JP2006283690A - Fuel injection control method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of bluish white smoke and deterioration of engine sound feeling in transition from a cold condition to a hot condition even if total demand injection quantity in relation to change of an operation condition decreases. <P>SOLUTION: In this fuel injection control method for an internal combustion engine, an accumulator type fuel injection device capable of multiple stage injection is provided, and main injection F and at least one of sub injection of sub injection preceding the main injection F, in an embodiment, sub injection delayed from pilot injections P1, P2 or main injection F, post injection R for example, are performed. An engine operation condition discrimination sensor discriminating the engine operation condition cold or hot is provided. Fuel total injection quantity is increased not to make sub injection such as pilot injection P2 extinct by retarding timing of main injection in the hot condition than timing of main injection F in the cold condition when the operation condition discrimination sensor detects change from the cold condition to the hot condition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection control method for an internal combustion engine that includes a pressure-accumulation fuel injection device capable of multi-stage injection, and performs either sub-injection of main injection and sub-injection prior to main injection or sub-injection delayed from main injection. .

  FIG. 13 shows an example of a multi-stage injection pattern in this type of internal combustion engine. One main injection F and two sub-injections preceding the main injection F, that is, first and second pilot injections P1, P2 and sub-injection delayed from the main injection F, that is, post-injection R.

  The conventional control of this multi-stage injection is to calculate the main injection amount by subtracting all the sub injection amounts from the total injection amount by calculating the total injection amount, the number of sub injections and each injection amount according to the operating state of the engine. It is supposed to be. Further, the injection priority is set for each of the sub-injections P1, P2, R and the main injection F, and when the calculated value becomes smaller than the preset minimum value (threshold value), the priority is set. By stopping from the lowest injection, an injection amount with a high priority is sufficiently secured.

  FIG. 12 shows an example of the injection priority in the multi-stage injection of FIG. 13, the cold injection amount, the minimum injection amount, and the warm injection amount of each injection. In FIG. 12, the first priority of the injection priority is naturally the main injection F, the second is the first pilot injection P1 on the side close to the main injection F, and the third is the post injection R. The fourth place is the second pilot injection P2 on the side farther from the main injection F. The minimum injection amount is 2 mm3 / st for the main injection F and 0.5 mm3 / st for each of the sub-injections P1, P2, R. Further, for example, when the total injection amount is 9 mm 3 / st, the injection amount in the cold state is 4 mm 3 / st for the main injection F, 1 mm 3 / st for the first and second pilot injections P 1 and P 2, and the post The injection R is 3 mm3 / st.

Patent Document 1 and the like are known technical documents of an internal combustion engine having a multi-stage injection pattern.
JP-A-11-93735

In the control of an internal combustion engine having a multi-stage injection pattern as shown in FIGS. 12 and 13, the required total injection amount of fuel depends on the engine temperature, the lubricating oil temperature, the cooling water temperature, or the like. When the temperature of the engine is low, the mechanical loss is large because the viscosity of the lubricating oil is high and the required total injection amount is increased.On the other hand, when the engine is warmed, the viscosity of the lubricating oil is decreased and the mechanical loss is reduced. The injection amount decreases.

For example, as shown in FIG. 12, if the required total injection amount in idling rotation at the time of cold is 9 mm3 / st, the viscosity of the lubricating oil decreases at the same engine speed when the idling rotation is warm. Loss is reduced and the required total injection quantity is reduced to 7.5mm3 / st. In the process of decreasing the required total injection amount, as shown in the middle part of FIG. 12, the injection amounts of the sub-injections P1, P2, and R are controlled so as to be maintained at a constant value in principle, so that 1 mm3 / st, 1 mm3, respectively. The injection amount of / st and 3 mm3 / st is maintained, while only the injection amount of the main injection F is reduced to 1.5 mm3 / st.

  However, since the minimum injection amount of the main injection F is set to 2 mm <3> / st, in order to sufficiently secure this minimum injection amount, as shown in the lower part of FIG. The pilot injection P2 is stopped, the injection amount is set to 0, and the amount corresponding to the injection amount of the second pilot injection P2 is controlled to be added to the main injection F.

