CLIMATIC CHAMBER HAVING THERMAL REGULATION FOR MOTION SIMULATOR, AND METHOD FOR THERMAL REGULATION, AND INSTALLATION KIT

In a thermally regulated climate chamber for testing equipment, a thermoelectric unit is arranged through the wall of the climate chamber, each thermoelectric unit having two faces, an internal face inside the climate chamber and an external face outside the climate chamber, wherein a heat exchange end for an external face of a thermoelectric unit of a secondary thermal regulation circuit is placed in thermal contact with each external face of thermoelectric unit, the secondary thermal regulation circuit being external to the climate chamber and including a heat-transfer fluid circuit, a cold source, a hot source, a mixing device, a circulation pump and sensors. A chamber temperature regulation system controls the electric current of the thermoelectric unit and to control at least the mixing device and the circulation pump of the secondary thermal regulation circuit as a function of a chamber temperature setpoint and of sensor measurements.

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Description
TECHNICAL FIELD

The present invention generally relates to the field of metrology. It relates to a thermally regulated climate chamber that may be embedded in a motion simulator as well as a thermal regulation method. It may also relate to a kit for installation of a thermally regulated climate chamber for a motion simulator. It finds applications for thermal characterization of equipment subject to dynamical tests in a motion simulator.

TECHNOLOGICAL BACKGROUND

Motion simulators are rotary machines intended to test equipment which may be sensors such as insulated inertial components or complete inertial systems, typically gyrometers, accelerometers, inertial units . . . . Most of these tests require a temperature characterization in order to evaluate and be able to compensate for the thermal drift of the equipment, both statically, i.e. by temperature steps, and dynamically, i.e. as a temperature ramp. In both cases, temperature setpoint following and temperature stability are important performance indicators. It is moreover preferable that the tests can be performed over a very wide range of temperatures, for example between −55° C. and +125° C.

For that purpose, climate chambers are conventionally implemented, in which the equipment is installed, the climate chamber being installed in a typically multi-axis motion simulator.

The known refrigeration systems used in motion simulators are conventionally of the mechanical type, based on the inverted Rankine cycle or of the open circuit type by liquid-phase CO2 or N2 expansion. These systems allow obtaining a very wide temperature range.

In the case of open-circuit systems, the gas is lost after expansion in the climate chamber and it is necessary that means are provided for controlling the level of oxygen in ambient air in the case of N2 or the level of gas used in the case of CO2. Mechanical systems operate in closed-circuit, without the level of oxygen in the air has to be controlled, and they use an evaporator in the climate chamber, which thus increases the weight of the latter and penalizes both the dynamics and the bandwidth of the motion simulators.

The previous systems use solenoid valves, usually of the on/off type, to control the liquid flow towards the evaporator and thus the cooling power in the climate chamber. The solenoid valve driving may compromise the position and speed stability performances through at least two phenomena which may be likened to impacts on the mechanical structure of the simulator:

    • motions of the solenoid valve armature, and
    • water hammers in the hydraulic circuit of the liquid phase.

Moreover, the operation is not continuous, because it consists of a series of successive cycles of refrigerant fluid injection/evaporation in the evaporator in the mechanical refrigeration case, or even of liquid N2 or CO2 directly in the volume of the climate chamber in the open circuit case. These cycles moreover generate a cooling power variation during the tests. This is known as pulse width modulation or PWM driving, the pulse width being the relative opening time of the solenoid valve, called cyclic ratio. An operating periodicity of several seconds is not negligible in view of the thermal inertia of the various components of the climate chamber, and it results therefrom unavoidable oscillations of the temperature. Moreover, this periodicity also penalizes the bandwidth insofar as it induces a pure delay in the control of the system.

It has therefore been proposed to use static refrigeration systems based on thermoelectric modules in order to avoid the above-mentioned problems. Indeed, the thermoelectric modules, also called Peltier modules, have several advantages:

    • Accurate regulation thanks to their great linearity and continuous operation: the power is constantly proportional to the current around an operating point.
    • Low time constant compared to the mechanical systems, which allows a significant increase of the system bandwidth and the disturbance rejection thereof and thus the temperature stability. The time constant is then negligible with respect to thermal inertia of the various components of the climate chamber.
    • Fully static system: without mechanical disturbances, contrary to the systems with fluids and embedded solenoid valves.
    • Use of thermoelectric modules for heat or cold production thanks to the reversibility thereof.

A thermoelectric cooling module has already been implemented in a motion simulator, but this has been made by installing the thermoelectric module directly on the equipment to be tested for temperature characterization thereof. The cooling is thus performed by direct conduction on the tested equipment as is standard practice in electronics for thermoelectric modules. There was therefore no thermal regulation by a climatic chamber.

Now, the equipment to be tested is generally a complex device whose surface may be consisted of materials having very different or low thermal conductivities and/or have irregular shapes limiting or preventing the direct attachment of one or several thermoelectric modules to the equipment.

It is therefore preferable to use a climate chamber in which the equipment to be tested may be installed, the temperature regulation being ensured inside the climate chamber.

Thermoelectric modules nevertheless suffer from certain limitations. In particular, at ambient temperature, single-stage thermoelectric modules do not produce more than 70-80° C. temperature difference, ΔT, between their cold and hot faces with powers of several hundreds watts in ideal conditions. The multi-stage versions (2, 3 or even 4 or 5 stacked modules, that is to say thermally in series) accept a greater temperature difference, ΔT, (up to 130° C.) but at the cost of very low powers, of the order of about twenty watts at ΔT=0, which makes them suitable for specific applications such as CCD/CMOS sensor cooling in order to reduce the thermal noise thereof. Indeed, the power and ΔT of the thermoelectric modules depend on the hot face temperature.

