Thermal fuse using Peltier and piezoelectric effect

Abstract

Peltier and Piezoelectric Thermal Fuse Passive cooling flow modulation device (1, 10) mounted in a wall (2) of a turbomachine separating a first zone (100) from a second zone (200) colder than the first, said wall (2) having an orifice (3) putting the first zone (100) in communication with the second zone (200).The device (1, 10) comprises a Peltier module (4) configured to generate an electrical voltage from a temperature gradient threshold, and housed in said wall (2) of the turbomachine, a plug (5, 50) having a first position suitable for blocking the orifice (3) and a second position suitable for unblocking the orifice (3), and at least one piezoelectric actuator (6, 60) electrically coupled to the Peltier module (4) and configured to maintain the plug (5, 50) in its first position in the absence of an electrical voltage from the Peltier module (4), and to actuate the plug in its second position in the presence of an electrical voltage and thus allow the injection of a cooling airflow (8) through the orifice (3). Fig. 1.

Description

Title of the invention: Thermal fuse using Peltier and piezoelectric effect. Technical field

[0001] The present exposition relates generally to turbomachinery, and more particularly to the passive modulation of a cooling flow in a cavity. Prior art

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0006] Turbines such as those used in aircraft turbomachinery generally comprise alternating stages of peripherally mounted stator blades and rotating blades. The stator blades may be attached to a stationary component such as a housing surrounding the turbine, and the rotating blades may be attached to a rotor located along a central axial line of the turbine. A compressed working fluid, such as steam, combustion gases, or air, flows along a gas path through the turbine to produce work. The stator blades accelerate and direct the compressed working fluid to a subsequent stage of rotating blades to transmit motion to the rotating blades, thus turning the rotor and doing work.

[0007] Various components (e.g., blades, nozzles, fairings, etc.) and areas (e.g., wheel spaces between the stator and rotor) of turbines are generally cooled in one way or another to remove the heat transferred by the path of the hot gas.

[0008] A gas such as compressed air from an upstream compressor can be supplied by at least one cooling circuit comprising one or more cooling passages to cool the turbine.

[0009] Furthermore, some ventilation flow rates are calibrated for critical cases and are therefore oversized for nominal operating conditions, resulting in lower efficiency. These flow rates are also often calibrated using fixed-section holes, which prevents adjustment.

[0010] Ventilation flow rates sized for failure scenarios result in efficiency losses under nominal conditions. One solution is to use additional flow rates activated only for failure scenarios. These flow rates must activate passively (based on temperature, for example) and must not be a source of lost material (such as a solid blockage that melts in the event of a failure).

[0011] There is therefore a real need to obtain a cooling system which is free, at least in part, from the disadvantages inherent in the aforementioned known configuration. Description of the invention

[0012] In a first aspect of the invention, a passive cooling flow modulation device is proposed for mounting in a wall of a turbomachine separating a first zone having a first temperature and a second zone having a second temperature lower than the first temperature, said wall having an orifice extending through the wall and putting the first zone in fluidic communication with the second zone,

[0013] According to a general feature of the invention, the device comprises: - a Peltier module configured to generate an electrical voltage from a temperature gradient threshold, and intended to be housed in said turbomachine wall, - a plug having a first position suitable for blocking said orifice and a second position suitable for releasing said orifice, and - at least one piezoelectric actuator electrically coupled to the Peltier module and configured, on the one hand, to maintain the stopper in its first position in the absence of electrical voltage from the Peltier module, and, on the other hand, to actuate the stopper in its second position in the presence of an electrical voltage delivered by the Peltier module and thus allow the injection of a cooling airflow through the orifice from the second zone to the first zone in response to a temperature increase in the first zone.

[0014] The device according to the invention uses the Seebeck effect of the Peltier module to power said at least one piezoelectric actuator and thus actuate the stopper to open the orifice in the presence of a supply voltage or a supply voltage above a threshold, or to close the orifice in the absence of a voltage or as long as the voltage is below the voltage threshold. The device thus functions as a thermal fuse, that is to say, a passive device reacting according to the temperature, and more precisely according to the temperature gradient, that is to say, the temperature difference that exists between the first zone and the second zone, the second zone corresponding to the supply duct for the cooling flow.

[0015] Furthermore, having a device that uses both a Peltier module and at least one piezoelectric actuator powered by the Peltier module to actuate a stopper offers the possibility of a configuration with the Peltier module located remotely from the stopper blocking the orifice. The Peltier module can thus be positioned strategically relative to the orifice that the stopper seals. In other words, the sensor (Peltier module) can be located remotely from the stopper and piezoelectric actuator(s) to perform the action.

