JP2006242040A - Laser ignition device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser ignition device reducing emission with efficiently using laser energy. <P>SOLUTION: This laser ignition device for an internal combustion engine is provided with an ignition laser irradiation device 5 irradiating ignition laser to air fuel mixture in a combustion chamber 10 of the internal combustion engine to activate the air fuel mixture, a concentration measurement laser irradiation device 7 irradiating concentration measurement laser in the combustion chamber 10 and measuring concentration of combustion product material produced by combustion of the air fuel mixture based on intensity of the concentration measurement laser, and a control device 30 changing equivalent ratio of the air fuel mixture based on concentration of the combustion product material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser ignition device for an internal combustion engine.

As an internal combustion engine ignition device, a laser ignition device for an internal combustion engine using laser light is disclosed in Patent Document 1, for example. The internal combustion engine laser ignition device is a device that condenses laser light emitted from a laser oscillator in a combustion chamber of an internal combustion engine by a lens, and activates an air-fuel mixture in the combustion chamber to ignite and burn.
JP-A-5-33755

  Here, the laser ignition device for an internal combustion engine needs to generate a laser beam with very large energy in order to burn the air-fuel mixture. On the other hand, the generation of laser light having such a large energy requires efficient use of energy.

  By the way, the air-fuel mixture burns in the combustion chamber of the internal combustion engine, whereby intermediate products and final products are generated. When the air-fuel mixture is burned in the combustion chamber, the combustion reaction of the intermediate product may not proceed due to the laser beam depending on the concentration of the intermediate product. As a result, emissions may be deteriorated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laser ignition device capable of reducing emission while efficiently using laser energy.

Means for Solving the Problems and Effects of the Invention

  An internal combustion engine laser ignition device according to the present invention includes an ignition laser light irradiation means for irradiating an air-fuel mixture in a combustion chamber of an internal combustion engine to activate the air-fuel mixture, and a concentration measuring device in the combustion chamber. Concentration measurement laser light irradiation means for measuring the concentration of a combustion product generated by irradiating laser light and burning the mixture based on the intensity of the concentration measurement laser light, and the concentration of the combustion product And equivalence ratio change control means for changing the equivalence ratio of the air-fuel mixture.

  According to the present invention, it is possible to measure the concentration of combustion products, particularly intermediate products, in the combustion chamber and change the equivalence ratio according to the concentration. That is, the air-fuel mixture in the combustion chamber can be reliably burned. Furthermore, a concentration measuring laser beam is used for measuring the concentration of the combustion product. That is, the laser energy can be efficiently used by using the laser energy for the ignition of the air-fuel mixture and the concentration measurement of the combustion product.

  The wavelength of the concentration measuring laser light is preferably in the vicinity of the absorption wavelength of the combustion product. That is, when the concentration measurement laser beam having a wavelength near the absorption wavelength of the combustion product is irradiated into the combustion chamber, the intensity of the concentration measurement laser beam in a region where the concentration of the combustion product is high becomes weak, and the combustion product The intensity of the laser beam for density measurement in the region where the density is low is increased. Thereby, the density | concentration of the combustion product which exists in a combustion chamber can be measured reliably.

  The laser ignition device for an internal combustion engine according to the present invention may further include laser light generating means for generating the ignition laser light and the concentration measurement laser light. That is, the laser light for ignition and the laser light for concentration measurement are generated by one laser light generating means. The laser light generated by the laser light generating means can be used for ignition and concentration measurement, for example, by spectroscopic analysis with a mirror or the like. As described above, by using the laser light generated by one laser light generating means for ignition and concentration measurement, it is possible to reliably use the laser energy efficiently.

  The equivalence ratio change control means may reduce the equivalence ratio when the concentration of the combustion products is greater than a predetermined value. The equivalence ratio change control means may reduce the equivalence ratio when either the maximum value or the average value of the concentration of the combustion products is larger than a predetermined value. In other words, when the concentration of combustion products is greater than a predetermined value, or when the maximum value or average value of the concentration of combustion products is greater than a predetermined value, the equivalent ratio is reduced so that excessive combustion products are generated. Can be suppressed. That is, the intermediate product is caused to act so as to advance the combustion reaction. Thereby, it can suppress that an emission deteriorates.

