JP2000161066A - Combustion device for internal combustion engine - Google Patents

Abstract

(57) Abstract: A combustion device for an internal combustion engine driven by a gaseous fuel that can prevent a combustion state from deteriorating. A natural gas is supplied to a combustion chamber of an engine.
A gas fuel injection valve 61 that injects directly into the inside is provided.
The gas fuel injection valve 61 is disposed such that natural gas injected from the valve 61 gathers around the ignition plug 51. Although gaseous fuel such as natural gas is difficult to mix with gas such as air, the gaseous fuel is likely to be unevenly distributed in the combustion chamber 16. However, by disposing the gaseous fuel injection valve 61 as described above, the ignition plug The natural gas concentration around 51 is an appropriate value for ignition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device for an internal combustion engine.

[0002]

2. Description of the Related Art Generally, liquid fuel such as gasoline is used as fuel for an internal combustion engine for an automobile. However, in recent years, gas fuels such as natural gas have attracted attention as alternative fuels to gasoline due to problems such as depletion of oil. As a fuel supply device for an internal combustion engine driven by such a gaseous fuel, for example, a fuel supply device described in Japanese Patent Application Laid-Open No. Hei 3-26835 is known.

[0003] The apparatus disclosed in the publication is a gas fuel injection valve for injecting gaseous fuel into a combustion chamber of an internal combustion engine, and a liquid fuel injection valve for injecting liquid fuel into an intake port communicating with the combustion chamber. And a valve. The gaseous fuel and the liquid fuel injected from the fuel injection valves are ignited by a spark plug in the combustion chamber and burn, and the combustion energy drives the internal combustion engine.

[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 supply amount of the liquid fuel, the fuel consumption rate of the liquid fuel can be suppressed.

[0005]

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 gaseous fuel is unevenly distributed in the combustion chamber. . For this reason, at the time of ignition by the ignition plug, the fuel of an appropriate concentration does not always exist around the ignition plug, and when the concentration of the fuel is inappropriate, the combustion state deteriorates.

In addition, when the engine temperature or the intake air temperature is low, such as when the internal combustion engine is started at a low temperature, a large amount of liquid fuel adheres to the inner wall of the intake port and becomes difficult to vaporize. Gets worse. 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 is difficult to obtain both good ignitability and suppression of the fuel consumption rate.

[0007] In addition, since there are currently only a limited number of replenishing locations such as gas stations equipped with a facility for replenishing gaseous fuel, the gaseous fuel consumption rate should be minimized in consideration of gaseous fuel replenishment. Is preferred. However, in the apparatus described in the above-mentioned publication, since gaseous fuel and liquid fuel are always supplied, if the gaseous fuel cannot be supplied, the internal combustion engine must be driven only with liquid fuel.

The gas fuel injection valve is exposed in the combustion chamber to inject and supply fuel to the combustion chamber. If the exposed portion of the gaseous fuel injection valve in the combustion chamber is excessively heated by heat during combustion or the like, the heat in the combustion chamber spontaneously ignites before the ignition by the ignition plug is performed. Preignition occurs and the combustion state is apt to deteriorate.

The present invention has been made in view of such circumstances, and a first object of the present invention is to provide an internal combustion engine driven by gaseous fuel which can prevent the combustion state from deteriorating. An engine combustion device is provided.

A second object of the present invention is to provide a combustion apparatus for an internal combustion engine which can achieve both good fuel ignitability and low fuel consumption rate even at a low temperature start of the engine. Is to do.

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 device for an internal combustion engine that can preferably prevent the occurrence of preignition in the internal combustion engine.

[0012]

According to the first aspect of the present invention, there is provided a fuel injection valve for injecting gaseous fuel into a combustion chamber, and a gaseous fuel injected and supplied by the fuel injection valve. In a combustion apparatus for an internal combustion engine having an ignition plug for performing ignition, the fuel injection valve is provided at a position where gaseous fuel injected and supplied from the injection valve gathers around the ignition plug.

