JP5991035B2 - Internal combustion engine and control method for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine that directly injects fuel into a combustion chamber and a control method for the internal combustion engine.

  Conventionally, in an internal combustion engine such as a diesel engine or a gasoline engine, air and fuel are supplied and mixed in a combustion chamber, and then control is performed to ignite the fuel by compression or ignition by a spark plug (hereinafter, premixing). Called the combustion method). Some premixed combustion systems are configured to supply a part of exhaust gas as EGR gas to the combustion chamber in addition to air. In the premixed combustion method for supplying EGR gas, the premixed degree of the air-fuel mixture is increased as compared with the conventional combustion, so that the smoke discharge amount and the NOx discharge amount can be suppressed.

  In addition, a configuration is disclosed in which two types of EGR gas having different temperatures are prepared, the supply ratio is controlled, and the temperature of the EGR gas supplied to the combustion chamber is adjusted (for example, see Patent Document 1). With this configuration, it is possible to appropriately control the ignition timing of the premixed gas regardless of whether the diesel engine is in a warm-up operation, a low-load operation, or a high-load operation. It was. This is because the temperature of the entire premixed gas can be controlled by controlling the temperature of the EGR gas supplied to the combustion chamber.

  However, a diesel engine employing a conventional premixed combustion system has a problem that the combustion noise is large. This is because the premixed gas in the combustion chamber ignites all at once, and a sharp pressure rise occurs. For this reason, this premixed combustion method has been difficult to employ especially during high-load operation where combustion noise increases.

  On the other hand, a configuration is disclosed in which part of fuel is oxidized with an oxidation catalyst to lower the octane number, and two types of fuel having different ignition timings are supplied to the combustion chamber (see, for example, Patent Document 2). With this configuration, the premixed gas in the combustion chamber can be prevented from igniting all at once. That is, the combustion of the premixed gas can be slowed down and the combustion noise can be suppressed. However, this configuration has a problem that the manufacturing cost of the diesel engine increases. This is because an oxidation catalyst or the like for oxidizing the fuel must be installed in the diesel engine.

  In addition, this configuration has a problem that fuel consumption is deteriorated. This is because a part of the energy is lost when the fuel is oxidized by the oxidation catalyst. That is, the energy held by the fuel is reduced by oxidation.

JP 2005-26655 A JP 2008-69694 A

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the combustion noise of the internal combustion engine in the internal combustion engine and the control method for the internal combustion engine adopting the premixed combustion system, and to improve the internal combustion engine. It is an object to provide an internal combustion engine and a control method for the internal combustion engine that can suppress an increase in manufacturing cost and deterioration of fuel consumption.

In order to achieve the above object, an internal combustion engine according to the present invention comprises a fuel injection nozzle for injecting fuel into a combustion chamber, wherein the internal combustion engine heats or cools at least a part of the fuel to produce a temperature. has a temperature control mechanism for generating a high-temperature-side fuel and cold-side fuel with a difference, the fuel injection nozzle has a fuel injection hole for injecting the hot side fuel, the fuel injection hole for injecting the low-temperature-side fuel In addition, in the process in which the intake air taken into the combustion chamber is compressed, control is performed such that a high-temperature side fuel and a low-temperature side fuel are injected into the combustion chamber to generate a premixed gas .

  With this configuration, the premixed gas can be prevented from igniting all at once, and combustion noise can be suppressed. This is because the ignition timing is different from the temperature difference between the injected low-temperature side fuel and high-temperature side fuel, and the combustion is slowed down.

  Further, the output of the internal combustion engine can be improved. This is because even during high-load operation, a premixed gas can be generated and burned, and the amount of input heat can be increased. That is, the premixed combustion method can be adopted over a wide range of operating states of the internal combustion engine.

  Furthermore, by providing a temperature difference in the fuel, even when the premixed gas is generated, ignition occurs before the temperature of the premixed gas becomes uniform, so that slowing of combustion can be realized.

  In addition, it is possible to realize the slow combustion of the premixed gas without deteriorating the fuel consumption. This is because in the above configuration, there is no process in which the fuel is oxidized and loses a part of its energy.

  In the internal combustion engine, the temperature control mechanism cools the fuel by a heating line that heats the fuel with exhaust heat of the internal combustion engine to generate the high-temperature side fuel, or a cooling device that is attached to the internal combustion engine. And it has at least one of the cooling lines which produce | generate the said low temperature side fuel, It is characterized by the above-mentioned.

  With this configuration, the combustion of the premixed gas can be slowed down without increasing the manufacturing cost of the internal combustion engine. This is because the high temperature side fuel can be heated by the exhaust heat of the internal combustion engine itself or the heat of the exhaust gas, for example, to about 600K, and the low temperature side fuel can be cooled by the cooling device, for example, to about 273K. . That is, there is no need to install an oxidation catalyst or the like that oxidizes the fuel.

