JPWO2015186682A1 - Injector unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a gas fuel such as CNG in an existing diesel engine. An injector unit that can be inserted into a through hole for inserting a light oil injector provided in a cylinder head of a compression ignition internal combustion engine having a combustion chamber of a first capacity, and has a second capacity smaller than the first capacity. A gas fuel injector designed for the combustion chamber of the first gas, an ignition means for igniting the gaseous fuel, a storage member for accommodating the gaseous fuel injector and the ignition means, and an injection time from the gaseous fuel injector is the second capacity It is set longer than that used in the combustion chamber. [Selection] Figure 3

Description

  The present invention relates to an injector unit. In particular, the present invention relates to an injector unit for making it possible to use gaseous fuel such as compressed natural gas (CNG) in an existing diesel engine.

  One method for reducing diesel exhaust is retrofit technology. Retrofit technology improves engine exhaust performance by changing or adding parts to an existing engine. For example, it is recommended by the United States Environmental Protection Agency (EPA) (Non-Patent Document 1).

  It is also effective to change the fuel from light oil to CNG as a method of reducing diesel exhaust gas. Therefore, it is conceivable to replace the light oil injector with a CNG injector.

  However, since CNG has an ignition temperature higher than that of light oil, it cannot be ignited by simply replacing the injector. Therefore, it is conceivable to use light oil as a pilot or to use ignition means such as a spark plug (Non-patent Document 2). Patent Document 1 is an example of the former, and Patent Documents 2 and 3 are examples of the latter.

http://www.epa.gov/cleandiesel/technologies/index.htm (US EPA homepage, May 30, 2014 search) “Development of high-efficiency large gas engine” (Mitsui Engineering & Shipbuilding Technical Report No.191 (2007-6), P.19-25) JP 2012-149537 A US Publication No. 2012-103302 US Pat. No. 8,915,528 JP 2007-113570 A International Publication No. 2012/005201

  However, when the configuration of Patent Document 1 is adopted, it is necessary to mount both a light oil tank and a natural gas tank on the automobile, which increases the weight of the automobile and increases the maintenance burden. Moreover, it is necessary to consider both light oil supply and natural gas supply, which is complicated for the driver.

  In the configuration described in Patent Document 2, it is necessary to separately provide an injector on the intake manifold side, and it is necessary to process a hole for inserting the injector. Therefore, it is not suitable for retrofit technology.

  When the configuration described in Patent Document 3 is adopted, it is not necessary to provide a hole in the manifold, but the structure is complicated and expensive, and thus is not suitable for the retrofit technique.

  The present invention has been made in view of this point.

  An aspect of the present invention is an injector unit that can be inserted into a through hole for inserting a light oil injector provided in a cylinder head of a compression ignition internal combustion engine having a combustion chamber of a first capacity. A gas fuel injector designed for a combustion chamber having a small second capacity, an ignition means for igniting the gaseous fuel, a storage member for accommodating the gaseous fuel injector and the ignition means, and an injection time from the gaseous fuel injector; It is set longer than when used in the combustion chamber of the second capacity.

  According to the injector unit of the present invention, gaseous fuel such as CNG can be used in an existing diesel engine.

It is sectional drawing of the diesel engine 10, and is a figure which shows the state in which the light oil injector 20 was inserted. It is sectional drawing of the diesel engine 10, and is a figure which shows the state by which the light oil injector 20 is not inserted. 2 is a cross-sectional view of the injector unit 1. FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a figure which shows the external shape of the CNG injector unit 2, the igniter 3, and the casing 4. FIG. It is sectional drawing of the diesel engine 10, and is a figure which shows the state by which the injector unit 1 was inserted. 2 is a cross-sectional front view of an igniter 3. FIG. This is an equivalent circuit of the igniter 3.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the following embodiment is a preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  Before describing the injector unit 1 according to the embodiment of the present invention, the configuration of the diesel engine 10 to which the injector unit 1 is attached will be described first.