  As described above, when one of the sub-injections is stopped and no longer injects when shifting from the cold state to the warm state, the function of the pilot injection is reduced. For example, the effect of preventing the generation of blue-white smoke is reduced.

  In addition, when the calculated value of the main injection amount at the transition from the cold state to the warm state fluctuates near the minimum injection amount of 2.0 mm3 / st, the second pilot injection P2 stops and injects. It will be repeated alternately, the feeling of engine sound will be worse, and the engine driver will be uncomfortable.

[Object of invention]
An object of the present invention is to stop a sub-injection such as a pilot injection or a post-injection in a fuel injection control method for an internal combustion engine having a multi-stage injection pattern even if the total required injection amount decreases with respect to a change in operating state. For example, by controlling so as not to be generated, it is possible to prevent the generation of blue and white smoke during the transition from the cold state to the warm state and to prevent deterioration of the engine sound feeling.

  In order to solve the above-mentioned problem, the invention according to claim 1 of the present application is provided with a pressure accumulation type fuel injection device capable of multi-stage injection, and at least one of main injection and sub-injection prior to main injection or sub-injection delayed from main injection. In the fuel injection control method for an internal combustion engine that performs sub-injection of the engine, an engine operation state determination sensor that determines whether the engine operation state is cold or warm is provided, and the operation state determination sensor changes the state from cold to warm. When detected, the timing of the main injection in the warm state is retarded from the timing of the main injection in the cold state, thereby increasing the total fuel injection amount so that the sub-injection does not disappear.

  According to a second aspect of the present invention, in the fuel injection control method for the internal combustion engine according to the first aspect, when the change from the cold state to the warm state is detected by the operating state determination sensor, the timing of the main injection during the warm state is determined. The total fuel injection amount is increased so that the sub-injection does not disappear by retarding the timing of the main injection in the cold state and also retarding the sub-injection prior to the main injection.

  According to a third aspect of the present invention, in the fuel injection control method for an internal combustion engine according to the first aspect, when the change from the cold state to the warm state is detected by the operating state determination sensor, the timing of the main injection during the warm state is determined. The total fuel injection amount is increased so that the sub-injection is not extinguished by retarding the timing of the main injection in the cold state and also retarding the sub-injection later than the main injection.

  According to a fourth aspect of the present invention, there is provided an internal combustion engine including an accumulator type fuel injection device capable of multi-stage injection and performing at least one of main injection and sub-injection prior to the main injection or sub-injection delayed from the main injection. In the fuel injection control method, the main injection is set as the first main injection, and a second main injection that increases or decreases the injection amount with a change in the required injection amount is added, which is the same handling as the first main injection. ing.

  According to a fifth aspect of the present invention, in the fuel injection control method for an internal combustion engine according to the fourth aspect, the two main injections have equal injection amounts.

  According to a sixth aspect of the present invention, in the fuel injection control method for an internal combustion engine according to the fourth aspect, the two main injections have different injection amounts.

  The invention according to claim 7 includes an accumulator type fuel injection device capable of multi-stage injection, and is an internal combustion engine that performs at least one of main injection and sub-injection preceding the main injection or sub-injection delayed from the main injection. In the fuel injection control method, the total fuel injection amount, the number of injections, and the ratio of each injection amount to the total injection amount are calculated according to the engine operating state, and the injection amount is calculated by the product of the total injection amount and the injection amount ratio for each injection. To do.

  The invention according to an eighth aspect switches the injection control according to the first to seventh aspects according to the engine operating state.

(1) When the engine is shifted from the cold state to the warm state, the required total injection amount decreases due to a decrease in the viscosity of the lubricating oil, etc. In the first aspect of the invention, the timing of the main injection is set lower than that during the cold state. By delaying and increasing (deteriorating) the fuel consumption, it is possible to suppress a decrease in the required total injection amount, thereby avoiding the stop of sub-injection such as pilot injection. Therefore, it is possible to prevent the generation of blue and white smoke and the deterioration of the feeling of engine sound during the transition.

(2) In the inventions according to claims 2, 3 and 4, the main injection and the sub-injection time such as the pilot injection or the post injection are delayed at the time of transition from the cold state to the warm state. A decrease in the required total injection amount at the time of transition can be suppressed, and stoppage of sub-injection can be avoided.

