JP4075165B2 - Combustion device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a combustion apparatus for an internal combustion engine.
[0002]
[Prior art]
In general, liquid fuel such as gasoline is used as a fuel for an internal combustion engine for automobiles. However, in recent years, gaseous fuels such as natural gas have attracted attention as alternative fuels for gasoline due to problems such as oil depletion. As a fuel supply device for an internal combustion engine driven by such gaseous fuel, for example, a device described in Japanese Patent Laid-Open No. 3-26835 is known.
[0003]
The apparatus described in the publication includes a gas fuel injection valve that injects and supplies gaseous fuel to a combustion chamber of an internal combustion engine, and a liquid fuel injection valve that injects and supplies liquid fuel to an intake port that communicates with the combustion chamber. I have. The gaseous fuel and liquid fuel injected from the fuel injection valves are ignited by the spark plug in the combustion chamber and burned, and the internal combustion engine is driven by the combustion energy.
[0004]
By supplying both gaseous fuel and liquid fuel as described above, good combustion can be obtained with gaseous fuel having good ignitability even if the amount of liquid fuel is reduced. By reducing the amount of liquid fuel supplied, the fuel consumption rate of the liquid fuel can be suppressed.
[0005]
[Problems to be solved by the invention]
However, since the gaseous fuel injected and supplied to the combustion chamber is difficult to mix with the air in the combustion chamber, the injected and supplied gaseous fuel is unevenly distributed in the combustion chamber. For this reason, at the time of ignition by the spark plug, fuel of an appropriate concentration does not necessarily exist around the spark plug, and the combustion state is deteriorated when the concentration of the fuel is inappropriate.
[0006]
In addition, when the engine temperature or intake air temperature is low, such as when the internal combustion engine is cold started, the liquid fuel adheres to the inner wall of the intake port and becomes difficult to vaporize, so the ignitability of the liquid fuel deteriorates. . Therefore, in order to maintain the good ignitability of the liquid fuel, it is necessary to increase the amount of the liquid fuel, and it becomes difficult to achieve both good ignitability and suppression of the fuel consumption rate.
[0007]
Furthermore, since replenishment locations such as a gas station equipped with a facility for replenishing gaseous fuel are currently limited, it is preferable to suppress the consumption rate of the gaseous fuel as much as possible in consideration of replenishment of gaseous fuel. However, since the apparatus described in the above publication always supplies gaseous fuel and liquid fuel, if the gaseous fuel cannot be replenished, the internal combustion engine must be driven only by the liquid fuel.
[0008]
The gas fuel injection valve is exposed in the combustion chamber in order to inject and supply fuel to the combustion chamber. If the portion exposed in the combustion chamber in the gaseous fuel injection valve is overheated excessively by heat during combustion, the fuel in the combustion chamber spontaneously ignites before ignition by the spark plug due to the heat. Preignition occurs and the combustion state is likely to deteriorate.
[0009]
The present invention has been made in view of such circumstances, and a first object thereof is combustion of an internal combustion engine that can prevent deterioration of a combustion state in an internal combustion engine driven by gaseous fuel. To provide an apparatus.
[0010]
A second object of the present invention is to provide a combustion apparatus for an internal combustion engine that can achieve both good ignitability of the fuel and suppression of the fuel consumption rate even when the engine is cold started. is there.
[0011]
A third object of the present invention is to provide a combustion apparatus for an internal combustion engine that can suppress the consumption rate of gaseous fuel.
A fourth object of the present invention is to provide a combustion apparatus for an internal combustion engine that can suitably prevent pre-ignition from occurring in the internal combustion engine.
[0012]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, there is provided a fuel injection valve that injects gaseous fuel into the combustion chamber, and an ignition plug that ignites the gaseous fuel injected and supplied by the fuel injection valve.A piston that reciprocates based on ignition of fuel by the spark plug, and an output shaft that rotates based on reciprocation of the piston;An internal combustion engine combustion apparatus comprising: the fuel injection valveIs such that the fuel injection direction is shifted from the central axis of the piston to a position closer to the output shaft than the position of the piston head at the time of ignition by the spark plug, and the injected fuel is directed to the spark plug. It was supposed to be provided with an inclination.
[0013]
  According to the configuration,The swirl is generated by the gaseous fuel injected from the fuel injection valve, and the swirl allows the gaseous fuel to be accurately collected around the spark plug.Therefore, the fuel concentration around the spark plug can be accurately set at the time of ignition, and the combustion state can be maintained satisfactorily.
[0015]
  AlsoAccording to this configuration, at the time of ignition by the spark plug, the fuel injection valve is hidden by the piston and is not exposed to the combustion chamber, so that it is possible to prevent the exposed portion from being overheated and easily causing preignition.
