JP2007016747A - Automobile exhaust heat power generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automobile exhaust heat power generation device for performing stable power supply while holding the power generating capability of a thermoelectric element independently of the operating condition of an internal combustion engine. <P>SOLUTION: The device comprises an exhaust passage 4 through which exhaust gas passes, the thermoelectric element 12 arranged for transmitting the heat of the exhaust gas from part 4b of the exhaust passage 4 to the high temperature side, a chemical heat pump 11 arranged for transmitting the heat to the high temperature side of the thermoelectric element 12, and a cooling water circulation passage 7 arranged for transmitting the heat to the low temperature side of the thermoelectric element 12. When detecting that the temperature of the exhaust gas is lower than a power generation temperature range on the high temperature side of the thermoelectric element 12 resulting from the operating condition of the engine 2, the chemical heat pump 11 opens a pressure regulating valve for giving hydrating reaction to magnesium oxide to exhaust heat from the thermoelectric element 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automobile exhaust heat power generation apparatus that generates power by a thermoelectric element disposed in an exhaust system of an internal combustion engine.

  Conventionally, in automobiles, the heat energy of exhaust gas discharged from each engine (internal combustion engine) is recovered and converted into electric power. For example, gas heat from an exhaust passage through which exhaust gas passes is transmitted to a high temperature end face. 2. Description of the Related Art There is known an exhaust heat power generation apparatus configured by disposing a possible thermoelectric conversion element and disposing a heat dissipating member on a low-temperature end face of the thermoelectric conversion element. (See Patent Document 1).

JP 11-36981 A

  According to Patent Document 1, the exhaust heat power generator described above generates power by the thermoelectromotive force generated by the Seebeck effect in accordance with the temperature difference generated between the high temperature end surface and the low temperature end surface of the thermoelectric conversion module. In this way, the heat energy of the exhaust gas can be recovered and converted into electric power.

  However, in general, the thermoelectric conversion element as described above has an optimum power generation temperature range unique to the element that can generate power most efficiently. Depending on the operating state of the internal combustion engine, this optimum power generation temperature range may be reduced. There may be times below.

  If the exhaust gas temperature falls below the optimum power generation temperature range due to the operating state of the internal combustion engine, the power supply to the drive target device may become unstable due to a decrease in power generation capacity.

  An object of the present invention is to provide an automotive exhaust heat power generation apparatus that can maintain the power generation capability of a thermoelectric element regardless of the operating state of an internal combustion engine and can stably supply power.

  An automobile exhaust heat power generation apparatus according to the present invention is an automobile exhaust heat power generation apparatus that generates electric power using a thermoelectric element disposed in an exhaust system of an internal combustion engine, through which exhaust gas passes and heats the high temperature side of the thermoelectric element. An exhaust passage arranged so as to be able to transmit, a heating means arranged so as to be able to transfer heat to the high temperature side of the thermoelectric element, and a low temperature side heat exchanger arranged so as to be able to transfer heat to the low temperature side of the thermoelectric element. And the heating means exhausts heat to the thermoelectric element when the exhaust gas temperature is lower than the power generation temperature range on the high temperature side of the thermoelectric element due to the operating state of the internal combustion engine.

  According to this configuration, even when the high temperature side of the thermoelectric element falls below the optimum power generation temperature range, the temperature change on the high temperature side of the thermoelectric element can be compensated because the high temperature side is heated by the heating means.

  In one embodiment of the present invention, the heating means is constituted by a chemical heat pump disposed so as to be able to transfer heat to a part of the exhaust passage, and the chemical heat pump includes a reaction portion, a condensing portion, and a communication passage. And a pressure regulating valve installed in the communication path, the reaction section dehydrates or hydrates the magnesium compound and water, the condensation section condenses water vapor, and the communication path includes: When the steam is circulated by connecting the reaction unit and the condensing unit, and the exhaust gas temperature is higher than the power generation temperature range on the high temperature side of the thermoelectric element due to the operating state of the internal combustion engine, the exhaust gas heat By causing the chemical heat pump to absorb heat by causing a hydration reaction in the reaction part, and if the exhaust gas temperature is lower than the power generation temperature range, causing the hydration reaction in the reaction part to Characterized in that to waste heat Manabu heat pump.

