JP2014152684A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device of an internal combustion engine capable of keeping proper injection of a liquid fuel of the internal combustion engine by suitably injecting the liquid fuel in accordance with a degree of deterioration of the liquid fuel.SOLUTION: A fuel injection control device 41 of an internal combustion engine 10 driven by selectively switching one of gasoline and CNG and injecting the same to a common combustion chamber 17, includes a stop time integrating portion 62 for integrating a gasoline injection stop time, an injection time adjusting portion 65 for adjusting a gasoline injection time so that the larger a thermal load is, the longer the gasoline injection time is, while considering the thermal load to the gasoline in the injection stop time, and a fuel injection control portion 61 executing control to inject the gasoline on the basis of the adjusted gasoline injection time.

Description

  The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a device for maintaining proper injection of the fuel of an internal combustion engine that operates by selectively switching a fuel to be used to one of liquid fuel and gaseous fuel.

The vehicle is equipped with an internal combustion engine that operates by supplying liquid fuel such as gasoline and gaseous fuel such as CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas) as fuel to be supplied to the combustion chamber. It is known to use as a drive source.
This type of internal combustion engine may cause problems when the frequency of use of liquid fuel such as gasoline is low. For example, in the case of gasoline, an unstable hydrocarbon (mainly an olefinic hydrocarbon) is oxidized to produce a substance such as chewing gum, a so-called gum-like substance, and an injector that injects fuel into the combustion chamber. It will cause problems such as clogging.
In order to solve this problem, for example, in Patent Document 1, when it is determined that the fuel injection region is in a gasoline injection region at a high load or the like, liquid fuel is supplementarily injected and supplied to the internal combustion engine. It has been proposed to prevent sticking to parts and deterioration.

JP 2003-206762 A

However, in the fuel injection control device for the internal combustion engine described in Patent Document 1, since the liquid fuel is only injected at a timing that depends on the driving state of the internal combustion engine at the time of high load, There is a case where the interval at which the injection is performed is increased. In addition, the fuel injection control device for the internal combustion engine does not consider the temperature environment that promotes the deterioration of the liquid fuel. For example, depending on the traveling state of the vehicle and the surrounding environment, the liquid fuel is deteriorated at an early stage. In some cases.
Accordingly, an object of the present invention is to provide a fuel injection control device for an internal combustion engine that maintains proper injection of the liquid fuel of the internal combustion engine by appropriately injecting the liquid fuel according to the degree of deterioration of the liquid fuel. .

A first aspect of the invention relating to a fuel injection control device for an internal combustion engine that solves the above-mentioned problem is a fuel injection for an internal combustion engine that is driven by selectively switching one of liquid fuel and gaseous fuel and injecting the fuel into a common combustion chamber. A control device, a stop time integration unit for integrating the injection stop time of the liquid fuel, and a thermal load on the liquid fuel during the injection stop time; An injection time adjustment unit that adjusts to increase the injection time; and a fuel injection control unit that executes control to inject the liquid fuel based on the injection time of the liquid fuel adjusted by the injection time adjustment unit. It is characterized by this.
According to a second aspect of the invention relating to the fuel injection control device for an internal combustion engine that solves the above-described problem, in addition to the specific matter of the first aspect, the injection time adjustment unit increases the thermal load on the liquid fuel. The fuel injection control unit is set in the deterioration time setting unit, and includes a deterioration time setting unit that adjusts the injection stop time accumulated by the stop time integration unit to be long and sets it as a thermal load deterioration time of the liquid fuel. The thermal load deterioration time that is applied is the liquid fuel injection time.

According to a third aspect of the invention relating to the fuel injection control device for an internal combustion engine that solves the above-mentioned problem, in addition to the specific matter of the second aspect, the stop time integrating unit is configured to provide the liquid fuel while the internal combustion engine is being driven. An in-drive stop time integration unit that integrates the injection stop time of the engine, and the injection time adjustment unit takes into account a thermal load on the liquid fuel during the operation of the internal combustion engine. The heat load deterioration time obtained by lengthening the injection stop time is set in the deterioration time setting unit.
According to a fourth aspect of the invention relating to a fuel injection control device for an internal combustion engine that solves the above-mentioned problem, in addition to the specific matter of the second or third aspect, the stop time integrating unit accompanies a stop of the internal combustion engine. A stop time integration unit for stopping the injection stop time of the liquid fuel is provided, and the injection time adjustment unit is stopped during the stop in consideration of a thermal load on the liquid fuel while the internal combustion engine is stopped. The thermal load deterioration time obtained by adjusting the injection stop time in the time integration unit to be long is set in the deterioration time setting unit.