In conventional solutions, a forced convection heat sink is often used on the hot face, but this one cannot go below ambient temperature, which limits the low temperature range that may be reached on the cold face.

Solutions have been proposed in this field, which are exposed in the following documents: U.S. Pat. No. 3,252,504 A, DE 10 2010 026601 A1 and WO 2008/010675 A1.

DISCLOSURE OF THE INVENTION

It is proposed, within the framework of the invention that relates to a climate chamber with thermoelectric unit(s), in particular for a motion simulator, to implement a secondary thermal regulation circuit that is applied to the faces(s) of the thermoelectric unit(s) that are outside the chamber, and that includes a means for cooling or heating a heat-transfer fluid of said secondary thermal regulation circuit and for exchanging caloric energy (or “calories” in the following of the text) with said external face(s) of the thermoelectric unit(s). In this system, the thermoelectric unit(s) of the climate chamber form a primary thermal regulation device. Moreover, the climate chamber inside, which is subject to the internal face(s) of the thermoelectric unit(s), is preferably of the forced convection type.

It is therefore possible to obtain a very wide range of temperatures while implementing a static thermal regulation device on the climate chamber. The secondary thermal regulation circuit implements one or several thermoelectric regulation units each including one or several thermoelectric modules.

More precisely, it is proposed according to the invention a thermally regulated climate chamber intended to test at least one piece of equipment, the climate chamber having a wall defining an internal space containing a gas and able to receive and contain said at least one piece of equipment to be tested, the internal space being thermally insulated from the environment outside the climate chamber, wherein at least one thermoelectric unit is arranged through the wall of the climate chamber, each thermoelectric unit having two faces, an internal face located inside the climate chamber and an external face located outside the climate chamber, and wherein one of both faces, called the cold face, is intended to absorb caloric energy, and the other one, called the hot face, is intended to reject caloric energy as a function of the electric current passing through said at least one thermoelectric unit, wherein a heat exchange end for an external face of a thermoelectric unit of a secondary thermal regulation circuit is placed in thermal contact with each external face of thermoelectric unit in order to exchange caloric energy between said at least one thermoelectric unit and said secondary thermal regulation circuit, the secondary thermal regulation circuit being external to the climate chamber and including a heat-transfer fluid circuit, a cold source, a hot source, a mixing device, a circulation pump and sensors, and wherein a chamber temperature regulation system is configured to control the electric current of said at least one thermoelectric unit and to control at least said mixing device and the circulation pump of the secondary thermal regulation circuit as a function of a chamber temperature setpoint and of sensor measurements.

It is understood that the principle of implementation of at least one thermoelectric unit arranged through, i.e. passing through, the wall of the climate chamber must be understood in a functional sense, which is to allow thermal exchanges between the climate chamber inside and outside. For example, the internal wall of the climate chamber may be metallic and the thermoelectric unit(s) are arranged against the external face of the metallic internal wall by passing through a layer of thermal insulation also arranged on the external face of this metallic internal wall.

Other non-limiting and advantageous features of the climate chamber according to the invention, taken individually or according to all the technically possible combinations, are the following:

    • a thermoelectric unit includes one or several thermoelectric modules, also called Peltier modules,
    • the secondary thermal regulation circuit thus includes a heat exchange end for an external face of a thermoelectric unit,
    • a gas mixing device is arranged inside the climate chamber in order to allow a mixing of the gas inside the chamber and on the internal face(s) of said at least one thermoelectric unit,
    • each internal face of thermoelectric unit includes a finned radiator,
    • the heat-transfer fluid remains in liquid phase in the secondary thermal regulation circuit,
    • the heat-transfer fluid has two phases, a gaseous phase and a liquid phase, in the secondary thermal regulation circuit,
    • preferably, the external face is a hot face and the internal face is a cold face, caloric energy being extracted from the inside of the climate chamber,
    • the external face is a cold face and the internal face is a hot face, caloric energy being sent inside the climate chamber,
    • the gas mixing device includes one or several fans,
    • the chamber temperature regulation system further controls the gas mixing device in order to adjust the gas mixing intensity in the chamber,
    • the internal space is thermally insulated from the environment outside the chamber, including the motion simulator, the chamber being attached to the motion simulator by thermally insulating fixings in order not to create thermal bridge between the motion simulator and the inside of the climate chamber,
    • the climate chamber is attached to a movable support of a motion simulator and the movable support can be set in motion by means of joints of said motion simulator,
    • in the case where the climate chamber is attached to the movable support of the motion simulator then, in the secondary thermal regulation circuit, the heat exchange end for an external face of a thermoelectric unit is arranged against the thermoelectric unit and is hence movable following the thermoelectric unit, the rest of the secondary thermal regulation circuit being arranged out of movable parts of the motion simulator and being connected to the heat exchange end by movable fluid seals passing through the joints of the motion simulator,
    • the climate chamber is fixed and motionless, a motion simulator being installed in the climate chamber, and the equipment is installed on a movable support of the motion simulator and the equipment may be set in motion by said motion simulator,
    • the temperature of the hot source is adjustable and the chamber temperature regulation system further adjusts the temperature of the hot source,
    • the chamber temperature regulation system is configured to regulate the temperature of the external face of the thermoelectric unit as a function of the chamber temperature setpoint and in such a way that the polarity of the current circulating in said at least one thermoelectric unit is constant, the internal face of the thermoelectric unit being a cold face absorbing caloric energy coming from the inside of the climate chamber,
    • one of the temperature sensors is a thermoelectric unit external face temperature sensor,
    • each thermoelectric unit includes a thermoelectric unit external face temperature sensor,
    • each thermoelectric unit is in contact with a heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit,
    • the heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit includes a fluid outlet on the downstream side and a temperature sensor is arranged on the fluid outlet of the heat exchange end of the secondary thermal regulation circuit,
    • the heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit includes a fluid outlet on the downstream side and the thermoelectric unit external face temperature sensor is arranged on the fluid outlet of the heat exchange end of the secondary thermal regulation circuit,
    • the external face temperature sensor is arranged against the external face of said at least one thermoelectric unit,
    • the chamber temperature regulation system is configured to ensure a continuous flow of the heat-transfer fluid in the heat exchange end of the secondary thermal regulation circuit,
    • the continuous flow of the heat-transfer fluid in the heat exchange end is a constant flow,
    • the continuous flow of the heat-transfer fluid in the heat exchange end is a smooth variable flow, the flow changes being progressive,
    • the chamber temperature regulation system is configured to control the heat-transfer fluid flow while avoiding a high-temperature cavitation of the heat-transfer fluid that would be due to a too high speed of the heat-transfer fluid,
    • the chamber temperature regulation system is configured to linearize the opening/flow ratio of the three-way valve by means of a piecewise interpolation in a look-up table,
    • the climate chamber includes at least one thermoelectric unit through the climate chamber,
    • a thermoelectric unit includes one thermoelectric module,
    • a thermoelectric unit includes several thermoelectric modules,
    • in a thermoelectric unit including several thermoelectric modules, the thermoelectric modules are electrically connected in series or in parallel or in a series-parallel arrangement,
    • the chamber includes at least two thermoelectric units through the climate chamber and the thermoelectric units are electrically connected in parallel,
    • a thermoelectric unit includes twenty thermoelectric modules electrically connected in series,
    • the chamber includes two units in parallel, each including five modules in series,
    • the chamber temperature regulation system includes at least two regulation loops, said at least two regulation loops being a main regulation loop controlling the electric current of said at least one thermoelectric unit and at least one secondary regulation loop controlling the secondary thermal regulation circuit,
    • the secondary regulation loop controlling the secondary thermal regulation circuit includes a hot and cold sharing regulation loop and a flow rate regulation loop,
    • the motion simulator includes movable fluid seals and movable electrical connections,
    • in the case of joints rotating about an axis, the movable fluid seals and the movable electrical connections are rotating,
    • in the case of translational joints, the movable fluid seals are flexible pipes and the movable electrical connections are flexible electrical cables.

The invention also relates to a method for thermal regulation of a climate chamber intended to test at least one piece of equipment, wherein a climate chamber with thermoelectric unit(s) according to the invention is implemented, said climate chamber being attached to a movable support of a motion simulator and the movable support being able to be set in motion through joints of said motion simulator, and wherein a secondary thermal regulation circuit including a heat exchange end for an external face of a thermoelectric unit is further implemented, the heat exchange end is arranged against the external face(s) of the thermoelectric unit(s), the rest of the secondary thermal regulation circuit being arranged out of movable parts of the motion simulator and being connected to the heat exchange end by movable fluid seals passing through the joints of the motion simulator.

The method can be declined according to all the procedural modes described or resulting from the functions of the physical means implemented.

In particular, a chamber temperature regulation system can also be implemented, which controls the electric current of said at least one thermoelectric unit and which controls at least the mixing device and the circulation pump of the secondary thermal regulation circuit as a function of a chamber temperature setpoint and of sensor measurements.

The invention finally relates to a kit for installation of a climate chamber in a motion simulator.

More precisely, it is a kit for installing a thermally regulated climate chamber in a motion simulator, the climate chamber being intended to test at least one piece of equipment, the motion simulator including a movable support set in motion by means of joints of said motion simulator, said kit including:

    • a climate chamber including a wall defining an internal space able to receive and contain said at least one piece of equipment to be tested, wherein the internal space can include a gas and is thermally insulated from the environment outside the climate chamber, the climate chamber including means for attachment to the movable support, the chamber further including at least one thermoelectric unit, said at least one thermoelectric unit being arranged through the wall of the climate chamber, each thermoelectric unit having two faces, an internal face located inside the climate chamber and an external face outside the climate chamber, and wherein one of both faces, called the cold face, is intended to absorb caloric energy and the other one, called the hot face, is intended to reject caloric energy as a function of an electric current passing through said at least one thermoelectric unit,
    • a secondary thermal regulation circuit including a heat-transfer fluid circuit, means for connection to a cold source, a hot source, a mixing device, a circulation pump and sensors, the heat-transfer fluid circuit having a heat exchange end for an external face of a thermoelectric unit intended to come into thermal contact with an external face of thermoelectric unit in order to exchange caloric energy between said at least one thermoelectric unit and said secondary thermal regulation circuit,
    • movable fluid seals intended to be installed in joints of the motion simulator to allow the circulation of the heat-transfer fluid of the secondary thermal regulation circuit between the heat exchange end that is intended to be installed in the motion simulator against the external face of the thermoelectric unit and the rest of the secondary thermal regulation circuit that is intended to be installed out of the movable parts of the motion simulator,
    • movable electrical connections intended to be installed in joints of the motion simulator to allow a circulation of electrical current,
    • a chamber temperature regulation system intended to control the electric current of said at least one thermoelectric unit and to control at least the mixing device and the circulation pump of the secondary thermal regulation circuit as a function of a chamber temperature setpoint and of sensor measurements.

The kit can further include a cold source.