  According to this configuration, the thermal energy when the temperature of the exhaust gas heat exceeds the power generation temperature range is accumulated, and when the temperature of the exhaust gas heat falls below the power generation temperature range, the stored thermal energy is released. Thus, since the thermoelectric element can be heated, it is not necessary to provide a special heat source dedicated to the thermoelectric element.

  In one embodiment of the present invention, in the exhaust passage, temperature detecting means for detecting the exhaust gas temperature is disposed, and an upper limit threshold and a lower limit threshold of a power generation temperature range on the high temperature side of the thermoelectric element are set in advance, When the exhaust gas temperature detected by the temperature detecting means is higher than the upper limit threshold or lower than the lower limit threshold, the pressure control valve is controlled to open.

  According to this configuration, the exhaust gas temperature is directly monitored by the temperature detection means, and the optimum temperature range for the thermoelectric element is set in advance, so that heat absorption and heat generation operation by the chemical heat pump are performed at appropriate timing. be able to.

In one embodiment of the present invention, the thermoelectric element, the reaction section, and a part of the exhaust passage are configured as a power generation unit.
According to this structure, mutual heat transfer can be performed efficiently.

  In one embodiment of the present invention, a catalytic converter is arranged in the middle of the exhaust passage, and the power generation unit is arranged downstream of the catalytic converter.

  According to this structure, it can prevent that the effect | action of a catalyst falls by the endothermic effect by a chemical heat pump, and the purification capacity of a catalytic converter falls.

  In one embodiment of the present invention, the power generation unit is disposed so as to include an exhaust passage portion in which the exhaust gas temperature changes in a range of 250 to 400 ° C. in a travel pattern of 10.15 mode fuel consumption. To do.

  According to this structure, since the magnesium compound of the chemical heat pump and water can be reacted efficiently, the heat absorption and exhaust heat capacity of the chemical heat pump can be maximized.

  In one embodiment of the present invention, the thermoelectric element is a tellurium-bismuth element.

  According to this configuration, the temperature range with the highest heat absorption and exhaust heat capacity of the chemical heat pump overlaps with the optimum power generation temperature range where the thermoelectric element can generate power efficiently, so that the overall operation efficiency of the exhaust heat power generator is maximized. Can be limited.

  According to this invention, even when the high temperature side of the thermoelectric element falls below the optimum power generation temperature range, the temperature change between the high temperature side and the low temperature side of the thermoelectric element is compensated by compensating for the temperature change on the high temperature side of the thermoelectric element. Since the temperature difference can be maintained at an optimum temperature difference at which power generation is performed efficiently, power generation capability can be maintained and stable power supply can be performed.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic explanatory view showing an exhaust heat power generation unit 1 and an exhaust system structure of an automobile according to an embodiment of the present invention. An engine 2 serving as an internal combustion engine is arranged in a vehicle according to this embodiment. An exhaust passage 4 extends rearward from the exhaust manifold 3 of the engine 2, and a catalytic converter 5, an exhaust heat power generation unit 1, and a silencer 6 are provided on the exhaust passage 4 in order from the upstream side of the exhaust gas flow. ing.

  The catalytic converter 5 uses an exhaust gas purification catalyst that purifies exhaust gas discharged from the combustion chamber of the engine 2, and this catalyst has the best purification capability when the air-fuel ratio is near the stoichiometric air-fuel ratio. It has the characteristics to demonstrate. The purification capacity of the catalyst also depends on the temperature of the exhaust gas heat. The higher the temperature of the exhaust gas heat is, the higher the performance is.

  The cooling device for the engine 2 includes a cooling water circulation passage 7 for circulating cooling water and a radiator 8 for cooling the cooling water, and a water jacket for cooling the vicinity of the combustion chamber of the engine 2 by a water pump (not shown) The engine is cooled by circulating the cooling water through the radiator 8.

