EP2039813A1 - Wärmekraftmaschine und Verfahren zur Steuerung der Wärmeleitfähigkeit der Oberfläche der Brennkammer - Google Patents

Wärmekraftmaschine und Verfahren zur Steuerung der Wärmeleitfähigkeit der Oberfläche der Brennkammer Download PDF

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Publication number
EP2039813A1
EP2039813A1 EP08163462A EP08163462A EP2039813A1 EP 2039813 A1 EP2039813 A1 EP 2039813A1 EP 08163462 A EP08163462 A EP 08163462A EP 08163462 A EP08163462 A EP 08163462A EP 2039813 A1 EP2039813 A1 EP 2039813A1
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EP
European Patent Office
Prior art keywords
thermal conductivity
phase
during
equal
engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP08163462A
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English (en)
French (fr)
Inventor
Jean-Bruno Zimmermann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PSA Automobiles SA
Original Assignee
Peugeot Citroen Automobiles SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Peugeot Citroen Automobiles SA filed Critical Peugeot Citroen Automobiles SA
Publication of EP2039813A1 publication Critical patent/EP2039813A1/de
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P9/00—Cooling having pertinent characteristics not provided for in, or of interest apart from, groups F01P1/00 - F01P7/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/02—Cylinders; Cylinder heads  having cooling means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/16—Pistons  having cooling means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2251/00—Material properties
    • F05C2251/04—Thermal properties
    • F05C2251/048—Heat transfer