[0018]
  Claim2In the described invention, the claims1In the described invention, the internal combustion engine is driven by a liquid fuel in addition to the gaseous fuel, and further includes a fuel switching means for switching the fuel of the internal combustion engine in accordance with the engine operating state.The.
[0019]
  According to this configuration, gas fuel with good ignitability is collected around the spark plug. Therefore, when gas fuel and liquid fuel are supplied simultaneously, good ignitability of the fuel is maintained even if the liquid fuel is reduced. You can get. Therefore, the fuel consumption rate is suppressed by reducing the liquid fuel.
According to a third aspect of the present invention, there is provided a combustion apparatus for an internal combustion engine comprising: a fuel injection valve that injects gaseous fuel into the combustion chamber; and an ignition plug that ignites the gaseous fuel injected and supplied by the fuel injection valve. The fuel injection valve is provided at a position where the gaseous fuel injected and supplied from the injection valve gathers around the spark plug, and the internal combustion engine is driven by liquid fuel in addition to the gaseous fuel. Fuel switching means for switching the fuel of the internal combustion engine in accordance with the state, wherein the fuel switching means switches the fuel of the engine and drives the internal combustion engine only by liquid fuel when preignition occurs in the internal combustion engine It was.
According to this configuration, gas fuel with good ignitability is collected around the spark plug. Therefore, when gas fuel and liquid fuel are supplied simultaneously, good ignitability of the fuel is maintained even if the liquid fuel is reduced. You can get. Therefore, the fuel consumption rate is suppressed by reducing the liquid fuel.
Further, according to this configuration, when pre-ignition occurs, the internal combustion engine is driven only by liquid fuel that is less ignitable than gaseous fuel, so that pre-ignition can be suitably prevented.
According to a fourth aspect of the invention, in the third aspect of the invention, the internal combustion engine includes: a piston that reciprocates based on ignition of fuel by the spark plug; and an output shaft that rotates based on the reciprocal movement of the piston. The fuel injection valve is provided at a position closer to the output shaft than the position of the piston head at the time of ignition by the spark plug.
According to this configuration, at the time of ignition by the spark plug, the fuel injection valve is hidden by the piston and is not exposed to the combustion chamber, so that it is prevented that the exposed portion is excessively heated and preignition is likely to occur.
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the fuel injection valve is inclined so that the fuel injection direction is deviated from the central axis of the piston and the injected fuel is directed toward the spark plug. It was supposed to be provided.
According to this configuration, swirl is generated by the gaseous fuel injected from the fuel injection valve, and the gaseous fuel is accurately collected around the spark plug by the swirl.
[0020]
  Claim6In the described invention, the claims2 to 5In the described invention, the fuel switching means switches the fuel of the internal combustion engine based on at least one of the engine temperature of the internal combustion engine and the intake air temperature.
[0021]
According to this configuration, by switching the fuel based on the engine temperature and intake air temperature of the internal combustion engine, it becomes possible to select and supply the fuel suitable for the engine temperature and intake air temperature.
[0022]
  Claim7In the described invention, the claims6In the invention described above, the fuel switching means switches the fuel of the engine when the temperature of at least one of the engine temperature and the intake air temperature of the internal combustion engine is lower than a predetermined reference value, It was supposed to be driven.
[0023]
According to this configuration, when the engine temperature or the intake air temperature is low, such as when the internal combustion engine is started at a low temperature, the internal combustion engine is driven only by a gas fuel with good ignitability, so the fuel increase to obtain good ignitability, etc. There is no need to do. Therefore, it is possible to achieve both good fuel ignitability and low fuel consumption rate.
[0024]
  Claim8In the described invention, the claims6In the described invention, the fuel switching means switches the fuel of the engine when the temperature of at least one of the engine temperature of the internal combustion engine and the intake air temperature is higher than a predetermined reference value, and uses the liquid fuel alone to It was supposed to be driven.
[0025]
According to this configuration, when at least one of the engine temperature and the intake air temperature of the internal combustion engine is higher than a predetermined reference value, the supply of the gaseous fuel is stopped, so that the consumption rate of the gaseous fuel is suppressed. Will be able to.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an automobile engine will be described with reference to FIGS.
[0029]
As shown in FIG. 1, the cylinder block 11a of the engine 11 is provided with a piston 12 connected to a crankshaft 14 that is an output shaft of the engine 11 via a connecting rod 13 so as to be reciprocally movable. The reciprocating movement of the piston 12 is converted into rotation of the crankshaft 14 by the connecting rod 13. The cylinder block 11a is provided with a water temperature sensor 11b for detecting the coolant temperature THW in the engine 11.