  The equivalent ratio change control means may change at least one of the fuel injection amount, the intake air amount, and the EGR rate, for example, as changing the equivalent ratio. For example, when the concentration of the combustion product is larger than a predetermined value, the fuel injection amount is reduced, the intake air amount is increased, or the EGR rate is lowered.

  Next, the present invention will be described in more detail with reference to embodiments.

(1) Configuration of in-cylinder direct injection internal combustion engine A direct injection internal combustion engine to which the laser ignition device for an internal combustion engine of the present invention is applied will be described. An in-cylinder direct injection internal combustion engine (hereinafter referred to as “engine”) in the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing the configuration of the engine of the present embodiment. FIG. 2 is a block diagram showing the laser light generator 20 and the control device 30.

  As shown in FIG. 1, the engine includes a cylinder block 1, a cylinder head (not shown), an intake valve 2, an exhaust valve 3, a fuel injection valve 4, an ignition laser beam irradiation device 5, and a piston. 6, a measurement laser light irradiation device 7, an energy intensity detection sensor 8, an exhaust gas recirculation device (EGR) 40, a laser light generation device 20, and a control device 30. The combustion chamber 10 of the engine is defined by the inner peripheral wall of the cylinder block 1, the top surface of the piston 6, and the ceiling inner wall of the cylinder head.

  The cylinder head includes an intake port 9a that is connected to an intake pipe that forms a passage through which intake air flows and guides intake air, and an exhaust port 9b that is connected to an exhaust pipe that forms a passage through which combustion gas flows and discharges exhaust gas. I have. An intake valve 2 is arranged to be opened and closed at the intake port 9a, and an exhaust valve 3 is arranged to be opened and closed at the exhaust port 9b. That is, the intake valve 2 blocks and allows the flow of intake air introduced from the intake pipe to the intake port 9a into the combustion chamber 10. The exhaust valve 9 b blocks and allows the flow of the combustion gas generated in the combustion chamber 10 to the exhaust port 3.

  The fuel injection valve 4 is provided in the cylinder head and directly injects fuel into the combustion chamber 10. Specifically, the fuel injection valve 4 injects and supplies fuel toward a cavity formed in the top surface of the piston 6 in the combustion chamber 10.

  The ignition laser beam irradiation device 5 irradiates the combustion chamber 10 with the ignition laser beam generated by the ignition laser beam generator 21 in the laser beam generator 20 described later. The ignition laser beam irradiation device 5 is disposed between the intake valve 2 and the exhaust valve 3 in the cylinder head. The ignition laser light irradiation device 5 includes an optical device for diverging or condensing the ignition laser light from the irradiation port, and an optical device for emitting the ignition laser light from the ignition laser light generator 21. And an optical fiber that can be transmitted with relatively little transmission loss. The optical device is provided with a lens or a lens group that diverges or condenses the ignition laser beam emitted from the irradiation port. The optical device is configured such that the focal position of the ignition laser beam is in the combustion chamber 10. This optical device may be provided with a beam splitter such as a mirror in order to guide the ignition laser beam from the ignition laser beam generator 21. Note that the irradiation port of the optical fiber is directed to the combustion chamber 10.

  The measurement laser beam irradiation device 7 irradiates the combustion chamber 10 with the measurement laser beam generated by the measurement laser beam generator 22 in the laser beam generator 20 described later. The measurement laser beam irradiation device 7 is disposed on the upper end side of the cylinder block 1 in a direction perpendicular to the axial direction of the cylinder. The measurement laser beam irradiation apparatus 7 includes a cylindrical lens and an optical fiber. The cylindrical lens is fixed to the front end side (left side in FIG. 1) of the housing, and irradiates the measurement laser light generated from the measurement laser light generator 22 into the combustion chamber 10. Specifically, the cylindrical lens is configured so that the measurement laser in the combustion chamber 10 has a planar shape 9a perpendicular to the axial direction of the cylinder. The optical fiber can be transmitted from the measurement laser beam generator 22 to the cylindrical lens without a relatively transmission loss.