[0016] According to a first embodiment, said at least one piezoelectric actuator may include a control module equipped with a voltage threshold comparator, the control module being configured to receive the voltage delivered by the Peltier module, compare it to an actuation voltage threshold, and actuate said at least one piezoelectric actuator when the voltage delivered by the Peltier module is greater than or equal to said activation voltage threshold.

[0017] According to a second embodiment, said at least one piezoelectric actuator and the cap can be configured with a reversible operation allowing alternation between the first position and the second position of the cap to open or close the orifice.

[0018] The thermal fuse thus created is a reusable thermal fuse.

[0019] According to a third embodiment, the passive device for modulating the cooling flow may comprise a ball as a stopper and two actuators piezoelectric each comprising a pivoting support rod cooperating together to move the ball between its first position and its second position.

[0020] The support rods can be moved to allow the rod to descend from the first position blocking the orifice to the second position opening the orifice, without the ball no longer being supported by the rods. The sphericity of the ball allows for different diameters at different heights, thus enabling it to be supported by two rods on either side of the connecting rod while being at different heights relative to the orifice.

[0021] In one embodiment, the device may further include a ball retention net allowing the ball to be held in a position distant from the orifice but close enough to the rods then spread apart to be caught again by the rods when they close to bring the ball back into the first position of plugging the orifice.

[0022] According to a fourth embodiment, the cap may comprise a cap and an articulated actuating rod configured to translate the cap between the first position and the second position, the device comprising a single piezoelectric actuator having a pusher acting on the articulated actuating rod.

[0023] In another aspect of the invention, a turbomachine is proposed comprising a wall separating a first zone having a first temperature from a second zone having a second temperature lower than the first temperature, said wall having an orifice extending through the wall and putting the first zone in fluidic communication with the second zone, said wall of the turbomachine comprising a passive flow modulation device as defined above.

[0024] One of said at least one wall is a wall of a stator of the turbomachine, and / or one of said at least one wall is a wall of a rotor of the turbomachine.

[0025] In another aspect of the invention, an aircraft is proposed comprising at least one turbomachine as defined above.

[0026] The aforementioned features and advantages, as well as others, will become apparent from the following detailed description and examples of embodiments of the invention. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0027] The attached drawings are schematic and are intended primarily to illustrate the principles of the exposition.

[0028] On these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs.

[0029] [Fig-1] Fig. 1 schematically illustrates a passive flux modulation device cooling according to a first embodiment in a first position.

[0030] [Fig.2] The [Fig.2] shows the passive device for modulating the cooling flow in a second position.

[0031] [Fig.3] Fig.3 shows the stopper and the piezoelectric actuators of the device of figures 1 and 2 in the first position.

[0032] [Fig.4] Fig.4 shows the stopper and the piezoelectric actuators of the device of figures 1 and 2 in the second position.

[0033] [Fig.5] Fig.5 shows the plug and piezoelectric actuators of a passive cooling flow modulation device according to a second embodiment.

[0034] [Fig.6] Fig.6 shows the stopper and the piezoelectric actuators of the device of Fig.5 in the second position. Description of the implementation methods

[0035] To make the explanation more concrete, an example of a passive cooling flow modulation device is described in detail below, with reference to the accompanying drawings. It should be noted that the invention is not limited to this example.

[0036] Figure 1 schematically illustrates a passive cooling flow modulation device 1 according to a first embodiment inserted into a wall 2 of a stator or rotor of a turbomachine. In this Figure 1, the device is in a first configuration that does not allow any cooling flow to pass through.

[0037] Figure 2 schematically illustrates the passive cooling flow modulation device 1 of Figure 1, but in a second configuration allowing a cooling flow to pass through.

[0038] Wall 2 separates a first zone 100 from a second zone 200. The first zone 100 has a first temperature, while the second zone 200 has a second temperature lower than the first temperature. Wall 2 has an orifice 3 extending through the wall 2 and establishing fluidic communication between the first zone 100 and the second zone 200. Wall 2 is configured to receive the passive cooling flow modulation device 1, and more specifically to house the various elements of the device 1 within wall 2.

[0039] The passive cooling flow modulation device 1 comprises a Peltier module 4, a plug 5, and two piezoelectric actuators 6.