The chamber of the kit can further include a gas mixing device, said gas mixing device being arranged inside the climate chamber in order to allow a mixing of the gas inside the chamber and on the internal face(s) of said at least one thermoelectric unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the primary thermal regulation device with a thermoelectric unit of the climate chamber, the latter being embedded in a motion simulator not shown, a heat exchange end of a secondary thermal regulation circuit being also shown,

FIG. 2 is a schematic view of the secondary thermal regulation circuit with heat-transfer fluid, external to the climate chamber, which is intended to exchange caloric energy with the hot face of the thermoelectric unit, and

FIG. 3 is a schematic view of an example of implementation with three regulation loops.

 DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description in relation with the appended drawings, given by way of non-limiting examples, will allow a good understanding of what the system and method of the invention consist of and of how they can be implemented.

In its principle, the system of the invention includes a thermal regulation of the internal volume of the climate chamber by arrangement in series/cascade of two thermal regulation means: a first one, called the primary thermal regulation device, and a second one, called the secondary thermal regulation circuit.

Thanks to the secondary thermal regulation circuit, it is possible to heat or cold the primary thermal regulation device, which allows increasing the temperature range reachable in the climate chamber as well as the thermal power available.

The primary thermal regulation device, which is static in its own operation, implements at least one thermoelectric unit to be able to control the temperature inside the climate chamber. For that purpose, at least one temperature sensor is arranged in the climate chamber. The internal face of each unit is located inside the climate chamber and the external face of each unit is located outside the climate chamber. Preferably, the internal face is the cold face and the direction of the current passing through the thermoelectric unit is thus imposed by the fact that the cold face, that which “sucks up” the calories, is on the internal side of/in the climate chamber. In certain operational alternatives, the internal face may become a hot face or a cold face by inversion of polarity of the current passing through the thermoelectric unit(s).

In the following description, it is described in priority a climate chamber that is movable because installed in a motion simulator and with a primary thermal regulation device whose internal face of the thermoelectric unit(s) is a cold face.

The climate chamber is integral with the motion simulator and is hence movable following the motions of the simulator joints, typically according to the axes of rotation and/or translation, and as a function of the way they are controlled. The motion simulator is typically multi-axes.

The climate chamber is filled with a gas. This gas may be air, ambient air or one or several specific gases other than air. The climate chamber, which may be open, in particular for positioning the equipment, and closed back, thermally insulates the inside of the chamber with respect of the external environment. The inside of the climate chamber may be air- and gas-tight and may be able to withstand vacuum or overpressure with respect to the outside, in particular for additional tests of (negative) pressure on the equipment. A tight climate chamber may also allow the introduction of specific gas(s), for example nitrogen or argon, for additional tests of tightness of the equipment itself, in particular for searching for leaks or risks of contamination in the equipment.

In other modes of implementation, the climate chamber is not designed to be tight to vacuum or overpressure pressure, the gaseous exchanges between the inside and the outside at pressure balance between the inside and the outside being however reduced and, in such a case, the internal gas is typically air and is at the environment atmospheric pressure.

The cold face of each thermoelectric unit 10, which is on FIG. 1 the internal face 11, includes a heat exchange surface that is preferably extended by the presence of a heater 1. The heat exchanges inside the climate chamber 3 are preferably favoured by a gas mixing device 2 internal to the climate chamber 3, typically at least one fan blowing or sucking on the exchange surface. A forced convection is hence implemented in the climate chamber 3. The heater 1 is a heat sink of the type used for cooling power components in electronics, for example a finned heater.

The hot face of the thermoelectric unit 10, that which “rejects” the calories “sucked up” by the cold face, is located outside the climate chamber and corresponds to the external face 14 of the thermoelectric unit 10.

Each thermoelectric unit is hence arranged through the wall of the climate chamber while avoiding the creation of a thermal bridge between the inside and the outside of the climate chamber.

The power supply of the thermoelectric unit(s) passes through the motion simulator joints and implements electrical connections with contacts or collectors, for example or the rotating or sliding type, or a contactless electrical energy transmission by induction or any other suitable means.

It is advantageous to implement several thermoelectric units and to connect the thermoelectric units in series to increase the supply voltage and thus reduce the flowing electrical current, thus limiting the wearing of the rotating electrical collectors arranged in the joints of the motion simulator and the CEM noise liable to be generated. It is also possible, by a suitable wiring between the thermoelectric units and using individual driving means, individually addressable, one for each thermoelectric unit, to reduce the total number of electrical links required, for example two for a power supply bus and one for a data link. The data may include addressed instructions sent to the individual driving means and sensor measurements with identifiers, the sensors being located in the motion simulator and in particular in the climate chamber.

In the preferred mode of implementation, in which there are several thermoelectric units, an individual and independent control of the power of each thermoelectric unit is implemented, based on the temperature of each cold face individually in the climate chamber. In such a case, each thermoelectric unit has its own cold face temperature sensor and its own current regulation.

In other modes of implementation, the control of power of the thermoelectric units is made as a whole for all the thermoelectric units, a single internal face temperature sensor or several temperature sensors with averaging of the internal face measurements being implemented and the current for all the thermoelectric units which are therefore regulated as a whole.

If a thermoelectric unit is consisted of several thermoelectric units, there is no individual regulation of each element (no sensor+element current regulation), the regulation being made on the thermoelectric unit as a whole, and preferably individually (one regulation per unit) in case of implementation of several thermoelectric units in the system.

As regards the external faces of the thermoelectric units in a system with several thermoelectric units, they are arranged in parallel in the secondary thermal regulation circuit.