(3) In the invention of claim 5, by increasing the number of times of the main injection, a decrease in each main injection accompanying a decrease in the required total injection amount is suppressed, whereby a sub-injection such as pilot injection or post injection is performed. Avoid stopping. Therefore, it is possible to prevent the generation of blue and white smoke and the deterioration of the feeling of engine sound during the transition. In this case, as in claim 6, when the injection amount of the first main injection and the injection amount of the second main injection are made equal, the control is simplified, while the two injection amounts are different, and the engine If each main injection amount is set according to the characteristics of the engine, the engine performance can be improved while preventing the generation of blue-white smoke and the like as described above.

(4) As in claim 7, the ratio of each sub-injection amount and main injection amount to the required total injection amount is kept constant without making the sub-injection amount constant with respect to the change in the required total injection amount. For example, the influence on the change in the main injection amount due to the change in the total injection amount can be reduced, and the stop of the sub-injection such as the pilot injection at the time of transition from the cold state to the warm state can be avoided.

(5) As in the eighth aspect, the engine performance can be improved in accordance with each operation state by switching the injection pattern control in the first to seventh aspects in accordance with the operation state of the engine.

[Embodiment 1]
(Configuration and control of internal combustion engine)
1 to 3 show a first embodiment of the present invention, in which each cylinder of a multi-cylinder internal combustion engine (for example, a diesel engine) 1 in FIG. 1 showing an internal combustion engine provided with a fuel injection control device of a multi-stage injection pattern. Each is provided with an injector 2 for fuel injection, and the fuel inlet of each injector 2 is gathered in a common rail (accumulation tube) 3 via a fuel high-pressure tube 4. The fuel inlet 3 a of the common rail 3 is connected to the high pressure pump 6 through the fuel supply pipe 5, and the suction port of the high pressure pump 6 is connected to the fuel tank 10. The surplus fuel outlet 3 b of the common rail 3 is connected to the fuel tank 10 via the overflow valve 9 and the fuel surplus pipe 7, and the surplus fuel outlet 11 of each injector 2 is connected to the fuel surplus pipe 7.

  The opening / closing operation parts (solenoids, etc.) of each injector 2 are electrically connected to the engine control unit 16 via wires 13, respectively, and each injector 2 is opened / closed by a predetermined opening / closing instruction signal from the engine control unit 16. It opens and closes at certain times, allowing high-pressure fuel to be injected into the cylinder.

  As an operation state determination sensor, for example, a cylinder determination sensor 21 provided on the camshaft, an engine speed / phase detection sensor 22 provided on the crankshaft, an accelerator sensor 23, a boost pressure sensor are provided at the input portion of the engine control unit 16. 24, the lubricating oil temperature sensor 25, the cooling water temperature sensor 26, the fuel temperature sensor 27, etc. are electrically connected, and the acceleration, rotation speed, accelerator opening, boost pressure, lubricating oil temperature, cooling water temperature detected by each sensor. The fuel temperature is input to the engine control unit 16. A rail pressure (accumulation) sensor 30 is provided in the vicinity of the fuel inlet 3 a of the common rail 3 and is electrically connected to the engine control unit 16 so that the detected rail pressure is input to the engine control unit 16. It has become.

  FIG. 3 shows a multi-stage injection pattern, in which one main injection F, two first and second pilot injections P1, P2 injected prior to the main injection F, and a time delayed from the main injection F are shown. It consists of post injection R. The injection amount of the main injection F is increased (decreased) as the rotational speed / engine load increases (decreases) in conjunction with the governor etc., but the injection amounts of the pilot injections P1, P2 and the post injection R are the rotational speeds.・ It is controlled independently of the increase in engine load.

  The upper part of FIG. 3 is an injection pattern in a cold state, and the lower part is an injection pattern in a warm state. The injection timing (injection start timing) T2 of the main injection F in the warm state is set to be delayed by a fixed angle θ1 from the injection timing (injection start timing) T1 of the main injection F in the cold state. The retardation amount θ1 increases the fuel consumption by retarding the injection timing of the main injection F by at least the retardation amount θ1 when the operating state is shifted from the cold state to the warm state. The F injection amount is set to a size (angle) that can be maintained above the minimum injection amount.

