JP5886597B2 - In-vehicle power generation system - Google Patents

Description

  The present invention relates to an on-vehicle power generation system, and more particularly to an on-vehicle power generation system mounted on a vehicle such as an automobile.

  Conventionally, in internal combustion engines such as automobile engines, heat exchangers such as boilers and air conditioning equipment, electric engines such as generators and motors, and various energy utilization devices such as light emitting devices such as lighting, for example, as exhaust heat, light, etc. A lot of thermal energy is released and lost.

  In recent years, from the viewpoint of energy saving, it is required to recover the released thermal energy and reuse it as an energy source. As such a method, thermoelectric conversion power generation using a pyroelectric element is known. Yes.

  Specifically, for example, a heating source that increases the temperature of each of the plurality of pyroelectric elements, a cooling source that decreases the temperature of each of the pyroelectric elements, a heating source and a cooling source, and / or a pyroelectric element A method of taking out DC power or AC power from a pyroelectric element by periodically raising and lowering the temperature of the pyroelectric element by a heating source and a cooling source using a power generation device including a moving unit that moves the element, It has been proposed (see, for example, Patent Document 1).

  On the other hand, in an internal combustion engine such as an automobile engine, the fuel stored in the fuel tank may evaporate in the tank, and when such fuel evaporative gas is discharged into the atmosphere, environmental pollution is caused.

  Therefore, in order to prevent environmental pollution, it is required to suppress the emission of evaporative gas into the atmosphere. As such a method, for example, the fuel evaporative gas is adsorbed and held by a charcoal canister and recovered. It is known that the gas supplied to the intake pipe is used as fuel.

  As such an apparatus, specifically, for example, an operating state detecting means for detecting an operating state of the internal combustion engine, an evaporative gas passage for introducing the fuel evaporative gas in the fuel tank into the intake passage, and an internal combustion engine There has been proposed a fuel evaporative emission control device including variable control means for variably controlling the passage area of the evaporative gas passage in accordance with the operating state (see, for example, Patent Document 2).

  In this fuel evaporative emission control device, a predetermined amount of air is supplied to the intake pipe, and fuel stored in the fuel tank is injected into the intake pipe by the fuel injection valve, and the fuel evaporative gas evaporated from the fuel tank Is supplied to the intake pipe through the evaporative gas passage. As a result, the air is mixed with the fuel supplied from the fuel tank and the fuel supplied as the evaporating gas, and the obtained air-fuel mixture is supplied to the internal combustion engine.

  Further, in this fuel evaporative emission control device, the operating state of the internal combustion engine is detected by the operating state detecting means such as an air-fuel ratio sensor provided in the exhaust pipe, and variable control means is provided according to the detected operating state. Thus, the passage area of the evaporative gas passage is controlled, the supply amount of the fuel evaporative gas is adjusted, and the air-fuel ratio of the air-fuel mixture is adjusted.

JP-A-11-332266 JP 62-20669 A

  On the other hand, as a power generation method described in Patent Document 1, it can be considered to mount a power generation device in a vehicle. Specifically, in a vehicle such as an automobile equipped with a fuel evaporative emission control device as described in Patent Document 2, a pyroelectric element is disposed in an exhaust pipe from which exhaust gas is exhausted from an internal combustion engine, The use of the exhaust gas as a heating source and a cooling source can also be considered.

  In such a case, as described above, air and fuel are supplied to the internal combustion engine, and the fuel is combusted to generate exhaust gas. The exhaust gas heats and cools the pyroelectric element in the exhaust pipe. .

  However, when the power generation device is mounted on the vehicle, depending on the vehicle state, the air-fuel ratio of the air-fuel mixture may become rich, and when this rich air-fuel mixture is supplied to the internal combustion engine, an unburned or incompletely burned state The fuel may be discharged into the exhaust pipe together with the exhaust gas.

  When a pyroelectric element is placed in the exhaust pipe, if unburned or incompletely burned fuel is discharged into the exhaust pipe, the fuel may adhere to the pyroelectric element and cause contamination of the element. As a result, the pyroelectric element may be damaged or the power generation efficiency may be reduced.

  In this regard, in the above-described fuel evaporative emission control device, the air-fuel ratio of the air-fuel mixture is made to be the stoichiometric air-fuel ratio by detecting the operating state of the internal combustion engine with an air-fuel ratio sensor and feedback-controlling the passage area of the evaporative gas passage. (Condition) is also considered.

