Thermal screen including a passage through which a cooling fluid flows

Abstract

Title: Internally cooled thermal shield. Thermal shield for the protection of a sensor of a motor vehicle, comprising at least one wall intended to block thermal radiation and at least one support for fixing the thermal shield, characterized in that at least the wall comprises at least one channel intended to be used by a cooling fluid of the motor vehicle. Figure for the abstract: Figure 1.

Description

Title of the invention: Heat shield comprising a passage through which a cooling fluid flows

[0001] The present invention relates to the field of thermal screens for motor vehicles which are used to protect electrical components from thermal radiation from certain elements of the vehicle.

[0002] Currently, in motor vehicles equipped with a thermal engine, the number of components is increasing while the space in the vehicle's engine compartment is increasingly limited. This is even more true for hybrid propulsion vehicles, because the engine compartment, in addition to housing the thermal engine and a gearbox, also accommodates an electric motor interacting with this gearbox. The components and accessories of these engines are therefore generally closer together.

[0003] This heat engine uses different types of sensors, among which there is a top dead center sensor which is usually located substantially at the junction of the heat engine and the gearbox.

[0004] It is known in the prior art to protect this sensor by means of a heat shield. Currently, the heat shield is arranged in front of the sensor and is in the form of a metal sheet whose role is to shield the heat released by components of the sensor present in the engine compartment.

[0005] In a particularly restricted engine compartment and where the number of components increases, the top dead center sensor, although protected by a prior art heat shield, is subjected to thermal stresses which are likely to distort its detection capacity. Indeed, at excessively high temperatures, the operation of the sensor is disrupted. The integrity of the electrical connections with a vehicle harness is also threatened by the high temperature which results, for example, from proximity to a catalytic converter or to an exhaust gas recirculation system.

[0006] Such a heat shield is also subject to dimensional constraints due to the components already present and which clutter the engine compartment. There is therefore today a need to improve the protection performance of the heat shield.

[0007] The present invention provides a heat shield crossed by a channel which transports a cooling fluid in order to better protect the sensor from the heat diffused by components of the thermal engine, for example the exhaust gas recirculation system, in particular its cooling exchanger. exhaust gases, and / or the catalytic converter located in the immediate vicinity of the sensor.

[0008] The main subject of the present invention is thus a heat shield for protecting a sensor of a motor vehicle, comprising at least one wall intended to shield thermal radiation and at least one support for fixing the heat shield, characterized in that at least the wall comprises at least one channel intended to be used by a cooling fluid of the motor vehicle.

[0009] The heat shield and its channel, as well as the sensor, are components of a powertrain of the vehicle, this powertrain comprising other elements or components releasing heat during their operation.

[0010] The heat shield according to the invention thus forms a more effective thermal barrier than the prior art because it is able to transfer the calories that it captures to a cooling fluid by means of its channel. It can therefore on a first face undergo significant thermal radiation, due to the proximity of hot components, while limiting the transfer of thermal energy on the sensor side, since this is transferred to the cooling fluid which circulates in the channel of the heat shield according to the invention.

[0011] The heat shield may comprise several walls intended to block the passage of thermal energy produced by certain components of the powertrain, so that this thermal energy does not reach the surrounding region of the sensor, which ultimately preserves the proper functioning of the latter.

[0012] The channel is any recess, conduit or space in the wall through which a coolant can flow. The wall may comprise a single channel or a plurality of channels.

[0013] According to another characteristic of the invention, the heat shield comprises at least one inlet interface through which a cooling fluid can enter the channel and at least one outlet interface through which the cooling fluid can exit the channel. Such interfaces are, for example, male sleeves on which a hose of the cooling circuit is positioned. The inlet interface and the outlet interface are advantageously arranged at two opposite ends of the wall of the heat shield according to the invention.

[0014] According to another characteristic of the invention, the wall of the heat shield comprises a first portion and a second portion, the second portion extending in a plane intersecting a plane of the first portion, the channel extending in the first portion and in the second portion.

[0015] The second portion of the heat shield extends at an angle substantially equal to 90° + / -15° relative to the first portion.

[0016] The sensor protection is thus more efficient since the thermal screen is in able to encompass or surround the sensor, and thus shield thermal radiation in at least two intersecting directions. This can be useful when the sensor is surrounded by two heat sources, for example.

[0017] The invention also covers an assembly which comprises a sensor of a heat engine of a motor vehicle and a heat shield as described in the present document. It is thus possible for the sensor and the heat shield according to the invention to be linked to each other before mounting on the powertrain so as to form a subassembly.

[0018] The invention also relates to a powertrain which comprises at least one heat engine and a gearbox coupled to the heat engine, said powertrain comprising the assembly mentioned above.

[0019] According to an optional feature of the invention, the sensor is a top dead center sensor. The heat shield is here assigned to the protection of this top dead center sensor because it is a sensor particularly sensitive to thermal radiation and installed in a position particularly close to several heat sources of the powertrain.

