WO2008111392A1

WO2008111392A1 - Control device for in-cylinder injection type spark ignition internal combustion engine

Info

Publication number: WO2008111392A1
Application number: PCT/JP2008/053338
Authority: WO
Inventors: Takeshi Ashizawa
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2007-03-06
Filing date: 2008-02-20
Publication date: 2008-09-18
Also published as: JP2008215266A

Abstract

A control device (1A) has air density confirmation means for confirming the density of air in a cylinder (57) into which fuel (FE) is injected, and also has fuel spray control means that, based on the air density at the time of fuel injection, controls at least either the diameter of particles of the sprayed fuel (FE) or the number of times of spraying. Because the fuel spray control means controls at least either the diameter of particles of sprayed fuel or the number of times of spraying with the control based on the air density in a cylinder at the time of the fuel injection, a swirl flow occurring when the fuel is injected can be reliably assisted and reinforced even if the air density in the cylinder changes depending on operation of the internal combustion engine.

Description

Specification

In-cylinder injection spark ignition internal combustion engine control device

Technical field

[0 0 0 1]

The present invention relates to a control device for a direct injection spark ignition internal combustion engine.

Background art

[0 0 0 2]

2. Description of the Related Art An in-cylinder spark ignition internal combustion engine called a direct injection type that obtains driving force by directly injecting and igniting fuel into a cylinder is known. With regard to this type of internal combustion engine, various techniques have been proposed for improving combustion and exhaust emission by forming a vortex flow such as a tumble flow or swirl flow in a cylinder. If a moderate vortex flow is formed in the cylinder, the turbulence of the air-fuel mixture can be increased at the ignition timing, and the combustion speed is improved, so that good combustion can be realized. This can also improve exhaust emissions.

[0 0 0 3]

However, in a direct injection type internal combustion engine that directly injects fuel into a cylinder, the injected fuel may adhere to a spark plug, a cylinder, a cylinder inner wall surface (cylinder wall surface), or the like. If the fuel injected in this way adheres to various locations in the cylinder, it may cause deterioration in combustion performance and exhaust. Therefore, Patent Document 1 includes spray characteristic setting means for setting the characteristics such as the direction of fuel injection from the injection hole of the multi-hole injector, the spray penetration force, and the spray particle size according to the combustion chamber shape and combustion performance. A combustion control device for an internal combustion engine is proposed. This combustion control device reduces the adhesion of fuel to the piston cavity by, for example, making the spray particle size smaller than a certain value. Therefore, it is said that the combustion control device of Patent Document 1 can suppress the deterioration of the exhaust performance if the combustion performance.

[0 0 0 4]

Patent Document 1: Japanese Patent Application Laid-Open No. 2 0 205-2 4 8 8 5 7

Disclosure of the invention

Problems to be solved by the invention

[0 0 0 5]

However, in the combustion control device of Patent Document 1, if the fuel adheres to the cylinder wall surface or the like, the ignition performance and exhaust gas deteriorate, so the spray direction and spray penetration are prevented so that the adhesion does not occur. It is only proposed to provide a spray characteristic setting means for setting force, spray particle size, etc. In other words, this combustion control device suppresses the deterioration of combustion and exhaust by simply reducing fuel adhesion in the cylinder, and does not intend to actively improve combustion performance or exhaust. Therefore, the combustion control device of Patent Document 1 cannot improve the combustion of the internal combustion engine and the exhaust emission. In Patent Document 1, no attempt is made to improve combustion by assisting the tumble flow by fuel injection, and the relationship between the spray particle size and the number of times of fogging and assist enhancement is not studied.

[0 0 0 6]

Accordingly, an object of the present invention is to provide a control device for a cylinder injection spark ignition internal combustion engine that can surely enhance the vortex airflow formed in the cylinder by fuel injection to improve combustion and exhaust. Is to provide.