  As described above, if the air-fuel ratio of the mixture ratio is not made rich, the fuel is prevented from being discharged to the exhaust pipe, so that the fuel can be prevented from adhering to the pyroelectric element.

  However, in such feedback control, first, it is determined that the air-fuel ratio of the air-fuel mixture is in a rich state, and based on the determination, the supply amounts of fuel and evaporative gas are controlled. There is a problem that always becomes rich. In particular, such feedback control cannot cope with the adjustment of the air-fuel ratio immediately after the fuel purge or during the increase of the fuel purge amount. At the same time, the fuel is discharged to the exhaust pipe, and the fuel adheres to the pyroelectric element, which may cause contamination of the element.

  The objective of this invention is providing the vehicle-mounted electric power generation system which can suppress the damage of a device and the fall of electric power generation efficiency.

  In order to achieve the above object, an in-vehicle power generation system according to the present invention is connected to an engine, an intake pipe for supplying air to the engine, connected to the engine, and exhausted from the engine. An exhaust pipe, a fuel tank for storing fuel, a fuel injection means for injecting fuel from the fuel tank to the engine, connected to the fuel tank and the intake pipe, and the fuel An evaporating gas passage for supplying evaporating gas from the tank to the intake pipe, an internal combustion engine provided in the evaporating gas passage and provided with a purge valve for opening and closing the evaporating gas passage, and provided in the exhaust pipe, A first device that is electrically polarized by supplying exhaust gas whose temperature rises and falls over time, and power is extracted from the first device. The purge valve is opened only when the temperature of the exhaust gas detected by the second device, the temperature detection means for detecting the temperature of the exhaust gas, and detected by the temperature detection means is equal to or higher than a predetermined temperature. And an allowable control means.

  According to the on-vehicle power generation system of the present invention, the opening of the purge valve is permitted by the control means only when the temperature of the exhaust gas detected by the temperature detection means is equal to or higher than the predetermined temperature.

  That is, according to such an in-vehicle power generation system, the purge valve is opened only when the temperature of the exhaust gas detected by the temperature detection means is equal to or higher than a predetermined temperature, and the evaporated gas is supplied to the intake pipe. Thereby, when the air-fuel ratio of the air-fuel mixture becomes rich, the temperature of the exhaust gas is always higher than the predetermined temperature.

  Therefore, when the fuel is attached to the first device by supplying the rich air-fuel mixture and discharging the unburned or incompletely burned fuel together with the exhaust gas to the exhaust pipe, the attached fuel is exhausted. The gas can be evaporated and / or burned by the heat of the gas, and contamination of the first device can be suppressed.

  As a result, according to such an in-vehicle power generation system, damage to the first device and a decrease in power generation efficiency can be suppressed.

It is a schematic structure figure of one embodiment of the in-vehicle power generation system of the present invention.

1. 1 is a schematic configuration diagram of an embodiment of an in-vehicle power generation system according to the present invention.

  In FIG. 1, an automobile 10 includes an in-vehicle power generation system 1.

  The in-vehicle power generation system 1 takes out electric power from the internal combustion engine 2, the first device 3 that is electrically polarized by being supplied with exhaust gas that is exhausted from the internal combustion engine 2 and whose temperature rises and falls over time. A second device 4 for detecting the air-fuel ratio, an air-fuel ratio sensor 5 as air-fuel ratio detecting means for detecting the air-fuel ratio, a temperature sensor 6 as temperature detecting means for detecting the temperature of the exhaust gas, and an air-fuel ratio sensor 5 The purge valve 25 (only when the temperature of the exhaust gas detected by the first control unit 7 that controls the engine control unit 28 (described later) based on the air-fuel ratio detected by the temperature sensor 6 and the temperature sensor 6 is equal to or higher than a predetermined temperature. And a second control unit 8 as a control means for allowing the opening operation described later.

  The internal combustion engine 2 is provided in an engine 11, an intake pipe 16 for supplying air to the engine 11, an exhaust pipe 17 for exhausting exhaust gas from the engine 11, a fuel tank 21 for storing fuel, and an intake pipe 16. A fuel injection device 20 as fuel injection means for supplying fuel from the fuel tank 21 to the engine 11, an evaporative gas passage 24 for supplying evaporative gas evaporating from the fuel tank 21 to the intake pipe 16, and an evaporative gas passage There is provided a purge valve 25 for opening and closing.

  The engine 11 is a device that outputs power of a vehicle or the like. For example, a single-cylinder type or a multi-cylinder type (for example, a 2-cylinder type, a 4-cylinder type, or a 6-cylinder type) is adopted. A multi-cycle method (for example, a 2-cycle method, a 4-cycle method, a 6-cycle method, etc.) is employed.