  Here, as shown in FIG. 2, the exhaust heat power generation unit 1 is capable of transferring heat to a part 4b of the exhaust passage 4 to which the heat exchanger fins 4a are attached and to the outer periphery of the part 4b of the exhaust passage 4. A chemical heat pump 11 disposed, a thermoelectric element 12 disposed so as to be capable of transferring heat from the chemical heat pump 11 to a high temperature side, and a heat exchanger disposed so as to be capable of transferring heat to a low temperature side of the thermoelectric element 12. A part 7b of the cooling water circulation passage 7 to which the fin 7a is attached and a temperature sensor 13 for detecting the exhaust gas temperature in the exhaust passage 4 downstream of the catalytic converter 5 shown in FIG. It is attached to the car body.

  In addition, about the low temperature side of the thermoelectric element 12, this is made into the part 7b of the cooling water circulation path 7, However, If it is a thing with a big cooling effect, it can also be comprised only with the heat exchanger fin 7a.

  Further, the temperature sensor 13 can be constituted by, for example, a thermocouple that performs temperature detection using thermoelectromotive force when different temperatures are given to two contact portions of two different materials, As indicated by a two-dot chain line in FIG. 2, the chemical heat pump 11 may be disposed in the vicinity of the reaction vessel 11 a or the thermoelectric element 12 on the high temperature side.

  In addition, the temperature sensor 13 can also be constituted by a thermistor whose electric resistance value varies depending on the ambient temperature. In either case, the temperature detection value can be converted into an electric signal for data processing. become.

  The chemical heat pump 11 mainly contains magnesium oxide (MgO), a reaction vessel 11a having heat exchanger fins 11b attached to the outer periphery, a capacitor 11c for condensing, liquefying or evaporating water vapor, and a reaction vessel 11a. And a pressure regulating valve 11e for opening and closing a water vapor passage 11d between the condenser 11c.

  The thermoelectric element 12 is formed by joining a plurality of P-type and N-type semiconductors, the exhaust passage 4 and the chemical heat pump 11 side on the high temperature side, and the part 7b side of the cooling water circulation passage 7 on the low temperature side. By setting to, power is generated according to the temperature difference between the high temperature side temperature due to the exhaust gas heat passing through the exhaust passage 4 and the low temperature side temperature due to the cooling water.

  In this embodiment, a tellurium-bismuth element is used as the thermoelectric element 12. In using this tellurium-bismuth element, the present applicant generates power most efficiently on the assumption that the low temperature side of the thermoelectric element 12 is cooled at about 80 ° C. by the cooling water passing through the cooling water circulation passage 7. It has been found that the temperature difference range, that is, the optimum temperature range on the high temperature side of the thermoelectric element 12 is about 270 to 280 ° C.

The illustrated embodiment is configured as described above, and the operation will be described below.
First, regarding magnesium oxide accommodated in the reaction vessel 11a of the chemical heat pump 11, the hydration reaction of magnesium oxide and the dehydration reaction of magnesium hydroxide (Mg (OH) ₂ ) are represented by the following reaction formulas. It is.
MgO + H ₂ O⇔Mg (OH) ₂ + ΔH
ΔH = −81.02 kJ / mol That is, the hydration reaction of magnesium oxide is an exothermic reaction, and the dehydration reaction of magnesium hydroxide is an endothermic reaction. This reaction is a reversible reaction that occurs in a two-phase system of water vapor as a gas and magnesium as a solid. Therefore, by making the endothermic reaction using exhaust heat of the exhaust gas, the energy that should be wasted is stored in the form of heat and is used as effective energy by causing the reverse reaction to occur when necessary. be able to.

  Next, the operation principle of the chemical heat pump 11 will be described with reference to the drawings. 3 and 4 are schematic diagrams showing the configuration and operating principle of the chemical heat pump 11 according to the present invention. FIG. 3 absorbs exhaust heat to cause dehydration of magnesium hydroxide (corresponding to calcination). ) Heat storage state, FIG. 4 shows the heat generation state due to the hydration reaction of magnesium oxide. By the way, calcination is a method of burning ore, and means sending hot air in order to maintain combustion inside the ore.