  The energy intensity detection sensor 8 detects the energy intensity of the measurement laser light emitted from the measurement laser light irradiation device 7. The energy intensity detection sensor 8 is disposed in the housing of the ignition laser light irradiation device 5. That is, the energy intensity detection sensor 8 is disposed between the intake valve 2 and the exhaust valve 3 in the cylinder head. The energy intensity detection sensor 8 can detect a wide range of energy intensity in the combustion chamber 10 as indicated by a broken line 8a in FIG.

  The exhaust gas recirculation device (EGR) 40 is a device that returns part of the exhaust gas to the intake system. The exhaust gas recirculation device 40 can appropriately change the ratio of returning exhaust gas to the intake system (EGR rate).

  As shown in FIG. 2, the laser light generator 20 is connected to a control device 30 and includes an ignition laser light generator 21 and a measurement laser light generator 22. The laser beam generator 20 is a device that generates one laser beam, and generates an ignition laser beam or a measurement laser beam based on a control signal and a measurement signal output from the controller 30. That is, the laser light generated by one laser light generator is used for both the ignition laser light and the measurement laser light. In the present embodiment, for convenience, a portion that generates the ignition laser light is referred to as an ignition laser light generator 21, and a portion that generates the measurement laser light is referred to as a measurement laser light generator 22. Here, the ignition laser beam generated by the ignition laser beam generator has thermal energy that can evaporate by heating the fuel. The measurement laser beam generated by the measurement laser beam generator 22 is a laser beam having a wavelength near the absorption wavelength of the combustion product, particularly the intermediate product.

  As illustrated in FIG. 2, the control device 30 includes various signal input units 31, a measurement signal output unit 32, an energy intensity measurement unit 33, a combustion product concentration measurement unit 34, and a control unit 35. . The various signal input unit 31 inputs various signals such as the engine speed, the throttle opening, the coolant temperature of the engine cooling water, and the temperature of the intake air sucked into the combustion chamber 10.

  The measurement signal output unit 32 outputs a measurement signal to the measurement laser beam generator 22 of the laser beam generator 20 when measuring the concentration of the combustion product in the combustion chamber 10. The timing at which the measurement signal output 32 outputs the measurement signal may be in any state of the internal combustion engine. Specifically, the timing may be any state such as immediately after the air-fuel mixture starts to burn, after the air-fuel mixture has finished burning, while the air-fuel mixture is burning, or before the air-fuel mixture starts to burn. Good.

  The energy intensity measurement unit 33 inputs a measurement signal from the measurement signal output unit 32. Furthermore, the energy intensity measurement unit 33 inputs the energy intensity detected by the energy intensity detection sensor 8 and measures the energy intensity in the combustion chamber 10. Specifically, the energy intensity measurement unit 33 measures the energy intensity of the measurement laser light irradiated into the combustion chamber 10 by the measurement laser light irradiation device 7. Here, since the measurement laser beam is composed of a wavelength component absorbed by the combustion product, particularly the intermediate product, the energy intensity of the measurement laser beam varies depending on the concentration of the combustion product in the combustion chamber 10. That is, as the concentration of the combustion product in the combustion chamber 10 is higher, the measurement laser beam is absorbed, and the energy intensity of the measurement laser beam is reduced. On the other hand, as the concentration of the combustion product in the combustion chamber 10 is lower, the measurement laser beam is not absorbed and the energy intensity of the measurement laser beam is higher.

  The combustion product concentration measurement unit 34 measures the concentration of the combustion product in the combustion chamber 10 based on the energy intensity of the measurement laser light in the combustion chamber 10 measured by the energy intensity measurement unit 33. The concentration of the combustion product is, for example, the maximum concentration of the combustion product, the average concentration of the combustion product, or the like.