[0020] According to a characteristic of the invention, the powertrain comprises at least one catalytic converter and at least one exhaust gas recirculation system, the heat shield being arranged between the sensor and the catalytic converter and / or the exhaust gas recirculation system, in particular between this sensor and a heat exchanger of the exhaust gas recirculation system. The proximity between this heat exchanger and the heat shield according to the invention is used to divert a portion of the coolant to the heat shield according to the invention.

[0021] The arrangement of the heat shield between the sensor and the catalytic converter and / or the exhaust gas recirculation system of the heat engine makes it possible to shield the thermal radiation emitted by the catalytic converter and / or the exhaust gas recirculation system, when they are operating, in order to reduce heating of the sensor.

[0022] According to another characteristic of the invention, the powertrain comprises a cooling circuit for at least the heat engine, the channel of the heat shield forming part of the cooling circuit.

[0023] When the powertrain includes an electric motor which participates in the traction of the vehicle, the cooling circuit also runs through the electric motor to cool it.

[0024] The cooling circuit channels a coolant which extracts calories from the engine(s) and transports them into a heat exchanger where these calories are discharged into another fluid, for example air.

[0025] According to another characteristic of the invention, the cooling circuit comprises at least a first branch assigned to the cooling of the exhaust gas recirculation system and a bypass branch which comprises at least the channel, the first branch and the bypass branch being fluidically in parallel with each other. It is understood here that the coolant passes simultaneously in the first branch and in the bypass branch. The heat exchange which takes place in the heat shield between the wall and the coolant is therefore distinct from the heat exchange carried out within the exhaust gas recirculation system. The bypass branch is thus qualified in that it diverts a portion of the coolant which circulates in the first branch to supply the channel of the heat shield. Once this channel has been used, the coolant rejoins the first branch.

[0026] The bypass branch of the cooling circuit is connected to the inlet interface and the outlet interface of the heat shield, while the first branch is connected to the exhaust gas recirculation system. It is understood here that the heat shield and the exhaust gas recirculation system are two strategic elements of the powertrain to be cooled to preserve the proper functioning of these components. Other characteristics, details and advantages of the invention will emerge more clearly on reading the description of a detailed embodiment which follows, given for informational and non-limiting purposes with reference to the appended schematic drawings, in which:

[0027] [Fig. 1] is a partial and perspective representation of a powertrain of a vehicle, equipped with a heat shield according to the invention;

[0028] [Fig.2] is a schematic representation illustrating the arrangement of certain components of the powertrain 2 of [Fig.l].

[0029] The features, variants and the different embodiments of the invention, as they have been described or as they will be presented in the detailed description which follows, can be associated with each other, in various combinations, to the extent that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0030] As a reminder, the invention proposes a heat shield 1 intended to equip a powertrain 2 of a motor vehicle and making it possible in particular to provide a thermal barrier function for a sensor 4 housed for example in a gearbox of the powertrain 2. This heat shield 1 is particular in that it has a channel 6 configured to allow the circulation of a cooling liquid, so as to increase its capacity to ward off thermal energy in order to limit the temperature of the air surrounding the sensor 4, and thus guarantee its proper functioning.

[0031] [Fig.l] represents a partial view of the powertrain 2 intended to be integrated into a motor vehicle, and equipped with such a heat shield 1.

[0032] As detailed in [Fig.l], the powertrain 2 comprises a set of components, including a gearbox 10 arranged on the left part of [Fig.l] and a heat engine 12 arranged on the right part of [Fig.l]. A sensor 4 is arranged at the junction of the gearbox 10 and the heat engine 12. Such a sensor 4 is for example a top dead center sensor of the heat engine 12. Furthermore, the sensor 4 is located near a heat shield 1 according to the invention. When they are both associated with each other, they form a set. [Fig.l] shows an environment relating to a top dead center sensor, but it is understood that the invention is not limited to such a sensor. The improved heat shield according to the invention is therefore intended to protect any sensor which may equip a heat engine.

[0033] The heat shield 1 has the function of protecting the sensor 4 against the heat induced by an exhaust gas recirculation system 14 and / or by a catalytic converter 16 (illustrated in [Fig.2]), also constituting the powertrain 2. The exhaust gas recirculation system 14, the catalytic converter 16, the sensor 14 and the heat shield 1 are arranged close to each other. With regard to the exhaust gas recirculation system 14, it is noted that the heat shield 1 is adapted to shield the thermal energy which is released by a specific heat exchanger of this exhaust gas recirculation system 14. The temperature of such a heat exchanger is particularly high because this component implements a heat exchange between the exhaust gases at the immediate outlet of the heat engine and a cooling fluid.The heat shield 1 thus finds a particular application with regard to this heat exchanger of the exhaust gas recirculation system 14.

[0034] When the heat engine 12 is in operation, the exhaust gas recirculation system 14 and the catalytic converter 16 release significant thermal radiation, responsible for an increase in the temperature in the environment of the powertrain 2. For this reason, the heat shield 1 is precisely arranged between the sensor 4 and this exhaust gas recirculation system 14 and / or the catalytic converter 16, so as to block this thermal radiation.

