JP2011157941A - Compression ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compression ignition internal combustion engine that can cope with a change of an operational state to control an ignition timing in a wide range. <P>SOLUTION: A compression ignition internal combustion engine 1 includes a gasoline tank 8 for accumulating gasoline serving as a first fuel with ignitability that is lower, between two kinds of fuels with ignitability different from each other, than the other, a light oil tank 11 for accumulating light oil serving as the second fuel with ignitability that is higher than the other, a first fuel injecting means 6 for injecting the gasoline accumulated in the gasoline tank 8 to an intake port 4, and a second fuel injecting means 9 for directly injecting the light oil accumulated in the light oil tank 11 within a combustion chamber 2. The engine also includes a first fuel pump 13 for supplying the gasoline accumulated in the gasoline tank 8 to the second fuel injecting means 9 and a control device 15 for controlling a volume ratio of the gasoline with the light oil which are injected by the second fuel injecting means 9. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a compression ignition internal combustion engine.

  In recent years, compression ignition internal combustion engines represented by premixed compression ignition internal combustion engines have been proposed because of their high thermal efficiency and low pollution. The compression ignition internal combustion engine introduces an air-fuel mixture of an oxygen-containing gas and a fuel capable of compression autoignition into a combustion chamber and compresses the mixture to cause the fuel to self-ignite.

  However, unlike the spark ignition internal combustion engine, the compression ignition internal combustion engine ignites the air-fuel mixture by self-ignition, so it is difficult to control the ignition timing. Further, the compression ignition internal combustion engine has a high concentration of the fuel at high load and is likely to cause knocking. On the other hand, at low load, the concentration of the fuel becomes lean, so that it is difficult to ignite and misfire. There's a problem.

  In order to control the ignition timing, intake air temperature control and control (EGR) for recirculating exhaust gas to intake air are performed. A compression ignition internal combustion engine using gasoline and light oil as two kinds of fuels having different ignitability is also known.

  The compression ignition internal combustion engine using gasoline and light oil injects light oil directly into a combustion chamber while injecting gasoline into an intake port. According to such a compression ignition internal combustion engine, the ratio of low ignitable fuel (gasoline) to high ignitable fuel (light oil) at high load is increased, and ignition to low ignitable fuel (gasoline) at low load. Increase the proportion of highly fuel (light oil). By doing in this way, it is supposed that adjustment of a certain ignition timing is possible (for example, refer patent documents 1 and 2).

JP 2005-98132 A JP 2005-83335 A

  However, in a compression ignition internal combustion engine that uses two types of fuels with different ignitability, it is difficult to sufficiently adjust the ignitability only by changing the ratio of fuel with high ignitability and fuel with low ignitability according to the load. There is an inconvenience.

  Therefore, the present invention eliminates such inconvenience, uses two types of fuels having different ignitability, and can control ignition timing over a wide range in response to changes in the operating state of the engine. The purpose is to provide.

  To achieve this object, the present invention provides a first fuel storage means for storing a first fuel having a lower ignitability than the other of two types of fuels having different ignitability, and a higher ignitability than the other. A second fuel storage means for storing a second fuel; a first fuel injection means for injecting the first fuel stored in the first fuel storage means into an intake port; and In a compression ignition internal combustion engine comprising: a second fuel injection unit that directly injects the second fuel stored in the fuel storage unit into the combustion chamber; the first fuel stored in the first fuel storage unit Supply means for supplying the second fuel injection means to the second fuel injection means, and fuel injection control means for controlling the volume ratio of the first fuel and the second fuel injected by the second fuel injection means It is characterized by providing.

  In a compression ignition internal combustion engine using two types of fuels having different ignitability, first, an oxidation reaction of a highly ignitable fuel directly injected into the combustion chamber starts, and the heat generation and expansion thereof cause the intake port to enter the combustion chamber. The self-ignition of the low ignitable fuel to be introduced is induced, and the combustion proceeds.

  In the compression ignition internal combustion engine of the present invention, the fuel injection control means supplies the first fuel and the second fuel to the second fuel injection means and controls the volume ratio of both fuels. As a result, the ignitability of the fuel directly injected into the combustion chamber is intermediate between the ignitability of the first fuel and the ignitability of the second fuel.