  Here, the high temperature side fuel can be about 600K, and the low temperature side fuel can be about 300K at room temperature. Further, the high temperature side fuel can be set to about 300K at room temperature, and the low temperature side fuel can be set to about 273K.

In order to achieve the above object, a control method for an internal combustion engine according to the present invention is a control method for an internal combustion engine having a fuel injection nozzle for injecting fuel into a combustion chamber, wherein the internal combustion engine heats part of the fuel. Alternatively, it has a temperature control mechanism for generating a high temperature side fuel and a low temperature side fuel having a temperature difference by cooling, and the fuel injection nozzle injects the high temperature side fuel and the low temperature side fuel. A fuel injection hole, wherein the temperature control mechanism heats or cools at least a part of the fuel to generate the high-temperature side fuel and the low-temperature side fuel; and the intake air sucked into the combustion chamber In a process in which air is compressed, the fuel injection nozzle injects the high temperature side fuel and the low temperature side fuel into a combustion chamber to generate a premixed gas, and premixing corresponding to the high temperature side fuel by compression I feel burned And initiating a premixed gas corresponding to said cold side fuel by compression, characterized by the step of initiating combustion. With this configuration, the same effects as described above can be obtained.

  According to the internal combustion engine and the control method of the internal combustion engine according to the present invention, in the internal combustion engine and the control method of the internal combustion engine adopting the premixed combustion method, the combustion noise of the internal combustion engine is suppressed and the manufacturing cost of the internal combustion engine is reduced. It is possible to provide an internal combustion engine and a control method for the internal combustion engine that can suppress the increase and the deterioration of fuel consumption.

1 is a diagram schematically illustrating an internal combustion engine according to an embodiment of the present invention. It is the figure which showed the outline of the plane of the combustion chamber of the internal combustion engine of embodiment which concerns on this invention. It is the graph which showed the analysis result of the combustion characteristic of the internal-combustion engine of an embodiment concerning the present invention. It is the figure which showed the outline of the heat exchange part of the internal combustion engine of embodiment which concerns on this invention. It is the figure which showed the outline of the heat exchange part of the internal combustion engine of different embodiment which concerns on this invention.

Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described. FIG. 1 shows an outline of the internal combustion engine 1. Internal combustion engine 1 includes a fuel tank 6, a high temperature-side fuel f _h and cold side fuel f _c temperature adjustment mechanism 4 for generating with a temperature difference a portion of the fuel heating or cooling to the combustion chamber 2 of the fuel A fuel injection nozzle 3 for injecting the gas into the nozzle and a piston 7.

The temperature control mechanism 4 includes a heating line 11 to heat the fuel to produce hot side fuel f _h, the fuel is cooled and a cooling line 12 to generate the low-temperature side fuel f _c. The heating line 11 is, for example waste heat and the body of the internal combustion engine such as a diesel engine, by the heat of the exhaust gas g _out, has a configuration to heat the fuel through the heat exchanger 13. Fuel that has been heated in the heat exchanger 13 is sent to the fuel injection nozzle 3 in a high temperature side fuel f _h.

The cooling line 12, for example by the cooling water w _c for circulating cooling water circuit 23 of the cooling device 22 such as a radiator or intercooler has a structure for cooling the fuel through the heat exchanger 13. Fuel that has been cooled in the heat exchanger 13 is sent to the fuel injection nozzle 3 becomes the low-temperature side fuel f _c. The fuel injection nozzle 3 has a fuel injection hole 5 for injecting independently a hot side fuel f _h and cold side fuel f _c.

In addition, although the temperature control mechanism 4 may be comprised so that it may have both the heating line 11 and the cooling line 12 as shown in FIG. 1, it can also be comprised so that it may have only one. For example, when the temperature control mechanism 4 has only the heating line 11, the fuel sent to the fuel injection nozzle 3 after being heated by the heating line 11 is the high-temperature side fuel f _h, and is sent to the fuel injection nozzle 3 at room temperature. the fuel may be a low-temperature side fuel f _c.

Also, if the temperature control mechanism 4 has only cooling line 12, it is sent to fuel delivered to the fuel injection nozzle 3 after being cooled by cooling lines 12 and the low temperature side fuel f _c, leaving the fuel injection nozzle 3 at room temperature the fuel and the high temperature side fuel f _h.

  Furthermore, the heat exchange part 13 should just have the structure which can heat or cool a fuel, and can apply the existing heat exchange technique.