  Hereinafter, the engine 11 in which the 4-cylinder type is adopted and the 4-cycle system is adopted in each cylinder will be described.

  The engine 11 includes a plurality (four) of cylinders 12 arranged in parallel. In FIG. 1, one cylinder 12 is taken out and the other cylinders 12 are omitted.

  Each cylinder 12 includes a piston 13, a combustion chamber 14, an ignition plug (not shown), and the like. The upstream side is connected to the intake pipe 16 and the downstream side is connected to the exhaust pipe 17.

  Each cylinder 12 includes an intake valve 18 at a connection portion connected to the intake pipe 16 and an exhaust valve 19 at a connection portion connected to the exhaust pipe 17.

  The intake valve 18 is provided at a connection portion between the cylinder 12 and the intake pipe 16 so that the cylinder 12 can be opened and closed.

  The exhaust valve 19 is provided at the connecting portion between the cylinder 12 and the exhaust pipe 17 so that the cylinder 12 can be opened and closed.

  Although not shown, the intake valve 18 and the exhaust valve 19 are urged in the closing direction by an elastic force such as a spring. The intake valve 18 and the exhaust valve 19 can open and close the cylinder 12 by, for example, rotation of a camshaft.

  The intake pipe 16 is provided to supply air to the engine 11, and its downstream end is connected to the cylinder 12 of the engine 11 and its upstream end is open to the outside air.

  The intake pipe 16 includes a throttle valve 27. For example, the throttle valve 27 can be opened and closed and the opening thereof can be adjusted in accordance with a driving operation such as depressing an accelerator pedal, and air can be taken into the engine 11 by the opening and closing.

  The exhaust pipe 17 is provided to exhaust the exhaust gas from the engine 11, and its upstream end is connected to the cylinder 12 of the engine 11.

  Further, although not shown in the drawing, a plurality (four) of exhaust pipes 17 connected to a plurality (four) of cylinders 12 are gathered into one on the downstream side of the engine 11 and the first device 3 (described later). The downstream end of the assembled exhaust pipe 17 is open to the outside air. As a result, exhaust gases discharged from the engine 11 can be collected and released to the outside air.

  The fuel tank 21 is a tank that stores fuel (for example, gasoline) supplied to the engine, and is formed of a heat-resistant pressure-resistant container or the like.

  The fuel injection device 20 includes a fuel supply pipe 22 and a fuel injection valve 23.

  The fuel supply pipe 22 is provided to supply fuel from the fuel tank 21 to the engine 11, and its upstream end is connected to the fuel tank 21 and its downstream end is connected to the fuel injection valve 23. It is connected.

  The fuel injection valve 23 is a valve for adjusting the amount of fuel supplied from the fuel tank 21 to the engine 11 and injecting the fuel to the engine 11, and is provided at the downstream end of the fuel supply pipe 22. It is provided and connected to the upstream side of the intake valve 18 of the intake pipe 16.

  The fuel injection valve 23 is not particularly limited, and a known injection valve can be used.

  Such a fuel injection valve 23 is electrically connected to the engine control unit 28 of the engine 11, and its opening / closing is controlled by the engine control unit 28.

  The engine control unit 28 operates the engine 11 (for example, the rotational speed of the engine 11 detected by a tachometer (not shown), for example, the pressure in the intake pipe 16 downstream of the throttle valve 27 detected by a pressure sensor (not shown)). Etc.), and is composed of a microcomputer including a CPU, a ROM, a RAM, and the like.

  The fuel injection valve 23 is electrically connected to the engine control unit 28, whereby a control signal from the engine control unit 28 can be input to the fuel injection valve 23. Thereby, the engine control unit 28 controls the opening and closing and the opening degree of the fuel injection valve 23, that is, the fuel injection amount (fuel supply amount to the engine 11) by the fuel injection valve 23 in accordance with the operating state of the engine 11. It is possible.

  The evaporative gas passage 24 is provided to supply evaporative gas evaporating from the fuel tank 21 to the intake pipe 16, and its upstream end is connected to the upper portion of the fuel tank 21, and the downstream end is The intake pipe 16 is connected to the upstream side of the fuel injection valve 23.

  An evaporative gas adsorption device 26 is interposed in the evaporative gas passage 24.

  The evaporative gas adsorption device 26 is a device for adsorbing and holding the evaporative gas evaporated from the fuel tank 21, and includes, for example, a known charcoal canister.