According to this configuration, the gaseous fuel injected from the fuel injection valve collects around the ignition plug, so that at the time of ignition, the fuel concentration around the ignition plug is set to an appropriate state, and the combustion state is maintained well. Will be able to

According to a second aspect of the present invention, in the first 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 that rotates based on reciprocation of the piston. A shaft, and the fuel injection valve is provided at a position closer to the output shaft than a 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 ignition plug, the fuel injection valve is hidden by the piston and is not exposed in the combustion chamber. Therefore, it is possible to prevent the exposed portion from being excessively overheated and easily causing preignition. Is done.

According to a third aspect of the present invention, in the second aspect of the present invention, the fuel injection valve has a fuel injection direction deviated from a center axis of the piston and the injected fuel is directed toward the spark plug. It is provided to be inclined.

According to this configuration, 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.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the internal combustion engine is driven by a liquid fuel in addition to the gaseous fuel. Fuel switching means further comprising fuel switching means for switching the fuel of the internal combustion engine according to the above.

According to this configuration, gaseous fuel having good ignitability is collected around the spark plug. Therefore, when supplying gaseous fuel and liquid fuel simultaneously, even if the liquid fuel is reduced, good ignition of the fuel is achieved. You will be able to maintain the sex. Therefore, the fuel consumption rate is suppressed by reducing the amount of the liquid fuel.

According to a fifth aspect of the present invention, in the fourth aspect of the 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.

According to this configuration, by switching the fuel based on the engine temperature and the intake air temperature of the internal combustion engine, it becomes possible to select and supply fuel appropriate for the engine temperature and the intake air temperature.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, 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, The internal combustion engine is driven only by gas fuel by switching the fuel of the engine.

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 the gas fuel having good ignitability. It is not necessary to increase the amount of fuel or the like. Therefore, it is possible to achieve both good ignitability of the fuel and suppression of the fuel consumption rate.

According to a seventh aspect of the present invention, in the fifth aspect of the 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 internal combustion engine is driven only by the liquid fuel by switching the fuel of the engine.

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 gaseous fuel is stopped.
The gas fuel consumption rate can be reduced.

According to the invention described in claim 8, in the invention described in any one of claims 4 to 7, the fuel switching means includes:
When a preignition occurs in the internal combustion engine, the fuel of the internal combustion engine is switched and the internal combustion engine is driven only by the liquid fuel.

According to this configuration, when preignition occurs, the internal combustion engine is driven only by the liquid fuel having a lower ignitability than the gaseous fuel, so that the preignition can be suitably prevented. .

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to an automobile engine will be described below with reference to FIGS.

As shown in FIG. 1, a piston 12 connected via a connecting rod 13 to a crankshaft 14, which is an output shaft of the engine 11, is provided on a cylinder block 11a of the engine 11 so as to be able to reciprocate. 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 water temperature THW of the cooling water in the engine 11.

A cylinder head 15 is provided at the upper end of the cylinder block 11a, 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 on the cylinder head 15 communicate with the combustion chamber 16. The intake port 17 and the exhaust port 18 communicate with an intake passage 32 and an exhaust passage 33. The intake passage 32 has an intake air temperature THA for detecting a temperature (intake air temperature) THA of air passing through the passage 32. A sensor 37 is provided.

At the downstream end of the intake passage 32, an intake port 1 is provided.
Fuel injection valve 50 for injecting gasoline into
Is provided. The liquid fuel injection valve 50 injects gasoline into the intake port 17 to form a mixture of gasoline and air when air in the intake passage 32 is sucked into the combustion chamber 16 during an intake stroke.

A gas fuel injection valve 61 for directly injecting and supplying natural gas into the combustion chamber 16 is provided above the cylinder block 11a. The gas fuel injection valve 61 is connected via a supply passage 62 to a gas tank 63 filled with natural gas. Supply passage 62
Of the gas fuel injection valve 61 from the gas tank 63
A pressure regulator 64 for keeping the pressure of the natural gas supplied to the pressure constant is provided. 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,
The natural gas is supplied to the combustion chamber 16.

On the other hand, the combustion chamber 1
An ignition plug 51 for igniting the fuel filled in the fuel cell 6 is provided. The ignition plug 51 is connected to the battery 5 of the automobile through an igniter module 53.
4 is connected. The igniter module 53 includes an igniter 53a for performing ignition by the ignition plug 51.
And electrodes 51a and 51b of the ignition plug 51 during fuel combustion.
An ion current detection circuit 53b for detecting an ion current flowing therebetween.