  When magnesium hydroxide is preferably calcined at about 250 to 450 ° C., sintering between the fine particles does not occur, so the obtained magnesium oxide maintains the original particle structure of magnesium hydroxide as it is, It is known that magnesium oxide having a large specific surface area and high exothermic reaction activity at high temperatures can be obtained.

  Therefore, even in the exhaust passage 4, in a so-called 10.15 mode fuel consumption traveling pattern in which the vehicle travels under a certain condition in order to approach the fuel consumption in a situation where the automobile is actually used, the exhaust gas temperature is not equal to the magnesium hydroxide. More preferably, the exhaust heat power generation unit 1 including the chemical heat pump 11 is disposed at a position where the temperature is 250 to 450 ° C. which is a preferable temperature range for baking.

  Therefore, the operation of the exhaust heat power generation unit 1 unit when the unit of the exhaust power generation apparatus 1 is disposed at a position where the exhaust gas temperature is 250 to 450 ° C. in the travel pattern of the 10.15 mode fuel efficiency is the exhaust gas temperature. 5 and FIG. 6 showing a time change of the chemical heat pump 11 and FIG. 6 which is a TP diagram (a diagram showing the equilibrium pressure P of water vapor with respect to the temperature T) in the cycle of the chemical heat pump 11 will be described. In FIG. 6, the horizontal axis represents the reciprocal of absolute temperature, and the vertical axis represents the logarithm of pressure (atm).

  The pressure adjustment valve 11e of the chemical heat pump 11 is opened and closed based on the exhaust gas temperature, and an upper limit threshold Ta and a lower limit threshold Tb are set to control the opening and closing of the pressure adjustment valve 11e. Yes. These thresholds Ta and Tb are set to about 270 ° C. and 280 ° C., respectively, as shown in FIG. 5, in accordance with the exhaust gas temperature range in which the thermoelectric element 12 made of tellurium-bismuth elements most efficiently generates power.

  In the chemical heat pump 11 configured as described above, for example, in the time zone A from time t1 to t2 shown in FIG. 5, the exhaust gas temperature is higher than the upper limit threshold Ta of the temperature range in which the thermoelectric element 12 efficiently generates power. In this case, the heat of the exhaust gas is absorbed, and the magnesium hydroxide in the reaction vessel 11a in FIG. 3 undergoes a dehydration reaction, changes into magnesium oxide, and releases high-temperature and high-pressure water vapor. The state of the water vapor in the chemical heat pump 11 at this time is defined as temperature T1 and pressure P1 (corresponding to the state (1) in FIG. 6).

  Here, when the temperature sensor 13 detects that the exhaust gas temperature is higher than the upper limit threshold Ta, the pressure control valve 11e is controlled to open, and a part of the water vapor discharged from the reaction vessel 11a is transferred to the condenser 11c. It moves, cools, condenses and liquefies, and heat is released at this time. At this time, the state of water vapor in the condenser 11c is the temperature T2 (<T1) and the pressure P2 (<P1) (corresponding to the state (2) in FIG. 6).

  Next, when the exhaust gas temperature becomes lower than the upper limit threshold Ta at time t2 and the temperature sensor 13 detects that the temperature is within the temperature range in which the thermoelectric element 12 generates power efficiently, pressure adjustment is performed in time zone B. The valve 11e is controlled to close, and when the water vapor in the reaction vessel 11a is cooled to a temperature T3 (<T1), the pressure drops to P3 (<T2) (corresponding to the state (4) in FIG. 6). ).

  Here, at time t3, when the temperature sensor 13 detects that the exhaust gas temperature has become lower than the lower limit threshold value Tb of the temperature range in which the thermoelectric element 12 efficiently generates power, the pressure control valve 11e is controlled to open. .

  At this time, if the pressure of the water vapor in the condenser 11c is higher than that in the reaction vessel 11a in the time zone C from time t3 to t4, the water vapor moves to the reaction vessel 11a in FIG. A hydration reaction occurs, and heat is radiated from the chemical heat pump 11.