According to a fifth aspect of the invention relating to the fuel injection control device for an internal combustion engine that solves the above-described problem, in addition to the specific matter of any one of the second to fourth aspects, the injection time adjustment unit includes the deterioration time. The thermal load deterioration time set in the setting unit is updated at an increasing rate according to the thermal load level of the liquid fuel while the liquid fuel injection is stopped, and is decreased according to the liquid fuel injection level. It is characterized by updating at a rate.
According to a sixth aspect of the invention relating to the fuel injection control device for an internal combustion engine that solves the above-mentioned problem, in addition to the specific matter of any one of the second to fifth aspects, the fuel injection control unit includes the deterioration time. When the thermal load deterioration time set in the setting unit exceeds a preset switching time, the fuel to be injected is switched to the liquid fuel and injection of the liquid fuel is started.
In a seventh aspect of the invention relating to a fuel injection control device for an internal combustion engine that solves the above-described problem, in addition to the specific matter of the sixth aspect, a remaining amount of liquid fuel in a fuel tank provided in the internal combustion engine is detected. A liquid fuel remaining amount detecting unit, wherein the fuel injection control unit detects the liquid fuel when the liquid fuel in the fuel tank detected by the liquid fuel remaining amount detecting unit is less than a preset remaining amount. And the injection of the gaseous fuel is continued.

Thus, according to the first aspect of the present invention, the liquid fuel injection time can be extended as the thermal load increases, and the liquid fuel is appropriately injected in accordance with the degree of deterioration of the liquid fuel. be able to. Therefore, it is possible to prevent a part that injects liquid fuel from being clogged, and it is possible to continuously maintain high-quality liquid fuel injection control.
According to the second aspect of the present invention, the injection stop time of the liquid fuel that is extended according to the thermal load is set as the thermal load deterioration time, and the liquid fuel is injected for the thermal load deterioration time. The liquid fuel can be injected for a time corresponding to the degree of deterioration of the liquid fuel, and the sticking of the components can be eliminated. Accordingly, the liquid fuel can be injected and recovered before clogging of the components that inject the liquid fuel or the like, and high-quality liquid fuel injection control can be continuously maintained.

According to the third aspect of the present invention, it is possible to consider the thermal load accompanying the temperature rise of the internal combustion engine that operates with gaseous fuel while stopping the liquid fuel. Therefore, liquid fuel can be injected and recovered before clogging with components that inject liquid fuel or the like with higher reliability, and high-quality liquid fuel injection control can be continuously maintained.
According to the fourth aspect of the present invention, it is possible to consider the thermal load due to the ambient temperature immediately after the internal combustion engine is stopped (fuel injection is stopped). Therefore, liquid fuel can be injected and recovered before clogging with components that inject liquid fuel or the like with higher reliability, and high-quality liquid fuel injection control can be continuously maintained.

According to the fifth aspect of the present invention, the thermal load deterioration time set as the liquid fuel injection time can be increased or decreased according to the thermal load or the degree of injection. Therefore, it is possible to inject the liquid fuel to the extent necessary for recovery, and it is possible to suppress the wasteful injection of the liquid fuel even though the liquid fuel has already been injected and recovery is in progress.
According to the sixth aspect of the present invention, when the thermal load deterioration time set according to the thermal load exceeds the switching time, the injection control is executed by switching from the gaseous fuel as the liquid fuel injection timing. be able to. Therefore, even when the conditions for injecting the gaseous fuel are continued, the liquid fuel can be injected and recovered before clogging of the components for injecting the liquid fuel and the injection control of the high-quality liquid fuel is continuously maintained. Can do.
According to the seventh aspect of the present invention, when the remaining amount is insufficient even at the timing of injecting the liquid fuel, the injection of the liquid fuel can be prohibited. Therefore, it can be avoided that the internal combustion engine stops due to fuel shortage.