When the fuel such as gasoline or natural gas in the combustion chamber 16 is ignited and burned, the combustion energy causes the piston 12 to reciprocate, causing the crankshaft 14 to rotate and the engine 11 to rotate.
Is driven. Further, the igniter module 53 is provided with the ignition plug 51 when the ignition is not performed.
A low voltage is applied between the electrodes 51a and 51b. Thus, an ion current flows between the electrodes 51a and 51b of the ignition plug 51 at the time of fuel combustion due to ions generated at the time of fuel combustion, and the ion current is detected by the ion current detection circuit unit 53b.

Therefore, in the case where so-called preignition occurs in which fuel spontaneously ignites in the combustion chamber 16 before ignition by the ignition plug 51, the ion current is generated earlier than usual. Therefore, the occurrence of preignition can be detected based on the timing of the generation of the ion current.

Here, the arrangement of the gaseous fuel injection valve 61 will be described in detail with reference to FIGS. The position of the gaseous fuel injection valve 61 in the direction of movement of the piston 12 (the vertical direction in FIG. 1) depends on the position of the piston 1 during ignition.
2 is located closer to the crankshaft 14 than the head. Therefore, at the time of ignition by the ignition plug 51, FIG.
As shown in FIG. 7, the gas fuel injection valve 61 is hidden by the piston 12 and is not exposed in the combustion chamber 16.
Accordingly, the gas fuel injection valve 61 is prevented from being excessively overheated by the heat generated when the fuel is burned, and the overheated gas fuel injection valve 61 is prevented from causing preignition. Will be able to do it.

The gas fuel injection valve 61 is arranged such that its fuel injection direction (the direction indicated by the arrow A in FIGS. 2 and 3) deviates from the central axis L of the piston 12 by a predetermined value α shown in FIG. Has been established. Further, the gas fuel injection valve 61
Is an angle β shown in FIG. 3 with respect to the radial direction of the piston 12 so that the injected natural gas goes to the spark plug 51.
It is provided only at an inclination.

Gas 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, a 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 in FIG.
And, as shown by an arrow B in a two-dot chain line in FIG. for that reason,
The natural gas concentration around the ignition plug 51 can be accurately set to a value suitable for combustion, and it becomes possible to prevent the concentration from becoming inappropriate and preventing the combustion state from deteriorating.

The predetermined value α and the angle β for determining the position and inclination of the gas fuel injection valve 61 are such that natural gas injected from the gas fuel injection valve 61 is accurately collected around the spark plug 51 by swirling. Such a value is set in advance.

Next, the electrical configuration of the combustion apparatus according to this embodiment will be described with reference to FIG. This combustion device includes an engine 11 such as a fuel injection amount, a fuel injection timing, and an ignition timing.
And an electronic control unit (hereinafter, referred to as “ECU”) 92 for controlling various operating states of the electronic control unit. This ECU
Reference numeral 92 denotes a logical operation circuit including a ROM 93, a CPU 94, a RAM 95, a backup RAM 96, and the like.

The ROM 93 is a memory that stores various control programs and maps and the like that are referred to when executing the various control programs.
The arithmetic processing is executed based on various control programs and maps stored in M93. Also, the RAM 95 stores the CPU 9
4 is a memory for temporarily storing the calculation results in step 4, data input from each sensor, and the like.
Is a nonvolatile memory for storing data to be stored when the engine 11 is stopped. And ROM93, CPU
The RAM 94, the RAM 95, and the backup RAM 96 are connected to each other via a bus 97, and are also connected to an external input circuit 98 and an external output circuit 99.

The external input circuit 98 includes a water temperature sensor 11
b, intake air temperature sensor 37, ion current detection circuit 53b,
And a gas pressure sensor 65 and the like. On the other hand, the external output circuit 99 is connected to the liquid fuel injection valve 50, the igniter 53a, the gas fuel injection valve 61, and the like.