[0030]
A cylinder head 15 is provided at the upper end of the cylinder block 11 a, and a combustion chamber 16 is provided between the cylinder head 15 and the piston 12. An intake port 17 and an exhaust port 18 provided in the cylinder head 15 communicate with the combustion chamber 16. The intake port 17 and the exhaust port 18 communicate with the intake passage 32 and the exhaust passage 33, and the intake passage 32 detects the temperature of the air passing through the passage 32 (intake air temperature) THA. A sensor 37 is provided.
[0031]
A liquid fuel injection valve 50 for injecting gasoline into the intake port 17 is provided at the downstream end of the intake passage 32. When the air in the intake passage 32 is sucked into the combustion chamber 16 during the intake stroke, the liquid fuel injection valve 50 injects gasoline into the intake port 17 to form an air-fuel mixture composed of gasoline and air.
[0032]
Further, a gas fuel injection valve 61 for directly injecting and supplying natural gas into the combustion chamber 16 is provided at the upper portion of the cylinder block 11a. The gas fuel injection valve 61 is connected to a gas tank 63 filled with natural gas via a supply passage 62. In the middle of the supply passage 62, a pressure regulator 64 is provided for making the pressure of the natural gas supplied from the gas tank 63 to the gaseous fuel injection valve 61 constant. The gas pressure in the supply passage 62 is detected by a gas pressure sensor 65. The gas fuel injection valve 61 injects natural gas when the gas in the combustion chamber 16 is compressed in the compression stroke, and supplies the natural gas to the combustion chamber 16.
[0033]
On the other hand, the cylinder head 15 is provided with a spark plug 51 for igniting the fuel filled in the combustion chamber 16. The spark plug 51 is connected to a vehicle battery 54 via an igniter module 53. The igniter module 53 includes an igniter 53a for performing ignition by the spark plug 51, and an ion current detection circuit unit 53b for detecting an ion current flowing between the electrodes 51a and 51b of the spark plug 51 during fuel combustion.
[0034]
When the fuel such as gasoline or natural gas in the combustion chamber 16 is ignited and burned, the piston 12 is reciprocated by the combustion energy, the crankshaft 14 is rotated, and the engine 11 is driven. Become so. The igniter module 53 applies a low voltage between the electrodes 51a and 51b of the spark plug 51 when ignition is not being performed. Thus, an ion current flows between the electrodes 51a and 51b of the spark plug 51 due to the ions generated during the combustion of the fuel, and the ion current is detected by the ion current detection circuit unit 53b.
[0035]
Therefore, when so-called preignition occurs, in which the fuel spontaneously ignites in the combustion chamber 16 before ignition by the spark plug 51, the generation time of the ion current is earlier than usual. Therefore, the occurrence of pre-ignition can be detected based on the generation time of the ion current.
[0036]
Here, the detail of the arrangement | positioning position of the said fuel injection valve 61 for gas is demonstrated with reference to FIGS. 1-3.
The arrangement position of the gas fuel injection valve 61 in the moving direction of the piston 12 (vertical direction in FIG. 1) is a position closer to the crankshaft 14 than the head of the piston 12 at the time of ignition. Therefore, at the time of ignition by the spark plug 51, the gas fuel injection valve 61 is hidden by the piston 12 and is not exposed in the combustion chamber 16 as shown in FIG. Therefore, the gas fuel injection valve 61 is prevented from being overheated excessively due to heat generated when the fuel is burned, and the overheated gas fuel injection valve 61 is prevented from causing pre-ignition. Will be able to.
[0037]
Further, the gas fuel injection valve 61 is disposed such that its fuel injection direction (direction indicated by an arrow A in FIGS. 2 and 3) is shifted from the central axis L of the piston 12 by a predetermined value α shown in FIG. Yes. Further, the gas fuel injection valve 61 is provided so as to be inclined by an angle β shown in FIG. 3 with respect to the radial direction of the piston 12 so that the injected natural gas is directed to the spark plug 51.
[0038]
Gaseous fuel such as natural gas is difficult to be mixed with gas such as air and tends to be unevenly distributed in the combustion chamber 16. However, by arranging the gas fuel injection valve 61 as described above, swirl is generated by the natural gas injected from the gas fuel injection valve 61 during the compression stroke, and the natural gas is generated by the swirl as shown in FIGS. 3 moves in a spiral shape as indicated by an arrow B in a two-dot chain line and is collected around the spark plug 51. Therefore, the natural gas concentration around the spark plug 51 can be accurately set to a value suitable for combustion, and it is possible to prevent the combustion state from deteriorating due to the inappropriate concentration.
