towards a radiator so as to cool the fluid. The first opening2and the second opening3are connected by a through section5. The valve10further comprises a plug disposed at least partially in the through section so as to selectively separate the first opening2from the second opening3. Said plug is configured to be closed below a threshold temperature and thus to separate the first opening2from the second opening3in a tight manner by closing the through section5, and to be open above the threshold temperature so as to fluidly connect the first opening2to the second opening3, with the through section5being fully open and able to let a nominal/maximum flow rate pass therethrough.

For this purpose, the plug comprises a thermostatic actuator4, a biasing means6and a flap8. The flap8is capable of opening when actuated by the thermostatic actuator4and of closing when biased by the biasing means6. The thermostatic actuator4typically comprises two actuation points and is capable of varying the distance and/or the force present between these two actuation points. A first actuation point is secured to the body1and a second actuation point is secured to the flap8.

The thermostatic actuator4comprises in particular a cylinder41and a rod42engaged in the cylinder41along its axis and capable of coming out of the cylinder41, said rod42being aligned in the direction D. The flap8with a substantially annular shape surrounds the periphery of the cylinder41and is secured thereto. As illustrated inFIGS.4and5, the rod42of the thermostatic actuator4is fixed relative to the body1of the thermostatic valve10and the cylinder41of the thermostatic actuator4is movable relative to the rod42and displaces the flap8to which it is secured. This relative displacement between the cylinder41and the rod42results from the change of state of an expansion material contained in the cylinder41and against which bears one of the ends of the rod42. This expansion material has in particular a threshold temperature beyond which it passes from the solid state to the liquid state and increases in volume. This increase in volume therefore generates a thrust force against the rod42, which leads to the displacement of the cylinder41due to the immobility of the rod42. In the case of a thermostatic actuator of the wax capsule type, the expansion material contained in the cylinder41is wax and the threshold temperature is generally comprised between 80° C. and 115° C. In the case of other thermostatic actuators, the threshold temperature may be less than 80° C. Thus, for thermostats equipping the air/water exchangers, this threshold temperature is comprised between 50° C. and 70° C. It may also be comprised between 20° C. and 50° C. for thermostats used in battery cooling circuits.

Thus, as represented inFIG.4, when the temperature of the cooling fluid is below the threshold temperature of the expansion material, the flap8closes the opening2of the body1, thus preventing any fluid output through the opening3. The cooling fluid F therefore circulates only between chambers24and25of the casing20through the conduit27.

As represented inFIG.5, when the temperature of the cooling fluid is greater than the threshold temperature of the expansion material, the cylinder41moves in the direction of the conduit27, which has the effect of moving the flap8away from the opening2of the body1, thus enabling a circulation of the cooling fluid F through the opening2, then in the through section5and finally through the opening3.

The reverse passage from the position represented inFIG.5to that represented inFIG.4occurs during the gradual drop in the temperature of the cooling fluid and under the impulsion of the biasing means6. In the represented embodiment, the biasing means6is a compression spring which is disposed between the partition26of the frame21, and an intermediate part7defining a cage which at least partially surrounds the cylinder41of the thermostatic actuator4and which bears against the flap8. The biasing means6therefore exerts, via the cage7, an axial thrust against the flap8which is antagonist to the axial thrust exerted by the thermostatic actuator4. Thus, the thermostatic actuator4ensures the opening of the flap8and the biasing means6ensures the closure of the flap8by pressing said flap8against its seat. Thus depending on the temperature, the thermostatic actuator4extends, opens the flap8and opposes the biasing means6by compressing it when the temperature exceeds the threshold temperature, while the biasing means6takes over, repels and closes the flap8and reduces the action of the thermostatic actuator4when the temperature drops below the threshold temperature.

