JP2006242042A - Purifying device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purifying device for an internal combustion engine capable of suppressing accumulation and storage of carbon-based compounds such as unburnt fuel and deposit sticking to a piston which partitions a combustion chamber of the internal combustion engine. <P>SOLUTION: The purifying device for the internal combustion engine is provided with a laser beam irradiation device 2 for irradiating the piston 13 partitioning the combustion chamber 3 of the internal combustion engine 1, with laser beams. Unburnt fuel existing around the piston 13 is vaporized by irradiating laser beams toward the piston 13. As a result, sticking of deposit or the like can be suppressed. Further, the deposit can be incinerated by irradiating the deposit sticking to the piston 13, with laser beams. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a purification device for an internal combustion engine. More specifically, the present invention relates to a purification device for an internal combustion engine that purifies deposits adhering to the combustion chamber of the internal combustion engine.

  In the combustion chamber of an internal combustion engine, unburned fuel may cause deposits (carbon-based compounds) due to chemical reactions other than combustion. When deposits accumulate in the combustion chamber, the behavior of the fuel in the combustion chamber fluctuates, greatly affecting the performance of the internal combustion engine. As a result, emissions may be deteriorated.

  To solve this problem, a technique is disclosed in which deposits are accumulated in an injection hole portion having a function of injecting fuel and a function of blowing air to the fuel using an air assist type fuel injection valve (Patent Document). 1). That is, a groove as a deposit accumulation is provided in an air assist passage for supplying air to be sprayed to the injected fuel on the outlet side of the nozzle hole.

In addition, a technique is disclosed in which a liquid repellent film including a fluoroalkyl group or the like is formed around the nozzle hole portion to suppress deposit adhesion (see Patent Document 2). In addition, as a method of forming the liquid repellent film on the surface of the nozzle hole, for example, the liquid repellent film is fired by a sol-gel method so that the surface has liquid repellency.
JP-A-5-187343 JP 10-159688 A

  However, since the technique according to Patent Document 1 only accumulates a certain amount of deposit, if a relatively large amount of deposit is generated, it is accumulated in the nozzle hole portion without being removed, which may affect the performance of the internal combustion engine. . In addition, since the technique according to Patent Document 2 is a method for weakening the adhesion between the surface of the nozzle hole and the deposit, even if the nozzle hole is formed with a liquid repellent film, it can be operated for a long time or at a relatively high temperature. Repeated exposure to the combustion gas or the like may reduce the effect of suppressing adhesion.

  The present invention has been made in view of such circumstances, and an internal combustion engine capable of suppressing accumulation and accumulation of unburned fuel and carbon-based compounds such as deposits adhering to the combustion chamber of the internal combustion engine. An object is to provide a purification device for an engine.

Means for Solving the Problems and Effects of the Invention

  The purification apparatus for an internal combustion engine of the present invention is characterized by comprising laser light irradiation means for irradiating a piston that divides a combustion chamber of the internal combustion engine with laser light. And the unburned fuel which exists in the vicinity of the piston can be evaporated by the laser beam emitted by the laser beam irradiation means. Furthermore, carbon-based compounds such as deposits attached to the piston can be incinerated by the laser light. In particular, by aligning the focal point of the laser beam irradiated by the laser beam irradiation means with the top surface of the piston, the unburned fuel existing near the top surface of the piston can be evaporated more securely and attached to the top surface of the piston. The above carbon-based compounds can be incinerated. Thus, according to this invention, it can suppress that a carbon-type compound accumulates and accumulate | stores in a piston. As a result, it is possible to suppress fluctuations in the behavior of the fuel in the combustion chamber caused by the carbon-based compound depositing on the piston and the deterioration of the emission.

  In addition, the laser beam irradiation means may be configured to irradiate the laser beam to a cavity formed on the top surface of the piston. The cavity formed on the top surface of the piston is a part that greatly affects the behavior of the fuel in the combustion chamber. If a carbon-based compound such as deposit adheres to the piston cavity, the behavior of the fuel in the combustion chamber may change. Therefore, by irradiating the cavity with laser light, the unburned fuel existing in the vicinity of the cavity can be evaporated and further, carbon-based compounds such as deposits attached to the cavity can be incinerated. Thereby, it can suppress that a carbon-type compound adheres to the cavity of the piston which is a part which has a big influence on the behavior of the fuel in a combustion chamber.