Means for solving the problem

[0 0 0 7]

The object is to control at least one of the spray particle size and the number of sprays of the fuel based on the air density confirmation means for confirming the air density in the cylinder into which the fuel is injected and the air density at the time of fuel injection. In-cylinder injection spark ignition, characterized in that it is achieved by a control device for an internal combustion engine.

[0 0 0 8]

According to the present invention, the fuel spray control means controls at least one of the fuel spray particle size and the number of sprays based on the air density in the cylinder at the time of fuel injection, so that the air in the cylinder can be controlled according to the operation of the internal combustion engine. Even if the density changes, it is possible to reliably obtain the effect of strengthening the vortex airflow when fuel is injected (hereinafter referred to as “jet effect”). Therefore, an internal combustion engine to which such a control device is applied can improve combustion and exhaust.

[0 0 0 9]

The fuel spray control means may control at least one of the spray particle size and the number of sprays so that the injected fuel does not penetrate the vortex.

[0 0 1 0]

The air density confirmation unit may estimate the air density based on an intake pressure and an intake temperature of an intake passage that supplies intake air into the cylinder.

[0 0 1 1]

The fuel spray control means changes the spray particle size in proportion to the air density. By doing so, the above jet effect may be obtained with certainty. The fuel spray control means may ensure that the jet effect is obtained by increasing the number of sprays as the air density is lower.

[0 0 1 2]

The swirl flow is a tumble flow, and the fuel spray control means assists and strengthens the tumble flow by injecting fuel near the intake bottom dead center. You may comprise as a control apparatus.

[0 0 1 3]

The swirl flow is a swirl flow, and the fuel spray control means assists and strengthens the swirl flow by injecting fuel near the intake bottom dead center. It can be configured as a control device.

The invention's effect

[0 0 1 4]

According to the present invention, there is provided a control device for an in-cylinder injection spark ignition internal combustion engine that can surely enhance the vortex airflow formed in the cylinder by fuel injection to improve combustion and exhaust. it can.

Brief Description of Drawings

[0 0 1 5]

1 is a diagram schematically showing an internal combustion engine system including a cylinder injection type spark ignition internal combustion engine to which a control device according to Embodiment 1 is applied.

FIG. 2 is an enlarged schematic view of the internal combustion engine shown in FIG.

FIG. 3 is a diagram showing an example of the relationship between the air density in a cylinder during fuel injection and the spray particle size suitable for obtaining the jet effect.

FIG. 4 is a flow chart summarizing a tumble flow enhancement process executed by the control device for an internal combustion engine realized by the ECU of the first embodiment.

FIG. 5 is a diagram schematically showing the relationship between the air density in the cylinder during fuel injection and the number of sprays suitable for obtaining the jet effect.

FIG. 6 is a flowchart summarizing a tumble flow enhancement process executed by a control device realized by ECU of the second embodiment.

FIG. 7 is a diagram schematically showing an internal combustion engine system including a direct injection spark ignition internal combustion engine to which a control device according to a third embodiment is applied. BEST MODE FOR CARRYING OUT THE INVENTION

[0016]

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

Example 1

[0017]

FIG. 1 is a diagram schematically showing an internal combustion engine system 100 including an in-cylinder spark ignition internal combustion engine 50 (hereinafter simply referred to as an internal combustion engine 50) to which the control device according to the first embodiment is applied. is there. The internal combustion engine system 100 includes an internal combustion engine 50, an intake system 10, a fuel injection system 20, an exhaust system 30 and the like attached thereto. This internal combustion engine system 100 is entirely controlled by E (Electronic Control Unit) 1 A. The ECU 1 A confirms the air density in the cylinder and changes the fuel spray particle size accordingly to ensure the jet effect that assists and strengthens the tumble flow formed in the cylinder. It also functions as each means for obtaining. This ECU 1 A will be described in detail later.

