JP2005273585A - Odorant processing unit of gaseous fuel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the desorption of an odorant from a deodorizing device to absorb the odorant in a gaseous fuel during the operation of an engine. <P>SOLUTION: As a result of the heating with a heater 22, an odorant composition absorbed in the deodorizing device 21 is desorbed from the deodorizing device 21 on condition that a catalyst temperature estimated value and an engine water temperature are not less than the predetermined values respectively, and fed into the CNG engine 10 and a catalyst device 27 at the downstream side. The odorant composition is well burned in the CNG engine 10, and sulfur poisoning resulting from the odorant composition in the catalyst device 27 is difficult to occur on the high-temperature condition of the catalyst and the high-load condition which is the air-fuel ratio is at a rich side. Then, the regeneration of the deodorizing device 21 can be performed during the engine operation, suppressing the sulfur poisoning of the catalyst device 27. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an odorant treatment apparatus for a gas fuel engine provided with a deodorizer for removing an odorant contained in gas fuel.

  In recent years, various gas fuel engines have been proposed in order to use gas fuels such as CNG (Compressed Natural Gas) and LPG (Liquid Petrol Gas) as fuel for internal combustion engines for automobiles. .

  By the way, an odorant is often added to the gas fuel used in such a gas fuel engine as a measure against gas leakage. However, when gas fuel containing an odorant is supplied to an engine equipped with an exhaust gas purification catalyst, the exhaust gas purification catalyst is deteriorated due to sulfur poisoning caused by components such as sulfur contained in the odorant. There is a problem of being promoted.

As a technique for removing an odorant from gas fuel in a gas fuel engine, Patent Document 1 provides a deodorization device (deodorization catalyst) for adsorbing the odorant in the fuel supply path, and the performance of the deodorization device is high. When it falls, the technique which supplies air while heating a deodorizing apparatus and reproduces this is disclosed.
JP-A-8-246957

  However, since the supply of air to the deodorizing device is performed on the intake side of the engine, the amount of intake air of the engine is changed to affect the operation. Therefore, the deodorizing device according to the method disclosed in Patent Document 1 is affected. Regeneration is inconvenient because it must be performed while the engine is stopped.

  On the other hand, as a result of earnest research on the removal of the odorant from the deodorizer, the present inventor has found that sulfur poisoning caused by the odorant component in the exhaust gas purification catalyst is a condition under which the catalyst is at a high temperature and the air-fuel ratio is It was found that it is difficult to occur under the condition of the rich side.

  The present invention has been made based on such new knowledge, and an object of the present invention is to provide means capable of performing regeneration of the deodorizing device during operation of the engine.

  The first aspect of the present invention is provided in a fuel supply path to a gas fuel engine having an exhaust gas purification catalyst on the exhaust side, adsorbing means for adsorbing an odorant from the gas fuel, and heating for heating the adsorbing means And an odorant treatment device for a gas fuel engine, wherein the temperature of the exhaust gas-purifying catalyst is obtained. An odorant for a gas fuel engine, wherein the control means operates the heating means when the temperature acquired by the catalyst temperature acquisition means exceeds a predetermined value. It is a processing device.

  In the first aspect of the present invention, when the temperature of the exhaust gas purifying catalyst exceeds a predetermined value, the control means operates the heating means, thereby suppressing sulfur poisoning of the exhaust gas purifying catalyst and Regeneration can be performed while the engine is running.

  The second aspect of the present invention is provided in a fuel supply path to a gas fuel engine provided with an exhaust gas purification catalyst on the exhaust side, adsorbing means for adsorbing an odorant from the gas fuel, and heating for heating the adsorbing means And an odorant treatment device for a gas fuel engine, wherein the temperature of the exhaust gas-purifying catalyst is obtained. And a catalyst temperature acquisition means for acquiring the air-fuel ratio of the gas fuel supplied to the gas fuel engine, and the control means has a predetermined value for the temperature acquired by the catalyst temperature acquisition means. An odorant treatment apparatus for a gas fuel engine, wherein the heating means is operated when the air-fuel ratio obtained by the air-fuel ratio acquisition means is richer than a predetermined value.

  In the second aspect of the present invention, the control means operates the heating means when the temperature of the exhaust gas purifying catalyst exceeds a predetermined value and the air-fuel ratio is richer than the predetermined value. The effect can be realized more suitably.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, embodiment shown below and its deformation | transformation are only an illustration to the last, and this invention is not necessarily limited by these.