  The upper part of FIG. 2 shows the priority of injection, the injection quantity in the cold state, and the minimum injection quantity of each injection, and the middle part shows the injection amount before the correction in the warm state (before the main injection delay angle). The lower row shows the injection amount after correction (after the main injection retardation) in the warm state.

(Function)
(1) During idle rotation in the engine cold state, the required total injection amount and the injection amount in each injection are as shown in the upper part of FIG. That is, the required total injection amount is 9 mm3 / st, the injection amount of the main injection F is 4 mm3 / st, the injection amounts of the first and second pilot injections P1, P2 are 1 mm3 / st, respectively, and the injection amount of the post injection R is 3 mm3 / st.

(2) When the warm-up operation is performed from the cold state and the lubricating oil temperature sensor 25 or the cooling water temperature sensor 26 in FIG. 1 detects that the lubricating oil temperature or the cooling water temperature becomes a certain value or more, the internal combustion engine It is determined that the state has shifted from the cold state to the warm state, and the injection timing of the main injection F is retarded from T1 to T2, as shown in the lower part of FIG. Note that the parameter for determining the transition from the cold state to the warm state is not limited to the lubricating oil temperature or the cooling water temperature, and various parameters such as the cylinder temperature and the exhaust temperature can be used.

(3) If the injection timing of the main injection F remains at T1 in the cold state, the required total fuel injection amount in the warm state decreases to 7.5 mm 3 / st as shown in the middle stage of FIG. In this case, since the injection amount of each sub-injection is constant and decreases by the injection amount of the main injection F, the main injection F is 1.5 mm 3 / st as in the case of FIG. The second pilot injection P2 having the lowest priority and lower than the amount (2.0 mm3 / st) is stopped.

  In order to avoid this, in the present embodiment, by delaying the injection timing of the main injection F (T1 → T2), a decrease in the required total injection amount during the transition from the cold state to the warm state is suppressed. For example, as shown in the lower part of FIG. 2, the decrease in the injection amount is suppressed to 8.5 mm 3 / st, thereby reducing the injection amount of the main injection F to 3.5 mm 3 / st, which is larger than the minimum injection amount. suppress. Therefore, the phenomenon of stopping the sub-injection as in the conventional example of FIG. 12 can be avoided, and the generation of blue and white smoke or the deterioration of the feeling of engine sound can be prevented.

[Second Embodiment]
FIG. 4 shows a second embodiment. At the time of transition from the cold state to the warm state, the injection timing of the main injection F is retarded by θ1, and at the same time, the pilot injections P1, P2 and the post injection R are injected. This is a control method in which the timing is retarded by θ1. Other basic controls are the same as those in the first embodiment, and a detailed description thereof will be omitted.

  Note that it is possible to set the control to retard only the pilot injection P1.P2 together with the main injection F, or to control only the post injection R together with the main injection F.

[Third Embodiment]
5 and 6 show a third embodiment, in which the conventional main injection is the first main injection F1, and at the time delayed from the main injection F1, the second is handled in the same manner as the main injection F1. This is an example in which the main injection F2 is added, and post injection is not performed. The injection amounts of the first main injection F1 and the second main injection F2 are set equally.

  The handling equivalent to the second main injection F2 is an injection set to always inject at a constant amount for the purpose of preventing blue and white smoke, such as the first and second pilot injections P1 and P2. Unlike the first main injection F1, for example, the increase / decrease is adjusted according to the increase / decrease in engine output.

  FIG. 6 shows a multi-stage injection pattern according to the third embodiment. The two first and second main injections F1 and F2 and the two first and first injections prior to the main injections F1 and F2. It consists of two pilot injections P1, P2. The injection amounts of the two main injections F1 and F2 are equal as described above, and increase (decrease) as the engine speed and engine load increase (decrease) in conjunction with the governor etc., but the pilot injections P1, P2 and The injection amount of the post injection R is controlled independently of the increase in the rotational speed and the engine load.

  The upper graph in FIG. 6 is an injection pattern in a cold state, and the lower graph is an injection pattern in a warm state. When the operating state is shifted from the cold state to the warm state, the injection amounts of both the main injections F1 and F2 are equally reduced as the required total injection amount decreases.