Next, the operation of the internal combustion engine 1 will be described. Part of the fuel in the fuel tank 6 is supplied to the fuel injection nozzle 3 via the heating line 11 that constitutes the temperature control mechanism 4. This fuel is heated by the heat exchanging unit 13 installed in the heating line 11 by receiving heat such as exhaust heat of the internal combustion engine main body or exhaust gas g _out and becomes high temperature side fuel f _h . Similarly, a part of the fuel in the fuel tank 6 is supplied to the fuel injection nozzle 3 via the cooling line 12 constituting the temperature adjustment mechanism 4. The fuel in the heat exchanger unit 13 installed in the cooling line 12 is cooled in the cooling water w _c circulating in the cooling device 22 such as a radiator or intercooler temperature becomes low side fuel f _c.

Next, in the process of the intake air g _in which is sucked into the combustion chamber 2 is compressed, the high temperature-side fuel f _h and the low temperature side fuel f _c is injected into the combustion chamber 2 from each separate fuel injection holes 5 The Here, the intake air g _in, in addition to the outside air, it is desirable to configure to include the EGR gas.

FIG. 2 shows a schematic plan view of the combustion chamber 2 when fuel is injected. The internal combustion engine 1 has a combustion chamber 2 and a fuel injection nozzle 3 disposed at the center of the combustion chamber 2. The fuel injection nozzle 3 has, for example, eight fuel injection holes 5. From each fuel injection hole 5, the high temperature-side fuel f _h and the low temperature side fuel f _c is injected, respectively.

Here, the fuel injection holes 5 corresponding to the high temperature side fuel f _h or cold side fuel f _c is preferably configured to be arranged alternately. Moreover, the fuel injection nozzle 3 should just be the structure which has at least 2 fuel injection hole 5, and this invention is not limited to the structure of FIG.

Next, ignition of the air-fuel mixture in the combustion chamber 2 will be described. First, the high temperature-side fuel f _h or cold side fuel f _c is injected into the combustion chamber 2 is compressed together with the intake air g _in. As the pressure rise in the combustion chamber 2, the premixed gas of the high temperature-side fuel f _h and the intake air g _in is ignited. This is because the high temperature side fuel f _h is easy to ignite because the temperature of the fuel itself is high. Thereafter, the premixed gas of the low temperature-side fuel f _c and the intake air g _in is ignited with a delay.

FIG. 3 shows the analysis result of the combustion characteristics of the internal combustion engine. In FIG. 3, the vertical axis represents the pressure (MPa) or heat generation rate (J / deg) in the combustion chamber 2, and the horizontal axis represents the crank angle (deg. ATDC). This heat generation rate is proportional to the magnitude of combustion noise. The solid line shows Example 30 of the present invention, and shows the analysis result when the temperature of the high temperature side fuel f _h is 600 K and the temperature of the low temperature side fuel f _c is 300 K (normal temperature). Further, as a comparative example, an analysis result when fuel is supplied in an internal combustion engine that does not have the temperature control mechanism 4 is shown. The broken line indicates the first comparative example 31 when the fuel temperature is 600K, and the alternate long and short dash line indicates the second comparative example when the fuel temperature is 300K. The fuel injection timing is 31 deg. The BTDC and the injection period were set to be 7 deg, and the analysis was performed under each condition.

  As shown in the lower part of FIG. 3, the peak of the heat generation rate when the premixed gas is ignited is the smallest in Example 30 of the present invention in which 300K and 600K fuels are supplied independently. . Specifically, the peak of the heat generation rate in Example 30 is about 13% compared to the first comparative example 31 in which the total amount of fuel supplied is 600K, and the total amount of fuel supplied is 300K. Compared with the comparative example 32 of 2, it decreases by about 24%. That is, it can be seen that Example 30 can slow down combustion of the air-fuel mixture and suppress combustion noise.

  As shown in the upper part of FIG. 3, in Example 30, the pressure peak in the combustion chamber 2 is approximately the same as those in the first and second comparative examples 31 and 32. That is, in this embodiment, it can be seen that there is no reduction in the kinetic energy extracted from the fuel.

With the above configuration, the following operational effects can be obtained. First, combustion noise can be suppressed. This is because the temperature difference between the high temperature side fuel f _h and the low temperature side fuel f _c to be injected into the combustion chamber 2, because the difference in the ignition timing occurs, is slowed down combustion. For this reason, it is possible to adopt the premixed combustion method even at the time of high-load operation, which has conventionally been difficult to employ the premixed combustion method.

  Second, the combustion of the premixed gas can be slowed down without increasing the manufacturing cost of the internal combustion engine. This is because there is no need to install an oxidation catalyst or the like that oxidizes the fuel.

  Thirdly, the combustion of the premixed gas can be slowed down without deteriorating the fuel consumption of the internal combustion engine. This is because consumption of new energy or reduction in energy amount due to fuel oxidation does not occur due to slowing of combustion.

The temperature of the hot-side fuel f _h and cold side fuel f _c is not particularly limited, the larger the temperature difference between the high temperature side fuel f _h and cold side fuel f _c, the temperature difference for the combustion becomes slow It is desirable to enlarge it.