  FIG. 1 is an overall schematic diagram showing a schematic configuration of an odorant treatment apparatus 1 for a gas fuel engine according to a first embodiment of the present invention. The CNG engine 10 according to the present embodiment is a port injection type internal combustion engine that injects CNG fuel into an intake port 10b communicating with a combustion chamber 10a by an injector 17, and is mounted on a vehicle.

  The combustion chamber 10a includes a cylinder bore, a cylinder head (not shown), and a piston that is reciprocally disposed in the cylinder bore. A concave cavity is formed in the intake side portion of the upper surface of the piston in order to establish so-called stratified combustion. A spark plug is disposed substantially at the center of the combustion chamber 10a. An intake valve is provided at the intake port 10b facing the combustion chamber 10a, and an exhaust valve is provided at the exhaust port. The injector 17 is disposed in the intake port 10b.

  The CNG engine 10 basically has the same configuration as that of a normal in-cylinder direct injection gasoline engine. However, in order to be able to supply CNG fuel, the configuration of the fuel supply system is a gasoline engine. Is different.

  The CNG fuel tank 12 is a cylinder for storing CNG fuel in a pressurized state at a high pressure (for example, about 20 MPa at the maximum). The CNG fuel tank 12 is provided with a pressure sensor 12a for detecting the internal pressure and a temperature sensor 12b for detecting the temperature.

  The delivery pipe 13 is for distributing the CNG fuel supplied via the high-pressure regulator 15 to each injector 17, a pressure sensor 13 a for detecting the pressure in the delivery pipe 13, and a temperature for detecting the temperature. And a sensor 13b. On the inlet side of the delivery pipe 13, a delivery cutoff valve 13 c for selectively blocking the supply of CNG fuel is provided.

  The CNG fuel tank 12 and the delivery pipe 13 are connected by a fuel supply pipe 14. The pressure of the CNG fuel is reduced to a predetermined regulator pressure Pa (for example, about 0.05 MPa) by the high pressure regulator 15 provided in the middle of the fuel supply pipe 14.

  A deodorizing device 21 is provided in the fuel supply path from the CNG fuel tank 12 to the delivery pipe 13 and downstream of the high pressure regulator 15. The deodorizing device 21 is formed by connecting gas pipes to both ends of a container filled with a deodorant of an appropriate shape such as a powdery body, a spherical body, or a honeycomb shape, and like a powdery body In the case where there is a possibility of diffusion due to the passage of gas, diffusion is prevented by providing filters on both sides thereof.

  The deodorizer used is supported by activated carbon, silica gel, activated alumina, synthetic zeolite, ion exchange resin, or catalyst for chemical reaction such as Pt-Pd, Mn-Au, Mn-Fe, etc. by physical and chemical adsorption. The zeolite ceramics and perovskite type oxidation catalysts that have been conventionally known are appropriately selected and used.

  As a specific example, if a deodorizer obtained by superimposing a honeycomb structure Mn—Fe catalyst and an Au—Fe catalyst is used, the gas fuel passes through the deodorizer, so that S ( The sulfur-based odor is deodorized by the Mn-Fe catalyst, and the N (amine-based) odor is deodorized by the Au-Fe catalyst. In addition, what was made porous as a deodorizing agent is more effective.

A heater 22 is installed in the vicinity of the deodorizing device 21 so as to be able to exchange heat with the deodorizing device 21. As the heater 22, it is preferable to use a rapidly heatable PTC heater including a PTC thermistor (Positive Temperature Coefficient Thermistor) made of a semiconductor ceramic mainly composed of barium titanate (BaTiO ₃ ), for example. A voltage supply circuit 23 for supplying power to the heater 22 is connected to the heater 22. The voltage supply circuit 23 boosts the DC voltage from the battery 24 and supplies it to the heater 22 at an arbitrary voltage value and timing, and includes a DC / DC converter and the like.

A catalyst device 27 as an exhaust gas purifying catalyst is connected to the exhaust side of the combustion chamber 10a via an exhaust manifold 25 and an exhaust pipe 26. The downstream side of the catalyst device 27 is open to the atmosphere via a silencer (not shown). As the catalyst device 27, various devices that can purify exhaust gas, such as a three-way catalyst, an oxidation catalyst, or a NOx reduction catalyst, can be used. Examples of the three-way catalyst include a Pt / Pd / Rh catalyst, a Pt / Pd catalyst, a Pt / Rh catalyst, a Pd / Rh catalyst, and the like. Examples of the oxidation catalyst include zeolite catalyst, Al ₂ O ₃ catalyst, Pt catalyst, Pd catalyst, Pt / Pd catalyst, Au catalyst and the like. Examples of the NOx reduction catalyst include a Pt / Al ₂ O ₂ catalyst, a Cu—ZSM-5 catalyst, a perovskite catalyst, an Au catalyst, and an occlusion reduction catalyst. In the catalyst device 27, any one of the above exhaust gas purifying catalyst powders is supported on a carrier made of ceramic formed in a honeycomb shape.