Next, the ECU 92 constructed as described above is used.
The outline of the fuel injection control executed through the 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.

When the water temperature THW and the intake air temperature THA are both lower than or equal to a predetermined value K1 (for example, -10 ° C.) and the engine 11 is operated at an extremely low temperature, the ECU 92 sets the gas fuel injection The valve 61 is driven to inject and supply only natural gas as fuel into the combustion chamber 16.

At extremely low temperatures, the ignitability of gasoline decreases. Therefore, if gasoline is supplied, it is necessary to increase the amount of gasoline in order to prevent the decrease in ignitability. Will be done. 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.

When the water temperature THW and the intake air temperature THA are both higher than the predetermined value K1 and equal to or lower than the predetermined value K2 (for example, 60 ° C.) and the engine 11 is operated in a normal low temperature state. The ECU 92 drives both the liquid fuel injection valve 50 and the gas fuel injection valve 61 to supply both gasoline and natural gas as fuel.

Also in this case, the natural gas to be injected is accurately collected around the spark plug 51, and
Since the surrounding natural gas concentration is set to an appropriate value for ignition, it is possible to maintain good ignitability to fuel even if the amount of gasoline injected is reduced. Therefore, the fuel consumption rate can be suppressed by reducing the amount of gasoline to be injected.

Further, when the water temperature THW and the intake air temperature THA are both higher than the predetermined value K2 and the engine has been completely warmed up, the ECU 92 drives the liquid fuel injection valve 50 to remove only gasoline. Supply as fuel.

At present, since there are few refueling locations such as gas stations equipped with a facility for replenishing gaseous fuel such as natural gas, the supply of natural gas is stopped after the completion of warm-up of the engine 11 as described above. It is preferable to suppress the consumption of the. By minimizing the consumption of natural gas, it is possible to reduce the driving situation in which the engine 11 is driven only by gasoline without being able to supply natural gas.

By switching the supplied fuel as described above, as shown in FIG. 5, the fuel of the engine 11 is only natural gas when "THW, THA <K1".
When “K1 ≦ THW, THA ≦ K2”, both gasoline and natural gas are used, and when “K2 <THW, THA”, only gasoline is used.

On the other hand, the ECU 92 detects the occurrence of preignition based on a signal from the ion current detection circuit 53b. When the occurrence of preignition is detected, the ECU 92 determines the water temperature THW and the intake air temperature TH.
Regardless of A, the supplied fuel is gasoline only.
By supplying only gasoline having a lower ignitability than natural gas, the occurrence of preignition can be suitably prevented.

Next, the procedure of the fuel injection control in the engine 11 will be described with reference to FIG. FIG.
4 is a flowchart illustrating a fuel injection control routine for switching fuel supplied to the engine 11. The fuel injection control routine is executed by the ECU 92, for example, by interruption every predetermined time.

In the same routine, the ECU 92 calculates the pressure of the natural gas in the supply passage 62 based on the detection signal from the gas pressure sensor 65 as a process of step S101, and based on the pressure, the remaining natural gas in the gas tank 63. Is determined to be “0”. In addition, the ECU 92
In step S102, it is determined whether or not preignition has occurred.

Then, the above steps S101 and S102
If the answer is NO in any of the processes, 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 process of step S107. Therefore, when there is no natural gas in the gas tank 63 or when preignition occurs, the engine 11 is driven only by gasoline.

If YES is determined in both the steps S101 and S102, the process proceeds to the step S103.
Proceed to. The processing after step S103 is the same as the water temperature TH.
This is for switching the fuel of the engine 11 according to W and the intake air temperature THA. The ECU 92 determines in step S1
In the process of Step 03, it is determined whether or not the water temperature THW and the intake air temperature THA are smaller than predetermined values K1 (−10 ° C.).
If HW, THA <K1, the process proceeds to step S105.

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 natural gas remaining amount is not “0” and preignition does not occur, the engine 11 is driven only by the natural gas when the operation is performed at a very low temperature.

In the process of step S103, the water temperature THW and the intake air temperature THA are set to the predetermined values K1 (−10
° C) or more, the process proceeds to step S104. The ECU 92 determines whether or not the water temperature THW and the intake air temperature THA are equal to or less than a predetermined value K2 (60 °) that is larger than the predetermined value K1 as the process of step S104,
If “THW, THA ≦ K2”, step S10
Proceed to 6.