[0039]
The predetermined value α and angle β that determine the position and inclination of the gas fuel injection valve 61 are values that allow the natural gas injected from the gas fuel injection valve 61 to be accurately collected around the spark plug 51 by the swirl. Is preset.
[0040]
Next, the electrical configuration of the combustion apparatus according to this embodiment will be described with reference to FIG.
The combustion apparatus includes an electronic control unit (hereinafter referred to as “ECU”) 92 for controlling various operating states of the engine 11 such as a fuel injection amount, a fuel injection timing, and an ignition timing. The ECU 92 is configured as a logical operation circuit including a ROM 93, a CPU 94, a RAM 95, a backup RAM 96, and the like.
[0041]
Here, the ROM 93 is a memory in which various control programs and maps to be referred to when executing the various control programs are stored, and the CPU 94 performs arithmetic processing based on the various control programs and maps stored in the ROM 93. Execute. The RAM 95 is a memory for temporarily storing calculation results in the CPU 94, data input from each sensor, and the like. The backup RAM 96 is a non-volatile memory for storing data to be saved when the engine 11 is stopped. The ROM 93, CPU 94, RAM 95, and backup RAM 96 are connected to each other via a bus 97 and are connected to an external input circuit 98 and an external output circuit 99.
[0042]
The external input circuit 98 is connected to the water temperature sensor 11b, the intake air temperature sensor 37, the ion current detection circuit unit 53b, the gas pressure sensor 65, and the like. On the other hand, a liquid fuel injection valve 50, an igniter 53a, a gas fuel injection valve 61, and the like are connected to the external output circuit 99.
[0043]
Next, an outline of fuel injection control executed through the ECU 92 configured as described above will be described.
The ECU 92 obtains a cooling water temperature THW and an intake air temperature (intake air temperature) THA of the engine 11 based on detection signals from the water temperature sensor 11b and the intake air temperature sensor 37.
[0044]
When both the water temperature THW and the intake air temperature THA are equal to or lower than a predetermined value K1 (for example, −10 ° C.) and the engine 11 is operated at an extremely low temperature, the ECU 92 opens the gas fuel injection valve 61. It is driven to inject and supply only natural gas into the combustion chamber 16 as fuel.
[0045]
Since the ignitability of gasoline decreases at extremely low temperatures, if gasoline is supplied, it is necessary to increase the amount of gasoline in order to prevent the decrease in ignitability, and the fuel consumption rate of gasoline will deteriorate. Become. However, by supplying only natural gas having better ignitability than gasoline at extremely low temperatures as described above, it is possible to achieve both good ignitability and suppression of the fuel consumption rate.
[0046]
Further, when both the water temperature THW and the intake air temperature THA are larger than the predetermined value K1 and not more than the predetermined value K2 (for example, 60 ° C.) and the engine 11 is operated in a normal low temperature state, the ECU 92 Both the liquid fuel injection valve 50 and the gas fuel injection valve 61 are driven to supply both gasoline and natural gas as fuel.
[0047]
Also in this case, since the injected natural gas is accurately collected around the spark plug 51 and the natural gas concentration around the spark plug 51 is set to an appropriate value for ignition, the amount of gasoline injected is reduced. However, good ignitability to fuel can be maintained. Therefore, the amount of gasoline to be injected can be reduced and the fuel consumption rate can be suppressed.
[0048]
Further, when both the water temperature THW and the intake air temperature THA are larger than the predetermined value K2 and the engine has been warmed up, the ECU 92 drives the liquid fuel injection valve 50 to supply only gasoline as fuel. To do.
[0049]
At present, since there are few replenishment locations such as gas stations equipped with facilities for replenishing gaseous fuel such as natural gas, the supply of natural gas is stopped after the engine 11 has been warmed up as described above to consume natural gas. It is preferable to suppress. Further, by suppressing the consumption of natural gas as much as possible, it is possible to reduce the driving situation in which the engine 11 is driven only by gasoline without being able to replenish natural gas.
[0050]
By switching the fuel supplied as described above, as shown in FIG. 5, the fuel of the engine 11 is only natural gas when “THW, THA <K1”, and when “K1 ≦ THW, THA ≦ K2”. Both gasoline and natural gas are gasoline only when “K2 <THW, THA”.
[0051]
On the other hand, the ECU 92 detects the occurrence of pre-ignition based on a signal from the ion current detection circuit unit 53b. When the occurrence of pre-ignition is detected, the ECU 92 uses only gasoline as the fuel to be supplied regardless of the water temperature THW and the intake air temperature THA. Thus, by supplying only gasoline having inferior ignitability as compared with natural gas, the occurrence of pre-ignition can be suitably prevented.