  However, if the water vapor pressure in the condenser 11c is lower than that in the reaction vessel 11a, a pump 11f for forcibly moving the water vapor to the reaction vessel 11a is appropriately provided as shown in FIGS. Also good.

  Here, along with the movement of the water vapor in the capacitor 11c, the water vapor pressure decreases in the capacitor 11c, and the condensed and liquefied water vapor evaporates, so the temperature in the capacitor 11c decreases. At this time, the state of water vapor in the condenser 11c is the temperature T4 (<T2) and the pressure P4 (<P2) (corresponding to the state (3) in FIG. 6).

  When the temperature sensor 13 detects that the exhaust gas temperature has become higher than the lower limit threshold Tb, in the time zone D, the pressure control valve 11e is controlled to be closed, and one cycle of heat storage and heat generation operation of the chemical heat pump 11 is performed. Ends. At this time, the state of water vapor in the reaction vessel 11a is the temperature T3 and the pressure P3 (corresponding to the state (4) in FIG. 6).

  Due to the heat generation operation accompanying the hydration reaction of magnesium oxide as described above, the exhaust passage 4 and the high temperature side of the thermoelectric element 12 (see FIG. 2) can be heated, so again at time t4 in FIG. The exhaust gas temperature can be set within a temperature range where the thermoelectric element 12 efficiently generates power. Accordingly, since the temperature difference between the temperature on the high temperature side and the temperature on the low temperature side of the thermoelectric element 12 can be maintained at an optimum value in terms of power generation efficiency, it is possible to maintain power generation capacity and perform stable power supply. It has become possible.

  When the exhaust gas temperature again becomes higher than the upper limit threshold Ta as in the time zone E from time t5 to t6, the chemical heat pump 11 performs the heat storage operation, and then the exhaust gas temperature is higher than the upper limit threshold Ta. When the temperature becomes low, the cycle of releasing the stored heat by the heat generation operation can be repeated.

  In this way, the exhaust gas heat that has risen excessively is absorbed and stored, and the stored heat is dissipated when the exhaust gas temperature decreases, thereby generating new thermal energy for the thermoelectric element 12 Therefore, it is not necessary to provide a heat source, so that it is possible to reduce the heat energy necessary for operating the entire system.

  Further, since the high temperature side of the thermoelectric element 12 can be heated in a short time from the time when the pressure regulating valve 11e is opened by using the exothermic action due to the chemical reaction of the magnesium compound, the exhaust gas as shown in FIG. It is suitable for an exhaust system in which fluctuations in gas temperature occur in a short time, and the time during which the power generation state of the thermoelectric element 12 is interrupted can be made as short as possible to provide a stable power supply system.

  Furthermore, a temperature sensor 13 for detecting the exhaust gas temperature is disposed in the exhaust passage 4, and an upper limit threshold Ta and a lower limit threshold Tb of the power generation temperature range on the high temperature side of the thermoelectric element 12 are set in advance. When the detected exhaust gas temperature is higher than the upper limit threshold Ta or lower than the lower limit threshold Tb, the pressure control valve 11e is controlled to open.

  Accordingly, the exhaust gas temperature can be grasped more accurately by directly monitoring the detected exhaust gas temperature, and the optimum temperature range for the thermoelectric element is set in advance. Driving can be performed at a more appropriate timing. Therefore, the operation loss of the exhaust heat power generation unit 1 as a whole system can be reduced as much as possible.

  By the way, in order to improve the power generation efficiency of the thermoelectric element 12, in FIG. 2, the thermoelectric element 12, the reaction vessel 11a of the chemical heat pump 11 and the part 4b of the exhaust passage 4 are integrated, and the exhaust heat power generation unit 1 It is preferable that it is comprised as this, Thereby, it can prevent that thermal energy is discharge | released outside from the clearance gap between each other. Therefore, it is possible to prevent the heat transfer efficiency from being lowered and the power generation efficiency from being lowered as a result.

  Here, in the chemical heat pump 11 in particular, with regard to the capacitor 11c, for example, weather conditions outside the vehicle, seasonal changes, etc., have an effect on state changes such as liquefaction and evaporation of water vapor in the heat storage operation and heat generation operation. Is preferably arranged at the bottom near the center of the vehicle.