Thermal insulation materials can be implemented to form the climate chamber 3. The climate chamber 3 may be single-component, made of a low thermal conductivity material, or multi-layer with, for example, an external layer of thermal insulator and an internal metal wall, possibly connected to the cold face, also liable to favour the distribution of heat into the chamber.

The purpose of the primary thermal regulation device is multiple:

    • Finely and rapidly regulating the temperature in the climate chamber, thanks to the low thermal inertia of said device and to the linear and continuous operation of the thermoelectric unit(s).
    • Widening the temperature range provided by the single secondary thermal regulation circuit, by working in addition with the ΔT of the thermoelectric unit(s).
    • Improving the thermal exchanges on the cold face and the internal caloric distribution thanks to the forced convection by mixing of the gas present in the internal volume of the climate chamber.

The secondary thermal regulation circuit 9, shown by way of example in FIG. 2, uses a heat-transfer fluid, and this circuit is intended to introduce or extract caloric energy into or from the external face 14 of the thermoelectric unit(s) 10. This secondary thermal regulation circuit 9 includes a heat exchange end 4 for an external face 14 of a thermoelectric unit 10. The fluid brought by the secondary thermal regulation circuit against the external face 14 of each thermoelectric unit may be at a low temperature, for example −10° C. or even less, −20° C., or a high temperature, for example 80° C., or even more, 120° C., or any other temperature in between. It is hence understood that the heat-transfer fluid, which is a liquid, is preferably intended to remain in liquid phase over the whole temperature range that is contemplated. For example, it is possible to use glycol water, i.e. water with glycol, and/or to provide a pressurized fluid.

Other fluids can be used: Ethylene glycol, methylene glycol, Coolanol® . . . . The fluids used have the advantage that they can be heated and cooled at least with respect to the ambient temperature. That way, the thermal range of operation of the thermoelectric units is increased, while maintaining a correct thermal/caloric power. Moreover, it is possible to use thermoelectric units with several thermoelectric elements mounted thermally in series/cascade, which also allows obtaining a greater thermal range but to the detriment of the thermal power.

It is understood that, in the case where there are several thermoelectric units, the heat exchange end 4 for an external face 14 of a thermoelectric unit 10 is divided into several entities, each entity being arranged on an external face 14 of a thermoelectric unit 10 and, in this case, these different entities are arranged in parallel in such a way that the various thermoelectric units receive heat-transfer fluid at the same temperature.

Therefore, given that the heat exchange end 4 for an external face 14 is against the thermoelectric unit(s) 10 of the climate chamber 3, it must follow the motions of this climate chamber.

Preferably, in the secondary thermal regulation circuit 9, only the heat exchange end 4 is placed on a movable part because against the thermoelectric unit(s) of the chamber placed in the motion simulator, the rest of the secondary thermal regulation circuit 9 being preferably fixed, outside the motion simulator. It is understood that fluid circuits or connections with movable fluid seals connect them both by passing through and/or over the joints of the motion simulator.

In one embodiment, other components of the secondary thermal regulation circuit 9 are embedded into the motion simulator.

The secondary thermal regulation circuit 9 includes the following elements, the words “upstream” and “downstream” being defined with reference to the direction of circulation of the heat-transfer fluid imposed by the pump 15 of the circuit:

    • A heat exchange end 4 for an external face 14 of a thermoelectric unit 10, possibly made of several entities in parallel in the case where there are several thermoelectric units.
    • An active means for ensuring the circulation of a heat-transfer fluid, in the example shown it is a circulation pump 15 controlled by the speed of the heat-transfer fluid. In a less efficient alternative, the circulation of the fluid is passive by using the difference in density between the cold and hot fluids. In another alternative, a phase change of the fluid is used for the circulation of the fluid.
    • A cold inlet for refrigerated fluid forming a cold source 8, coming for example from a water chiller.
    • A heater exchanger or hot source 12 to possibly heat the heat-transfer fluid it receives, for example a circulating or, preferably, counter-circulating heater. Any other means for heating the heat-transfer fluid can be used, for example by Joule effect with an electric resistance, by electromagnetic radiation with in particular a suitable heat-transfer fluid.
    • A controlled mixing device 13 for adjusting the temperature of the circulating heat-transfer fluid, for example a three-way valve.
    • Sensors to take measurements and temperatures of the fluid 5a, 5b, 5c, 5d, of the heat-transfer fluid flow rate 6, of the heat-transfer fluid pressure 7.
    • An electronic and/or digital chamber temperature regulation system for controlling the various effectors, including pump, heat exchanger, heater, current of the thermoelectric unit(s) in intensity and possibly polarity, as a function of measurements of the sensors and of a temperature setpoint. In practice, this chamber temperature regulation system is shared between the primary thermal regulation device and the secondary thermal regulation circuit 9.

The secondary thermal regulation circuit is configured with two opposite ends, on one side, the heat exchange end 4 for an external face 14, already described and, on the other side, a cold inlet connected to a water chiller forming the cold source 8. The cold source can be adjustable in temperature or not. This cold source 8 allows cooling the heat-transfer fluid to a low temperature, possibly and preferably negative in degrees Celsius. The heat-transfer fluid so cooled to a low temperature is in fluid relation with an upstream side of the three-way valve 13. This three-way valve has an upstream side 16 towards the cold source 8, a downstream side 17 towards the pump 15, the hot source 12 then the heat exchange end 4 and has a recirculation side 15 connected to the return circuit 18 canalizing the heat-transfer fluid that has passed through the heat exchange end 4. The upstream side 16 and the recirculation side 15 are heat-transfer fluid inlets whose respective flow rate ratio can be adjusted. The downstream side 17 is a heat-transfer fluid outlet.