[0052]
Next, the procedure of fuel injection control in the engine 11 will be described with reference to FIG. FIG. 6 is a flowchart showing a fuel injection control routine for switching the fuel supplied to the engine 11. The fuel injection control routine is executed through the ECU 92 by, for example, a time interruption every predetermined time.
[0053]
In this routine, as the process of step S101, the ECU 92 obtains the pressure of the natural gas in the supply passage 62 based on the detection signal from the gas pressure sensor 65, and the natural gas remaining amount in the gas tank 63 is “0” based on the pressure. Is determined. Moreover, ECU92 judges the presence or absence of pre-ignition generation as a process of step S102.
[0054]
If NO is determined in any of the processes in steps S101 and S102, the process proceeds to step S107. The ECU 92 drives the liquid fuel injection valve 50 to inject and supply only gasoline to the engine 11 as the processing of step S107. Therefore, when there is no natural gas in the gas tank 63 or pre-ignition occurs, the engine 11 is driven only by gasoline.
[0055]
If YES is determined in both steps S101 and S102, the process proceeds to step S103. The processing after step S103 is for switching the fuel of the engine 11 in accordance with the water temperature THW and the intake air temperature THA. The ECU 92 determines whether or not the water temperature THW and the intake air temperature THA are smaller than a predetermined value K1 (−10 ° C.) as processing of step S103, and if “THW, THA <K1”, the process proceeds to step S105.
[0056]
The ECU 92 drives the gas fuel injection valve 61 to inject and supply only natural gas to the engine 11 as the process of step S105. Therefore, under the condition that the remaining amount of natural gas is not “0” and pre-ignition is not generated, the engine 11 is driven only by natural gas when the operation is performed at a very low temperature.
[0057]
If it is determined in step S103 that the water temperature THW and the intake air temperature THA are equal to or higher than the predetermined value K1 (−10 ° C.), the process proceeds to step S104. In step S104, the ECU 92 determines whether or not the water temperature THW and the intake air temperature THA are equal to or smaller than a predetermined value K2 (60 °) greater than the predetermined value K1, and “THW, THA ≦ K2”. If so, the process proceeds to step S106.
[0058]
In step S106, the ECU 92 drives the liquid fuel injection valve 50 and the gas fuel injection valve 61 to inject and supply both gasoline and natural gas to the engine 11. Therefore, when a normal low temperature operation is performed under the condition that the remaining amount of natural gas is not “0” and pre-ignition is not generated, the engine 11 is driven by both gasoline and natural gas. It becomes like this.
[0059]
If it is determined in step S104 that the water temperature THW and the intake air temperature THA are larger than the predetermined value K2 (60 ° C.), the routine proceeds to step S107, where only gasoline is injected. After executing any of the processes of steps S105 to S106 according to the water temperature THW and the intake air temperature THA as described above, the ECU 92 once ends this fuel injection control routine.
[0060]
According to the embodiment described in detail above, the following effects can be obtained.
(1) Since the gas fuel injection valve 61 is disposed at a position closer to the crankshaft 14 than the head of the piston 12 at the time of ignition in the moving direction of the piston 12 (vertical direction in FIG. 1), ignition by the ignition plug 51 Sometimes the gas fuel injection valve 61 is hidden by the piston 12. Therefore, the gas fuel injection valve 61 is not exposed in the combustion chamber 16 when the ignition plug 51 is ignited, and the gas fuel injection valve 61 is excessively overheated by heat generated when the fuel is burned. Is prevented. The overheated gas fuel injection valve 61 can be prevented from causing pre-ignition.
[0061]
(2) The fuel injection valve 61 for gas is injected so that the fuel injection direction (the direction indicated by the arrow A in FIGS. 2 and 3) is shifted from the center axis L of the piston 12 by a predetermined value α. Is inclined by an angle β with respect to the radial direction of the piston 12 so as to face the spark plug 51. As a result, the swirl is generated by the natural gas injected during the compression stroke, and the swirl causes the natural gas to move spirally as shown by the two-dot chain arrow B in FIGS. Will be collected accurately. Accordingly, even when gaseous fuel such as natural gas that is difficult to be mixed with gas such as air is directly injected into the combustion chamber 16, the natural gas concentration around the spark plug 51 is accurately set to a value suitable for combustion. It is possible to prevent the combustion state from deteriorating due to an inappropriate concentration.