  In addition, by using a tellurium-bismuth-based element as the thermoelectric element 12, a temperature range (about 270 to 280 ° C.) in which the thermoelectric element 12 can efficiently generate power and calcining magnesium hydroxide in the chemical heat pump 11, The optimum temperature range (about 250 to 450 ° C.) at which magnesium oxide having high exothermic reaction activity at high temperature can be obtained from magnesium hydroxide overlaps.

  Therefore, the heat generation operation when the temperature on the high temperature side of the thermoelectric element 12 is reduced is most efficiently performed, and the power generation efficiency of the power generation element 12 is improved. Therefore, the operation efficiency of the exhaust heat power generation unit 1 as a whole system is improved. Can be maximized.

  Furthermore, in the relationship between the exhaust heat power generation unit 1 and the catalytic converter 5 shown in FIG. 1, the exhaust heat power generation unit 1 is disposed downstream of the exhaust gas flow from the catalyst converter 5. As a result, it is possible to prevent the catalytic action from being lowered by the passage of exhaust gas whose temperature has been lowered by the endothermic action of the chemical heat pump 11 and the purification ability of the catalytic converter 5 to be lowered.

  By the way, irrespective of the operation state of the engine 2, in order to achieve the purpose of maintaining the power generation capability of the thermoelectric element 12 and performing stable power supply, it is not necessarily a requirement to perform the heat storage operation.

  For example, as in the exhaust heat power generation device 21 shown in FIG. 7, heat transfer to the high temperature side of the thermoelectric element 32 instead of the chemical heat pump 11 that raises the exhaust gas temperature due to heat generated by the hydration reaction of magnesium oxide. The heater 34 may be disposed as possible, and may be connected to the battery 35 mounted on the vehicle via the switch 36. It should be noted that in this other embodiment, detailed description of the same operation and the like as in the first embodiment will be omitted.

  Specifically, when the temperature sensor 33 detects that the exhaust gas temperature in the exhaust passage 24 is lower than the lower limit threshold of the temperature range in which the thermoelectric element 32 efficiently generates power on the high temperature side of the thermoelectric element 32, the switch 36 is closed and the heater 34 is heated by receiving power supply from the battery 35. And since this heat is transmitted to the high temperature side of the thermoelectric element 32, the temperature difference between the high temperature side and the low temperature side increases again, and the power generation state of the thermoelectric element 32 can be stabilized.

  Thereby, the existing battery 35 generally mounted on the vehicle can be used as a supplementary heat source, and the heater 34 composed of an electric heating coil is used, so that the entire exhaust power generator 21 can be made. Space can be saved.

  By the way, it is not limited to detecting the exhaust gas temperature for operating the thermoelectric elements 12 and 32 efficiently using the temperature sensors 13 and 33. For example, by detecting that the amount of depression of the accelerator pedal (that is, the accelerator opening) or the opening of the throttle valve has become a predetermined amount or less, it is indirectly determined that the exhaust gas temperature decreases after a predetermined time. It may be.

  Also, due to the relationship between the vehicle running speed and the accelerator pedal depression amount, the exhaust gas temperature tends to rise when the accelerator pedal is depressed at low speeds, and there is no change in the accelerator pedal depression amount at high speeds. In some cases, the exhaust gas temperature state may be indirectly determined by assuming that the exhaust gas temperature tends to decrease.

In these cases, the accelerator opening and throttle opening sensors used for other purposes can also be used for controlling the thermoelectric element according to the present invention.
Other functions and effects are the same as in the first embodiment.