FIG. 1 is a diagram showing an embodiment of a fuel injection control device for an internal combustion engine according to the present invention, and is a linked block diagram showing a schematic overall configuration of the internal combustion engine. FIG. 2 is a functional block diagram showing the configuration of the fuel injection control device. FIG. 3 is a graph for calculating a coefficient for evaluating deterioration due to the thermal load of the liquid fuel based on the water temperature. FIG. 4 is a graph for calculating a coefficient for evaluating the deterioration due to the thermal load of the liquid fuel based on the intake air temperature. FIG. 5 is a graph for calculating a coefficient for evaluating the deterioration due to the thermal load of the liquid fuel based on the outside air temperature. FIG. 6 is a graph for calculating a coefficient for evaluating the deterioration of the liquid fuel due to the thermal load based on the engine speed and the intake pressure. FIG. 7 is a graph for calculating a coefficient for evaluating deterioration due to the thermal load of the liquid fuel based on the engine load and the vehicle speed. FIG. 8 is a graph for calculating a coefficient for evaluating the deterioration of the liquid fuel due to the thermal load based on the stop time and the outside air temperature. FIG. 9 is a main flowchart illustrating a control process (control method) for executing fuel injection of gasoline. FIG. 10 is a sub-flowchart for explaining the gasoline injection time adjustment process (adjustment method) in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 10 are diagrams illustrating an embodiment of a fuel injection control device for an internal combustion engine according to the present invention.
(Configuration of internal combustion engine)
In FIG. 1, an internal combustion engine 10 includes a mechanism for connecting a piston 11 to a piston rod 12 and reciprocatingly accommodating it in a cylinder bore 15, and is mounted as a drive source in a vehicle or the like. In the internal combustion engine 10, a combustion chamber 17 is formed between the lower inner surface of the cylinder head 16 above the cylinder bore 15 and the upper surface of the piston 11. The internal combustion engine 10 reciprocates the piston 11 in the vertical direction in the figure by repeating combustion expansion and exhaust by igniting a mixture of intake combustion air and injected fuel introduced into the combustion chamber 17. ing. As a result, the internal combustion engine 10 transmits the driving force of the reciprocating piston 11 via the piston rod 12, the transmission, or the like, thereby rotating the axle, for example, to realize traveling of the vehicle. Here, the internal combustion engine 10 ignites the air-fuel mixture in the combustion chamber 17 by applying a high voltage boosted by the ignition coil 19 to a spark plug (not shown) and causing it to spark.

In the internal combustion engine 10, an intake valve 13 and an exhaust valve 14 are disposed in a cylinder head 16. The intake valve 13 and the exhaust valve 14 are respectively connected to the combustion chamber 17 by a drive cam (intake cam and exhaust cam) 28a that rotates integrally with the camshaft 28 moved (lifted) in the pressing direction in the figure. And an opening edge of the exhaust port 22 to form a gap.
An air cleaner 25 is connected to the intake port 21 via a surge tank 26 so as to construct an intake side manifold 23 for intake of clean outside air. A catalytic converter 27 containing a catalyst 27a is connected to the exhaust port 22 so as to construct an exhaust side manifold 24 for exhausting the cleaned combustion gas. A throttle valve 29 that is linked to the accelerator pedal of the vehicle is disposed on the upstream side of the surge tank 26. The internal combustion engine 10 controls the intake air amount of the combustion air (outside air) mixed with the fuel by adjusting the opening of the throttle valve 29 so as to optimize the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 17. It has become.

In addition, the internal combustion engine 10 can selectively supply two types of fuel, that is, liquid fuel gasoline and gas fuel CNG (LPG may be used) as fuel to be injected into the combustion chamber 17. A gasoline injector (liquid fuel injector) 31 and a CNG injector (gaseous fuel injector) 32 are arranged in the vicinity.
The gasoline injector 31 is connected to a liquid fuel tank 33 via a liquid fuel supply pipe 34. The gasoline injector 31 injects gasoline stored in the liquid fuel tank 33 under normal pressure and supplies the gasoline into the combustion chamber 17 via the intake port 21. The liquid fuel tank 33 is provided with a remaining amount sensor (liquid fuel remaining amount detecting unit) 33a for detecting that the stored gasoline is used until a certain amount of remaining amount is reached. It is connected to a control device 41 which will be described later.
The CNG injector 32 is connected to a gaseous fuel tank 36 via a gaseous fuel supply pipe 37. The CNG injector 32 adjusts the pressure of the CNG stored in the gaseous fuel tank 36 in a high pressure state, injects it, and supplies it to the combustion chamber 17 via the intake port 21. Here, in the gaseous fuel supply pipe 37, since it is difficult to cut off the supply of gaseous CNG (gaseous fuel) into the combustion chamber 17 only by the CNG injector 32, a stop valve 39 is arranged together with the pressure reducing valve 38. doing.

(Configuration of fuel injection control device)
The internal combustion engine 10 includes a control device 41 constructed by a CPU, a memory, and the like. The control device 41 executes a control program stored in advance based on various parameters, sensor information, and the like, and performs overall control of the entire vehicle including air-fuel ratio control of fuel supplied to the internal combustion engine 10.
Here, in addition to the remaining amount sensor 33a, the control device 41 includes an intake air temperature sensor 42, an upstream oxygen sensor (air-fuel ratio sensor) 43, a downstream oxygen sensor 44, an engine water temperature sensor 45, a crank An angle sensor (speed detector) 46, a cam angle sensor 47, a fuel changeover switch 48, an outside air temperature sensor 49, an intake pressure sensor 51, and a vehicle speed sensor 52 are connected.