[0062]
(3) When “K1 ≦ THW, THA ≦ K2” and the engine 11 is operated in a normal low temperature state, both gasoline and natural gas are used as fuels. It will be gathered accurately around. Therefore, even if the natural gas concentration around the spark plug 51 is set to an appropriate value for ignition and the amount of gasoline to be injected is reduced, good fuel ignition can be maintained. Therefore, the fuel consumption rate of the gasoline can be suppressed by reducing the amount of the injected gasoline.
[0063]
(4) When the engine 11 is operated at a very low temperature with “THW, THA <K1”, only natural gas is used as fuel. Since the ignitability of gasoline decreases at that extremely low temperature, it is necessary to increase the amount of gasoline in order to prevent the above-mentioned decrease in ignitability if gasoline is supplied, and the fuel consumption rate of gasoline will deteriorate. It becomes. However, by using only natural gas that has better ignitability than gasoline at extremely low temperatures as described above, it is possible to achieve both good ignitability and suppression of the fuel consumption rate.
[0064]
(5) In the state where “K2 <THW, THA” and the engine 11 has been warmed up, only gasoline is used as fuel, and the consumption of natural gas is suppressed. At present, since there are few replenishment locations such as gas stations equipped with facilities for replenishing gaseous fuel such as natural gas, the supply of natural gas is stopped after the engine 11 has been warmed up as described above to consume natural gas. It is preferable to suppress. Further, by suppressing the consumption of natural gas as much as possible, it is possible to reduce the driving situation where the engine 11 is driven only by gasoline without being able to replenish natural gas.
[0065]
(6) When the occurrence of pre-ignition is detected, regardless of the water temperature THW and the intake air temperature THA, the fuel to be supplied is only gasoline that is less ignitable than natural gas. Will be able to.
[0066]
In addition, this embodiment can also be changed as follows, for example.
In the present embodiment, the preignition is detected based on the ionic current flowing between the electrodes 51a and 51b of the spark plug 51. However, instead of this, a sensor for detecting the ionic current may be provided separately from the spark plug 51. Further, instead of detecting the pre-ignition based on the ion current, the pre-ignition may be detected using another method. As such a method, it is conceivable to detect pre-ignition based on the pressure in the combustion chamber 16, the vibration of the cylinder block 11a, the combustion light, and the like.
[0067]
-When pre-ignition occurs, the fuel of the engine 11 is not necessarily limited to gasoline.
In this embodiment, the fuel is switched based on both the water temperature THW and the intake air temperature THA. However, instead of this, the fuel may be switched based on either the water temperature THW or the intake air temperature THA. .
[0068]
The temperature at which the fuel of the engine 11 is switched, that is, the predetermined value K1 and the predetermined value K2 may be changed as appropriate. For example, the predetermined value K1 and the predetermined value K2 may be the same value. In this case, natural gas and gasoline are not supplied simultaneously.
[0069]
-Gasoline may be supplied in addition to the supply of natural gas in a cryogenic state, or natural gas may be supplied in addition to the supply of gasoline in a warm-up completed state.
-It is not always necessary to switch the fuel based on the water temperature THW and the intake air temperature THA.
[0070]
The present invention may be applied to the engine 11 that is driven only by natural gas supply without gasoline supply.
The predetermined value α and angle β for determining the position and angle of the gas fuel injection valve 61 may be appropriately changed.
[0071]
A gas fuel injection valve 61 may be provided on the cylinder head 15 side and exposed in the combustion chamber 16. In this case, in order to collect the natural gas injected from the gaseous fuel injection valve 61 around the spark plug 51, it is preferable to provide a recess in the head of the piston 12.
[0072]
-In this embodiment, although natural gas was illustrated as gaseous fuel, it replaces with this, for example, you may employ | adopt hydrocarbon gas, such as methane, ethane, propane, butane, hydrogen, and a gasoline vaporized material.
[0073]
In the present embodiment, gasoline is exemplified as the liquid fuel, but light oil, kerosene, heavy oil, methanol, ethanol, animal and vegetable oils, and the like may be employed instead.
Next, technical ideas other than the claims that can be grasped from the above embodiments will be described together with the effects thereof.
[0074]
(1) A fuel injection valve that injects fuel into the combustion chamber, an ignition plug that ignites the fuel injected and supplied by the fuel injection valve, a piston that reciprocates by combustion of fuel based on the ignition, and the piston In an internal combustion engine combustion apparatus comprising an output shaft that rotates based on the reciprocal movement of the engine, the fuel injection valve is provided at a position closer to the output shaft than the position of the piston head at the time of ignition by the ignition plug. A combustion apparatus for an internal combustion engine.
[0075]
According to this configuration, when the ignition plug is ignited, the fuel injection valve is hidden by the piston and is not exposed to the combustion chamber, so that the exposed portion is excessively overheated to prevent preignition from being easily generated. can do.