The three-way valve 13 allows controlling, by introducing more or less cold, the temperature of the heat-transfer fluid that is sent to the heat exchange end 4 thanks to the pump 15 arranged on the downstream side of the three-way valve then through the heater exchanger or hot source 12, before reaching the heat exchange end 4. The hot source 12 allows heating the heat-transfer fluid passing through it. The hot source 12 can be adjustable in temperature or not.

Therefore, the three-way valve allows controlling the recirculation rate of the fluid that has passed through the heat exchange end 4 with respect to the fluid coming from the water chiller through the cold inlet or cold source 8. Therefore, the temperature of the fluid on the downstream side 17 of the three-way valve can be made colder with respect to the recirculating heat-transfer fluid (that which exits from the heat exchange end 4), by increasing the flow coming from the upstream side 16 of the three-way valve 13. The heater exchanger or hot source 12 makes it possible to heat the heat-transfer fluid coming from the downstream side 17 of the three-way valve through the pump 15.

The three-way valve 13 hence makes it possible to control the quantity of fluid at the exit of the water chiller and it is thus an actuator making it possible to control the “cooling power”. In the chamber temperature regulation system, “the cooling power” provided by the three-way valve is linearized in terms of opening by the use of a “Look-up table” to optimize the regulation.

The heater exchanger makes it possible to heat the heat-transfer fluid. It is hence an actuator making it possible to control the “heating power”.

Therefore, as a function of the recirculation rate within the three-way valve 13 and of the heating level provided by the heater exchanger 12, the temperature of the heat-transfer fluid sent into the heat exchange end 4 of the secondary thermal regulation circuit 9 can be adjusted. An adjustment can thus be made between a low temperature, that of the water chiller of the cold inlet 8 when the recirculation through the three-way valve 13 is stopped (upstream side flow rate=downstream side flow rate in the three-way valve) and in the absence of heating by the heater exchanger 12 and a high temperature corresponding to that of the maximum possible heating by the heater exchanger 12 when the recirculation is total in the three-way valve (upstream side flow rate=0). The intermediate temperatures are obtained by suitable controls of the recirculation rate in the three-way valve 13 and of the heating level of the heater exchanger 12.

It is understood that it is possible to position the pump at other locations, for example by inverting the pump 15 and the heater exchanger 12, or by placing the pump 15 in the return circuit 18.

The temperature sensors 5a, 5b, 5c, 5d are placed:

    • 5a, on the upstream side 16 of the three-way valve to measure the temperature of the heat-transfer fluid coming from the water chiller of the cold inlet 8.
    • 5d downstream, i.e. at the exit of the heat exchange end 4 for an external face 14 of a thermoelectric unit 10, on the heat-transfer fluid return circuit 18.
    • 5b, on the downstream side of the three-way valve 13.
    • 5c downstream, i.e. at the exit of the heater exchanger 12.

It is understood that it is possible to reduce the number of temperature sensors in the simplified modes of implementation.

Thanks to the possibility to regulate the temperature at the heat exchange end 4 of the secondary thermal regulation circuit 9, the whole efficiency of the system can be optimized by offsetting the temperature adjustment point of the secondary thermal regulation circuit as a function of the climate chamber temperature setpoint. Moreover, the possibility to change the temperature adjustment point of the secondary thermal regulation circuit allows avoiding the most possible the inversion of polarity of the current circulating in the thermoelectric units, extending that way their life duration by avoiding the mechanical stress due to the operation inversion and the functional inversion of hot face into cold face and the reverse.

Generally, the regulation system implements both the secondary thermal regulation circuit 9 and the primary thermal regulation device with thermoelectric unit(s) to regulate according to measurements and a temperature setpoint, the temperature in the climate chamber.

In the example disclosed now of the chamber temperature regulation system, the two actuators (three-way valve and heater exchanger) of the secondary thermal regulation circuit and the associated sensors make it possible to create a hot and cold sharing regulation/control loop whose purpose is to regulate the temperature of the fluid in the heat exchange end 4. The proper setpoint of this regulation loop is based on an optimization criterion of the operating point of the primary thermal regulation device that is function of the temperature setpoint for the climate chamber.

Another flow rate regulation loop allows controlling the pump 15 as a function of the flow rate. This regulation is necessary to avoid the high-temperature cavitation of the fluid, as the saturation vapour pressure can be very different between the two temperature ends of the secondary thermal regulation circuit 9. The limitation of the heat-transfer fluid flow rate in the pipes is also useful to reduce the wearing of the latter and to reduce the energy consumption of the pump 15.

The pressure sensor 7 and the flowmeter 6 placed in the return circuit 18 allow monitoring the state of the secondary thermal regulation circuit 9, in particular of the cold part on the cold inlet side, due to possible freezing of the fluid, leaks and other problems.

It is understood that it is possible to place these sensors or other sensors at other places.

More generally, in the example shown, this is the same heat-transfer fluid that is used at the cold inlet and at the heat exchange end for an external face of thermoelectric unit. In alternatives, the fluids can be separated between these two ends using a heat exchanger between both. Moreover, it is understood that other structures of secondary thermal regulation circuit can be used by the person skilled in the art to provide a heat-transfer fluid at the heat exchange end 4 in a range of suitable controllable temperatures. For example, a second three-way valve may be provided, connected to a hot source of heat-transfer fluid.

In alternatives, it may be provided an assembly with a three-way valve in splitter or mixer mode, an assembly without a three-way valve but with a plate or tube heat exchanger . . . .

The chamber temperature regulation system thus includes several partially interdependent control loops.

The main regulation loop acts on the primary thermal regulation device and relates to the regulation of the internal temperature, denoted Ti, the climate chamber, which is made by application of a current and/or a voltage regulated over the thermoelectric units, in practice Peltier components.