  1 and 2 are cross-sectional views showing a configuration of a diesel engine 10 which is an example of a compression ignition internal combustion engine. FIG. 1 is a view showing a state in which the light oil injector 20 is inserted into the through hole 11 of the cylinder head 6, and FIG. 2 is a view showing a state in which the light oil injector 20 is not inserted.

  With reference to these drawings, the diesel engine 10 includes a cylinder head 6, a cylinder liner 7 joined to the cylinder head 6, and a piston 8 that is in sliding contact with the cylinder liner 7. A space surrounded by these members is a combustion chamber.

  The cylinder head 6 is provided with an intake port and an exhaust port. An intake valve 9A is disposed at the boundary between the intake port and the combustion chamber. An exhaust valve 9B is disposed at the boundary between the exhaust port and the combustion chamber.

  The cylinder head 6 is provided with a through hole 11. This through-hole 11 is a hole for attaching the light oil injector 20 which injects light oil originally.

  Next, the configuration of the injector unit 1 according to this embodiment will be described. FIG. 3 is a cross-sectional view of the injector unit 1. FIG. 4 is another cross section of the injector unit 1, and is a cross-sectional view taken along the line AA of FIG. 5 is a cross-sectional view taken along the line BB in FIG.

  With reference to these drawings, the injector unit 1 includes a CNG injector 2 for injecting CNG as a kind of gaseous fuel, an igniter 3 as ignition means, and a casing 4 for housing them.

  When the outer diameter D1 of the casing 4, the outer diameter D2 of the CNG injector 2, and the outer diameter D3 of the igniter 3 are defined as shown in FIG. 6, as an example, D11 = 30 mm, D12 = 20 mm, D2 = 10 mm, D3 = 5 mm is there. The casing 4 has a size that matches the through hole 11 of the cylinder head 6. As shown in FIG. 7, the injector unit 1 can be inserted into the cylinder head 6 together with the casing 4. Thereby, the exchange operation from the light oil injector 20 becomes easy. In addition, from the viewpoint of heat dissipation of the CNG injector 2 and the igniter 3, the casing 4 preferably employs a metal having high thermal conductivity.

  The capacity of the combustion chamber of the diesel engine 10 changes due to the vertical movement of the piston 8, but the capacity when the piston 8 reaches bottom dead center is 2 liters.

  The CNG injector 2 is designed for a 0.5 liter combustion chamber instead of 2 liters. The CNG injector for 2 liters has a large volume, so that the igniter 3 cannot be stored in the through hole 11. Therefore, in this embodiment, such an injector is employed.

  However, a 2 liter engine requires more fuel than a 0.5 liter engine. Simply, it is thought that about four times as much fuel is required. However, since the injection rate for the 0.5 liter injector is low, the amount of fuel necessary for the operation of the 2 liter engine cannot be injected during the normal injection time. Therefore, the injection time of the CNG injector 2 is set to a time longer than the normal injection time. The injection control of the CNG injector 2 is executed by a control circuit such as an ECU (not shown).

  The igniter 3 is for igniting CNG fuel. As described above, CNG has an ignition temperature higher than that of light oil, and cannot be ignited by simple compression ignition. Therefore, an igniter 3 is provided. As the igniter 3, a spark plug, a corona discharge plug (for example, EcoFlash (US registered trademark) manufactured by BorgWarner), a microwave discharge plug, or the like can be used.

  The microwave discharge plug is a plug having a 2.45 GHz band microwave resonance structure developed by the applicant of the present application. The configuration of the plug is also described in Japanese patent applications (Japanese Patent Application Nos. 2014-111755 and 2013-171781) filed by the present applicant, but will be briefly described here.

  Referring to FIG. 8, the microwave discharge plug (igniter 3) is mainly composed of a case 51, a center electrode, and an insulator 59 that is provided between the case portion and the center electrode and insulates them. A ground electrode 51 a is formed at the tip of the case 51. A discharge electrode 55a is formed at the tip of the center electrode. A potential difference is generated between the discharge electrode 55a and the ground electrode 51a, thereby causing discharge.

  The center electrode is divided into an input side electrode 53, a coupling portion electrode 54, and an output side electrode 55.

