JP2009074439A - Engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine system which uses water ethanol as fuel and which can easily perform cold startup with a simple constitution without using a low boiling point component such as gasoline. <P>SOLUTION: The engine system stores water ethanol in a first tank 12, and stores ethanol water of the ethanol concentration appropriate for steam reforming in a second tank. A reformer 30 performs the steam reforming of the ethanol water supplied from the second tank, and generates reformed gas containing hydrogen. A condensation pressure accumulator 34 performs pressure accumulation of the reformed gas, and supplies the reformed gas, which has been subjected to pressure accumulation, to a combustion chamber 26 by a gas-feeding instrument 36. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine system, and more particularly, to an engine system that improves combustion by using a reformed gas generated by reforming ethanol.

  Conventionally, an engine for a water-containing ethanol vehicle running in Brazil is known. In this engine, low-boiling components such as gasoline are used during cold start, and fuel is increased during acceleration.

Further, a fuel cell system is known in which an unreformed raw material is recovered and reused after passing through a catalyst for reforming reaction (Patent Document 1). The S / C (water vapor / carbon ratio: Steam / Carbon) of the reforming part in this fuel cell system is S / C = 2.0, and further, air is introduced and O ₂ /C=0.4. It is said. Moreover, the raw material cooled to about 70 ° C. and recovered as a condensed component is separated into ethanol and water, ethanol is returned to the reforming section, and water is returned to the evaporation section. Note that the steam reforming reaction in the fuel cell system is C ₂ H ₅ OH + 3H ₂ O => 6H ₂ + 2CO ₂ (S / C = 1.5, excluding air).

In addition, when trying to obtain power by burning the reformed gas generated by the engine, it is better not to have too much water vapor concentration from the viewpoint of combustion stability. Better. However, when the condensate component of the unreformed raw material is recovered and only the reformed gas is supplied to the engine and burned, a large volume of gaseous fuel must be supplied, and the air charging efficiency is reduced. The combustion reaction is H ₂ + 1 / 2O ₂ ⇒H ₂ O, CO + 1 / 2O ₂ ⇒CO ₂ , CH ₄ + 2O ₂ ⇒CO ₂ + 2H ₂ O, and when H ₂ or CO burns a lot, The number of moles is reduced, which is not preferable for obtaining power. However, there are advantageous aspects for obtaining power, such as an increase in the combustion temperature and an increase in the maximum pressure, and a possibility of lean combustion.

Thus, in the case of an automobile engine, it is better to supply power by supplying liquid fuel and maintaining charging efficiency than supplying only gaseous fuel. By supplying liquid fuel as well, when high output is desired, high output can be obtained by natural intake or by using a low pressure ratio supercharger without using an expensive high pressure ratio supercharger. be able to.
JP 2006-315922 A

  However, in a conventional engine for a hydrous ethanol vehicle, when a spark ignition engine is used, the second fuel containing a low-boiling component such as gasoline is supplied at the time of cold start such as 0 ° C. or lower. Has a problem that it is necessary to supply another fuel and the handling becomes complicated. Alternatively, there is a problem that it is necessary to have a large secondary battery in order to increase the vapor pressure of the fuel by electric heating at the cold start such as 0 ° C. or less.

  The present invention has been made to solve the above-described problems. In an engine using hydrous ethanol as a fuel, stable operation can be performed with a simple configuration without using low-boiling components such as gasoline. An object is to provide an engine system.

  In order to achieve the above object, an engine system according to the present invention includes a first tank that contains hydrous ethanol, a second tank that contains ethanol having a lower ethanol concentration than the hydrous ethanol, and heating the first tank. At least one of reforming means for reforming ethanol supplied from two tanks to generate reformed gas containing hydrogen, hydrous ethanol from the first tank, and reformed gas generated by the reforming means And supply means for supplying the fuel to the combustion chamber.

  According to the engine system of the present invention, water-containing ethanol is stored in the first tank, and ethanol having a lower ethanol concentration than water-containing ethanol is stored in the second tank. Further, the ethanol supplied from the second tank is reformed by heating by the reforming means, and a reformed gas containing hydrogen is generated.