In order to ensure opening of the flap8for fluid temperatures below the threshold temperature of the expansion material of the thermostatic actuator, the valve10advantageously has displacement means making it possible to displace the first point of actuation of the thermostatic actuator4. In the represented embodiment, the first actuation point is defined by an abutment element13against which abuts one of the ends of the rod42of the thermostatic actuator. As illustrated in detail inFIGS.4and9, this abutment element13comprises a hollow cylindrical ring131having a helical groove135on its outer boundary, said groove135defining a tapped portion, and a central hub132connected to said ring131by means of several radial fins136, for example four radial fins136angularly spaced from each other. The central hub132is aligned with the rod42and in contact with the latter at its end133which faces the cylinder41. As illustrated inFIG.8, the end133of the central hub132notably has an axial bore134which is dimensioned to receive the end421of the rod42which protrudes from the cylinder41, the shape of the bore134being advantageously complementary to that of the rod42. As illustrated inFIG.7, the other end137of the central hub132is connected to a connecting element16disposed astride between the through section5and an outer compartment15accommodating an electric actuator14. As illustrated inFIG.10, the end137of the central hub132might for example be connected to the connecting element16by a sliding connection, the sliding connection resulting from the presence of splines138along the end137intended to slide inside a cavity162of the connecting element16, said cavity162having a shape complementary to that of the end137. Thus, the connecting element16may transmit a torque to the central hub132, the two parts being free in translation. The electric actuator14is capable of transmitting a rotational movement to the connecting element16around the axis D such that the connecting element16is capable of transmitting a torque to the central hub132. So as to avoid any entry of fluid into the outer compartment15, an O-ring gasket17is disposed around the connecting element16, at the level of an annular groove161formed at the periphery of said connecting element16, such that the O-ring gasket17is positioned inside an opening191formed in a wall19separating the through section5from the outer compartment15.

The rotational movement of central hub132is transmitted to the ring131via radial fins136. As represented inFIGS.4and9, the ring131is disposed in the cavity formed by the first portion11of the body1in such a way as to come into contact with the inner boundary thereof. Given that this inner boundary is provided with a helically-shaped raised protrusion18, said protrusion18forming a threaded portion into which is screwed the tapped portion of the ring131, during the rotation of the ring131, a concomitant translational displacement along the axial direction D of the abutment element13, occurs. This translational displacement makes it possible in particular to repel the rod42towards of the cylinder41when the abutment element13moves away from the connecting element16. In the case where the temperature of the fluid is lower than the threshold temperature of the expansion material, the expansion material contained in cylinder41is in a solid state. The translational displacement of the rod42is therefore transmitted directly to the cylinder41.

As illustrated inFIG.6, the cylinder41may therefore move towards the conduit27under the action of the abutment element13, which has the effect of moving the flap8away from the opening2of the body1, thus enabling a circulation of the cooling fluid F through the opening2, then in the through section5and finally through the opening3.

The reverse passage from the position represented inFIG.6to that represented inFIG.4occurs when the direction of rotation of the electric actuator14is reversed. Indeed, this rotational movement in the opposite direction leads to a translational movement of the abutment element13towards the connecting element16due to the interaction between the tapped portion of the ring131and of the threaded portion of the body1. The thermostatic actuator4, which is secured to the flap8, is then repelled, under the action of the biasing means6and via the cage7, towards the connecting element16until the flap8comes to rest against its seat, thus closing the opening2of the body1.

Of course, the disclosure is not limited to the embodiment described above and illustrated by the various figures, this embodiment having been provided only as example. Modifications are still possible, in particular with regards to the constitution of the various elements or by substitution with technical equivalents, yet without departing from the scope of the disclosure.

In particular, the casing20could also be a water inlet manifold for a cooling circuit of an engine.

Moreover, in another variant of the disclosure (not represented), the abutment element13could be slidingly mounted in the body1, so that it is locked in rotation but may move according to the axial direction D. It will be screwed into the connecting element16, or, conversely, said connecting element16being screwed into the abutment element13, the screwing/unscrewing of the abutment element13, respectively of the connecting element16, ensuring the axial displacement of the abutment element13.

This variant could be made for example by overmolding a metal insert or a metal tapped rod.