The ECU 92 executes the liquid fuel injection valve 50 and the gas fuel injection valve 61 in step S106.
To drive both gasoline and natural gas into the engine 11
To be injected. Therefore, under the condition that the natural gas remaining amount is not “0” and preignition does not occur, the engine 11 is driven by both gasoline and natural gas when the operation is performed in a normal low temperature state. Become like

In the process of step S104, the water temperature THW and the intake air temperature THA are set to the predetermined values K2 (60).
If it is determined that the temperature is greater than (° C.), the process proceeds to step S107, and only gasoline is injected. After executing any one 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 the fuel injection control routine.

According to the above-described embodiment, the following effects can be obtained. (1) Regarding the moving direction of the piston 12 (the vertical direction in FIG. 1), 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. Sometimes the gas fuel injection valve 61 is hidden by the piston 12. Accordingly, the gaseous fuel injection valve 61 is not exposed in the combustion chamber 16 at the time of ignition by the ignition plug 51, and the gaseous fuel injection valve 61 may be excessively overheated by the heat when the fuel is burned. Is prevented. Then, it is possible to prevent the overheated gaseous fuel injection valve 61 from causing preignition.

(2) The gas fuel injection valve 61 is injected such that its fuel injection direction (the direction indicated by the arrow A in FIGS. 2 and 3) deviates from the center axis L of the piston 12 by a predetermined value α. The natural gas is provided at an angle β with respect to the radial direction of the piston 12 so as to head toward the spark plug 51. As a result, 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 a two-dot chain line arrow B in FIGS. Will be able to be collected accurately. Therefore, even when gaseous fuel such as natural gas which is difficult to be mixed with gas such as air is directly supplied to the combustion chamber 16, the natural gas concentration around the ignition plug 51 is set to a value suitable for combustion. It can be prevented that the concentration becomes inappropriate and the combustion state deteriorates.

(3) When the engine 11 is operated in a normal low temperature state with “K1 ≦ THW, THA ≦ K2”, both gasoline and natural gas are used as fuel. It will be accurately collected around the spark plug 51. Therefore, the natural gas concentration around the spark plug 51 is set to a value appropriate for ignition, and good ignition of fuel can be maintained even if the amount of gasoline injected is reduced. Therefore, by reducing the amount of gasoline to be injected, the fuel consumption rate of the gasoline can be suppressed.

(4) When the engine 11 is operated under the condition of "THW, THA <K1" and extremely low temperature, only natural gas is used as fuel. At extremely low temperatures, the ignitability of gasoline decreases, so 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 deteriorates. Becomes However, by using only natural gas having better ignitability than gasoline as fuel at extremely low temperatures as described above, it is possible to achieve both good ignitability and suppression of fuel consumption rate.

(5) When “K2 <THW, THA” and the engine 11 has been completely warmed up, only gasoline is used as fuel and natural gas consumption is suppressed. At present, there are few refueling locations such as gas stations equipped with facilities for refueling gaseous fuels such as natural gas.
As described above, it is preferable to stop the supply of the natural gas after the completion of the warm-up of the engine 11 to suppress the consumption of the natural gas.
By minimizing the consumption of natural gas, it is possible to reduce the driving situation in which the engine 11 is driven only by gasoline without being able to supply natural gas.

(6) When the occurrence of preignition is detected, regardless of the water temperature THW and the intake air temperature THA, the supplied fuel is limited to gasoline which is less ignitable than natural gas. It is possible to suitably prevent such a situation.

The present embodiment can be modified, for example, as follows. In the present embodiment, the electrodes 51a, 51 of the ignition plug 51
Although the preignition is detected based on the ion current flowing between b and b, a sensor for detecting the ion current may be provided separately from the ignition plug 51 instead. Also, instead of detecting preignition based on ion current,
The pre-ignition may be detected using another method. As such a method, it is conceivable to detect preignition based on the pressure in the combustion chamber 16, the vibration of the cylinder block 11a, the combustion light, and the like.