  Then, at least one of the water-containing ethanol from the first tank and the reformed gas generated by the reforming unit is supplied to the combustion chamber by the supply unit. When supplying hydrous ethanol to the combustion chamber, not only supplying hydrous ethanol directly to the combustion chamber, but also supplying hydrous ethanol to the intake pipe and supplying the hydrous ethanol to the combustion chamber via the intake pipe .

  As described above, the second tank contains ethanol having a low ethanol concentration, reforms the ethanol from the second tank, generates a reformed gas containing hydrogen, and supplies the reformed gas to the fuel chamber. Because it is possible to use a reformed gas generated from ethanol suitable for fuel, stable operation is possible with a simple configuration without using low-boiling components such as gasoline in an engine using hydrous ethanol as a fuel. .

  The reforming means according to the present invention can reform ethanol using exhaust heat. As a result, the exhaust heat is used to perform reforming, which is an endothermic reaction, and the exhaust heat is recovered, so that the thermal efficiency can be improved.

  The reforming means according to the present invention can perform steam reforming of ethanol. As described above, the reforming means can use a steam reforming method in which a mixed liquid composed of ethanol and water is gasified by exhaust heat and reformed.

  Moreover, the ethanol concentration of ethanol stored in the second tank can be set to 60% to 80%. Thereby, the reformed gas can be efficiently generated from ethanol having an ethanol concentration suitable for steam reforming.

  The engine system according to the present invention detects the ethanol concentration of ethanol stored in the second tank and the recovery means for recovering the unreformed raw material that has not been reformed by the reforming means to the second tank. It can further include a detection means and a concentration control means for controlling the ethanol concentration of the ethanol in the second tank to be within a predetermined concentration range lower than the water-containing ethanol based on the ethanol concentration detected by the detection means. . Thereby, even if unreformed raw materials are collected in the second tank, the ethanol concentration of the ethanol in the second tank can be kept within a predetermined concentration range.

  The concentration control means can control the first tank so that the water-containing ethanol in the first tank is supplied to the second tank when the ethanol concentration detected by the detection means is lower than a predetermined concentration range. .

  When the ethanol concentration detected by the detecting means is higher than a predetermined concentration range, the concentration control means is configured to heat and distill the ethanol stored in the second tank and supply the azeotropic component to the first tank. The second tank can be controlled.

  The engine system according to the present invention further includes a pressure accumulating means for accumulating the reformed gas generated by the reforming means at a predetermined pressure, and the supply means is the reformed gas accumulated by the pressure accumulating means when the engine is started or accelerated. Gas can be supplied to the combustion chamber. As a result, when the engine is started or accelerated, the accumulated reformed gas can be supplied to the combustion chamber to compensate for the insufficient fuel.

  As described above, according to the engine system of the present invention, ethanol having a low ethanol concentration is accommodated in the second tank, and the reformed ethanol is generated by reforming the ethanol from the second tank. Since the reformed gas generated from ethanol suitable for reforming can be used by supplying it to the fuel chamber, it is easy to use water-containing ethanol as a fuel without using low-boiling components such as gasoline. With such a configuration, an effect that stable operation is possible is obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, an engine system 10 according to an embodiment of the present invention includes a first tank 12 that contains hydrous ethanol (95% ethanol water), and a first pump 14 that pumps up the hydrous ethanol in the first tank 12. And a fuel injector 22 for injecting water-containing ethanol supplied from the first tank 12 via a fuel supply pipe (not shown).

  The engine system 10 includes an intake pipe 24 through which the intake air is taken in, a throttle valve (not shown) that controls the intake amount, and an exhaust pipe 28 through which exhaust gas generated by combustion in the combustion chamber 26 passes. .

  Furthermore, the engine system 10 includes a second tank 16 that stores ethanol water in a predetermined ethanol concentration range, a second pump 18 that pumps up the ethanol water in the second tank 16, an evaporator 29 that gasifies the ethanol water, A reformer 30 that generates reformed gas by steam reforming, a condensing accumulator 34 that collects unreformed raw materials to generate condensed components, and accumulates the reformed gas at a predetermined pressure, and a condensing accumulator Gas supply device 36 for supplying the reformed gas accumulated in 34 to the intake pipe 24, an ethanol concentration sensor 38 for detecting the ethanol concentration of the ethanol water in the second tank 16, and the temperature of the ethanol water in the second tank 16. A temperature sensor 40 to detect, a temperature controller 42 for controlling the temperature of the second tank 16 using cooling water and exhaust heat, and an electronic control unit (hereinafter “ CU "that.) And a 44.