  The evaporative gas adsorbing device 26 can adsorb and hold the evaporated gas evaporated from the fuel tank 21 and can release the adsorbed evaporated gas to the evaporated gas passage 24 when the engine 11 is driven. .

  The purge valve 25 is a valve for opening and closing the evaporative gas passage 24 and adjusting the opening thereof, and is provided downstream of the evaporative gas adsorption device 26 in the evaporative gas passage 24. The purge valve 25 is electrically connected to a first control unit 7 (described later), and its opening / closing and opening degree are controlled by the first control unit 7.

  The first device 3 is a device which is discharged from the internal combustion engine 2 (engine 11) and is electrically polarized by increasing or decreasing the temperature with time by supplying exhaust gas whose temperature increases or decreases with time.

  The electric polarization referred to here is a phenomenon in which a potential difference occurs due to dielectric polarization due to displacement of positive and negative ions due to crystal distortion, such as a piezo effect and / or a phenomenon in which a dielectric constant changes due to a temperature change and a potential difference occurs, such as pyroelectric It is defined as a phenomenon in which an electromotive force is generated in a material such as an effect.

  More specifically, examples of the first device 3 include a device that is electrically polarized by a piezo effect, a device that is electrically polarized by a pyroelectric effect, and the like.

  The piezo effect is an effect (phenomenon) in which when a stress or strain is applied, it is electrically polarized according to the magnitude of the stress or strain.

  The first device 3 that is electrically polarized by the piezo effect is not particularly limited, and a known piezo element (piezoelectric element) can be used.

  When a piezo element is used as the first device 3, the piezo element is, for example, in contact with (exposed to) exhaust gas in a state where its periphery is fixed by a fixing member and volume expansion is suppressed. Arranged in the exhaust pipe 17.

  The fixing member is not particularly limited, and for example, a second device 4 (for example, an electrode) described later can be used.

  In such a case, the piezo element is heated or cooled by the temperature change of the exhaust gas with time, and thereby expanded or contracted.

  At this time, since the volume expansion of the piezo element is suppressed by the fixing member, the piezo element is pressed by the fixing member and is electrically polarized by the piezo effect (piezoelectric effect) or phase transformation near the Curie point. . Thereby, as will be described in detail later, power is extracted from the piezo element via the second device 4.

  In addition, such a piezo element is normally maintained in a heated state or a cooled state, and when its temperature becomes constant (that is, a constant volume), the electric polarization is neutralized, and then cooled or heated, Again, it is electrically polarized.

  Therefore, as described above, when the exhaust gas periodically changes in temperature and the high temperature state and the low temperature state are periodically repeated, the piezo element is periodically heated and cooled. Electrical polarization and its neutralization are repeated periodically.

  As a result, electric power is extracted as a waveform (for example, alternating current, pulsating flow, etc.) that fluctuates periodically by the second device 4 described later.

  The pyroelectric effect is, for example, an effect (phenomenon) in which the insulator is electrically polarized in accordance with a change in temperature when the insulator (dielectric) is heated and cooled, and includes the first effect and the second effect. It is out.

  The first effect is an effect in which, when the insulator is heated and cooled, it spontaneously polarizes due to the temperature change and generates a charge on the surface of the insulator.

  In addition, the second effect is an effect that pressure deformation occurs in the crystal structure due to temperature changes during heating and cooling of the insulator, and piezoelectric polarization occurs due to stress or strain applied to the crystal structure (piezo effect, piezoelectric effect). ).

  The device that is electrically polarized by such a pyroelectric effect is not particularly limited, and a known pyroelectric element can be used.

  When a pyroelectric element is used as the first device 3, the pyroelectric element is disposed in the exhaust pipe 17 so as to be in contact (exposed) with the exhaust gas.

  In such a case, the pyroelectric element is heated or cooled by the temperature change of the exhaust gas with time, and is electrically polarized by the pyroelectric effect (including the first effect and the second effect). Thereby, although mentioned later in detail, electric power is taken out from the pyroelectric element via the second device 4.

  Also, such pyroelectric elements are usually maintained in a heated state or a cooled state, and when the temperature becomes constant, the electric polarization is neutralized, and then cooled or heated again to be electrically polarized again. .

  Therefore, when the temperature of the exhaust gas changes periodically as described above and the high temperature state and the low temperature state are periodically repeated, the pyroelectric element is periodically heated and cooled. The electrical polarization of the element and its neutralization are repeated periodically.