In correspondence between the configuration of the present invention and the above-described embodiment,
The internal combustion engine of the present invention corresponds to the engine 2,
Similarly,
The heating means corresponds to the chemical heat pump 11, the heater 34, and the battery 35,
The exhaust heat power generator corresponds to the exhaust heat power generation unit 1,
The reaction part corresponds to the reaction vessel 11a,
The condensing part corresponds to the capacitor 11c,
The temperature detection means corresponds to the temperature detection sensors 13 and 33,
The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic explanatory drawing which shows the exhaust heat power generator and exhaust system structure of the motor vehicle which concern on embodiment of this invention. The enlarged view which shows the principal part of the waste heat power generator shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is the structure and operating principle of the chemical heat pump which concerns on this invention, Comprising: The schematic which shows the dehydration reaction of magnesium hydroxide. BRIEF DESCRIPTION OF THE DRAWINGS It is the structure and operating principle of the chemical heat pump which concerns on this invention, Comprising: The schematic which shows the hydration reaction of magnesium oxide. The figure which shows the time range of the exhaust gas temperature in the driving pattern of 10.15 mode fuel consumption, and the temperature range which a thermoelectric element produces electric power efficiently. The TP diagram which shows the equilibrium pressure P of the water vapor | steam with respect to the temperature T which showed the cycle of the chemical heat pump. The enlarged view which shows the principal part of the exhaust heat power generator which concerns on another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 21 ... Waste heat power generation unit 2 ... Engine 4, 24 ... Exhaust passage 5 ... Catalytic converter 7 ... Cooling water circulation passage 11 ... Chemical heat pump 11a ... Reaction vessel 11c ... Condenser 11d ... Water vapor passage 11e ... Pressure regulating valve 12, 32 ... Thermoelectric elements 13, 33 ... temperature detection sensor 34 ... heater 35 ... battery

Claims (7)

An automotive exhaust heat power generation apparatus that generates electric power with a thermoelectric element arranged in an exhaust system of an internal combustion engine,
An exhaust passage through which exhaust gas passes and is arranged so that heat can be transferred to the high temperature side of the thermoelectric element;
Heating means arranged to be able to transfer heat to the high temperature side of the thermoelectric element;
Including a low-temperature side heat exchanger arranged to transfer heat to the low-temperature side of the thermoelectric element,
The heating means is
An automotive exhaust heat power generation apparatus that exhausts heat to a thermoelectric element when an exhaust gas temperature is lower than a power generation temperature range on a high temperature side of the thermoelectric element due to an operating state of the internal combustion engine. The heating means is constituted by a chemical heat pump arranged to be able to transfer heat to a part of the exhaust passage,
The chemical heat pump includes a reaction unit, a condensing unit, a communication path, and a pressure regulating valve installed in the communication path.
The reaction part dehydrates or hydrates the magnesium compound and water,
The condensing part condenses water vapor,
The communication path connects the reaction part and the condensing part to distribute the water vapor,
When the exhaust gas temperature is higher than the power generation temperature range on the high temperature side of the thermoelectric element due to the operating state of the internal combustion engine, the chemical heat pump is caused to generate a hydration reaction in the reaction part by the exhaust gas heat. Endothermic,
The exhaust heat power generator for automobiles according to claim 1, wherein, when the exhaust gas temperature is lower than the power generation temperature range, the chemical heat pump exhausts heat by causing a hydration reaction in the reaction part. In the exhaust passage, a temperature detecting means for detecting the exhaust gas temperature is disposed,
An upper limit threshold and a lower limit threshold of the power generation temperature range on the high temperature side of the thermoelectric element are set in advance,
The automobile exhaust heat power generation apparatus according to claim 2, wherein when the exhaust gas temperature detected by the temperature detection means is higher than the upper limit threshold or lower than the lower limit threshold, the pressure control valve is controlled to open. . The automobile exhaust heat power generation device according to claim 2 or 3, wherein the thermoelectric element, the reaction section, and a part of the exhaust passage are integrated as a power generation unit. A catalytic converter is arranged in the middle of the exhaust passage,
The exhaust heat power generator for an automobile according to claim 4, wherein the power generation unit is disposed downstream of the catalytic converter. 6. The exhaust heat power generator for an automobile according to claim 4, wherein the power generation unit is disposed so as to include a portion of an exhaust passage in which an exhaust gas temperature changes in a range of 250 to 400 ° C. in a travel pattern of 10.15 mode fuel efficiency. . The exhaust heat power generator for automobiles according to any one of claims 2 to 6, wherein the thermoelectric element is a tellurium-bismuth element.

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