[0018]

First, an outline of the internal combustion engine system 100 will be described with reference to FIG. The intake system 10 is configured to introduce intake air (air) into the internal combustion engine 50. The intake system 10 includes an air cleaner 1 1 for filtering the intake air, a air flow meter 12 for measuring the amount of air, a throttle valve 13 for adjusting the flow rate of the intake air, a surge tank 14 for temporarily storing the intake air, and an intake air for the internal combustion engine. It includes an internal hold 15 that distributes to each of the 50 cylinders, an intake port 52a formed in the cylinder head of the internal combustion engine 50, and the like. Therefore, an intake passage is formed including the passage downstream of the air cleaner 11, the surge tank 14, the intake manifold 15, the intake port 52 a, and the like.

[0019]

In this embodiment, the intake bear hold 15 is provided with an intake pressure sensor 16 for detecting the intake pressure and an intake air temperature sensor 17 for detecting the intake air temperature. The outputs of these sensors 16 and 17 are supplied to ECU 1A.

[0020]

The fuel injection system 20 is configured to pump the fuel FE and inject it directly into the combustion chamber 57 (also referred to as “in-cylinder”). The fuel injection system 20 includes an injector 21 and a fuel tank 22 that stores a fuel FE supplied to the injector 21. Injector 21 Between the fuel tank 2 2 and the fuel tank 2 2, the fuel feed pump 2 3 that supplies fuel to the injector 21 and the high-pressure pump 2 that changes the pressure of the fuel supplied to the injector 21 (hereinafter referred to as “fuel pressure”) 4 is deployed. The injector 21 is opened at an appropriate injection timing under the control of the ECU 1A and injects the fuel FE into the cylinder. The fuel injection amount is adjusted by the length of the valve opening period until the injector 21 is closed under the control of the ECU 1A. That is, the ECU 1 A controls the drive of the injector 21 to appropriately control the number of fuel injections and the fuel injection amount. Further, the high-pressure pump 24 is configured to make the spray particle size. When the fuel pressure is controlled via the high-pressure pump 24 under the control of the ECU 1A, the spray particle size can be increased or decreased by changing the injection pressure of the fuel injected from the injector 21. For example, if ECU 1 A raises the fuel pressure to increase the spray pressure, the spray particle size will decrease proportionally.

[0 0 2 1]

The exhaust system 30 is configured to exhaust the exhaust gas generated in the cylinder of the internal combustion engine 50 to the outside of the machine. The exhaust system 30 includes an exhaust port 5 2 b formed in the cylinder head, an exhaust manifold 31 and the like.

[0 0 2 2]

FIG. 2 is an enlarged schematic view of the internal combustion engine 50 shown in FIG. The same parts are denoted by the same reference numerals as in FIG. With reference to FIG. 2, the structure of the internal combustion engine 50 will be described in more detail.

[0 0 2 3]

The internal combustion engine 50 includes a cylinder block 5 1, a cylinder head 5 2, a piston 5 3, an ignition bracket 5 4, an intake valve 5 5, an exhaust valve 5 6, and the like, in the same manner as a general internal combustion engine. It consists of The internal combustion engine 50 shown in the first embodiment is, for example, an in-line 4-cylinder in-cylinder spark ignition internal combustion engine. However, the internal combustion engine 50 may have other appropriate cylinder arrangement structure and number of cylinders. In FIG. 2, the main part of the cylinder 51a is shown as a representative of each cylinder with respect to the internal combustion engine 50. In this embodiment, the other cylinders have the same structure. The cylinder block 51 is formed with a substantially cylindrical cylinder 51a. A piston 53 is accommodated in the cylinder 5 l a.

[0 0 2 4]

A cylinder head 52 is fixed to the upper surface of the cylinder block 51. Combustion chamber 5 7 is a space surrounded by cylinder block 5 1, cylinder head 5 2 and biston 5 3 It is formed as. In addition to the intake port 5 2 a for guiding the intake air to the combustion chamber 5 7, the cylinder head 52 has an exhaust port 5 2 b for exhausting the burned gas from the combustion chamber 5 7. Further, an intake valve 55 and an exhaust valve 56 are provided for opening and closing the intake port 52a and the exhaust port 52b. Note that the internal combustion engine 50 may have an intake / exhaust valve structure including an appropriate number of intake valves 55 and exhaust valves 56 per cylinder.