  As a result, electric power is extracted as a waveform (for example, alternating current, pulsating flow, etc.) that fluctuates periodically by the second device 4 described later.

Specifically, as described above, the first device 3 is a known pyroelectric element (for example, BaTiO ₃ , CaTiO ₃ , (CaBi) TiO ₃ , BaNd ₂ Ti ₅ O ₁₄ , BaSm ₂ Ti _4. O ₁₂ , lead zirconate titanate (PZT: Pb (Zr, Ti) O ₃ ), etc., known piezo elements (eg, quartz (SiO ₂ ), zinc oxide (ZnO), Rochelle salt (potassium sodium tartrate) _{(KNaC 4 H 4 O 6)} , lead zirconate titanate (PZT: Pb (Zr, Ti ) O 3), lithium niobate (LiNbO _3), lithium tantalate (LiTaO _3), lithium tetraborate _(Li 2 B ₄ O ₇ ), Langasite (La ₃ Ga ₅ SiO ₁₄ ), Aluminum Nitride (AlN), Tourmaline, Poly Vinylidene fluoride (PVDF) or the like can be used.

  These first devices 3 can be used alone or in combination of two or more.

  The Curie point of the first device 3 is, for example, −77 ° C. or higher, preferably −10 ° C. or higher, for example, 1300 ° C. or lower, preferably 900 ° C. or lower.

  The relative dielectric constant of the first device 3 (insulator (dielectric)) is, for example, 1 or more, preferably 100 or more, more preferably 2000 or more.

  In such an in-vehicle power generation system 1, the higher the relative permittivity of the first device 3 (insulator (dielectric material)), the higher the energy conversion efficiency and the higher voltage the electric power can be extracted. If the relative dielectric constant is less than the lower limit, the energy conversion efficiency may be low, and the voltage of the obtained power may be low.

  The first device 3 (insulator (dielectric)) is electrically polarized by the temperature change of the exhaust gas. The electrical polarization may be any of electronic polarization, ion polarization, and orientation polarization.

  For example, it is expected that a material that exhibits polarization by orientation polarization (for example, a liquid crystal material) can improve power generation efficiency by changing its molecular structure.

  A plurality of such first devices 3 are arranged in the exhaust pipe 17 at intervals, for example, and fixed by the second device 4 (and a fixing member (not shown) provided if necessary). Yes. In FIG. 1, one first device 3 is extracted and shown, and the other first devices 3 are omitted.

  As a result, the first device 3 can contact (expose) the exhaust gas through the second device 4 in the exhaust pipe 17.

  The second device 4 is provided to extract power from the first device 3.

  More specifically, the second device 4 is not particularly limited, but, for example, two electrodes (for example, a copper electrode, a silver electrode, etc.) disposed opposite to each other with the first device 3 interposed therebetween, for example, ., And the like, and are electrically connected to the first device 3.

  In addition, the second device 4 is electrically connected to the battery 9 via a booster (not shown), an AC / DC converter (AC-DC converter) (not shown), etc., if necessary. Yes.

  The air-fuel ratio sensor 5 is a sensor that detects the air-fuel ratio of the air-fuel mixture in the engine 11 and is provided in the exhaust pipe 17 so as to be in contact with the exhaust gas.

As the air-fuel ratio sensor 5, for example, an O ₂ sensor that detects that the air-fuel mixture is in a rich state or a lean state by detecting the oxygen concentration in the exhaust gas, for example, from the oxygen ion concentration in the exhaust gas A known air-fuel ratio sensor such as a linear A / F sensor for detecting the air-fuel ratio of the air-fuel mixture can be used.

  The temperature sensor 6 is a sensor that detects the temperature of the exhaust gas, and is provided on the downstream side of the air-fuel ratio sensor 5 in the exhaust pipe 17 so as to be in contact with the exhaust gas. Examples of the temperature sensor 6 include known temperature sensors such as an infrared radiation thermometer and a thermocouple thermometer.

  Further, as the temperature sensor 6, although not shown, an exhaust gas temperature prediction device can be used. In the exhaust gas temperature prediction device, for example, from the load and rotation speed of the engine 11, for example, the exhaust gas recirculation amount by an exhaust gas recirculation (EGR) system (not shown), for example, the ignition timing in the engine 11, the outside air temperature, etc. The combustion temperature of the air-fuel mixture in the engine 11 can be predicted, and the temperature of the exhaust gas can be predicted from the fuel temperature.