[0076]
(2) In the combustion apparatus for an internal combustion engine according to (1), the fuel injection valve is inclined so that the fuel injection direction is deviated from the central axis of the piston and the injected fuel is directed to the ignition plug. Combustion device for an internal combustion engine provided as
[0077]
According to this configuration, a swirl is generated by the fuel injected from the fuel injection valve, and the fuel is accurately collected around the spark plug by the swirl.
(3) In a combustion apparatus for an internal combustion engine that switches the fuel of the internal combustion engine between gaseous fuel and liquid fuel according to the engine operating state, the fuel of the engine is switched based on at least one of the engine temperature and the intake air temperature of the internal combustion engine An internal combustion engine combustion apparatus comprising fuel switching means.
[0078]
According to this configuration, by switching the fuel based on the engine temperature and the intake air temperature of the internal combustion engine, it is possible to select and supply the fuel suitable for the engine temperature and the intake air temperature.
[0079]
(4) In the combustion apparatus for an internal combustion engine according to (3), the fuel switching means is configured such that when at least one of the engine temperature and the intake air temperature of the internal combustion engine is lower than a predetermined reference value, the fuel of the engine A combustion apparatus for an internal combustion engine that drives the internal combustion engine only with gaseous fuel by switching between them.
[0080]
According to this configuration, when the engine temperature or intake air temperature of the internal combustion engine is low, the internal combustion engine is driven only with gaseous fuel with good ignitability, so it is necessary to increase the fuel to obtain good ignitability. Disappear. For this reason, it is possible to achieve both good ignitability of the fuel and suppression of the fuel consumption rate.
[0081]
(5) In the combustion apparatus for an internal combustion engine as set forth in (3), the fuel switching means is configured such that when at least one of the engine temperature and the intake air temperature of the internal combustion engine is higher than a predetermined reference value, A combustion apparatus for an internal combustion engine that switches the engine to drive the internal combustion engine only with liquid fuel.
[0082]
According to this configuration, when at least one of the engine temperature and the intake air temperature of the internal combustion engine is higher than a predetermined reference value, the supply of the gaseous fuel is stopped, so that the consumption rate of the gaseous fuel is suppressed. Can do.
[0083]
(6) In a combustion apparatus for an internal combustion engine in which the fuel of the internal combustion engine is switched between gaseous fuel and liquid fuel in accordance with the engine operating state, when pre-ignition occurs in the internal combustion engine, the fuel of the engine is switched and only the liquid fuel is used. A combustion apparatus for an internal combustion engine, comprising fuel switching means for driving the internal combustion engine.
[0084]
According to this configuration, when pre-ignition occurs, the internal combustion engine is driven only by the liquid fuel that is inferior in ignitability than the gaseous fuel, so that pre-ignition can be suitably prevented.
[0085]
【The invention's effect】
  According to invention of Claim 1, it injects from a fuel injection valve.RuGaseous fuelCreates a swirl that allows gas fuel to be accurately collected around the spark plugTherefore, the fuel concentration around the spark plug can be accurately set at the time of ignition, and the combustion state can be maintained satisfactorily.
[0086]
  AlsoWhen the ignition plug is ignited, the fuel injection valve is hidden by the piston and is not exposed in the combustion chamber, so that it is possible to prevent the exposed portion from being overheated and easily causing preignition.
[0088]
  Claim2According to the described invention, since the gas fuel having good ignitability is collected around the spark plug, when the gas fuel and the liquid fuel are supplied, the good ignitability of the fuel can be obtained even if the liquid fuel is reduced. Will be able to get maintained. Therefore, the fuel consumption rate is suppressed by reducing the liquid fuel.
According to the third aspect of the invention, since the gaseous fuel with good ignitability is collected around the spark plug, when the gaseous fuel and the liquid fuel are supplied, even if the amount of the liquid fuel is reduced, the fuel quality is good. The ignitability can be maintained. Therefore, the fuel consumption rate is suppressed by reducing the liquid fuel. In addition, when preignition occurs, the internal combustion engine is driven only by liquid fuel that is less ignitable than gaseous fuel, so that preignition can be suitably prevented.
According to the fourth aspect of the present invention, at the time of ignition by the spark plug, the fuel injection valve is hidden by the piston and is not exposed to the combustion chamber, so that the exposed portion is excessively heated and preignition is likely to occur. Can be prevented.
According to the fifth aspect of the present invention, the swirl is generated by the gaseous fuel injected from the fuel injection valve, and the gaseous fuel is accurately collected around the spark plug by the swirl.