  Here, when the ethanol concentration is high and higher than 80%, carbon is deposited during reforming and the catalyst is deteriorated, the amount of reformed gas generated is remarkably reduced, and the recovery operation is frequently performed. The advantage of having a system is reduced. In addition, when the ethanol concentration is low and lower than 60%, it is frozen at a low temperature from around -40 ° C. or the viscosity increases, so that the reforming raw material cannot be sent to the reformer. It cannot be modified until thawed. Moreover, a large amount of heating heat is required due to the evaporation and temperature rise of water vapor, and the size of the heat exchange part is increased.

  Therefore, in the present embodiment, the predetermined ethanol concentration range of the ethanol water stored in the second tank 16 is set to a range of 60% to 80% (approximately S / C = 0.5 to 1.0 range). It is preferable to do.

  Further, the engine system 10 pumps up the water-containing ethanol in the first tank 12 and supplies it to the second tank 16, and the azeotropic component obtained when the ethanol water in the second tank 16 is distilled by heating. An azeotropic component supply valve 46 that controls whether or not to supply to one tank 12 and a condensation that controls whether or not the condensed component of the unreformed raw material recovered by the condensing accumulator 34 is returned to the second tank 16. And a component supply valve 48.

  The ECU 44 includes the first pump 14, the second pump 18, the fuel injector 22, the gas supplier 36, the ethanol concentration sensor 38, the temperature sensor 40, the temperature controller 42, the third pump 45, the azeotropic component supply valve 46, And the condensing component supply valve 48, the first pump 14, the second pump 18, the fuel injector 22, the gas supply unit 36, the temperature controller 42, the third pump 45, the azeotropic component supply valve 46, and the condensing component. Each of the component supply valves 48 operates according to the control of the ECU 44. Note that FIG. 1 shows only the connection relationship of the portion directly related to the present embodiment.

  The first pump 14 takes in the water-containing ethanol stored in the first tank 12 and supplies it to the fuel injector 22 through the fuel supply pipe. The fuel injector 22 injects water-containing ethanol for a predetermined amount and for a predetermined time in accordance with the control of the ECU 44.

The second pump 18 takes in the ethanol water stored in the second tank 16 and supplies it to the evaporator 29. The evaporator 29 absorbs exhaust heat by ethanol water passing through an internal heat exchange pipe (not shown), gasifies the ethanol water, and gasifies it to the reformer 30 via the pipe (not shown). Supply the ethanol water. The reformer 30 performs steam reforming of gasified ethanol water using a catalyst (C ₂ H ₅ OH + H ₂ O => 4H ₂ + 2CO), and mainly contains hydrogen, carbon dioxide, carbon monoxide, and methane. The mixed gas is generated as the reformed gas, and the reformed gas is supplied to the condensing accumulator 34.

In the reformer 30, even if ethanol and H ₂ O are reacted in equimolar amounts, CH ₄ and CO ₂ are actually generated. As shown in FIG. 2, H ₂ O is more than ethanol. It remains unreacted. Therefore, the condensing accumulator 34 collects the unreformed raw material that has not been reformed by the steam reforming by the reformer 30, and the condensed component of the recovered unreformed raw material according to the opening / closing of the condensing component supply valve 48. Is returned to the second tank 16. Further, the condensation pressure accumulator 34 accumulates the reformed gas supplied from the reformer 30 at a predetermined pressure and supplies it to the gas supplier 36. The gas supplier 36 supplies the reformed gas to the intake pipe 24 for a predetermined amount and for a predetermined time in accordance with the control of the ECU 44.

  The temperature controller 42 heats and distills the ethanol water stored in the second tank 16 using exhaust heat under the control of the ECU 44 to generate ethanol water having an azeotropic concentration (95%). Moreover, the temperature controller 42 will cool the ethanol water accommodated in the 2nd tank 16 using cooling water according to control of ECU44, when heating distillation is complete | finished.