FIG. 4 shows an example of the configuration of the heat exchange unit. The heat exchange unit 13A, the heat transfer tubes 15 inserted into a part made of metal and the cooling water w _c circulating radiator and intercooler, etc. of the cooling water circuit 23, and inserted into a portion of the cooling line 12 for supplying fuel A metal contact tube 16 and a metal band 17 for maintaining and fixing the contact between the heat transfer tube 15 and the contact tube 16 are provided. The heat transfer tube 15, the contact tube 16, and the band 17 are preferably made of a material having high thermal conductivity. Specifically, for example, aluminum, copper, or an alloy thereof can be used.

Moreover, as the contact tube 16, it is desirable to employ a tube whose both ends are bent. This is because this configuration facilitates the handling of the fuel pipe (cooling line 12), ensures a large contact area between the contact tube 16 and the heat transfer tube 15 , and improves the heat exchange efficiency. Furthermore, in order to improve the heat exchange efficiency of the heat exchanging portion 13A, the contact tube 16 and the heat transfer tube 15 can be configured to have an elliptical or rectangular cross-sectional area, thereby increasing the contact area.

  The fuel flowing through the cooling line 12 is cooled via the contact tube 16, the heat transfer tube 15 and the band 17. The contact tube 16 constituting the heat exchanging portion 13A is directly brought into contact with the exhaust gas passage 21 shown in FIG. 1 or a casing such as a diesel engine in addition to the heat transfer tube 17 installed in the cooling water circuit 23. It may be configured. In this case, the fuel is heated.

  FIG. 5 shows a different embodiment of the heat exchange section. The heat exchanging portion 13 </ b> B includes a heat transfer tube 15 similar to the above, and a contact jacket 18 for bringing fuel into contact with the periphery of the heat transfer tube 15. The fuel supplied to the contact jacket 18 can directly exchange heat with the heat transfer tube 15. Therefore, compared with the contact tube 16 shown in FIG. 4, the contact jacket 18 increases the manufacturing cost but can further improve the heat exchange efficiency.

  As described above, in the internal combustion engine adopting the premixed combustion method and the control method of the internal combustion engine, the combustion noise of the internal combustion engine can be suppressed, and the increase in the manufacturing cost of the internal combustion engine and the deterioration of the fuel consumption can be suppressed. And a method for controlling an internal combustion engine. In the present invention, the internal combustion engine such as a conventional diesel engine can be changed only by changing the fuel injection nozzle 3, installing the heat exchanging portion 13, and changing the fuel pipe (heating line 11 and cooling line 12). Reduction of combustion noise can be realized. Further, the present invention can be applied to a gasoline engine or the like in addition to a diesel engine.

1 internal combustion engine 2 combustion chamber 3 the fuel injection nozzle 4 temperature adjustment mechanism 5 the fuel injection hole 11 heated line 12 cooling line 22 cooling device _{f h} hot side fuel _{f c} cold side fuel

Claims (3)

In an internal combustion engine having a fuel injection nozzle for injecting fuel into a combustion chamber,
The internal combustion engine has a temperature control mechanism for generating a high temperature side fuel and a low temperature side fuel having a temperature difference by heating or cooling at least a part of the fuel;
The fuel injection nozzle has a fuel injection hole for injecting the high temperature side fuel and a fuel injection hole for injecting the low temperature side fuel ,
An internal combustion engine that controls to generate a premixed gas by injecting high temperature side fuel and low temperature side fuel into the combustion chamber in a process in which intake air taken into the combustion chamber is compressed .   The temperature control mechanism cools the low temperature side fuel by heating the fuel with exhaust heat of the internal combustion engine to generate the high temperature side fuel, or cooling the fuel with a cooling device attached to the internal combustion engine. The internal combustion engine according to claim 1, further comprising at least one of a cooling line that generates In a control method for an internal combustion engine having a fuel injection nozzle for injecting fuel into a combustion chamber,
The internal combustion engine has a temperature control mechanism that generates a high temperature side fuel and a low temperature side fuel having a temperature difference by heating or cooling a part of the fuel, and the fuel injection nozzle injects the high temperature side fuel. A fuel injection hole and a fuel injection hole for injecting the low-temperature side fuel;
The temperature control mechanism heating or cooling at least a part of the fuel to generate the high temperature side fuel and the low temperature side fuel; and
In a process in which the intake air taken into the combustion chamber is compressed, the fuel injection nozzle injects the high temperature side fuel and the low temperature side fuel into the combustion chamber to generate a premixed gas;
Starting precombustion corresponding to the high temperature side fuel by compression, and
A control method for an internal combustion engine, comprising: a step of starting combustion of a premixed gas corresponding to the low temperature side fuel by compression.

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