[0 0 2 5]

The ignition bracket 54 is fixed to the cylinder head 52 with an electrode projecting approximately at the center above the combustion chamber 57. The injector 21 is also disposed in the cylinder head 52 with the fuel injection hole projecting into the combustion chamber 57 from a position adjacent to the spark plug 5 4 above the combustion chamber 57.

[0 0 2 6]

An intake control valve 5 8 for generating a tumble flow (vertical vortex flow) T in the combustion chamber 5 7 is disposed in the intake port 5 2 a. The intake control valve 58 has a structure for generating a tumble flow T in the combustion chamber 57 by causing the intake air AR to drift in the intake port 52a under the control of ECU1A.

[0 0 2 7]

The intake control valve 58 has a plate-like valve body and is set so as to rotate around a support shaft 59 set on the lower side of the inner wall of the intake port 52a. Although not shown here, the opening degree of the intake control valve 58 is adjusted by an actuator whose drive is controlled by E C U 1 A. FIG. 2 illustrates a state in which a tumble flow T is formed in the cylinder by closing the intake control valve 58 to restrict the flow path in the intake board 52a. The tumble flow T formed here is a forward tumble flow T that turns clockwise so as to rise in the intake valve 55 in the combustion chamber 57.

[0 0 2 8]

Under the control of the ECU 1 A, the injector 21 is set to inject the fuel FE in the vicinity of the intake stroke bottom dead center. The nozzle hole 2 1 HL of the indicator 21 is directed in the direction along the tumble flow T. As a result, the injected fuel FE assists and strengthens the tumbling flow T. The strengthened tumble flow T is maintained until the ignition timing. As a result, good combustion can be obtained by increasing the turbulence of the air-fuel mixture at the ignition timing and appropriately increasing the combustion speed. [0 0 2 9]

By the way, when the internal combustion engine 50 is in an operating state, the atmosphere (gas state) in the combustion chamber 57 (in the cylinder) changes every moment. More specifically, the atmosphere in the cylinder differs between when the internal combustion engine is in a low load state and when it is in a high load state. The weight ratio (AZ F) between the air and the fuel that make up the air-fuel mixture filled in the cylinder is generally set to the theoretical air-fuel ratio (around 14.3) regardless of the load. The air density is low at low loads, and the air density is high at high loads.

[0 0 3 0]

Here, for example, on the basis of the high load state where the air density is high, the fuel injection condition of the injector 21 is set so that the tumble flow is enhanced at the time of fuel injection (so that the jet effect is obtained). It is possible to set. However, in this case, when the air density is low as in the case where the internal combustion engine 50 is in an addling operation, there may be a problem that the tumble flow cannot be enhanced by fuel injection.

[0 0 3 1]

As described above, the fuel injection conditions for high load and high air density are set so that the spray speed is relatively high and the fuel is blown away. However, when this condition setting is applied to an atmosphere with a low air density, the sprayed fuel penetrates the tumble flow that is to be assisted (that is, the spray assists in enhancing the flow of the tumble flow. Without impact) may collide with the wall of the combustion chamber 57. This means that if the air density is changed to a low level, the jet effect cannot be obtained.

[0 0 3 2]

On the contrary, if the injection conditions are set so that the jet effect can be obtained when the air density is low and the load is low, the opposite inconvenience occurs. That is, in an atmosphere where the internal combustion engine is highly loaded and the air density is high, the spray rate from the injector 21 is too low to strengthen the tumble flow.

Therefore, a control device realized by ECU 1 A is applied to the internal combustion engine 50 shown in FIG. 1 so as to obtain the jet effect as described above. This point will be described in detail below.