  The first control unit 7 is a device for controlling the engine control unit 28 based on the air-fuel ratio detected by the air-fuel ratio sensor 5 and controlling the opening and closing of the fuel injection valve 23, and includes a CPU, a ROM and a RAM. And so on.

  The first control unit 7 is electrically connected to the air-fuel ratio sensor 5 and the engine control unit 28 as indicated by broken lines in FIG. 1, and the air-fuel ratio detected by the air-fuel ratio sensor 5 can be input as an electric signal. In addition, according to the detection, the engine control unit 28 can adjust the opening and closing and the opening degree of the fuel injection valve 23.

  The second control unit 8 is composed of a microcomputer including a CPU, a ROM, a RAM, and the like that allow the purge valve 25 to open based on the temperature of the exhaust gas detected by the temperature sensor 6.

As shown by a broken line in FIG. 1, the second control unit 8 is electrically connected to the temperature sensor 6 and the purge valve 25, and the exhaust gas temperature detected by the temperature sensor 6 can be input as an electric signal. In addition, the purge valve 25 is allowed to open only when the temperature of the exhaust gas detected by the temperature sensor 6 is equal to or higher than a predetermined temperature.
2. Power Generation Method A power generation method using the above-described on-vehicle power generation system 1 will be described in detail below.

  In this in-vehicle power generation system 1, the piston 11 is repeatedly moved up and down in the cylinder 12 by driving the engine 11. Thus, for example, in the 4-cycle system, an intake process, a compression process, an explosion process, an exhaust process, and the like are sequentially performed. To be implemented.

  More specifically, in the engine 11, first, the throttle valve 27 is opened, air is supplied from the intake pipe 16, and a predetermined amount of fuel is supplied (injected) from the fuel supply pipe 22 by the fuel injection valve 23. Is done.

  In the engine 11, the evaporated gas evaporated in the fuel tank 21 and adsorbed in the evaporative gas adsorbing device 26 is released from the evaporative gas adsorbing device 26 as necessary, and the intake pipe 16 is passed through the evaporative gas passage 24. To be supplied.

  As a result, the air and the fuel supplied through the fuel supply pipe 22 (and the fuel supplied through the evaporative gas passage 24 as necessary) are mixed.

  Then, the air-fuel mixture is supplied to the combustion chamber 14 of the cylinder 12 by opening the intake valve 18 (intake process).

  Next, the intake valve 18 is closed and the piston 13 is raised, so that the air-fuel mixture in the combustion chamber 14 is compressed and heated to a high temperature (compression process).

  Next, the air-fuel mixture is ignited by an ignition plug (not shown) and burned explosively, and the piston 13 is pushed down by the explosion (explosion process).

  Thereafter, the exhaust valve 19 is opened, and the gas (exhaust gas) generated by the combustion is exhausted from the cylinder 12 (exhaust process).

  As described above, in the engine 11, the fuel is combusted and power is output, and high-temperature exhaust gas passes through the exhaust pipe 17 in the exhaust process.

  At this time, the heat of the engine 11 is transmitted through the exhaust gas, and the temperature of the exhaust gas (the internal temperature of the exhaust pipe 17) rises in the exhaust process. On the other hand, in other processes (intake process, compression process, explosion process), the amount of exhaust gas in the exhaust pipe 17 is reduced, so the temperature of the exhaust gas (internal temperature of the exhaust pipe 17) decreases.

  As described above, the temperature of the exhaust gas rises in the exhaust process and falls in the intake process, the compression process, and the explosion process, that is, rises and falls over time.

  In particular, since each of the above steps is periodically repeated sequentially according to the piston cycle, the exhaust gas periodically changes in temperature with the repetition cycle of each of the above steps, more specifically, The high temperature state and the low temperature state are periodically repeated.

  In such an in-vehicle power generation system 1, the temperature of the internal combustion engine 2 and the exhaust gas is, for example, 200 to 1200 ° C., preferably 700 to 900 ° C. in the high temperature state, and the temperature in the low temperature state is the above-described temperature. Less than the temperature in the high temperature state, more specifically, for example, 100 to 800 ° C., preferably 200 to 500 ° C., and the temperature difference between the high temperature state and the low temperature state is, for example, 10 to 600 ° C., 20 to 500 ° C.

  Moreover, the repetition period of these high temperature states and low temperature states is, for example, 10 to 400 cycles / second, preferably 30 to 100 cycles / second.

  In the in-vehicle power generation system 1, as described above, the first device 3 is disposed inside the exhaust pipe 17.