  The upper part of FIG. 5 shows the ratio of the main injection quantity, the priority of injection, the injection quantity in the cold state, and the minimum injection quantity of each injection, and the lower part shows the injection amount in the warm state.

The operation will be described.
(1) During idle rotation in the engine cold state, the required total injection amount and the injection amount in each injection are as shown in the upper part of FIG. That is, the required total injection amount is 9 mm 3 / st, the injection amounts of the main injections F 1 and F 2 are 3.5 mm 3 / st, respectively, and the injection amounts of the first and second pilot injections P 1 and P 2 are 1 mm 3 / st, respectively. .

(2) When the warm-up operation is performed from the cold state and it is detected by the lubricating oil temperature sensor 25 or the cooling water temperature sensor 26 in FIG. It is determined that the state has shifted to the warm state, and the injection amount changes as shown in the lower part of FIG. That is, the required total injection amount is reduced from 9 mm 3 / st to 7.5 mm 3 / st as the viscosity of the lubricating oil temperature decreases, whereas the injection amounts of the first and second pilot injections P 1 and P 2 are cold. On the other hand, the injection amount of both the main injections F1 and F2 is reduced to 2.75 mm3 / st in accordance with the decrease of the required total injection amount. In this embodiment, since the main injection is increased twice, the amount of decrease in the injection amount of each main injection is small compared to the conventional example of FIG. 12, and a value larger than the minimum injection amount 2 mm 3 / s. Thus, the phenomenon of stopping the sub-injection as in the conventional example of FIG. 12 can be avoided, and the generation of blue-white smoke or the deterioration of the feeling of engine sound can be prevented. Further, since the injection amounts of the first and second main injections F1 and F2 are equal, the control becomes easy. Note that the parameter for determining the transition from the cold state to the warm state is not limited to the lubricating oil temperature or the cooling water temperature, and various parameters such as the cylinder temperature and the exhaust temperature can be used.

  Note that the main injection can be increased to 3 or more.

[Fourth Embodiment]
7 and 8 show the fourth embodiment. As in the third embodiment, the conventional main injection is the first main injection F1, and the main injection F1 is delayed from the main injection F1. This is an example in which a second main injection F2 that is handled in the same manner as the injection F1 is added, and post injection is not performed. A different configuration from the third embodiment is that the injection amounts of the first main injection F1 and the second main injection F2 are different. Specifically, the injection amount of the first main injection F1 is set larger than the injection amount of the second main injection F2, and the ratio is 4: 3. Other configurations are the same as those of the third embodiment, and detailed description thereof is omitted.

The operation will be described.
(1) During idle rotation in the engine cold state, the required total injection amount and the injection amount in each injection are as shown in the upper part of FIG. That is, the required total injection amount is 9 mm 3 / st, the injection amount of the first main injection F 1 is 4 mm 3 / st, the injection amount of the second main injection F 2 is 3 mm 3 / st, and the first and second pilots The injection amounts of the injections P1 and P2 are 1 mm3 / st, respectively.

(2) When the warm-up operation is performed from the cold state and it is detected by the lubricating oil temperature sensor 25 or the cooling water temperature sensor 26 in FIG. It is determined that the state has shifted to the warm state, and the injection amount changes as shown in the lower part of FIG. That is, the required total injection amount is reduced from 9 mm 3 / st to 7.5 mm 3 / st as the viscosity of the lubricating oil temperature decreases, whereas the injection amounts of the first and second pilot injections P 1 and P 2 are cold. While maintaining the same 1 mm 3 / st as in the state, the injection amounts of both the main injections F 1 and F 2 are reduced to 3.14 mm 3 / st and 2.36 mm 3 / st, respectively, as the required total injection amount decreases. In this embodiment, since the main injection is increased to twice, the second main injection P2 having a small injection amount is larger than the minimum injection amount 2 mm3 / s as compared with the conventional example of FIG. Thus, the phenomenon of stopping the sub-injection as in the conventional example of FIG. 12 can be avoided, and the generation of blue-white smoke or the deterioration of the feeling of engine sound can be prevented. Also, the injection amounts of both main injections F1, F2 are made different, but the ratio of the injection amounts of both main injections F1, F2 is improved so that the engine performance is improved according to the operating state of the engine or the type of engine. Can be set. Note that the parameter for determining the transition from the cold state to the warm state is not limited to the lubricating oil temperature or the cooling water temperature, and various parameters such as the cylinder temperature and the exhaust temperature can be used.