When the preignition occurs, it is not always necessary to use only gasoline as fuel for the engine 11. In the present embodiment, the fuel is switched based on both the water temperature THW and the intake air temperature THA. Alternatively, the fuel may be switched based on either the water temperature THW or the intake air temperature THA. .

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 appropriately changed.
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 at the same time.

Gasoline may be supplied in addition to the supply of natural gas when the temperature is extremely low, or natural gas may be supplied in addition to the gasoline when the warm-up is completed. -It is not always necessary to switch the fuel based on the water temperature THW and the intake air temperature THA.

The present invention may be applied to an engine 11 driven only by the supply of natural gas without supplying gasoline. The predetermined value α and the angle β for determining the position and the angle of the gas fuel injection valve 61 may be changed as appropriate.

The gas fuel injection valve 61 may be provided on the cylinder head 15 side to be exposed in the combustion chamber 16. In this case, in order to collect the natural gas injected from the gas fuel injection valve 61 around the ignition plug 51, it is preferable to provide a recess in the head of the piston 12.

In this embodiment, natural gas is exemplified as the gaseous fuel, but instead of this, for example, methane, ethane,
Hydrocarbon gases such as propane and butane, hydrogen, and gasoline vapors may be employed.

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 used instead. Next, technical ideas other than the claims that can be grasped from the above embodiments are described below together with their effects.

(1) A fuel injection valve for injecting fuel into the combustion chamber, an ignition plug for igniting the fuel injected and supplied by the fuel injection valve, and a piston reciprocating by combustion of the fuel based on the ignition. An output shaft that rotates based on the reciprocal movement of the piston, wherein the fuel injection valve is provided at a position closer to the output shaft than a position of the piston head at the time of ignition by the spark plug. A combustion device for an internal combustion engine.

According to this configuration, at the time of ignition by the ignition plug, the fuel injection valve is hidden by the piston and is not exposed to the combustion chamber, so that pre-ignition is easily generated due to excessively overheating of the exposed portion. Can be prevented.

(2) In the combustion apparatus for an internal combustion engine according to the above (1), the fuel injection valve of the fuel injection valve is displaced from the center axis of the piston, and the injected fuel is directed toward the spark plug. The combustion device of the internal combustion engine is provided so as to be inclined.

According to this configuration, swirl is generated by the fuel injected from the fuel injection valve, and the swirl allows the fuel to be accurately collected around the spark plug. (3) In a combustion device for an internal combustion engine that switches between fuel for the internal combustion engine between gaseous fuel and liquid fuel according to the engine operating state, the fuel for the internal combustion engine is switched based on at least one of the engine temperature and the intake air temperature. A combustion device for an inner-edge engine comprising a fuel switching means.

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 appropriate for the engine temperature and the intake air temperature.

(4) In the combustion device for an internal combustion engine according to the above (3), the fuel switching means is provided when at least one of the engine temperature of the internal combustion engine and the intake air temperature is lower than a predetermined reference value. A combustion device for an internal combustion engine that switches the fuel of the engine and drives the internal combustion engine using only gaseous fuel.

According to this configuration, when the engine temperature or the intake air temperature of the internal combustion engine is low, the internal combustion engine is driven only by a gas fuel having good ignitability. There is no need to do it. Therefore, it is possible to achieve both good ignition performance of the fuel and suppression of the fuel consumption rate.

(5) In the combustion device for an internal combustion engine according to the above (3), when at least one of the engine temperature of the internal combustion engine and the intake air temperature is higher than a predetermined reference value, A combustion device for an internal combustion engine that switches the fuel of the engine and drives the internal combustion engine using only liquid fuel.

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 gaseous fuel is stopped.
The consumption rate of the gaseous fuel can be suppressed.

(6) In a combustion apparatus for an internal combustion engine that switches between the fuel of the internal combustion engine and the liquid fuel in accordance with the operating state of the engine, when preignition occurs in the internal combustion engine, the fuel of the internal combustion engine is switched to change the liquid A combustion device for an internal combustion engine including a fuel switching means for driving the internal combustion engine only with fuel.