  Therefore, when exhaust gas discharged from the engine 11 (internal combustion engine 2) is introduced into the exhaust pipe 17, the exhaust gas is supplied to the first device 3 in the exhaust pipe 17, and the first device 3 The exhaust gas is contacted (exposed) through the second device 4 and heated and / or cooled.

  In other words, the first device 3 is heated and / or cooled by the temperature change over time of the engine 11 (internal combustion engine 2) and the exhaust gas that transfers the heat of the engine 11.

  And thereby, the 1st device 3 can be periodically made into a high temperature state or a low temperature state, and the effect (for example, piezo element, pyroelectric element, etc.) according to the element (for example, piezo element, pyroelectric element, etc.) , Piezo effect, pyroelectric effect, etc.).

  Therefore, in this in-vehicle power generation system 1, the electric power can be extracted from each first device 3 through the second device 4 as a waveform (for example, alternating current, pulsating current) that periodically varies.

  Thereafter, in this method, for example, as indicated by a dotted line in FIG. 1, the electric power obtained as described above is boosted by a booster (not shown) connected to the second device 4 as necessary, and AC / DC conversion is performed. After being converted to a DC voltage in a container (not shown), the battery 9 is charged. The electric power stored in the battery 9 can be used as appropriate as power for the automobile 10 and various electric components mounted on the automobile 10.

On the other hand, the exhaust gas used for power generation passes through the first device 3 and is then purified by a known catalyst or the like and discharged to the outside air.
3. Control Method (1) First Control Unit In the automobile 10 on which the above-described on-vehicle power generation system 1 is mounted, the purge valve 25 is opened when the evaporative gas adsorption device 26 adsorbs and holds a predetermined amount or more of evaporative gas. Then, fuel (evaporated gas) is supplied through the evaporative gas passage 24. When the amount of the evaporated gas adsorbed and held by the evaporated gas adsorption device 26 is less than the predetermined amount, the purge valve 25 is closed and the supply of the evaporated gas is stopped.

  On the other hand, in the automobile 10, fuel is supplied from the fuel injection valve 23, and the supply amount is determined by the engine control unit 28 in the above-described operation state of the automobile 10 (for example, the rotational speed of the engine 11, the intake pipe 16 The pressure is controlled based on the pressure.

  The engine control unit 28 is controlled by the first control unit 7 based on detection by the air-fuel ratio sensor 5.

  Specifically, in the control by the first control unit 7, first, the air-fuel ratio of the air-fuel mixture supplied to the engine 11 is detected by the air-fuel ratio sensor 5, and the state of the air-fuel mixture is detected by the first control unit 7. Input as an electrical signal.

  When the first control unit 7 determines that the engine is in a rich state based on the air-fuel ratio detected by the air-fuel ratio sensor 5, the engine control unit 28 is controlled by the first control unit 7, and the fuel supply amount is reduced. Will be reduced. On the other hand, when it is determined that the air-fuel ratio is in the lean state, the engine control unit 28 is controlled by the first control unit 7 and the fuel supply amount is increased.

Thus, the fuel supply amount is adjusted so that the total amount of evaporative gas and fuel becomes a predetermined amount corresponding to the operating state of the automobile 10, and the air-fuel ratio of the air-fuel mixture is adjusted to the stoichiometric state.
(2) Second Control Unit In the automobile 10 in which the above-described on-vehicle power generation system 1 is mounted, the air-fuel ratio can be feedback controlled to the stoichiometric state as described above. In this control, first, the air-fuel ratio of the air-fuel mixture is in a rich state Since the fuel supply amount is controlled based on the determination, there is a problem that the air-fuel ratio of the air-fuel mixture always becomes rich.

  In particular, in such feedback control, for example, immediately after the purge valve 25 is opened from the closed state, or while the fuel supply amount is being adjusted, the feedback control cannot catch up, and the state of the air-fuel mixture May become rich.

  When this rich air-fuel mixture is supplied to the engine 11, unburned or incompletely burned fuel may be discharged to the exhaust pipe 17 together with the exhaust gas.

  In the on-vehicle power generation system 1 described above, since the first device 3 is disposed in the exhaust pipe 17, when unburned or incompletely burned fuel is discharged into the exhaust pipe 17, the fuel is first It may adhere to the device 3 and cause contamination (for example, clogging) of the first device 3. As a result, the first device 3 may be damaged or the power generation efficiency may be reduced.

  Therefore, in the in-vehicle power generation system 1, the purge valve 25 is controlled by the second control unit 8 to suppress contamination of the first device 3.