  The intake air temperature sensor 42 is installed on the downstream side of the air cleaner 25 and detects the intake air temperature of the combustion air supplied to the combustion chamber 17. The upstream oxygen sensor 43 is installed on the upstream side of the catalytic converter 27, and detects the oxygen concentration in the exhaust gas after combustion exhausted from the combustion chamber 17 to detect the combustion state. The downstream oxygen sensor 44 is installed on the downstream side of the catalytic converter 27, and detects the purification status by detecting the oxygen concentration in the exhaust gas after the purification treatment by the catalyst 27a. The engine water temperature sensor 45 detects the engine coolant temperature. The crank angle sensor 46 detects the crank angle of a crankshaft (not shown) for the purpose of detecting the drive speed (drive speed), synchronizing the fuel injection timing, and the like. The cam angle sensor 47 detects the cam angle of the intake side camshaft 28 (intake cam 28a). The fuel changeover switch 48 performs a changeover operation of the fuel to be used manually according to the driving situation such as when the driver is warming up or accelerating. The outside air temperature sensor 49 detects the temperature of outside air as combustion air through a space in which the internal combustion engine 10 is stored, that is, the so-called engine room. The intake pressure sensor 51 detects an intake pressure (negative pressure) when the mixture of intake combustion air and injected fuel in the intake manifold 23 is introduced into the combustion chamber 17. The vehicle speed sensor 52 detects the rotational speed (vehicle speed) of the axle.

  The control device 41 selectively switches between liquid fuel and gas fuel having different properties and supplies the fuel to the internal combustion engine 10 (combustion chamber 17), so that the fuel supplied into the combustion chamber 17 is changed from gasoline to CNG or CNG. It is designed to switch from gasoline to gasoline as appropriate. For example, the control device 41 may detect the internal combustion engine 10 during a manual switching operation by the fuel switch 48, when a fuel shortage is detected in the liquid fuel tank 33 or the gaseous fuel tank 36, or during a warm-up operation or a steady operation or acceleration. The fuel to be used is switched according to the operation mode. As the operation mode of the internal combustion engine 10, an inexpensive CNG can be selected during warm-up operation or steady operation, and gasoline can be selected during acceleration or climbing that requires torque. That is, the fuel injection control device including the fuel injection control unit 61 is configured so that the control device 41 executes the fuel switching control process of the gasoline injector 31 and the CNG injector 32.

  By the way, when the internal combustion engine 10 is used less frequently, unstable components (for example, hydrocarbons such as olefinic hydrocarbons) contained in gasoline (liquid fuel) are oxidized into a gum-like substance such as chewing gum. There is a possibility of clogging parts that change quality and distribute gasoline. From this, the fuel injection control unit 61 of the control device 41 appropriately controls the injection of gasoline from the gasoline injector 31 at a necessary and sufficient time to avoid the generation of gum-like substances. It is supposed to run.

As shown in FIG. 2, the control device 41 also functions as a fuel injection control unit 61 that executes the generation avoidance process of the gum-like substance, and includes a stop time integrating unit 62, a driving stop time integrating unit 63, a stop A control program and a memory for functioning also as the middle stop time integrating unit 64, the injection time adjusting unit 65, and the deterioration time setting unit 66 are prepared in advance.
The stop time integration unit 62 uses the timer function to add and record the time during which the gasoline injection from the gasoline injector 31 is stopped in the memory for each stop. The stop time integration unit 62 functions as a stop time integration unit 63 during driving that integrates the stop time of gasoline injection accompanying the CNG injection from the CNG injector 32 while the internal combustion engine 10 is being driven. It also functions as a stop time integration unit 64 during stoppage that integrates the stop time of the accompanying gasoline injection.

The injection time adjustment unit 65 derives a thermal load applied to the gasoline, and adjusts the gasoline injection stop time accumulated by the stop time integration unit 62 to be longer as the thermal load is larger, thereby deteriorating the thermal load of the gasoline. Recording is set in the deterioration time setting unit 66 secured in the memory as time. That is, the injection time adjustment unit 65 uses the heat load deterioration time recorded and set in the deterioration time setting unit (memory) 66, so that the larger the thermal load on the gasoline during the stop time, the larger the gasoline load accumulated and recorded in the memory. The injection stop time is adjusted longer.
The injection time adjustment unit 65 considers the thermal load applied to gasoline based on the temperature information detected by the intake air temperature sensor 42, the engine water temperature sensor 45, and the outside air temperature sensor 49, and heat in the deterioration time setting unit 66. The load degradation time is derived (adjusted). In addition to this, the injection time adjustment unit 65 is based on the correlation between the driving rotational speed of the internal combustion engine 10 detected by the crank angle sensor 46 and the intake air pressure of the air-fuel mixture detected by the intake pressure sensor 51, or by the throttle valve 29. The thermal load deterioration time is derived based on the correlation between the throttle opening and the vehicle speed detected by the vehicle speed sensor 52.
The injection time adjustment unit 65 derives the thermal load during the gasoline injection stop time accumulated by the stop time integration unit 62 from the heat load deterioration time recorded and set in the deterioration time setting unit 66, and the degree of the heat load. When the gasoline is injected, an update process is executed that shortens (decreases) according to the injection time when gasoline injection is performed.