  In the engine system configured as described above, when the driver turns on an ignition switch (not shown), the ECU 44 executes a concentration control processing routine shown in FIG.

  First, in step 100, the ethanol concentration of the ethanol water in the second tank 16 detected by the ethanol concentration sensor 38 is acquired. In step 102, the ethanol concentration acquired in step 100 is within the range of 60% to 80%. It is determined whether or not.

  If the ethanol concentration of the ethanol water is less than 60% in step 102, the third pump 45 is pumped to pump up the water-containing ethanol in the first tank 12 and supply it to the second tank 16 in step 104. Control and return to step 100. As a result, the ethanol concentration of the ethanol water in the second tank 16 is increased.

  If the ethanol concentration of the ethanol water is higher than 80% in step 102, the temperature controller 42 distills the ethanol water in the second tank 16 and heats the second tank 16 in step 106. The azeotropic component supply valve 46 is controlled so as to supply the azeotropic component to the first tank 12, and the process returns to Step 100. As a result, the ethanol concentration of the ethanol water in the second tank 16 is reduced. In step 106, the temperature controller 42 is set so that the ethanol water in the second tank 16 is heated and distilled using the exhaust heat in accordance with the temperature of the ethanol water in the second tank 16 detected by the temperature sensor 40. At the same time, the azeotropic component supply valve 46 is controlled so as to return the azeotropic component (95% ethanol water) to the first tank 12. When the ethanol concentration of the ethanol water in the second tank 16 becomes 80% or less, the heating distillation is stopped, and the temperature of the ethanol water in the second tank 16 detected by the temperature sensor 40 is changed using the cooling water. The temperature controller 42 is controlled so as to cool the ethanol water in the two tanks 16.

  If the ethanol concentration in the ethanol water is in the range of 60% to 80% in step 102, the process returns to step 100 without performing the process of step 104 or 106.

  As described above, when the concentration control processing routine is executed, the ethanol concentration of the ethanol water in the second tank 16 is kept within a range of 60% to 80% suitable for steam reforming.

  Further, the ECU 44 executes a stored gas supply process routine shown in FIG. First, in step 120, it is determined whether the engine has been started, that is, whether the engine speed has reached a predetermined value or more, and the process waits in step 120 until the engine is started. And if it determines with the engine having started, it will transfer to step 122. FIG.

  In step 122, the gas supplier 36 is controlled so that the reformed gas accumulated in the condensing accumulator 34 is supplied to the intake pipe 24. As a result, the reformed gas is supplied to the combustion chamber 26 via the intake pipe 24, so that it is easy to start in the cold state and the operability in the cold state is ensured.

  In the next step 124, normal operation control is performed, the fuel injector 22 is controlled so as to inject water-containing ethanol from the first tank 12 into the intake pipe 24, and the reformed gas generated by the reformer 30 is taken in. The gas supply 36 is controlled to supply the pipe 24. As a result, the water-containing ethanol and the reformed gas are supplied to the combustion chamber 26 via the intake pipe 24. The reformed gas supplied at the time of normal operation control may be a reformed gas that is not accumulated or may be a reformed gas that is accumulated.

  In step 126, it is determined whether or not the vehicle is accelerating. If it is determined that the vehicle is accelerating based on the output from the vehicle speed sensor or the acceleration sensor, the condensation pressure accumulator 34 is used in step 128. The gas supplier 36 is controlled so as to supply the accumulated reformed gas to the intake pipe 24, and the process returns to step 124. As a result, the accumulated reformed gas is supplied to the combustion chamber 26 via the intake pipe 24, so that insufficient fuel during acceleration can be compensated and stable acceleration can be performed.

  If it is determined in step 126 that the vehicle is not accelerating, it is determined in step 130 whether the engine has stopped, that is, whether the engine speed has become less than a predetermined value, and it is determined that the engine has stopped. If it is determined that the engine is not stopped, the process returns to step 124, and normal operation control is performed.