[0089]
  Claim6According to the described invention, by switching the fuel based on the engine temperature and the intake air temperature of the internal combustion engine, it is possible to select and supply the fuel suitable for the engine temperature and the intake air temperature.
[0090]
  Claim7According to the described invention, when the engine temperature or the intake air temperature is low, such as when the internal combustion engine is started at a low temperature, the internal combustion engine is driven only by the gas fuel having good ignitability, so that the fuel increase to obtain good ignitability Etc. are no longer necessary. For this reason, it is possible to achieve both good ignitability of the fuel and suppression of the fuel consumption rate.
[0091]
  Claim8According to the described invention, when the temperature of at least one of the engine temperature and the intake air temperature of the internal combustion engine is higher than a predetermined reference value, the supply of the gaseous fuel is stopped, so that the consumption rate of the gaseous fuel is suppressed. be able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an engine to which a combustion apparatus according to an embodiment is applied.
FIG. 2 is a plan sectional view of a cylinder block in the engine.
FIG. 3 is a longitudinal section of the cylinder block.
FIG. 4 is a block diagram showing an electrical configuration of the combustion apparatus.
FIG. 5 is a diagram showing a fuel switching mode with respect to changes in cooling water temperature and intake air temperature.
FIG. 6 is a flowchart showing a procedure of fuel injection control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine, 11b ... Water temperature sensor, 12 ... Piston, 14 ... Crankshaft, 16 ... Combustion chamber, 37 ... Intake temperature sensor, 50 ... Fuel injection valve for liquid, 51 ... Spark plug, 53 ... Igniter module, 53a ... Igniter 53b ... Ion current detection circuit part 61 ... Fuel injection valve for gas, 92 ... Electronic control unit (ECU).

Claims (8)

A fuel injection valve that injects gaseous fuel into the combustion chamber, an ignition plug that ignites the gaseous fuel injected and supplied by the fuel injection valve, a piston that reciprocates based on ignition of the fuel by the ignition plug, and An internal combustion engine combustion apparatus comprising an output shaft that rotates based on a reciprocating movement of a piston ,
The fuel injection valve is positioned at a position closer to the output shaft than the position of the piston head at the time of ignition by the spark plug so that the fuel injection direction is deviated from the central axis of the piston, and the injected fuel is ignited. A combustion apparatus for an internal combustion engine, wherein the combustion apparatus is provided so as to be inclined toward the plug . The combustion apparatus for an internal combustion engine according to claim 1,
The internal combustion engine is driven by liquid fuel in addition to the gaseous fuel, and further includes fuel switching means for switching the fuel of the internal combustion engine according to the engine operating state.
A combustion apparatus for an internal combustion engine. In a combustion apparatus for an internal combustion engine, comprising: a fuel injection valve that injects gaseous fuel into a combustion chamber; and an ignition plug that ignites gaseous fuel injected and supplied by the fuel injection valve.
The fuel injection valve is provided at a position where the gaseous fuel injected and supplied from the injection valve gathers around the spark plug,
The internal combustion engine is also driven by liquid fuel in addition to the gaseous fuel, and further comprises a fuel switching means for switching the fuel of the internal combustion engine according to the engine operating state,
When the pre-ignition occurs in the internal combustion engine, the fuel switching means switches the fuel of the engine and drives the internal combustion engine only with liquid fuel.
A combustion apparatus for an internal combustion engine. The internal combustion engine includes a piston that reciprocates based on ignition of fuel by the spark plug, and an output shaft that rotates based on the reciprocation of the piston,
The fuel injection valve is provided at a position closer to the output shaft than the position of the piston head at the time of ignition by the spark plug.
A combustion apparatus for an internal combustion engine according to claim 3 . The combustion apparatus for an internal combustion engine according to claim 4 , wherein the fuel injection valve is provided so as to be inclined so that a fuel injection direction is deviated from a central axis of the piston and the injected fuel is directed toward the ignition plug . The combustion apparatus for an internal combustion engine according to any one of claims 2 to 5, wherein the fuel switching means switches the fuel of the internal combustion engine based on at least one of an engine temperature of the internal combustion engine and an intake air temperature . It said fuel switching means according to claim at least one of the temperature of the engine temperature and the intake air temperature of the internal combustion engine is low Itoki than a predetermined reference value, to drive the internal combustion engine only by the gaseous fuel by switching the fuel in the same engine 6. A combustion apparatus for an internal combustion engine according to 6 . It said fuel switching means, when at least one of the temperature of the engine temperature and the intake air temperature of the internal combustion engine is higher than a predetermined reference value, claim to drive the internal combustion engine only by the liquid fuel switches the fuel of the engine 6 A combustion apparatus for an internal combustion engine as described.

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