Specifically, as shown in FIG. 3, the injection time adjustment unit 65 has a water temperature deterioration coefficient Cwt set corresponding to the temperature detected by the engine water temperature sensor 45 (engine water temperature). As the water temperature deterioration coefficient Cwt, when the engine water temperature reaches 80 ° C. or higher when it is determined that the warm-up operation of the internal combustion engine 10 is completed, the water temperature deterioration coefficient Cwt = 0 is switched to Cwt = 1, and the engine water temperature is 80 ° C. A larger coefficient value is set as the value rises.
Thus, until the engine water temperature reaches 80 ° C., the injection time adjustment unit 65 multiplies the gasoline injection stop time by the stop time integration unit 62 by the water temperature deterioration coefficient Cwt = 0 to invalidate the heat load deterioration time (= 0). And a thermal load deterioration time obtained by multiplying the gasoline injection stop time according to the magnitude of the thermal load by multiplying by a larger coefficient value as the engine water temperature rises from 80 ° C. is recorded and set in the deterioration time setting unit 65. be able to.

Further, an intake air temperature degradation coefficient Cint corresponding to the detected temperature (intake air temperature) of the intake air temperature sensor 42 is set in the injection time adjustment unit 65. As shown in FIG. 4, the intake temperature deterioration coefficient Cint is assumed that the higher the intake combustion air introduced into the combustion chamber 17 together with the injected fuel, the greater the thermal load given to the quality of the gasoline. The intake air temperature degradation coefficient Cint multiplied by the gasoline injection stop time is set so as to increase.
In the injection time adjustment unit 65, an outside air temperature degradation coefficient Cair corresponding to the detected temperature (outside air temperature) of the outside air temperature sensor 49 is set. As shown in FIG. 5, when the outside air temperature deterioration coefficient Cair reaches 40 ° C. or more, which is considered to give a thermal load enough to alter gasoline, the outside air temperature deterioration coefficient Cair = 1. It is set to multiply the gasoline injection stop time by the stop time integrating unit 62 so as to increase.
Thereby, the injection time adjustment unit 65 takes into account the magnitude of the thermal load given to the quality of the gasoline not only from the engine water temperature but also from the intake air temperature of the combustion air and the outside air temperature at which the combustion air is introduced. Can be recorded and set in the deterioration time setting unit 66.

The injection time adjustment unit 65 is set with a drive deterioration coefficient Cload derived based on the correlation between the rotational speed of the internal combustion engine 10 detected by the crank angle sensor 46 and the intake pressure detected by the intake pressure sensor 51. Yes. As shown in FIG. 6, the drive deterioration coefficient Cload is set to Cload = 1 within the range of the rotational speed and the intake pressure when the internal combustion engine 10 is idling. On the other hand, the driving deterioration coefficient Cload is driven from the idling range to a high rotation range or a high load. As the shift to, the more heat is generated, the greater the thermal load on the quality of the gasoline, so it is set to increase according to the trend.
Similarly, a vehicle speed deterioration coefficient Cspd derived based on the correlation between the throttle opening by the throttle valve 29 and the vehicle speed detected by the vehicle speed sensor 52 is set in the injection time adjustment unit 65. As shown in FIG. 7, the vehicle speed deterioration coefficient Cspd is such that, as the vehicle speed is slow even at a high load with a large throttle opening, such as uphill, the less the inflow of outside air to the heat generation, the less the thermal load on the gasoline quality. Since it grows larger, it is set to grow according to the tendency.
Thereby, the injection time adjustment unit 65 extends the gasoline injection stop time in consideration of not only the environment such as the ambient temperature but also the thermal load applied to the quality of gasoline in accordance with the driving conditions of the vehicle and the internal combustion engine 10. It is possible to record and set the thermal load degradation time in the degradation time setting unit 66.