  The engine electronic control unit (ECU) 30 (hereinafter referred to as ECU 30) is configured as a well-known one-chip microprocessor having a CPU, a RAM, a ROM, and an input / output interface coupled to each other by a bidirectional bus. On the input side of the ECU 30, in addition to the sensors 12 a, 12 b, 13 a, and 13 c described above, a water temperature sensor 31 provided in the cooling water path of the CNG engine 10, and a crank angle sensor provided in the vicinity of the crankshaft of the CNG engine 10 32, an air flow meter 33 for detecting the intake air amount provided upstream of the intake passage of the CNG engine 10, an intake air temperature sensor 34 for detecting the intake air temperature, an accelerator sensor 35 provided in the vicinity of the accelerator pedal in the passenger compartment, etc. The various sensors are connected. In addition to the injector 17 and the high voltage regulator 15, a voltage supply circuit 23 and the like are connected to the output side of the ECU 30. The ECU 30 inputs signals from various sensors according to programs stored in the ROM and various maps and reference values, executes arithmetic processing based on the input signals, and controls signals for various actuators based on the calculation results. In addition to the odorant desorption process described below, fuel injection control, ignition timing control, and the like, which are performed separately from the present invention, are executed.

  The odorant detachment process in the first embodiment configured as described above will be described below. The odorant desorption routine shown in FIG. 2 is repeatedly executed during operation of the CNG engine 10. The ECU 30 first reads the detection values of the various sensors described above (S10).

  Next, it is determined whether the catalyst temperature in the catalyst device 27 is equal to or higher than a predetermined value (S20). The catalyst temperature is calculated based on the engine water temperature detected by the water temperature sensor 31, the engine speed NE detected by the crank angle sensor 32, and the engine speed NE and the intake air amount Q from the air flow meter 21. Based on the engine load (Q / NE), it is estimated (calculated) by a predetermined map. In step S20, the estimated value is compared with a predetermined reference value stored in the ROM of the ECU 30, and affirmative when the estimated value exceeds the reference value.

  Next, it is determined whether the engine water temperature is equal to or higher than a predetermined value (S30). The engine water temperature is calculated based on a detection signal from the water temperature sensor 31. In step S30, the calculated value is compared with a predetermined reference value stored in the ROM of the ECU 30, and affirmative when the calculated value exceeds the reference value. The reference value here is experimentally determined in advance so that the sulfur component in the odorant is almost completely combusted in the combustion chamber 10a if the engine water temperature exceeds this.

  Next, it is determined whether the air-fuel ratio in the combustion chamber 16 is on the rich side (S40). The air-fuel ratio is calculated based on the engine speed NE detected by the crank angle sensor 32 and the intake air amount detected by the air flow meter 21. In step S40, the calculated air-fuel ratio is compared with a predetermined reference value stored in the ROM of the ECU 30, and affirmative when the calculated value is richer than the reference value.

  If both of steps S20 to S40 are positive, that is, if the estimated catalyst temperature value and the engine water temperature are each equal to or higher than a predetermined value and the air-fuel ratio is richer than the predetermined value, the heater 22 heats the deodorizing device 21. Is performed (S50). This heating is realized by duty control of the voltage supply circuit 23 by the ECU 30.

  This heating is performed for a predetermined time such that the odorant component adsorbed by the deodorizing device 21 is sufficiently desorbed, and the routine is exited on the condition that the predetermined time has passed (S60). In addition, when the result is negative in any of steps S20 to S40, that is, when the estimated catalyst temperature value or the engine water temperature is less than a predetermined value, or when the air-fuel ratio is leaner than the predetermined value, the deodorizer 21 Is not heated.

  As described above, in the present embodiment, the odorant component adsorbed by the deodorizing device 21 as a result of heating by the heater 22 is the deodorizing device 21 under the condition that the estimated catalyst temperature and the engine water temperature are equal to or higher than the predetermined values, respectively. The odorant component is well burned in the CNG engine 10 and is odorized in the catalyst device 27. Since sulfur poisoning due to the components of the agent is unlikely to occur under conditions where the catalyst is at a high temperature and under a high load condition where the air-fuel ratio is rich, it does not remain in the CNG engine 10 and the catalyst device 27 and is harmless. Will be disassembled. Therefore, in the present embodiment, regeneration of the deodorizing device 21 can be performed during operation of the engine while suppressing sulfur poisoning of the catalyst device 27 that is an exhaust gas purifying catalyst.