According to the modes of implementation, the main regulation loop may act wholly on all the thermoelectric units or also act individually through an individual local loop for each thermoelectric unit.

The chamber temperature setpoint Tic provided by the user is preferably filtered, generally by a low-pass filter also called setpoint filter, and the result of this filtering Ticf is compared to Ti, and the difference Ticf−Ti is supplied to a first corrector C1, which may be of the proportional integral (PI) or proportional integral derivative (PID) type, or also of another type, and which will calculate the current and/or voltage command sent to the thermoelectric units.

A hot and cold sharing regulation loop is implemented for controlling the secondary thermal regulation circuit. The temperature, denoted Te, of the heat-transfer fluid, preferably glycol water, of the secondary thermal regulation circuit, essentially allowing a cooling, is controlled by means of a shared command (“Split/range”) that distributes the hot action (heat created for example by an electrical resistance, cf. “external res. pow.”=power of the external resistance of the hot source in FIG. 3) and the cold action (created by the opening and degree of opening of the three-way valve and possibly the closing thereof). A second corrector C2 is used for the regulation of Te. The setpoint Tec of this loop depends of the setpoint Tic and is calculated by means of a piecewise interpolation in a look-up table.

It can be noted that dynamic couplings exist, shown by dotted arrows: The internal temperature Ti has an influence on Te, as Te has an indirect influence on Ti. In the described example, these couplings are neglected for the synthesis of the command law but it is understood that, in other versions, they can be taken into account.

Finally, still for controlling the secondary thermal regulation circuit, the water flow rate of the internal circuit, denoted D, is controlled by means of a third flow rate regulation loop including in this example a corrector of the PI or PID type denoted C3. The setpoint of this loop is denoted Dc. The actuator of this loop being the voltage and/or the current of the pump of the secondary thermal regulation circuit.

The three regulation loops with their respective correctors C1, C2 and C3 are shown in FIG. 3. In relation with the first corrector C1, C2 and C3, U/I corresponds to the regulated current and/or voltage sent to the thermoelectric units of the climate chamber.

In relation with the second corrector C2, “External res. Pow.” corresponds to the power control of the electrical resistance (hot source). It is to be noted that it possible to use a heater exchanger other that an electrical resistance and that, in this case, the command will be adapted accordingly. Still for the second corrector C2, “Degree of opening of the valve” corresponds to the opening/closing and degree of opening command of the three-way valve (cold source).

Finally, in relation with the third corrector C3, “U pump” corresponds to a voltage control in this example, but it may also be more generally provided a current and/or voltage command.

Thanks to the invention, it is possible to obtain very high speeds of temperature variation in the climate chamber, of the order of 5° C./min, and cycles making it possible to pass from the ambient temperature or lower to 100° C. and the reverse, by steps, with a regulation accuracy lower than 0.5° C.

Finally, it is contemplated, within the framework of the invention, that the heat exchange end further/also includes a device for direct heat exchange with the inside of the chamber and that is connected to the rest of the fluid circuit of the secondary thermal regulation circuit 9 via a controlled valve in order to achieve an accelerated temperature regulation of the enclosure, the controlled valve then cutting the fluid circuit and letting the thermoelectric unit(s) act together with the secondary thermal regulation circuit 9 as described hereinabove.

Claims

1. A thermally regulated climate chamber intended to test at least one piece of equipment, the climate chamber having a wall defining an internal space containing a gas and able to receive and contain said at least one piece of equipment to be tested, the internal space being thermally insulated from the environment outside the climate chamber,

wherein at least one thermoelectric unit is arranged through the wall of the climate chamber, each thermoelectric unit having two faces, an internal face located inside the climate chamber and an external face located outside the climate chamber, and wherein one of both faces, called the cold face, is intended to absorb caloric energy and the other one, called the hot face, is intended to reject caloric energy as a function of the electric current passing through said at least one thermoelectric unit,
wherein a heat exchange end for an external face of a thermoelectric unit of a secondary thermal regulation circuit is placed in thermal contact with each external face of thermoelectric unit in order to exchange caloric energy between said at least one thermoelectric unit and said secondary thermal regulation circuit, the secondary thermal regulation circuit being external to the climate chamber and including a heat-transfer fluid circuit, a cold source, a hot source, a mixing device, a circulation pump and sensors, and
wherein a chamber temperature regulation system is configured to control the electric current of said at least one thermoelectric unit and to control at least the mixing device and the circulation pump of the secondary thermal regulation circuit as a function of a chamber temperature setpoint and of sensor measurements.

2. The climate chamber according to claim 1, wherein the climate chamber is attached to a movable support of a motion simulator and the movable support can be set in motion by means of joints of said motion simulator.

3. The climate chamber according to claim 1, wherein the temperature of the hot source is adjustable and the chamber temperature regulation system further adjusts the temperature of the hot source.

4. The climate chamber according to claim 1, wherein the chamber temperature regulation system is configured to regulate the temperature of the external face as a function of the chamber temperature setpoint and in such a way that the polarity of the current circulating in said at least one thermoelectric unit is constant, the internal face being a cold face absorbing caloric energy coming from the inside of the climate chamber.

5-11. (canceled)

12. The climate chamber according to claim 3, wherein the chamber temperature regulation system is configured to regulate the temperature of the external face as a function of the chamber temperature setpoint and in such a way that the polarity of the current circulating in said at least one thermoelectric unit is constant, the internal face being a cold face absorbing caloric energy coming from the inside of the climate chamber.