The injection time adjusting unit 65 is set with a continuation time during which the internal combustion engine 10 stops, that is, a maximum soak time coefficient Csoak that multiplies the so-called soak time Tsoak. As shown in FIG. 8, the maximum soak time coefficient Csoak is considered to give a thermal load enough to alter the gasoline when the temperature detected by the outside air temperature sensor 49 (outside air temperature) is left for a long time. When the temperature reaches 30 ° C. or more, the maximum soak time coefficient Csoak = 0 is increased, and a larger coefficient value is set as the outside air temperature increases from 30 ° C.
Thus, the injection time adjusting unit 65 is configured to add the maximum soak time coefficient to the gasoline injection stop time by the stop time integrating unit 62 (stop time integrating unit 64 during stop), that is, the soak time Tsoak until the outside air temperature reaches 30 ° C. The soak time Tsoak extended by multiplying the maximum soak time coefficient Csoak having a larger coefficient value as the outside air temperature increases from 30 ° C. is set to be invalidated by multiplying by Csoak = 0. The outside air temperature during the soak time may be calculated by using the average value to calculate the soak time Tsoak, and the soak time Tsoak is calculated by calculating and integrating every preset period. May be.

  Then, the fuel injection control unit 61 appropriately changes the timing based on the thermal load degradation time in the degradation time setting unit 66, for example, when the thermal load degradation time exceeds a preset switching time. For example, the gasoline injection is executed only for the amount of time, for example, for the heat load deterioration time. At this time, if the gasoline stored in the liquid fuel tank 33 detected by the remaining amount sensor 33a is less than the preset remaining amount (is insufficient), the fuel injection control unit 61 controls the injection of this gasoline. Is prohibited and CNG injection control is executed. The gasoline injection time may be calculated by performing arithmetic processing such as multiplying a parameter based on the thermal load deterioration time.

Specifically, as shown in the main flowchart of FIG. 9, when the control device 41 confirms an ignition (IG) -on (ON) operation for starting the internal combustion engine 10 (step S1), the control device 41 will be described later at the time of the previous IG-ON. The thermal load deterioration time Tdet-total ′ recorded and held in the memory by the control process is read and read and held as process target data (step S2).
Next, the outside air temperature during the stop time (soak time Tsoak) of the internal combustion engine 10 timed by the stop time integration unit 64 is obtained from the detection information of the outside air temperature sensor 49 to determine the maximum soak time coefficient Csoak. Weighting is performed by multiplying the time Tsoak (step S3), and as shown in the following equation (1), the heat load deterioration time Tdet-total 'at the time of the previous IG-OFF stored in the memory is included. The thermal load deterioration time Tdet-total at the current IG-ON time is calculated (step S4).
Tdet-total = Tdet-total ′ + Tsoak × Csoak (1)

Next, it is confirmed whether or not the calculated thermal load deterioration time Tdet-total is shorter than a preset limit deterioration time Tlim (step S5). If it is shorter, the preset normal time Tusual is switched. On the other hand, when the thermal load deterioration time Tdet-total is equal to or longer than the limit deterioration time Tlim, the preset deterioration time Tunusual is set as the switching time (step S7). . In addition, it is set to Tuusual <Tunusual.
Next, it is confirmed whether or not the internal combustion engine 10 is started (operated) with gasoline (step S8). If it is not gasoline, that is, if it is started with CNG, the process proceeds directly to step S12 while starting with gasoline. If it is determined that the elapsed time after the start has exceeded the switching time Tchng, the operation with gasoline is continued (step S9).

In step S9, after confirming that the elapsed time after the start of the internal combustion engine 10 has exceeded the switching time Tchng, the switching time Tchng is subtracted from the calculated thermal load deterioration time Tdet-total (step S10). After that, control for appropriately selecting and switching between gasoline and CNG according to the operation mode of the internal combustion engine 10 is executed (step S11), and calculation processing of a thermal load deterioration time Tdet-total during switching control described later is executed (step S11). S12).
When it is confirmed in the calculation process of step S12 that the engine is not in the IG-ON state, that is, it is confirmed that the internal combustion engine 10 is in the stopped state, the calculated thermal load deterioration time Tdet-total is recorded in the deterioration time setting unit 66. Simultaneously with the holding (step S13), the time measurement processing of the stop time of the internal combustion engine 10 of the stop time integrating unit 62 is started (step S14).

In the calculation process of the thermal load deterioration time Tdet-total in step S12, as shown in the sub-flowchart of FIG. 10, after resetting the number of repetitions (i) of the calculation process of the thermal load deterioration time Tdet-total (step S101), When it is confirmed again that it is in the IG-ON state (step S102), the number of repetitions (i) is incremented (+1) (step S103), and then the internal combustion engine 10 is operated with CNG (gas fuel). It is confirmed whether it is (step S104).
If it is confirmed in step S102 that the engine is not in the IG-ON state, the process proceeds to step S13 in the main flowchart of FIG. 9 to record and hold the calculated thermal load deterioration time Tdet-total and to stop the internal combustion engine 10. Is finished (step S14) and waits until the next IG-ON.