[0035] As detailed in [Fig.2], the heat shield 1 comprises one or more walls 20 configured to shield the thermal radiation released by the cooling system. culation of the exhaust gases 14 and / or the catalytic converter 16 when these two elements are in operation. The walls 20 of the heat shield 1 comprise at least one first portion 22 and one second portion 24. In the example illustrated here, the first portion 22 is perpendicular to the second portion 24 so as to form an L-shaped heat shield. Such a conformation is advantageous in that it makes it possible to surround the sensor 4 on at least two of its sides, so as to protect it as well as possible. Of course, the orthogonal arrangement of the portions is not limiting and they can be arranged differently, as long as their respective planes are intersecting, as is for example the case in [Fig. 1].

[0036] The heat shield 1 also comprises a fixing support 40 secured to the wall. This fixing support 40 carries the wall and its channel, and makes it possible to secure the heat shield to the powertrain.

[0037] At least one of the portions 22, 24, and advantageously the first portion 22 and the second portion 24, comprises the channel 6 in which the cooling liquid 8 circulates, represented by arrows in [Fig. 2]. In doing so, the cooling liquid captures calories present on the wall of the heat shield 1 according to the invention, and evacuates them from the area where the sensor 4 is located.

[0038] The first portion 22 comprises a first interface 26 of the heat shield 1. The second portion 24 comprises a second interface 28 of the heat shield 1. The first interface 26 is the part through which the coolant 8 enters the channel 6. The second interface 28 is the part through which the coolant 8 leaves the channel 6. These interfaces 26, 28 can receive pipes 30, 32, the end of which is threaded onto the interface, then sealed by means of a collar.

[0039] The channel 6 is part of the cooling circuit 34 of the heat engine 12. The cooling circuit 34 comprises a first branch 36 dedicated to the cooling of the exhaust gas recirculation system 14, in particular its heat exchanger. The cooling circuit 34 also comprises a bypass branch 38, which from a fluidic point of view, is at least partly in parallel with the first branch 36.

[0040] According to the example illustrated in Figures 1 and 2, the bypass branch 38 is attached to the first branch 36. It is understood here that the bypass branch 38 originates on the first branch 36, upstream of the heat shield 1, and joins it downstream of this same heat shield 1.

[0041] The bypass branch 38 comprises the channel 6 which passes through the heat shield 1, for the passage of the coolant 8 circulating in the direction of the arrows shown in [Fig.2]. The cooling circuit 34, by channeling the coolant 8, thus makes it possible to capture calories present at the level of the exhaust gas recirculation system 14 as well as at the level of the heat shield 1 according to the invention.

[0042] This prevents the sensor 4, for example a top dead center sensor, from being subjected to too high a temperature, which would be likely to distort the measurement or detection of this sensor 4.

[0043] The heat shield 1 is fixed to the gearbox casing 10 by any fixing means, for example using a screw 42 which secures the fixing support 40 to the gearbox.

[0044] The invention, as just described, achieves the aim it set itself, and makes it possible to propose a heat shield which can be optimized and more efficient compared to the heat shields currently used to provide a cooling function making it possible to reduce the temperature of the environment of a sensor integrated into a vehicle, while retaining the arrangement of the elements attached to this sensor.

[0045] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically effective combination of such means.

Claims

Claims

1. Powertrain (2) of a motor vehicle comprising at least one heat engine (12) and a gearbox (10) coupled to the heat engine (12), said powertrain (2) comprising an assembly comprising a sensor (4) of the heat engine (12) and a heat shield (1) for protecting the sensor (4), the sensor (4) being a top dead center sensor, the heat shield (1) comprising at least one wall (20) intended to shield thermal radiation and at least one fixing support (40) of the heat shield (1), characterized in that at least the wall (20) comprises at least one channel (6) intended to be used by a cooling fluid (8) of the motor vehicle.

2. Powertrain (2) according to claim 1, wherein the heat shield (1) comprises at least one inlet interface (26) through which a cooling fluid (8) can enter the channel (6) and at least one outlet interface (28) through which the cooling fluid (8) can exit the channel (6).

3. Powertrain (2) according to claim 1 or 2, wherein the wall (20) of the heat shield (1) comprises a first portion (22) and a second portion (24), the second portion (24) extending in a plane intersecting a plane of the first portion (22), the channel (6) extending in the first portion (22) and in the second portion (24).

4. Powertrain (2) according to any one of the preceding claims, comprising at least one catalytic converter (16) and at least one exhaust gas recirculation system (14), characterized in that the heat shield (1) is arranged between the sensor (4) and the catalytic converter (16) and / or the exhaust gas recirculation system (14).

5. Powertrain (2) according to any one of the preceding claims, comprising a cooling circuit (34) of at least the heat engine (12), the channel (6) of the heat shield (1) forming part of the cooling circuit (34).

6. Powertrain (2) according to the preceding claim, in which the cooling circuit (34) comprises at least a first branch (36) assigned to the cooling of the exhaust gas recirculation system (14) and a bypass branch (38) which comprises at least the channel (6), the first branch (36) and the bypass branch (38) being fluidically parallel to each other.

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