[Fifth Embodiment]
9 and 10 show a fifth embodiment, which has a configuration in which the injection amount ratio of each injection to the required total injection amount is fixed.

  FIG. 10 shows a multistage injection pattern in the present embodiment. One main injection F, two first and second pilot injections P1, P2 injected prior to the main injection F, and the main injection F It is comprised from the post-injection R of the time delayed from. The injection amount of the main injection F is adjusted so as to increase / decrease in accordance with the increase / decrease of engine load, rotation speed and output in conjunction with the governor etc. Also, the injection amounts of the pilot injections P1, P2 and the post injection R are The ratio is adjusted so as to increase / decrease in accordance with the increase / decrease of engine load, rotation speed, and output in conjunction with the governor while maintaining the mutual ratio constant. In short, the total injection amount of fuel, the number of injections, and the ratio of each injection amount to the total injection amount are calculated according to the engine operating state, and the injection amount is calculated by the product of the total injection amount and the injection amount ratio for each injection. .

  The upper graph in FIG. 10 is an injection pattern in a cold state, and the lower graph is an injection pattern in a warm state. When the operating state is shifted from the cold state to the warm state, all the injections F, P1, P2 and R decrease in the injection amount while maintaining the mutual ratio constant as the required total injection amount decreases. .

(Function)
(1) During idle rotation in the engine cold state, the required total injection amount and the injection amount in each injection are as follows: the required total injection amount is 9 mm 3 / st, and the main injection F injection amount is 4 mm 3 / st, the injection amounts of the first and second pilot injections P1, P2 are 1 mm3 / st, respectively, and the injection amount of the post injection R is 3 mm3 / st.

(2) When the warm-up operation is performed from the cold state and it is detected by the lubricating oil temperature sensor 25 or the cooling water temperature sensor 26 in FIG. It is determined that the state has shifted to the warm state, and the required total injection amount is decreased from 9 mm3 / st to 7.5 mm3 / st as shown in the lower part. In this case, since the pilot injection P1P2 and the post injection R are reduced at the same ratio together with the main injection F, the reduction of the main injection F is up to 3.11 mm3 / st, and the minimum injection amount of the main injection F (2.0 mm3 / st) Greater value. Therefore, the phenomenon of stopping the sub-injection as in the conventional example of FIG. 12 can be avoided, and the generation of blue and white smoke or the deterioration of the feeling of engine sound can be prevented. Note that the parameter for determining the transition from the cold state to the warm state is not limited to the lubricating oil temperature or the cooling water temperature, and various parameters such as the cylinder temperature and the exhaust temperature can be used.

[Other embodiments]
It is also possible to switch each fuel injection control of the first to fifth embodiments according to the operating state in one internal combustion engine.

  For example, FIG. 11 is a graph of the engine speed and fuel injection amount of one internal combustion engine. In the low speed rotation region X1, the control method of the fifth embodiment, that is, the ratio of main injection to sub injection is shown. A control method that is always constant is adopted, and the control method of the fourth embodiment, that is, a control method in which main injection is increased is adopted in the region X2 in which the fuel injection amount is in the intermediate region in the medium speed rotation region. . In the remaining region X3, the conventional control method as shown in FIGS. 12 and 13 is adopted.