  The output side electrode 55 has a discharge electrode 55 a and a shaft portion 55 b, and is electrically coupled to the coupling portion electrode 54. The coupling portion electrode 54 has a bottomed cylindrical shape. The input side electrode 53 is electrically connected to an oscillation circuit MW provided outside the injector unit 1 via the input end 52.

  FIG. 9 is a diagram showing an equivalent circuit of the igniter 3. An AC signal (voltage V1, frequency 2.45 GHz) input from the oscillation circuit MW is connected to a series resonant circuit including a capacitor C3, a reactance L, and a capacitor C2 via a capacitor C1 (here, C1 is C2). , It is assumed to be sufficiently smaller than C3). A discharge unit is provided in parallel with the capacitor C3.

  Here, C1 corresponds to a coupling capacitance, is determined by the shapes and gaps of the coupling portion electrode 54 and the input side electrode 53, and is a portion for performing impedance matching between the oscillation circuit and the igniter 3. The input side electrode 53 can be moved in the axial direction, thereby adjusting the impedance.

  The capacitor C <b> 2 is a grounded capacitor formed by the coupling portion electrode 54 and the case 51. This is determined by the shape of the electrode 54, the gap with the case 51, and the dielectric constant of the insulator 59c.

  The reactance L corresponds to a coil component of the shaft portion 55 b of the output side electrode 55.

  The capacity C3 is a discharge capacity formed by the output side electrode 55 and the case 51. This is determined by the shapes of the discharge electrode 55a and the shaft portion 55b, the gap between the output-side electrode 55 and the case 51, the thickness of the insulator 59c, the dielectric constant, and the like. If C3 >> C2 is designed, the potential difference between both ends of the capacitor C3 can be made sufficiently larger than V1, and as a result, a high potential is generated in the discharge part (gap between the discharge electrode 55a and the ground electrode 51a). be able to.

（但し、

）As described above, when it can be considered that the coupling capacitance C1 is sufficiently small, the capacitance C3, the reactance L, and the capacitance C2 form a series resonance circuit, and the resonance frequency f can be expressed by Equation 1.

(However,

)

  That is, when f = 2.45 GHz, the igniter 3 is designed so that the discharge capacity C3, the coil reactance L, and the ground capacity C2 satisfy the relationship of Formula 1.

  Further, the igniter 3 can be made compact by adopting the above configuration.

  Further, as described above, in the igniter 3, a high voltage is generated between the discharge electrode and the ground electrode, and discharge is generated by the high voltage. By this discharge, electrons are emitted from the gas molecules in the vicinity thereof to generate non-equilibrium plasma, and the fuel is easily ignited. In this way, the igniter 3 functions as an ignition means.

  The embodiment of the present invention has been described above. The scope of the present invention is determined based on the invention described in the claims, and should not be limited to the above embodiment.

DESCRIPTION OF SYMBOLS 1 Injector unit 2 Injector 3 Igniter 4 Casing 6 Cylinder head 7 Cylinder liner 8 Piston 9A Intake valve 9B Exhaust valve 10 Diesel engine 11 Through-hole

Claims (2)

An injector unit insertable into a through hole for inserting a light oil injector provided in a cylinder head of a compression ignition internal combustion engine having a first capacity combustion chamber,
A gaseous fuel injector designed for a combustion chamber of a second volume smaller than the first volume;
Ignition means for igniting gaseous fuel;
A gas fuel injector and a storage member for storing the ignition means;
An injector unit characterized in that the injection time from the gaseous fuel injector is set to be longer than that used in the combustion chamber of the second capacity. The ignition means has a case portion, a center electrode, and an insulator that insulates the case portion and the center electrode,
The center electrode has a first electrode for inputting microwaves, a second electrode capacitively coupled to the first electrode, and a third electrode including a discharge part for generating discharge,
Perform microwave impedance matching using the first and second electrodes,
A series circuit including a ground capacitance determined by the second electrode and the case portion, a coil reactance component of the third electrode, and a discharge capacity determined by the third electrode and the case portion is configured to resonate with the microwave. The injector unit according to claim 1.

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