  The control unit 35 is based on the various signals input to the various signal input unit 31 and the concentration of the combustion product measured by the combustion product concentration measuring unit 34, and the intake valve 2, the exhaust valve 3, the fuel injection valve 4, the ignition The laser beam generator 21 and the exhaust gas recirculation device 40 are controlled. For example, the control unit 35 controls the energization period of the fuel injection valve 5 by starting and stopping energization of the coil of the fuel injection valve 5. The amount of fuel injected and supplied into the combustion chamber 10 is controlled by controlling the energization period of the fuel injection valve 5 by the ECU 6. The control unit 35 controls the opening / closing of the intake valve 2 and the opening / closing of the exhaust valve 2. In this way, the intake air amount sucked into the combustion chamber 10 is controlled by the control of the opening and closing of the intake valve 2 by the control unit 35. By controlling the opening and closing of the exhaust valve 2 by the control unit 35, control is performed to exhaust the exhaust gas from the combustion chamber 10 to the exhaust port 9b. Furthermore, the control unit 35 controls the ignition laser light generation unit 21 to generate the ignition laser light. Specifically, the control unit 35 controls the generation timing of the ignition laser beam generated by the ignition laser beam generation unit 21 and the intensity of the ignition laser beam. Further, the control unit 35 controls the EGR rate of the exhaust gas recirculation device 40.

  Here, the control unit 35 controls the intake valve 2, the exhaust valve 3, the fuel injection valve 4, and the ignition laser light generation unit 21 based on the combustion product concentration measured by the combustion product concentration measurement unit 34. This is as described above. Specifically, control is performed to change the equivalence ratio in accordance with the maximum concentration or average concentration of the combustion purified product. For example, when the maximum concentration or average concentration of the combustion products is larger than a predetermined value, the equivalence ratio is controlled to be reduced. On the other hand, control is performed to increase the equivalence ratio when the maximum concentration or average concentration of the combustion products is a predetermined value or less. The equivalence ratio is the stoichiometric air-fuel ratio of the air-fuel mixture with respect to the actual air-fuel ratio of the air-fuel mixture. Further, the predetermined value for comparing the maximum concentration or the average concentration of the combustion products varies depending on the timing at which the energy intensity detection sensor 8 measures the energy intensity of the measurement laser beam. Of course, the predetermined value varies depending on the maximum concentration of the combustion products and the average concentration of the combustion products.

  The control performed to reduce the equivalence ratio includes control for reducing the fuel injection amount injected by the fuel injection valve 4, control for increasing the intake air amount, control for reducing the EGR rate, and the like. By reducing the equivalence ratio in this manner, the combustion reaction of the intermediate product in the combustion chamber 10 can be caused to proceed. As a result, emissions can be improved. In order to reduce the equivalence ratio, all of the above control may be executed, or any of the above controls may be selected.

It is a figure which shows the structure of the engine of this embodiment. 2 is a block diagram showing a laser beam generator 20 and a control device 30. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Cylinder block, 2: Intake valve, 3: Exhaust valve, 4: Fuel injection valve, 5: Laser beam irradiation apparatus for ignition, 6: Piston, 7: Laser beam irradiation apparatus for measurement, 8: Energy intensity detection sensor, 9a: intake port, 9b: exhaust port, 10: combustion chamber, 20: laser beam generator, 21: laser beam generator for ignition, 22: laser beam generator for measurement, 30: controller, 40: exhaust gas re- Circulator

Claims (6)

Laser light irradiation means for ignition that irradiates an air-fuel mixture in a combustion chamber of an internal combustion engine with an ignition laser light to activate the air-fuel mixture;
A concentration measurement laser beam irradiation means for measuring the concentration of a combustion product generated by irradiating the combustion chamber with a concentration measurement laser beam and burning the mixture based on the intensity of the concentration measurement laser beam; ,
Equivalent ratio change control means for changing the equivalent ratio of the mixture based on the concentration of the combustion products;
A laser ignition device for an internal combustion engine.   The laser ignition device for an internal combustion engine according to claim 2, wherein the wavelength of the concentration measurement laser light is in the vicinity of an absorption wavelength of the combustion product.   The laser ignition device for an internal combustion engine according to claim 1 or 2, further comprising laser light generating means for generating the ignition laser light and the concentration measurement laser light.   The laser ignition device for an internal combustion engine according to any one of claims 1 to 3, wherein the equivalence ratio change control means reduces the equivalence ratio when the concentration of the combustion product is larger than a predetermined value.   5. The laser ignition device for an internal combustion engine according to claim 4, wherein the equivalence ratio change control means reduces the equivalence ratio when either the maximum value or the average value of the concentration of the combustion products is larger than a predetermined value. 6. The laser ignition device for an internal combustion engine according to claim 1, wherein the equivalence ratio change control means changes at least one of a fuel injection amount, an intake air amount, and an EGR rate.

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