[0040] The Peltier module 4 is configured to generate an electrical voltage from a temperature gradient threshold. It is housed in a first housing provided in the wall 2.

[0041] In the first embodiment illustrated in particular in Figures 1 and 2, the stopper 5 is a ball which can be moved by the piezoelectric actuators 6 between a first position in which it blocks the orifice 3 and a second position in which a passage is opened between the mouth of the orifice 3 and the ball to allow a flow of cooling air to circulate from the second zone 200 to the first zone 100.

[0042] The two piezoelectric actuators 6 are electrically coupled to the Peltier module 4. Each comprises a pivoting support rod 65 that can be moved by an actuating rod 66. The support rods 65 cooperate to move the ball 5 between its first position and its second position, as illustrated more precisely in Figures 3 and 4. In the absence of a supply voltage delivered by the Peltier module 4, the support rods 65 of the piezoelectric actuators 6 are in a position illustrated in Figures 1 and 3, and thus hold the ball 5 in its first position, thereby blocking the orifice 3.In the presence of a supply voltage delivered by the Peltier module 4, the support rods 65 of the piezoelectric actuators 6 are in a position illustrated in figures 2 and 4, and release the ball 5 to move it into its second position, thus creating a passage and allowing the injection of a cooling airflow through the orifice 3 from the second zone 200 to the first zone 100 in response to a temperature increase in the first zone 100.

[0043] The Peltier module 4 delivers a voltage thanks to the Seebeck effect. Thus, from a certain temperature gradient between the first zone 100 and the second zone 200, the Peltier module 4 delivers a supply voltage to the piezoelectric actuators 6.

[0044] In one embodiment, a control module may be provided upstream or within the piezoelectric actuators 6, the control module comprising a comparator configured to compare the received voltage value to an actuation voltage threshold. If the received voltage is greater than the actuation voltage threshold, the piezoelectric actuators 6 are actuated. Otherwise, they are not.

[0045] The passive cooling flow modulation device 1 illustrated in Figures 1 and 2 further includes a ball retention net 7 attached to the wall 2 to hold the ball 5 within the orifice 3 of the wall 2 even when the ball is in the second position.

[0046] Figure 5 schematically illustrates a passive cooling flow modulation device 10 according to a second embodiment, inserted into a wall 2 of a stator or rotor of a turbomachine. In this Figure 5, the device 10 is in a first configuration, not allowing any cooling flow to pass through.

[0047] Figure 6 schematically illustrates the passive cooling flow modulation device 10 of Figure 5, but in a second configuration allowing a cooling flow 8 to pass through.

[0048] In the second embodiment illustrated in figures 5 and 6, the device still includes a Peltier module 4, but the ball acting as a stopper is replaced by a stopper 50 guided in translation and an articulated actuating rod 55 configured to translate the stopper 50 between a first position blocking the orifice 3 and a second position opening a passage for a cooling flow 8. The stopper 50 is for example frustoconical.

[0049] The articulated rod comprises three connecting rods 56 mechanically coupled in series by ball joints 57 providing the articulation. One of these three connecting rods 56 is integral with the plug 50. The length of the articulated actuating rod 55 can thus be modulated between an extended, or deployed, position, in which the articulated actuating rod 55 has its maximum length and pushes the frustoconical plug 50 into the orifice 3 to plug the latter as illustrated in [Fig. 5], and a compact, or folded, position, in which the articulated actuating rod 55 has a length shorter than the maximum length and displaces the frustoconical plug 50 out of the orifice 3, thus freeing a passage for a cooling flow 8 as illustrated in [Fig. 6].

[0050] In this second embodiment, the device 10 comprises a single piezoelectric actuator 60 equipped with a pusher acting on the articulated actuating rod at the level of a ball joint to move the articulated rod out of its stretched position.

[0051] The articulated actuating rod 55 further comprises a spring 58 mechanically coupled between the articulated actuating rod 55 and a support 20 mechanically fixed to the wall 2, enabling the spring to exert a thrust to keep the frustoconical plug 50 closed in the deployed position of the articulated actuating rod 55. More specifically, the thrust of the spring 58 is transmitted to the plug 50 via the articulated actuating rod 55 and a piston. This piston is interposed between the spring 58 and a ball joint 57 at the end of the rod 55, the ball joint forming a articulation between the rod 55 and the piston. In this deployed position, the two connecting rods 56, articulated at their two ends, have slightly moved beyond a position of strict alignment to remain slightly misaligned against a stop as shown in [Fig. 5].The effort required by the pusher 62 of the piezoelectric actuator 60 to unlock this deployed position and cause the opening of the cap 50 depends in particular on the stiffness of the spring 58.