In step S104, when it is confirmed that the internal combustion engine 10 is not operating with gas fuel (CNG), that is, the internal combustion engine 10 is operating with gasoline, the heat load deterioration time Tdet-total associated with gasoline injection is determined. Update processing is performed. In this update process, the repetition interval time of this sub-flowchart (calculation process of thermal load degradation time Tdet-total) is determined from the previous thermal load degradation time Tdet-total (i-1) recorded and held in the degradation time setting unit 66. The calculation of the following equation (2) for subtracting Tint is performed and the thermal load deterioration time Tdet-total is rewritten and updated (step S201). Then, the process returns to step S102 and the same processing is repeated.
Tdet-total (i) = Tdet-total (i-1) -Tint (2)

On the other hand, in step S104, when it is confirmed that the internal combustion engine 10 is operating with gas fuel (CNG), in other words, the internal combustion engine 10 is not operating with gasoline, the stop time accumulating unit 63 during driving is determined to be CNG. As shown in the following equation (3), a weighting process for multiplying the above-described coefficient C according to the thermal load applied to the gasoline is performed on the in-drive stop time Tstp for integrating the stop time of gasoline injection accompanying operation. The deterioration time Tdet (i) is calculated (step S105).
Tdet (i) = Tstp × Cwt × Cint × Cair × Cload × Cspd (3)
Cwt: water temperature deterioration coefficient, Cint: intake air temperature deterioration coefficient, Cair: outside air temperature deterioration coefficient
Cload: Driving deterioration coefficient, Cspd: Vehicle speed deterioration coefficient

Subsequently, the thermal load deterioration time Tdet-total (i) is calculated by adding the stop time Tstp during driving to the previous heat load deterioration time Tdet-total (i-1) recorded and held in the deterioration time setting unit 66. After the calculation of the following equation (4) is performed and the thermal load degradation time Tdet-total is rewritten and updated (step S106), the thermal load degradation time Tdet-total is larger than the preset limit degradation time Tlim. Whether or not (step S107).
Tdet-total (i) = Tdet-total (i-1) + Tdet (i) (4)

When it is confirmed in step S106 that the thermal load deterioration time Tdet-total is equal to or shorter than the limit deterioration time Tlim, the process returns to step S102 and the same process is repeated while maintaining the operation of the internal combustion engine 10 by CNG. When it is confirmed that the thermal load deterioration time Tdet-total is longer than the limit deterioration time Tlim, the remaining amount of gasoline in the liquid fuel tank 33 is subsequently checked (step S108).
If the remaining amount of gasoline is equal to or less than the preset remaining amount in step S108, the process returns to step S102 and the same processing is repeated while maintaining the operation of the internal combustion engine 10 by CNG, while the remaining amount of gasoline is set. If it is confirmed that the amount is greater than the remaining amount, the fuel for forcibly operating the internal combustion engine 10 is forcibly switched from CNG to gasoline (step S109).

After this, it is confirmed again that it is in the IG-ON state (step S110), and it repeats from the previous thermal load degradation time Tdet-total (i-1) in the degradation time setting unit 66 as in step S201. The calculation of the above formula (2) for subtracting the interval time Tint is performed, and the thermal load deterioration time Tdet-total is rewritten and updated (step S111).
Then, after confirming that the updated thermal load deterioration time Tdet-total has become smaller than a preset value, the process returns to step S110 repeatedly, and after the operation of the internal combustion engine 10 with gasoline is continued (step S112), returning to step S102, the same processing is repeated.
If it is confirmed in step S110 that the engine is not in the IG-ON state, the process proceeds to step S13 in the main flowchart of FIG. 9 to record and maintain the calculated thermal load deterioration time Tdet-total and An end process for starting the stop time is executed (step S14), and the process waits until the next IG-ON.

  Therefore, before the gasoline deteriorates due to the heat load in the route routed in the engine room that houses the internal combustion engine 10 to generate a gum-like substance and clog the injector and the like, the thermal load of the gasoline is reduced. It can be consumed by being injected into the combustion chamber for a corresponding period of time, and it is possible to prevent clogging due to the gum substance caused by the deterioration of the gasoline and maintain high quality gasoline injection continuously.