  Therefore, according to the compression ignition internal combustion engine of the present invention, the volume ratio between the first fuel and the second fuel supplied to the second fuel injection means via the fuel injection control means is controlled. Thus, the ignition timing can be controlled in a wide range.

  In the compression ignition internal combustion engine of the present invention, the fuel injection control means may determine a volume ratio between the first fuel and the second fuel injected by the second fuel injection means, so that an engine load is It is preferable to increase the ratio of the second fuel as the ratio decreases and to increase the ratio of the first fuel as the engine load increases. By doing so, according to the compression internal combustion engine of the present invention, the ignition timing can be controlled in a wide range in accordance with the change in the operating state of the engine.

  In the compression ignition internal combustion engine of the present invention, the first fuel may be any fuel as long as it is less ignitable than the other of the two types of fuel, for example, gasoline is used. be able to. In the compression ignition internal combustion engine of the present invention, the second fuel may be any fuel as long as it has a higher ignitability than the other of the two types of fuel, but for example, light oil is used. be able to.

  Furthermore, the compression ignition internal combustion engine of the present invention supplies a first fuel pump that supplies the first fuel to the second fuel injection means, and supplies the second fuel to the second fuel injection means. A second fuel pump, wherein the fuel injection control means determines a volume ratio of the first fuel and the second fuel injected by the second fuel injection means to the first fuel pump. And the driving force of the second fuel pump.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory sectional drawing which shows the structure of the compression ignition internal combustion engine of this invention. The graph which shows the relationship between a crank angle and a heat release rate when the volume ratio of the 1st fuel and the 2nd fuel is changed in the compression ignition internal combustion engine of this invention.

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

  As shown in FIG. 1, the compression ignition internal combustion engine 1 of the present embodiment includes a cylindrical combustion chamber 2 and a piston 3 slidable along the inner wall of the combustion chamber 2. An intake port 4 and an exhaust port 5 communicate with the upper part. Note that a piston ring (not shown) is interposed between the inner wall of the combustion chamber 2 and the piston 3 so that the piston ring is in sliding contact with the inner wall of the combustion chamber 2.

  The intake port 4 can be opened and closed by an intake valve 4a, and the exhaust port 5 can be opened and closed by an exhaust valve 5a. The intake port 4 is provided with first fuel injection means 6 for injecting gasoline as the first fuel into the intake port 4. The first fuel injection means 6 is connected to the gasoline via the first fuel conduit 7. It is connected to the tank 8. Further, a second fuel injection means 9 for directly injecting light oil as the second fuel into the combustion chamber 2 is disposed in a substantially central portion of the upper portion of the combustion chamber 2. It is connected to the light oil tank 11 through the second fuel conduit 10.

  A connecting conduit 12 branches off from the middle of the first fuel conduit 7 and is connected to the second fuel conduit 10 via a first fuel pump 13. The second fuel conduit 10 is provided with a second fuel pump 14 on the upstream side of the connecting portion with the connecting conduit 12.

  The compression ignition internal combustion engine 1 also includes a control device 15 that controls the operation of the first fuel injection unit 6, the second fuel injection unit 9, the first fuel pump 13, and the second fuel pump 14. The control device 15 detects an output signal from an accelerator sensor (not shown), a torque sensor, a rotational speed, a crank angle, a temperature in the combustion chamber 2, and the like, and thereby the first fuel injection means 6, the second fuel injection means 9, The operation of the first fuel pump 13 and the second fuel pump 14 is controlled.

  Next, the operation of the compression ignition internal combustion engine 1 of the present embodiment will be described.

  In the compression ignition internal combustion engine 1, in the compression stroke, the control device 15 injects gasoline as the first fuel into the intake port 4 via the first fuel injection means 6, and opens the intake valve 4a to supply gasoline. It is introduced into the combustion chamber 2. At the same time, the control device 15 directly injects fuel having higher ignitability than the first fuel into the combustion chamber 2 via the second fuel injection means 9.