  In the present embodiment, the heater 22 is operated on the condition that the air-fuel ratio is richer than the predetermined value, so that the effect of the present invention can be more suitably realized.

  In addition, the sulfur component contained in the odorant generally has the property of accelerating the corrosion of the mechanical structure around the combustion chamber, such as the cylinder bore and piston ring, and the corrosion of other mechanical structures in the engine by melting into the engine oil. However, in the present embodiment, the high temperature load at which the engine water temperature is equal to or higher than a predetermined value is also set as the condition for executing the heating by the heater 22 (S30), so that the sulfur component is almost completely within the combustion chamber 10a. By being burned, corrosion of the CNG engine 10 can be suppressed.

  In the above embodiment, the catalyst temperature is estimated (calculated) based on the engine water temperature, the engine speed, and the engine load. However, the catalyst temperature in the present invention may be estimated (calculated) from other parameters. . Furthermore, it goes without saying that a catalyst temperature sensor may be provided in or near the catalyst device 27 to directly detect the catalyst temperature.

  In the above embodiment, the catalyst temperature is equal to or higher than the predetermined value and the engine water temperature is equal to or higher than the predetermined value, which are different conditions for operating the heater 22, but the engine water temperature is high, for example. In some cases, it can be estimated with high probability that the catalyst temperature is high, or conversely, the engine temperature is high when the catalyst temperature is high. Therefore, for example, the heating by the heater 22 may be performed only on the condition that the engine water temperature exceeds a predetermined value, and even with such a configuration, the effects of the present invention can be obtained to a considerable extent and belong to the category of the present invention. Is.

  Moreover, although the example using the deodorizing apparatus 21 using activated carbon etc. was demonstrated in the said embodiment, the deodorizing apparatus thru | or adsorption | suction means in this invention may be things other than what was illustrated above, and an odorant is substantially carried out by heating. If the deodorizing apparatus can desorb components and regenerate the apparatus, the effects of the present invention can be suitably realized.

  Moreover, in the said embodiment, although the PTC heater was utilized as the heater 20, you may utilize other types of electrothermal heaters, such as what utilized the Ni-Cr wire, as a heater in this invention, and also cooling water or A heater using exhaust heat of the engine such as exhaust may be used as the heating means.

  In the above embodiment, an example in which the present invention is applied to an engine that realizes so-called stratified combustion has been described. However, sulfur poisoning caused by components such as sulfur contained in the odorant is a so-called stoichiometric system at an ideal air-fuel ratio. This may occur even in an engine that establishes combustion, and the present invention can be applied to such a stoichiometric combustion engine (for example, one that uses a three-way catalyst). Moreover, although the said embodiment demonstrated the example which applied this invention about the port-injection type engine, this invention is applicable not only to a port-injection type engine but an in-cylinder direct injection type or a mixer-type engine.

1 is an overall schematic diagram of an odorant treatment apparatus for a gas fuel engine according to an embodiment of the present invention. It is a flowchart which shows the odorant removal | desorption process in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 CNG engine 12 CNG fuel tank 13 Delivery pipe 17 Injector 21 Deodorizing device 22 Heater 27 Catalytic device 30 Engine electronic control unit (ECU)

Claims (2)

An adsorbing means for adsorbing an odorant from the gas fuel, a heating means for heating the adsorbing means, and a heating means provided in a fuel supply path to a gas fuel engine having an exhaust gas purification catalyst on the exhaust side; A control means for controlling and desorbing the odorant from the adsorption means, an odorant treatment apparatus for a gas fuel engine,
Further comprising catalyst temperature acquisition means for acquiring the temperature of the exhaust gas purifying catalyst,
The odorant treatment apparatus for a gas fuel engine, wherein the control means operates the heating means when the temperature acquired by the catalyst temperature acquisition means exceeds a predetermined value. Provided in a fuel supply path to a gas fuel engine having an exhaust gas purification catalyst on the exhaust side, adsorbing means for adsorbing an odorant from the gas fuel, heating means for heating the adsorbing means, and the heating means A control means for controlling and desorbing the odorant from the adsorption means, an odorant treatment apparatus for a gas fuel engine,
Catalyst temperature acquisition means for acquiring the temperature of the exhaust gas purifying catalyst;
Air-fuel ratio acquisition means for acquiring the air-fuel ratio of the gas fuel supplied to the gas fuel engine,
The control means operates the heating means when the temperature acquired by the catalyst temperature acquisition means exceeds a predetermined value and the air-fuel ratio acquired by the air-fuel ratio acquisition means is richer than a predetermined value. An odorant treatment device for a gas fuel engine.

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