Here, in the present embodiment, the thermal load is derived using the sensor information necessary for determining the driving condition of the internal combustion engine 10, but the present invention is not limited to this. For example, the gasoline injector 31, piping, etc. It is also possible to perform switching control with higher accuracy by installing a sensor that directly detects the temperature and measuring the accurate temperature.
Further, as the gasoline injection control, when the injection time (valve opening time) of the gasoline injector 31 is extended longer than a preset condition, the timing for switching to CNG (gas fuel) injection is delayed. May be. Specifically, the fuel injection of the internal combustion engine 10 is performed by opening the injector 31 and the like for a predetermined time, and the fuel injection is increased and decreased so that the air-fuel ratio repeats rich and lean. For this reason, when the gasoline injector 31 or the like is clogged with gasoline gum-like substance, even if the set time is opened, fuel injection for the set time cannot be performed, and the air-fuel ratio fluctuates to the lean side. Therefore, it is determined that the air-fuel ratio must be changed to a richer side, and the valve opening time is increased. Even if the thermal load deterioration time Tdet (i) is increased as the increase amount of the valve opening time becomes larger than the predetermined valve opening time, the same effect can be obtained.

  The scope of the present invention is not limited to the illustrated and described exemplary embodiments, but includes all embodiments that provide the same effects as those intended by the present invention. Further, the scope of the invention is not limited to the combinations of features of the invention defined by the claims, but may be defined by any desired combination of particular features among all the disclosed features. .

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Piston 17 Combustion chamber 29 Throttle valve 31 Gasoline injector 32 CNG injector 33 Liquid fuel tank 33a Remaining amount sensor 34 Liquid fuel supply pipe 41 Controller 42 Intake air temperature sensor 45 Engine water temperature sensor 46 Crank angle sensor 49 Outside air temperature sensor 51 Intake pressure sensor 52 Vehicle speed sensor 61 Fuel injection control unit 62 Stop time integration unit 63 Stop time integration unit during driving 64 Stop time integration unit during stop 65 Injection time adjustment unit 66 Deterioration time setting unit

Claims (7)

A fuel injection control device for an internal combustion engine that is driven by selectively switching one of liquid fuel and gaseous fuel and injecting the fuel into a common combustion chamber,
Considering the thermal load on the liquid fuel during the injection stop time and the stop time integrating unit for integrating the liquid fuel injection stop time, the liquid fuel injection time is lengthened as the thermal load increases. And an injection time adjusting unit that adjusts the liquid fuel, and a fuel injection control unit that performs control to inject the liquid fuel based on the injection time of the liquid fuel adjusted by the injection time adjusting unit. Engine fuel injection control device. The injection time adjustment unit adjusts the injection stop time accumulated by the stop time integration unit longer as the thermal load on the liquid fuel is larger, and sets a deterioration time setting unit as the heat load deterioration time of the liquid fuel. prepare for,
2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control unit sets the thermal load deterioration time set in the deterioration time setting unit as an injection time of the liquid fuel. 3. The stop time integrating unit includes a driving stop time integrating unit that integrates the injection stop time of the liquid fuel during driving of the internal combustion engine,
The injection time adjustment unit takes the thermal load deterioration time obtained by adjusting the injection stop time in the drive stop time integration unit longer in consideration of the thermal load on the liquid fuel during driving of the internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 2, wherein the fuel injection control device is set in a setting unit. The stop time integration unit includes a stop time integration unit during stop that integrates the injection stop time of the liquid fuel accompanying the stop of the internal combustion engine,
The injection time adjustment unit considers the thermal load deterioration time obtained by adjusting the injection stop time in the stop time integration unit longer in consideration of the thermal load on the liquid fuel while the internal combustion engine is stopped. The fuel injection control device for an internal combustion engine according to claim 2 or 3, wherein the fuel injection control device is set in a setting unit.   The injection time adjustment unit updates the thermal load deterioration time set in the deterioration time setting unit at an increasing rate according to the thermal load on the liquid fuel during the stop of the injection of the liquid fuel, The fuel injection control device for an internal combustion engine according to any one of claims 2 to 4, wherein the fuel injection control device is updated at a reduction rate corresponding to the degree of injection of the liquid fuel.   The fuel injection control unit switches the fuel to be injected to the liquid fuel and starts the injection of the liquid fuel when the thermal load deterioration time set in the deterioration time setting unit exceeds a preset switching time. The fuel injection control device for an internal combustion engine according to any one of claims 2 to 5, wherein: A liquid fuel remaining amount detecting unit for detecting a remaining amount of liquid fuel in a fuel tank provided in the internal combustion engine;
The fuel injection control unit prohibits the injection of the liquid fuel when the liquid fuel in the fuel tank detected by the liquid fuel remaining amount detection unit is less than a preset remaining amount, The fuel injection control device for an internal combustion engine according to claim 6, wherein the injection is continued.

Images