According to this configuration, when preignition occurs, the internal combustion engine is driven only by the liquid fuel having a lower ignitability than the gaseous fuel, so that the preignition can be suitably prevented.

[0085]

According to the first aspect of the present invention, the gaseous fuel injected from the fuel injection valve collects around the ignition plug, so that the fuel concentration around the ignition plug is set to an appropriate state at the time of ignition, thereby achieving a combustion state. Can be maintained satisfactorily.

According to the second 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 in the combustion chamber, so that the exposed portion is excessively heated and preignition is easily generated. Can be prevented.

According to the third aspect of the invention, a 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.

According to the fourth aspect of the present invention, since the gaseous fuel having 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 is reduced. Can maintain good ignitability. Therefore, the fuel consumption rate is suppressed by reducing the amount of the liquid fuel.

According to the fifth aspect of the present 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 appropriate fuel for the engine temperature and the intake air temperature. .

According to the sixth aspect of the present 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 gaseous fuel having good ignitability. It is not necessary to increase the amount of fuel or the like to obtain the fuel consumption. Therefore, it is possible to achieve both good ignition performance of the fuel and suppression of the fuel consumption rate.

According to the present invention, 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. Fuel consumption rate can be suppressed.

According to the eighth aspect of the invention, when the preignition occurs, the internal combustion engine is driven only by the liquid fuel which is inferior to the gaseous fuel, so that the preignition can be suitably prevented. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an engine to which a combustion device 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 electric configuration of the combustion device.

FIG. 5 is a diagram showing a mode of switching fuel 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 ... Liquid fuel injection valve, 51 ... Spark plug, 53 ... Igniter module, 53a ... Igniter Reference numeral 53b denotes an ion current detection circuit unit, 61 denotes a gas fuel injection valve, and 92 denotes an electronic control unit (ECU).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 21/02 F02M 21/02 LS 43/00 43/00 61/14 310 61/14 310S 310A 63 / 00 63/00 PF term (reference) 3G023 AA01 AA02 AA18 AB03 AC05 AC07 AC08 AD03 AD09 AD12 3G066 AA01 AA02 AB02 AB04 AB05 AB06 AD10 AD12 BA00 BA14 BA17 CC32 CD26 DB01 DC13 DC14 DC18 3G092 AA01 AA05 AA12 AB03 AB03 AB03 EA09 EA11 FA16 FA24 HA04Z HB09Z HC05Z HE08Z

Claims (8)

[Claims] 1. A combustion apparatus for an internal combustion engine comprising: a fuel injection valve for injecting gaseous fuel into a combustion chamber; and a spark plug for igniting gaseous fuel injected and supplied by the fuel injection valve. Wherein the gaseous fuel injected and supplied from the injection valve gathers around the spark plug. 2. 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 reciprocation of the piston. The combustion device for an internal combustion engine according to claim 1, wherein the combustion device is provided at a position closer to the output shaft than a position of the piston head at the time of ignition. 3. The internal combustion engine according to claim 2, wherein the fuel injection valve is provided so that its fuel injection direction is deviated from a center axis of the piston and that the injected fuel is inclined toward the spark plug. Combustion equipment. 4. A combustion apparatus for an internal combustion engine according to claim 1, wherein said internal combustion engine is driven by a liquid fuel in addition to said gaseous fuel, and is driven by an engine operating state. A combustion device for an internal combustion engine, further comprising fuel switching means further comprising fuel switching means for switching fuel of the internal combustion engine. 5. A combustion apparatus for an internal combustion engine according to claim 4, wherein said fuel switching means switches 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. 6. 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, the fuel switching means switches the fuel of the internal combustion engine to operate the internal combustion engine using only gaseous fuel. The combustion device for an internal combustion engine according to claim 5, which is driven. 7. 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 fuel switching means switches the fuel of the internal combustion engine to operate the internal combustion engine using only liquid fuel. The combustion device for an internal combustion engine according to claim 5, which is driven. 8. The fuel switching means, when preignition occurs in the internal combustion engine, switches the fuel of the internal combustion engine to drive the internal combustion engine only with liquid fuel.
8. The combustion device for an internal combustion engine according to any one of 7 above.