Definitions

  • the field of the invention is that of land, sea or air vehicles comprising a high efficiency heat engine. Optimizing the efficiency of the engine is a significant problem given the rising cost of energy and pollution problems.
  • the consumption of the vehicle becomes today a criterion of purchase of first rank with the consumers and finally a major problem for the car manufacturers.
  • the efficiency of the heat engine is partly related to the heat exchange between the gas mixture in combustion and the walls of the combustion chamber.
  • the gaseous mixture is a fuel mixture and can be of any type of fuel: gasoline, diesel, gas, biofuel for example.
  • the heat exchanges vary throughout this cycle, whether in intensity or in direction, the direction of exchange always remaining consistent with physics, that is to say from hot bodies to cold bodies .
  • the exchange takes place in the direction of the cylinder towards the gases and, during the combustion and exhaust phases, in the direction of the gases towards the walls of the chamber of combustion.
  • Two types of combustion chamber behavior may be desired by the engine manufacturer.
  • the goal may be to obtain the greatest heat exchange possible with the heat transfer liquid, to ensure a minimum rise in the air load and fuel mixture.
  • the goal is to obtain the least heat exchange with the outside of the combustion chamber in order to conserve the maximum energy released during combustion to convert it into work. .
  • the patent whose publication number is JP11236636 describes a material that could be used in an automotive engine and whose thermal conductivity changes in correlation with the change in temperature.
  • the patent proposes a motor concept using a variable conductivity material depending on the temperature that can be used to protect the sensitive parts at a high temperature.
  • the variation of conductivity is not controllable and the device therefore always undergoes heat exchange. In some cases, these variations are detrimental to performance.
  • the subject of the present invention is a heat engine comprising a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that, at least one of said walls, is constituted by a material , whose thermal conductivity Cp varies, by applying an electric field controlled by a control unit of the motor.
  • the thermal conductivity C p can vary cyclically in phase with the phases of the motor cycles.
  • the principle can be applied locally to only one of these elements or to those of a specific part of the combustion chamber or even to all the elements constituting the combustion chamber.
  • the basic principle is related to the physical fact that thermal conductivity usually goes hand in hand with electrical conductivity. For example, metals that are good conductors of electricity are also good thermal conductors.
  • the type of variable conductivity material used for the present invention is of the type described in the patent applications W02005124790 and W08807224 .
  • the method of the invention can use any type of material whose thermomechanical resistance characteristics are compatible with the constraints specific to the combustion chambers, but whose thermal conductivity is controllable.
  • the first patent describes a material for which the thermal conductivity can vary by the application of an electric field.
  • This external electric field has the effect of orienting the electric dipoles or exciting the mode of vibration of the photons so as to promote the thermal conductivity, or conversely to limit heat exchange.
  • the patent in question refers to a composite material containing a resin of elements reacting to the external fields.
  • the second patent describes a material whose electrical conductivity varies by exposure to light or heat. This action involves a change of structure within the material changing its conductivity properties.
  • the heat engine comprises a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that, at least one of said walls, is constituted by a material, whose thermal conductivity C p varies, by applying an electric field controlled by a control unit of the motor, this electric field being distinct from one wall to the other.
  • a control unit of the motor for example, it is possible to allow maximum thermal exchange at the walls of the cylinder and both to limit the exchanges at the intake valves to optimize the preparation of the mixture during injection on these hot valves.
  • the present invention also relates to the method for controlling the thermal conductivity of the walls of the combustion chamber of said device.
  • it may be a four-stroke combustion engine whose cycle is divided into four phases: the admission of air by the opening of the intake valve and the descent of the piston, the compression of the air by raising the piston and the closing of the valve, the combustion of the gaseous mixture which pushes the piston and releases a part of the energy, and the exhaust of the gases burned by the opening of the the exhaust valve and the raising of the piston.
  • the control method therefore consists in cyclically varying in phase with these four phases of the engine the thermal conductivity of the walls of the combustion chamber.
  • a first control strategy can be, in the case where one seeks to optimize the yield and limit the transmission of energy to the heat transfer gases, to limit heat exchange during the combustion phase and, in the case where one seeks to keep a maximum of enthalpy to operate the supercharging system, to limit heat exchange during the exhaust phase.
  • the supercharging is to introduce air into the cylinder at a pressure above atmospheric pressure to optimize the efficiency of the engine.
  • we pilot the thermal conductivity of the walls of the chamber. combustion to promote heat exchange during the intake and compression phases.
  • rattling is a phenomenon of unwanted micro-explosions that can appear and damage the engine during combustion.
  • the reasons for their appearance may be too high a temperature of the gas mixture during the admission or the presence of hot spots inside the combustion chamber.
  • This strategy is not limited to a particular type of engine and is applicable to spark ignition engines as well as for diesel engines, the gas mixture of which ignites spontaneously.
  • a second control strategy is this time to limit exchanges during compression and combustion phases and instead to promote them during the intake and exhaust phases. Limiting the exchanges, during the compression phase by reducing the thermodynamic losses associated with the decrease in gas temperature, makes it possible to obtain the highest temperature at the end of compression, which is advantageous for combustion of the self-ignition type. Gasoline or diesel fuel mixtures and, during the combustion phase can increase the yield. On the contrary, favoring exchanges during the intake phase makes it possible to optimize the freshest possible air filling and to avoid any enthalpy during the exhaust.
  • a third strategy for controlling the thermal conductivity similar to the previous one consists in the combustion phase while the thermal conductivity is minimal to allow maximum heat exchange at a specific time, which depends on the engine and the course of combustion.
  • the purpose of the maneuver is to limit the risk of occurrence of knocking phenomenon due to a combustion chamber temperature too high.
  • This invention makes it possible to no longer fully undergo thermal transfers taking place in a motor cycle.
  • the control of the thermal conductivity of the walls of the combustion chamber optimizes the efficiency of the engine by avoiding heat transfer during the phases where the combustion energy must be transformed into work. For the user this results in a gain in vehicle consumption.
  • Another important asset for the engine manufacturer is the possibility of winning on the rattling limit by controlling temperature rises.
  • the rattling limit is usually a limiting factor for motor designers. Indeed, for a given engine, the compression ratio can not be increased indefinitely.
  • the invention also makes it possible to improve the control of the combustion and thus to extend the life of the engine while avoiding the appearance of this phenomenon.
  • By controlling the thermal conductivity to the maximum for the sensitive components they are protected from too high temperatures when the engine is hot and conversely, by limiting the thermal conductivity optimizes the rise in temperature of the engine and the catalyst when the engine is still cold.
  • the Figures 1, 2 , 3 and 4 represent the evolution of the position of the piston P p and that of the thermal conductivity of the walls of the combustion chamber C p of a four-stroke heat engine.
  • all the walls of the elements forming the combustion chamber consists of a material whose thermal conductivity is controlled by the control unit by applying an electric field. This material is of the type described in the patents of the description of the invention.
  • the graphic windows of the Figures 1, 2 , 3 and 4 describe on a motor cycle the displacement of the piston P p and the control of the thermal conductivity of the walls during the four phases of the engine cycle.
  • the four phases of the engine, intake, compression, combustion and exhaust, are delineated on the graphs by the dashed vertical lines.
  • Phase t0 to t1 represents the admission phase.
  • the piston At t0 the piston is in the up position and evolves by a downward movement up to t1 where it reaches its low position.
  • the intake valves are in the open position allowing air to enter.
  • Phase t1 to t2 represents the compression phase.
  • the piston At t1, the piston is in the low position and evolves by an upward movement until t2 where it reaches its high position.
  • the gas mixture is compressed.
  • Phase t2 to t3 represents the combustion phase.
  • the piston At t2 the piston is in the up position and evolves by a downward movement until t3 where it reaches its low position.
  • the gaseous mixture is ignited, either controlled type or auto-ignited type according to the engine.
  • phase t3 to t4 is the exhaust phase.
  • the piston is in the low position and evolves by an upward movement towards its high position.
  • the burned gas mixture is discharged through the opening of the valves to the exhaust duct.
  • the time evolution of the position of the piston Pp is a sinusoidal curve.
  • the control of the thermal conductivity of the walls of the elements constituting the combustion chamber of the engine Cp is such that the thermal conductivity of the walls of the elements constituting the combustion chamber of the engine comprises high constant values and low constant values, so that the temporal variation of the thermal conductivity is a succession of crenellations.
  • This control method makes it possible to limit the rise in temperature of the incoming charge in the engine during admission and compression, which reduces the risk of knocking.
  • the thermal conductivity is minimal in order to increase the efficiency of the transformation of thermal energy into working energy.
  • the driving process of the figure 2 is advantageous for combustion engines of auto-ignited type.
  • the thermal conductivity is minimal to obtain the most isentropic compression possible.
  • controlling the thermal conductivity makes it possible to optimize the filling of fresh air and to release gases at a less harmful temperature, for example for the collector or the catalyst.
  • the process of figure 3 for controlling the thermal conductivity of the walls of the combustion chamber is managed so that at a given moment of the combustion phase, the thermal conductivity, equal to the low value before this moment, becomes high in order to limit the appearance of rattling phenomena.
  • the invention offers the possibility of adjusting the rise in temperature of the combustion chamber according to the characteristics of the engine. It is then possible to approach the rattling limits by acting on the engine's capabilities to limit or promote heat exchange with the outside.
  • variable thermal conductivity material it is possible to apply the variable thermal conductivity material to a part of the elements of the combustion chamber or to the whole of the combustion chamber. Thus, it is conceivable to act on the thermal conductivity specifically at specific locations in the combustion chamber. More generally, the invention can be applied to any type of heat engine, gasoline engine, diesel or biofuel for example. The control of the conductivity is then configurable according to the desired effect.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
EP08163462A 2007-09-19 2008-09-02 Wärmekraftmaschine und Verfahren zur Steuerung der Wärmeleitfähigkeit der Oberfläche der Brennkammer Ceased EP2039813A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR0757662A FR2921112B1 (fr) 2007-09-19 2007-09-19 Moteur thermique et procede de pilotage de la conductive thermique des parois de la chambre de combustion