  Specifically, in this control, first, the temperature of the exhaust gas discharged from the engine 11 is detected by the temperature sensor 6, and the temperature of the exhaust gas is input to the second control unit 8 as an electrical signal.

  The second control unit 8 allows the purge valve 25 to open only when it is determined in the second control unit 8 that the temperature of the exhaust gas is equal to or higher than a predetermined temperature (for example, 700 ° C. or higher).

  That is, in this in-vehicle power generation system 1, the purge valve 25 is opened only when the temperature of the exhaust gas is determined to be equal to or higher than the predetermined temperature in the second control unit 8, and the evaporated gas is supplied to the intake pipe 16. . In addition, when the evaporation gas adsorbed and held in the evaporation gas adsorption device 26 is less than a predetermined amount, the purge valve 25 is closed and the supply of the evaporation gas is stopped.

  At this time, the opening degree of the fuel injection valve 23 is controlled by the first control unit 7 and the engine control unit 28 so that the total amount of evaporative gas and fuel becomes a predetermined amount corresponding to the driving state of the automobile 10. The supply amount is adjusted.

  On the other hand, when the second control unit 8 determines that the temperature of the exhaust gas is lower than the predetermined temperature, the purge valve 25 is closed and the supply of the evaporative gas is stopped. The opening degree of the fuel injection valve 23 is controlled by the unit 28, and the fuel supply amount is adjusted so that the total amount of evaporative gas and fuel becomes a predetermined amount corresponding to the driving state of the automobile 10.

When the purge valve 25 is closed, the fuel is supplied only from the fuel injection valve 23, and the supply amount is adjusted by the first control unit 7 and the engine control unit 28 with good responsiveness.
4). As described above, in this in-vehicle power generation system 1, the opening operation of the purge valve 25 is permitted only when the temperature of the exhaust gas detected by the temperature sensor is equal to or higher than the predetermined temperature by the second control unit 8. ing.

  That is, according to such an in-vehicle power generation system 1, the purge valve 25 is opened only when the temperature of the exhaust gas detected by the temperature sensor 6 is equal to or higher than a predetermined temperature, and the evaporated gas is supplied to the intake pipe. Thus, when the air-fuel ratio of the air-fuel mixture becomes rich, the temperature of the exhaust gas is always higher than the predetermined temperature.

  Therefore, when the fuel is attached to the first device 3 by supplying the rich air-fuel mixture and discharging the unburned or incompletely burned fuel together with the exhaust gas to the exhaust pipe 17, the attached fuel Can be evaporated and / or burned by the heat of the exhaust gas, and contamination of the first device 3 can be suppressed.

  As a result, according to such an in-vehicle power generation system 1, damage to the first device 3 and reduction in power generation efficiency can be suppressed.

  In the above description, the first control unit 7, the second control unit 8, and the engine control unit 28 are provided as separate bodies. For example, the first control unit 7, the second control unit 8, and the engine are provided. Two or more of the control units 28 may be provided integrally.

DESCRIPTION OF SYMBOLS 1 In-vehicle power generation system 2 Internal combustion engine 3 1st device 4 2nd device 5 Air-fuel ratio sensor 6 Temperature sensor 7 1st control unit 8 2nd control unit 11 Engine 16 Intake pipe 17 Exhaust pipe 20 Fuel injection apparatus 21 Fuel tank 24 Evaporative gas Passage 25 purge valve

Claims (1)

engine,
An intake pipe connected to the engine for supplying air to the engine;
An exhaust pipe connected to the engine for discharging exhaust gas from the engine;
A fuel tank for storing fuel,
A fuel injection means provided in the intake pipe for injecting fuel from the fuel tank to the engine;
An evaporative gas passage connected to the fuel tank and the intake pipe and supplying evaporative gas evaporating from the fuel tank to the intake pipe; and
An internal combustion engine provided with a purge valve provided in the evaporative gas passage and opening and closing the evaporative gas passage;
A first device provided in the exhaust pipe and electrically polarized by supplying exhaust gas whose temperature rises and falls over time;
A second device for extracting power from the first device;
Temperature detecting means for detecting the temperature of the exhaust gas;
Control means for allowing the opening operation of the purge valve only when the temperature of the exhaust gas detected by the temperature detection means is equal to or higher than a predetermined temperature ,
The in-vehicle power generation system, wherein the first device is a piezo element and is disposed in the exhaust pipe so as to be in contact with the exhaust gas in a state where volume expansion is suppressed. .

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