  At this time, the control device 15 mixes gasoline into the light oil in the second fuel conduit 10 through the connection conduit 12 from the first fuel conduit 7, and uses the mixture of gasoline and light oil as the second fuel for the second time. The fuel is supplied to the fuel injection means 9. Mixing of gasoline and light oil is performed by controlling the driving force of the first fuel pump 13 and the second fuel pump 14 by the control device 15 so that the predetermined volume ratio of gasoline and light oil is obtained. Specifically, in the mixing of the gasoline and light oil, the control device 15 detects the engine load by an output signal from the accelerator sensor, the torque sensor, etc., and the lower the engine load, the higher the ratio of light oil, The higher the engine load, the higher the proportion of gasoline. When the engine load is low, the fuel supplied to the second fuel injection means 9 may be substantially only light oil.

  The gasoline and light oil vaporize in the combustion chamber 2, form an air-fuel mixture with the air in the combustion chamber 2, and are self-ignited by being further compressed. Here, the self-ignition starts with an oxidation reaction of highly ignitable fuel that is directly injected into the combustion chamber 2. Then, due to heat generation and expansion of the highly ignitable fuel, self-ignition of gasoline as a low ignitable fuel introduced from the intake port 4 to the combustion chamber 2 is induced.

  In the compression ignition internal combustion engine 1, as described above, the highly ignitable fuel directly injected into the combustion chamber 2 is a mixture of the gasoline and light oil, and the volume ratio of both is changed according to the engine load. Yes. Accordingly, the highly ignitable fuel directly injected into the combustion chamber 2 has an intermediate ignitability between gasoline ignitability and light oil ignitability. The ignition timing can be controlled over a wide range in response to changes in the operating state.

  Next, the volume ratio of the mixture of gasoline and light oil is changed as a highly ignitable fuel under the conditions of the rotational speed of the compression ignition internal combustion engine 1 of 1500 ppm and the engine load of 350 kPa, and the mixture is directly put into the combustion chamber 2. The change in the ignition timing of the injected was investigated. The results are shown in FIG. 2 as the change in heat generation rate with respect to the crank angle.

  From FIG. 2, it is clear that the ignition timing is retarded as the mixing ratio (volume ratio) of gasoline to light oil increases.

  DESCRIPTION OF SYMBOLS 1 ... Compression ignition internal combustion engine, 2 ... Combustion chamber, 4 ... Intake port, 4a ... Intake valve, 5a ... Exhaust valve, 6 ... First fuel injection means, 8 ... Gasoline tank, 9 ... Second fuel injection means, 11 ... Light oil tank, 13 ... first fuel pump, 14 ... second fuel pump, 15 ... control device.

Claims (4)

A first fuel storage means for storing a first fuel having a lower ignitability than the other of the two types of fuels having different ignitability;
A second fuel storage means for storing a second fuel having higher ignitability than the other;
First fuel injection means for injecting the first fuel stored in the first fuel storage means into an intake port;
A compression ignition internal combustion engine comprising: a second fuel injection unit that directly injects the second fuel stored in the second fuel storage unit into a combustion chamber;
Supply means for supplying the first fuel stored in the first fuel storage means to the second fuel injection means;
A compression ignition internal combustion engine comprising fuel injection control means for controlling a volume ratio between the first fuel and the second fuel injected by the second fuel injection means.   2. The compression internal combustion engine according to claim 1, wherein the fuel injection control means sets the volume ratio of the first fuel and the second fuel injected by the second fuel injection means to a low engine load. The compression internal combustion engine is characterized in that the proportion of the second fuel is increased, and the proportion of the first fuel is increased as the engine load increases.   2. The compression ignition internal combustion engine according to claim 1, wherein the first fuel is gasoline and the second fuel is light oil.   The compression ignition internal combustion engine according to any one of claims 1 to 3, wherein the first fuel pump supplies the first fuel to the second fuel injection means, and the second fuel is supplied to the second fuel injection means. A second fuel pump for supplying to the second fuel injection means, wherein the fuel injection control means is a volume of the first fuel and the second fuel injected by the second fuel injection means. The compression ignition internal combustion engine, wherein the ratio is controlled by the driving force of the first fuel pump and the second fuel pump.

Images