[0052] Optionally, particularly if the wall 2 is a wall of an annular stator of the turbomachine, an additional spring 59 with a lower stiffness, compared to the stiffness of the spring 58, may be provided at least for the plugs 50 arranged on one upper half of the wall 2. Each additional spring 59 provides a force in the opposite direction to that of the corresponding spring 58, and is provided sufficient to overcome the weight of a plug 50 and an articulated actuating rod 55 arranged at 12 o'clock on the wall annular 2. In this way, the opening of the cap 50 following the unlocking of the closed position by the piezoelectric actuator 60 is guaranteed by the effort of the additional spring 59 despite the fact that the weight of the cap tends to bring it back to the closed position.

[0053] Piezoelectric actuators can be direct or amplified actuators using multilayer ceramics. The displacement obtained in direct actuators is equal to the deformation of the piezoelectric material, allowing strokes between 0 and 100 µm. However, they can also be, and more generally will be, amplified actuators, in which a mechanical device amplifies this movement by a factor of 2 to 20. Amplified actuators generally have strokes between 0.1 and 1 mm.

[0054] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

Claims

Demands

1. A passive cooling flow modulation device (1, 10) intended to be mounted in a wall (2) of a turbomachine separating a first zone (100) having a first temperature and a second zone (200) having a second temperature lower than the first temperature, said wall (2) having an orifice (3) extending through the wall (2) and putting the first zone (100) in fluidic communication with the second zone (200), characterized in that the device (1, 10) comprises: - a Peltier module (4) configured to generate an electrical voltage from a temperature gradient threshold, and intended to be housed in said wall (2) of the turbomachine, - a plug (5, 50) having a first position adapted to plug said orifice (3) and a second position adapted to release said orifice (3), and - at least one piezoelectric actuator (6, 60) electrically coupled to the Peltier module (4) and configured, on the one hand, to hold the cap in place (5,50) in its first position in the absence of electrical voltage from the Peltier module (4), and, on the other hand, to actuate the stopper in its second position in the presence of an electrical voltage delivered by the Peltier module (4) and thus allow the injection of a cooling airflow (8) through the orifice (3) from the second zone (200) to the first zone (100) in response to a temperature increase in the first zone (100).

2. Passive flux modulation device (1, 10) according to claim 1, wherein said at least one piezoelectric actuator (6, 60) comprises a control module having a voltage threshold comparator, the control module being configured to receive the voltage delivered by the Peltier module (4), compare it to an actuation voltage threshold, and actuate said at least one piezoelectric actuator (6, 60) when the voltage delivered by the Peltier module (4) is greater than or equal to said activation voltage threshold.

3. A passive flow modulation device (1, 10) according to any one of claims 1 to 2, wherein said at least one piezoelectric actuator (6, 60) and the plug (5, 50) are configured with reversible operation allowing alternation between the first position and the second position of the cap (5, 50) to open or close the orifice (3).

4. Passive flow modulation device (1) according to any one of claims 1 to 3, comprising a ball (5) as a stopper and two piezoelectric actuators (6) each having a pivoting support rod (6) cooperating together to move the ball (5) between its first position and its second position.

5. Passive flow modulation device (10) according to any one of claims 1 to 3, wherein the stopper (50) is connected to an articulated actuating rod (55) configured to translate the stopper (50) between the first position and the second position, the device (10) comprising a single piezoelectric actuator (60) having a pusher acting on the articulated actuating rod (55).

6. Turbomachine comprising at least one wall (2) separating a first zone (100) having a first temperature from a second zone (200) having a second temperature lower than the first temperature (100), said wall (2) having an orifice (3) extending through the wall (2) and putting the first zone (100) into fluidic communication with the second zone (200), characterized in that said wall (2) of the turbomachine comprises a passive cooling flow modulation device (1, 10) according to any one of claims 1 to 5.

7. Turbomachine according to claim 6, wherein at least one of said walls (2) is a wall of a stator of the turbomachine.

8. Turbomachine according to any one of claims 6 or 7, wherein at least one of said walls (2) of the turbomachine is a wall of a rotor of the turbomachine.

9. Aircraft comprising at least one turbomachine according to any one of claims 6 to 8.

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