  Next, the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a purification device for an internal combustion engine according to the present embodiment. As shown in FIG. 1, the internal combustion engine purification apparatus includes an internal combustion engine 1, a laser light irradiation device 2 as laser light irradiation means, and a control device (ECU).

  As shown in FIG. 1, an internal combustion engine 1 includes a cylinder block 11, a cylinder head 12 having an intake valve 12a and an exhaust valve 12c, a piston 13 that reciprocates on the inner peripheral wall of the cylinder block 11, a combustible mixture or a fuel. This is a known internal combustion engine that includes an ignition device 14 that ignites the fuel and the like, and a fuel injection valve 15. The combustion chamber 3 of the internal combustion engine 1 is partitioned by the inner peripheral wall of the cylinder block 11, the top surface of the piston 13, and the ceiling inner wall of the cylinder head 12.

  The cylinder head 12 is connected to an intake pipe that forms a passage through which intake air flows to guide intake air 12b, and an exhaust port 12d that connects to an exhaust pipe that forms a passage through which combustion gas flows and exhausts exhaust gas It has. An intake valve 12a can be opened and closed at the intake port 12b, and an exhaust valve 12c can be opened and closed at the exhaust port 12d. That is, the intake valve 12a blocks and allows the flow of intake air introduced from the intake pipe to the intake port 12b to the combustion chamber 3. The exhaust valve 12c blocks and allows the flow of the combustion gas generated in the combustion chamber 3 to the exhaust port 12d.

  The ignition device 14 is a well-known ignition device including, for example, an ignition plug. The fuel injection valve 15 is provided on the ceiling wall side of the cylinder head 12 and directly injects fuel into the combustion chamber 3. Specifically, the fuel injection valve 15 injects and supplies fuel toward the cavity 13 a formed in the top surface of the piston 13 in the combustion chamber 3.

  The laser beam irradiation device 2 is provided on the ceiling wall side of the cylinder head 12. The laser light irradiation device 2 diverges laser light from an irradiation port and radiates thermal energy to the irradiation scheduled region according to the wide angle or narrow angle where the light diverges. Specifically, the laser light irradiation device 2 includes a laser generation device that generates laser light, an optical device that emits or condenses laser light from an irradiation port, and optically transmits laser light from the laser generation device. It is a well-known laser transmission device having an optical fiber that can be transmitted without a transmission loss to an optical device. The optical fiber is held in a substantially cylindrical casing fixed to the ceiling wall of the cylinder head 12 so that the irradiation port of the optical fiber is directed into the combustion chamber 3. More specifically, the irradiation port of the optical fiber is fixed so as to be directed to the cavity 13 a formed in the piston 13 that partitions the combustion chamber 3. The optical device is provided with a lens or a lens group that diverges or condenses laser light emitted from the irradiation port. In this optical device, the focal position of the laser light irradiated into the combustion chamber 3 is adapted to the cavity 13 a formed in the piston 13. This optical device may be provided with a beam splitter such as a mirror in order to guide laser light from the laser generator.

  The laser light generated by the laser light irradiation device 2 has thermal energy capable of incinerating a relatively flame-retardant deposit as compared with fuel. Therefore, the laser beam generated by the laser beam irradiation device 2 has a thermal energy higher than the thermal energy that can evaporate by heating the fuel.

  The ECU (not shown) is connected to the fuel injection valve 15, the intake valve 12 a, the exhaust valve 12 c, and the laser light irradiation device 2. This ECU controls the energization period of the fuel injection valve 15 by starting and stopping energization of the coil of the fuel injection valve 15. The amount of fuel injected and supplied into the combustion chamber 3 is controlled by controlling the energization period of the fuel injection valve 15 by the ECU. The ECU also controls opening / closing of the intake valve 12a and opening / closing of the exhaust valve 12c. In this manner, the intake air amount taken into the combustion chamber 3 is controlled by controlling the opening / closing of the intake valve 12a by the ECU. Exhaust gas is controlled from the combustion chamber 3 to the exhaust port 12d by controlling the opening and closing of the exhaust valve 12c by the ECU. Further, the ECU controls the irradiation timing and irradiation intensity of the laser light irradiated by the laser light irradiation device 2. The control by the ECU is appropriately changed according to the operation state of the internal combustion engine 1, for example, the throttle opening, the rotation angle position of the crankshaft, the coolant temperature, and the like.