13. The climate chamber according to claim 1, wherein the chamber temperature regulation system is configured to ensure a continuous flow of the heat-transfer fluid in the heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit.

14. The climate chamber according to claim 3, wherein the chamber temperature regulation system is configured to ensure a continuous flow of the heat-transfer fluid in the heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit.

15. The climate chamber according to claim 4, wherein the chamber temperature regulation system is configured to ensure a continuous flow of the heat-transfer fluid in the heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit.

16. The climate chamber according to claim 12, wherein the chamber temperature regulation system is configured to ensure a continuous flow of the heat-transfer fluid in the heat exchange end for an external face of a thermoelectric unit of the secondary thermal regulation circuit.

17. The climate chamber according to claim 1, wherein the chamber temperature regulation system is configured to control the heat-transfer fluid flow while avoiding a high-temperature cavitation of the heat-transfer fluid that would be due to a too high speed of the heat-transfer fluid.

18. The climate chamber according to claim 13, wherein the chamber temperature regulation system is configured to control the heat-transfer fluid flow while avoiding a high-temperature cavitation of the heat-transfer fluid that would be due to a too high speed of the heat-transfer fluid.

19. The climate chamber according to claim 16, wherein the chamber temperature regulation system is configured to control the heat-transfer fluid flow while avoiding a high-temperature cavitation of the heat-transfer fluid that would be due to a too high speed of the heat-transfer fluid.

20. The climate chamber according to claim 1, including at least two thermoelectric units through the climate chamber and the thermoelectric units are electrically connected in parallel.

21. The climate chamber according to claim 1, wherein the chamber temperature regulation system includes at least two regulation loops, said at least two regulation loops being a main regulation loop controlling the electric current of said at least one thermoelectric unit and at least one secondary regulation loop controlling the secondary thermal regulation circuit.

22. The climate chamber according to claim 12, wherein the chamber temperature regulation system includes at least two regulation loops, said at least two regulation loops being a main regulation loop controlling the electric current of said at least one thermoelectric unit and at least one secondary regulation loop controlling the secondary thermal regulation circuit.

23. The climate chamber according to claim 19, wherein the chamber temperature regulation system includes at least two regulation loops, said at least two regulation loops being a main regulation loop controlling the electric current of said at least one thermoelectric unit and at least one secondary regulation loop controlling the secondary thermal regulation circuit.

24. The climate chamber according to claim 21, wherein the secondary regulation loop controlling the secondary thermal regulation circuit includes a hot and cold sharing regulation loop and a flow rate regulation loop.

25. The climate chamber according to claim 23, wherein the secondary regulation loop controlling the secondary thermal regulation circuit includes a hot and cold sharing regulation loop and a flow rate regulation loop.

26. A method for thermal regulation of a climate chamber intended to test at least one piece of equipment, wherein a climate chamber with thermoelectric unit according to claim 1 is implemented, the climate chamber being attached to a movable support of a motion simulator and the movable support being able to be set in motion by means of joints of said motion simulator, and wherein a secondary thermal regulation circuit including a heat exchange end for an external face of a thermoelectric unit is further implemented, the heat exchange end is arranged against the external face of the thermoelectric unit, the rest of the secondary thermal regulation circuit being arranged out of movable parts of the motion simulator and being connected to the heat exchange end by movable fluid seals passing through the joints of the motion simulator.

27. A kit for installing a thermally regulated climate chamber in a motion simulator, the climate chamber being intended to test at least one piece of equipment, the motion simulator including a movable support set in motion by means of joints of said motion simulator, said kit including:

a climate chamber including a wall defining an internal space able to receive and contain said at least one piece of equipment to be tested, the internal space being able to contain a gas and being thermally insulated from the environment outside the climate chamber, the climate chamber including means for attachment to the movable support, the chamber further including at least one thermoelectric unit, said at least one thermoelectric unit being arranged through the wall of the climate chamber, each thermoelectric unit having two faces, an internal face located inside the climate chamber and an external face outside the climate chamber, and wherein one of both faces, called the cold face, is intended to absorb caloric energy and the other one, called the hot face, is intended to reject caloric energy as a function of the electric current passing through said at least one thermoelectric unit,
a secondary thermal regulation circuit including a heat-transfer fluid circuit, means for connection to a cold source, a hot source, a mixing device, a circulation pump and sensors, the heat-transfer fluid circuit having a heat exchange end for an external face of a thermoelectric unit intended to come into thermal contact with an external face of thermoelectric unit in order to exchange caloric energy between said at least one thermoelectric unit and said secondary thermal regulation circuit,
movable fluid seals intended to be installed in joints of the motion simulator to allow the circulation of the heat-transfer fluid of the secondary thermal regulation circuit between the heat exchange end that is intended to be installed in the motion simulator against the external face of the thermoelectric unit and the rest of the secondary thermal regulation circuit that is intended to be installed out of the movable parts of the motion simulator,
movable electrical connections intended to be installed in joints of the motion simulator to allow a circulation of electrical current,
a chamber temperature regulation system intended to control the electric current of said at least one thermoelectric unit and to control at least the mixing device and the circulation pump of the secondary thermal regulation circuit as a function of a chamber temperature setpoint and of sensor measurements.
Patent History
Publication number: 20240318876
Type: Application
Filed: Jul 11, 2022
Publication Date: Sep 26, 2024
Inventors: Romain SORANT (SAINT-GERMAIN-EN-LAYE), Mehdi BUSSUTIL (SAINT-GERMAIN-EN-LAYE), Bernard VAU (SAINT-GERMAIN-EN-LAYE)
Application Number: 18/579,016
Classifications
International Classification: F25B 21/02 (20060101);