1 is a piping diagram of an internal combustion engine to which the present invention is applied. It is a figure which shows the relationship between the injection priority in the 1st Embodiment of this invention, the injection quantity at the time of cold, the minimum injection quantity, the injection quantity at the time of warming before correction | amendment, and the injection quantity at the time of warming after correction | amendment. . It is a figure which shows the injection pattern at the time of cold and the injection pattern at the time of warm in the 1st Embodiment of this invention. It is a figure which shows the injection pattern at the time of cold and the injection pattern at the time of warm in the 2nd Embodiment of this invention. It is a figure which shows the relationship between the injection priority in the 3rd Embodiment of this invention, the cold injection quantity, the minimum injection quantity, and the warm injection quantity by a table | surface. It is a figure which shows the injection pattern at the time of cold and the injection pattern at the time of warm in the 3rd Embodiment of this invention. It is a figure which shows the relationship between the injection priority in the 4th Embodiment of this invention, the cold injection quantity, the minimum injection quantity, and the warm injection quantity by a table | surface. It is a figure which shows the injection pattern at the time of cold and the injection pattern at the time of warm in the 4th Embodiment of this invention. It is a figure which shows the relationship between the injection ratio in the 5th Embodiment of this invention, the injection priority, the injection quantity at the time of cold, the minimum injection quantity, and the injection quantity at the time of warm. It is a figure which shows the injection pattern at the time of a cold state, and the injection pattern at the time of a warm state in the 5th Embodiment of this invention. It is a figure which shows each utilization area | region in the case of using combining the control method of each embodiment on the graph of an engine speed and fuel injection amount. It is a figure which shows the relationship between the injection priority in the prior art example, the injection quantity at the time of cold, the minimum injection quantity, the injection quantity at the time of warming before correction | amendment, and the injection quantity at the time of warming after correction | amendment. It is a figure which shows the injection pattern at the time of cold in a prior art example, and the injection pattern at the time of warm.

Explanation of symbols

1 Internal combustion engine 2 Injector 3 Common rail (pressure accumulator)
6 High-pressure pump 16 Engine control unit 25 Lubricating oil temperature sensor (an example of an engine operating state determination sensor)
26 Cooling water temperature sensor (an example of an engine operating state determination sensor)

Claims (8)

In a fuel injection control method for an internal combustion engine, comprising an accumulator fuel injection device capable of multi-stage injection, and performing at least one of main injection and sub-injection prior to the main injection or sub-injection delayed from the main injection,
Equipped with an engine operating state determination sensor for determining whether the engine operating state is cold or warm,
When the change from the cold state to the warm state is detected by the operation state determination sensor, the sub-injection does not disappear by delaying the main injection timing in the warm state from the main injection timing in the cold state. A fuel injection control method for an internal combustion engine, characterized by increasing the total fuel injection amount. The fuel injection control method for an internal combustion engine according to claim 1,
When the change from the cold state to the warm state is detected by the operation state determination sensor, the timing of the main injection during the warm state is delayed from the timing of the main injection during the cold state, and the sub-injection prior to the main injection The fuel injection control method for an internal combustion engine is characterized by increasing the total fuel injection amount so that the sub-injection does not disappear by retarding. The fuel injection control method for an internal combustion engine according to claim 1,
When the change from the cold state to the warm state is detected by the operation state determination sensor, the timing of the main injection in the warm state is retarded from the timing of the main injection in the cold state and is delayed from the main injection. A fuel injection control method for an internal combustion engine, wherein the total injection amount of fuel is increased by retarding injection so that the sub-injection does not disappear. In a fuel injection control method for an internal combustion engine, comprising an accumulator fuel injection device capable of multi-stage injection, and performing at least one of main injection and sub-injection prior to the main injection or sub-injection delayed from the main injection,
A fuel injection control method for an internal combustion engine, characterized in that the main injection is a first main injection, and a second main injection that is handled in the same manner as the first main injection is added. The fuel injection control method for an internal combustion engine according to claim 4,
2. A fuel injection control method for an internal combustion engine, wherein the two main injections have equal injection amounts. The fuel injection control method for an internal combustion engine according to claim 4,
The fuel injection control method for an internal combustion engine, wherein the two main injections have different injection amounts. In a fuel injection control method for an internal combustion engine, comprising an accumulator fuel injection device capable of multi-stage injection, and performing at least one of main injection and sub-injection prior to the main injection or sub-injection delayed from the main injection,
The total injection amount of fuel, the number of injections, and the ratio of each injection amount to the total injection amount are calculated according to the engine operating state, and the injection amount is calculated by the product of the total injection amount and the injection amount ratio for each injection. A fuel injection control method for an internal combustion engine. 8. A fuel injection control method for an internal combustion engine, wherein each injection control according to claim 1 is performed by switching according to an engine operating state.

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