  The operation of the purification apparatus for an internal combustion engine configured as described above will be described. First, the operation of the internal combustion engine 1 will be described. In the internal combustion engine 1, intake air is guided into the combustion chamber 3 through the intake port 12b when the intake valve 12a is opened. Further, fuel is injected and supplied from the fuel injection valve 15 toward the cavity 13 a formed in the piston 13 in the combustion chamber 3. When the ignition device 14 is ignited, the combustible air-fuel mixture composed of the intake air introduced into the combustion chamber 3 and the fuel injected and supplied from the fuel injection valve 15 is ignited and combusted. Then, the piston 13 reciprocates and the crankshaft that is the output shaft of the internal combustion engine 1 rotates. The combustion gas after combustion is exhausted from the combustion chamber 3 to the exhaust port 12d by opening the exhaust valve 12c.

  Next, operation | movement of the laser beam irradiation apparatus 2 is demonstrated. The laser light irradiation device 2 generates laser light based on a control signal from the ECU, and irradiates the combustion chamber 3 with the laser light. Specifically, the laser beam irradiation device 2 irradiates the cavity 13 a formed in the piston 13 that partitions the combustion chamber 3 so that the focal position of the laser beam is aligned. However, since the piston 13 reciprocates, the laser light irradiation device 2 controls the irradiation timing of the laser light according to the rotational angle position of the crankshaft corresponding to the reciprocating position of the piston 13.

  And since the thermal energy of the laser beam irradiated into the combustion chamber 3 by the laser beam irradiation device 2 is larger than the energy that can evaporate by heating the fuel, the unburned fuel existing near the top surface of the piston 13 It will evaporate. Furthermore, the thermal energy of the laser beam irradiated into the combustion chamber 3 by the laser beam irradiation device 2 has energy capable of burning the deposit. Therefore, the deposit is incinerated by irradiating the laser beam to the deposit attached to the cavity 13a in the piston 13 in particular.

Here, the process of incineration of the deposit by laser light will be described. For ease of explanation, the carbon combustion formula will be described assuming that carbon (C) is a carbon-based compound such as deposit. The combustion formula of carbon is represented by carbon (C) + oxygen (O ₂ ) → CO ₂ . The speed of shifting from the left side to the right side is represented by a reaction rate constant K, and K = Ae ^{−E / RT} . Here, A is a constant determined by the concentration, E is energy required for activation, and T is temperature. When the laser beam is irradiated, the carbon (C), that is, a deposit made of a carbon-based compound, promotes a combustion reaction due to a temperature rise and activation due to condensing of the laser beam energy. In other words, it is possible to ignite and incinerate at a relatively lower temperature than the conventional ignition temperature of the deposit due to the activation effect of the laser light irradiation.

  As described above, since the unburned fuel existing in the vicinity of the piston 13 can be evaporated by the laser light irradiation device 2, it is possible to suppress deposits from accumulating and accumulating on the piston 13. Even after deposits are accumulated and accumulated on the piston 13, the deposits can be incinerated. Thereby, since the fluctuation | variation of the behavior of the fuel in the combustion chamber 3 can be suppressed, the performance of the internal combustion engine 1 can be maintained. Furthermore, the emission can be improved.

  In the above embodiment, the focal position of the laser beam irradiated by the laser beam irradiation device 2 is adjusted to the cavity 13a formed in the piston 13, but the present invention is not limited to this. If the focal position of the laser beam is matched with any position on the top surface of the piston 13, the vaporization of unburned fuel existing near the top surface of the piston 13 and the deposit attached to the top surface of the piston 13 are achieved. Can be incinerated. However, the cavity 13a of the piston 13 is a part that greatly influences the behavior of the fuel in the combustion chamber 3 and further the performance of the internal combustion engine, so that the focal position of the laser beam can be adjusted to the cavity 13a of the piston 13 in particular. The effect is great.

It is a figure which shows the purification apparatus of the internal combustion engine in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Internal combustion engine 2: Laser beam irradiation apparatus 11: Cylinder block 12: Cylinder head 12a: Intake valve 12b: Intake port 12c: Exhaust valve 12d: Exhaust port 13: Piston 13a: Cavity 14: ignition device, 15: fuel injection valve, 3: combustion chamber

Claims (3)

  A purification apparatus for an internal combustion engine, comprising: laser light irradiation means for irradiating a piston that partitions a combustion chamber of the internal combustion engine with laser light.   The purification apparatus for an internal combustion engine according to claim 1, wherein the laser light irradiated by the laser light irradiation means incinerates deposits attached to the piston. The internal combustion engine purification device according to claim 1 or 2, wherein the laser light irradiation means irradiates the laser beam to a cavity formed on a top surface of the piston.

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