  As described above, according to the engine system according to the embodiment of the present invention, ethanol water in which the ethanol concentration is maintained within a predetermined concentration range is stored in the second tank, and ethanol water from the second tank is stored. Steam reforming generates a reformed gas containing hydrogen and supplies it to the fuel chamber, so that the reformed gas generated from ethanol water suitable for reforming can be used. Therefore, stable operation is possible with a simple configuration without using low-boiling components such as gasoline.

  Further, exhaust heat is used to perform steam reforming, which is an endothermic reaction, and exhaust heat is recovered, so that thermal efficiency can be improved.

  Further, the reformed gas can be efficiently generated by keeping the ethanol concentration of the ethanol water in the second tank within a predetermined concentration range suitable for steam reforming.

  In addition, since the accumulated reformed gas is supplied to the combustion chamber when the engine is started or accelerated, insufficient fuel can be supplemented without using low-boiling components such as gasoline. In addition, since the amount of fuel increase at the time of engine start or acceleration can be greatly reduced as compared with the prior art, fuel consumption can be improved and emissions can be reduced.

  In the above embodiment, the case where the water-containing ethanol and the reformed gas from the first tank are supplied to the combustion chamber during normal operation control has been described as an example. However, during normal operation control, the first tank is used. Only the hydrous ethanol from may be supplied to the combustion chamber.

  In addition, the case where the accumulated reformed gas is supplied to the combustion chamber at the time of engine start and acceleration has been described as an example, but water-containing ethanol from the first tank is supplied to the combustion chamber together with the accumulated reformed gas. You may do it.

1 is a schematic diagram showing a configuration of an engine system according to an embodiment of the present invention. A reforming temperature is a graph showing the relationship between the amount of each of H _{2 O} and ethanol as the condensation component of unmodified starting material. It is a flowchart which shows the content of the density | concentration control processing routine in ECU of the engine system which concerns on embodiment of this invention. It is a flowchart which shows the content of the stored pressure gas supply process routine in ECU of the engine system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine system 12 1st tank 14 1st pump 16 2nd tank 18 2nd pump 22 Fuel injector 24 Intake pipe 26 Combustion chamber 29 Evaporator 30 Reformer 34 Condensing accumulator 36 Gas supply 38 Ethanol concentration sensor 40 Temperature sensor 42 Temperature controller

Claims (8)

A first tank for containing hydrous ethanol;
A second tank containing ethanol having a lower ethanol concentration than the hydrous ethanol;
Reforming means for reforming ethanol supplied from the second tank by heating and generating a reformed gas containing hydrogen;
Supply means for supplying at least one of hydrous ethanol from the first tank and the reformed gas generated by the reforming means to a combustion chamber;
Engine system equipped with.   The engine system according to claim 1, wherein the reforming means reforms the ethanol using exhaust heat.   The engine system according to claim 1 or 2, wherein the reforming means performs steam reforming of the ethanol.   The engine system according to any one of claims 1 to 3, wherein the ethanol concentration of the ethanol stored in the second tank is 60% to 80%. A recovery means for recovering, in the second tank, an unreformed raw material that has not been reformed in the reforming by the reforming means;
Detection means for detecting the ethanol concentration of the ethanol contained in the second tank;
Based on the ethanol concentration detected by the detection means, a concentration control means for controlling the ethanol concentration of the ethanol in the second tank to be within a predetermined concentration range lower than the water-containing ethanol;
The engine system according to any one of claims 1 to 4, further comprising:   The concentration control means controls the first tank so that the water-containing ethanol in the first tank is supplied to the second tank when the ethanol concentration detected by the detection means is lower than the predetermined concentration range. The engine system according to claim 5.   The concentration control means, when the ethanol concentration detected by the detection means is higher than the predetermined concentration range, heat-distills ethanol stored in the second tank and supplies an azeotropic component to the first tank. The engine system according to claim 5 or 6, wherein the second tank is controlled to do so. A pressure accumulating means for accumulating the reformed gas generated by the reforming means at a predetermined pressure;
The engine system according to any one of claims 1 to 7, wherein the supply means supplies the reformed gas accumulated by the pressure accumulation means to the combustion chamber when the engine is started or accelerated.

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