Publications (1)

Publication Number Publication Date
EP2039813A1 true EP2039813A1 (de) 2009-03-25

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP08163462A Ceased EP2039813A1 (de) 2007-09-19 2008-09-02 Wärmekraftmaschine und Verfahren zur Steuerung der Wärmeleitfähigkeit der Oberfläche der Brennkammer

Country Status (2)

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EP (1) EP2039813A1 (de)
FR (1) FR2921112B1 (de)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1528160A (en) * 1975-08-08 1978-10-11 Nat Res Dev Silicon nitride based components
US4321898A (en) * 1977-11-16 1982-03-30 Robert Bosch Gmbh Internal combustion engine with temperature controlled combustion chamber walls
GB2148144A (en) * 1983-10-18 1985-05-30 Secr Defence Thermally active coating
WO1988007224A1 (en) 1987-03-18 1988-09-22 Dai Nippon Insatsu Kabushiki Kaisha Material having variable conductivity
JPH11236636A (ja) 1998-02-20 1999-08-31 Toyota Central Res & Dev Lab Inc 熱伝導率可変材料
WO2005124790A2 (en) 2004-06-15 2005-12-29 Siemens Power Generation, Inc. High thermal conductivity materials aligned within resins
EP1681454A2 (de) * 2005-01-14 2006-07-19 Fuji Jukogyo Kabushiki Kaisha Zylinderbuchse und Zylinderblock
JP2007077951A (ja) * 2005-09-16 2007-03-29 Aisin Seiki Co Ltd 内燃機関用ピストン

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1528160A (en) * 1975-08-08 1978-10-11 Nat Res Dev Silicon nitride based components
US4321898A (en) * 1977-11-16 1982-03-30 Robert Bosch Gmbh Internal combustion engine with temperature controlled combustion chamber walls
GB2148144A (en) * 1983-10-18 1985-05-30 Secr Defence Thermally active coating
WO1988007224A1 (en) 1987-03-18 1988-09-22 Dai Nippon Insatsu Kabushiki Kaisha Material having variable conductivity
JPH11236636A (ja) 1998-02-20 1999-08-31 Toyota Central Res & Dev Lab Inc 熱伝導率可変材料
WO2005124790A2 (en) 2004-06-15 2005-12-29 Siemens Power Generation, Inc. High thermal conductivity materials aligned within resins
EP1681454A2 (de) * 2005-01-14 2006-07-19 Fuji Jukogyo Kabushiki Kaisha Zylinderbuchse und Zylinderblock
JP2007077951A (ja) * 2005-09-16 2007-03-29 Aisin Seiki Co Ltd 内燃機関用ピストン

Also Published As

Publication number Publication date
FR2921112B1 (fr) 2009-11-20
FR2921112A1 (fr) 2009-03-20

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