[0 0 3 3]

First, an outline of the mechanism employed in the internal combustion engine 50 for assisting and strengthening the tumble flow by directly injecting fuel into the cylinder will be described. The equation of motion of one spray sprayed from the indicator 21 can be expressed by the following equation (1).

ma = (-C d X p XV ² XS) / 2-(1)

Where, m: mass of fog

a: Acceleration of spray direction

C d: Air resistance coefficient of spray particles

P: Air density in the cylinder

V: Spraying speed

s: Front projected area of spray particles.

The above equation (1) can be modified and expressed as equation (2).

a = (-C d X, ο XV ² XS) / (2 X m)---(2)

[0034]

Here, in the case of a direct injection type internal combustion engine, the Reynolds number is sufficiently large, so the Cd value is substantially constant regardless of the conditions.

The Reynolds number is an index that characterizes an object moving in a fluid, and is expressed by velocity X length ÷ fluid viscosity coefficient. The Reynolds number increases as the object is larger, the speed is faster, and the viscosity is smaller. Therefore, a large Reynolds number means a flow with relatively strong inertial action.

[0035]

The air density p in the cylinder is obtained by the constant C_ (1 + 0.00367 X air temperature) X air absolute pressure. If the spray particle radius is r, the front projected area S of the spray particle is proportional to r ² and the mass m of the spray particle is proportional to r ³ .

[0036]

Therefore, the above formula (2) can be further expressed as the following general formula (3).

a = (-(constant) X air density / (spray particle radius r X spray velocity V) ··· (3) The above equation (3) shows that when the air density p increases, the spray particle radius r is When proportionally increased, (air density / o) / (spray particle radius r) does not change, indicating that the spray flight distance with respect to time can be made substantially the same. Is changed in proportion to the air density p, it is possible to suppress the above-mentioned situation such as the spray velocity being too fast and penetrating the tumble flow. Reliable `` jet effect '' that assists and strengthens tumble flow by injection Can get to.

[0037]

The inventor of the present application pays attention to the mechanism described above, and has devised a control device that can reliably obtain the jet effect by adjusting the spray particle size according to the air density in the cylinder. As described above, the control device for the internal combustion engine 50 is realized by the ECU 1A. The ECU 1A functions as an air density confirmation means for confirming the air density in the cylinder and a fuel spray control means. The ECU 1A confirms by estimating the air density P in the cylinder based on the outputs of the sensors 16 and 17, sets the fog conditions suitable for the atmosphere in the cylinder at that time, and sends the fuel FE from the injector 21. Let spray. Therefore, the tumbling flow formed in the cylinder can be reinforced stably.

[0038]

As shown in FIG. 1, the internal combustion engine 50 includes a crank angle sensor 71 that generates an output pulse proportional to the rotational speed NE, a water temperature sensor 72 for detecting the water temperature of the internal combustion engine 50, an accelerator pedal (not shown) ) Various sensors such as an accelerator sensor 73 for detecting the amount of depression (accelerator opening) are provided and supplied to ECU 1A. Therefore, the ECU 1 A can also confirm the operating state of the internal combustion engine 50.

[0039]

The ECU 1A includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output circuit, and the like (not shown). The ROM is configured to store a program in which various processes executed by the CPU are described and a series of data used in the program. In this embodiment, in addition to the program for controlling the internal combustion engine 50, an intake pressure sensor A program for estimating the air density in the cylinder from 16 and the intake temperature sensor 17 and setting the spray particle size based on this is stored.

[0040]

In this embodiment, the ECU 1 A controls the high pressure pump 24 to change the fuel pressure. Then, the fuel injection pressure from the injector 21 is changed. The ECU 1 A estimates the air density in the combustion chamber 57 from the outputs of the intake pressure sensor 16 and the intake temperature sensor 17, and changes the fuel pressure according to the estimated result. More specifically, the ECU 1A increases the spray particle size in proportion to the air density when the air density changes. Conversely, if the air density changes toward lowering, the spray particle size is reduced in proportion to this. [0041]

FIG. 3 shows an example of the relationship between the air density in the cylinder during fuel injection and the spray particle size suitable for obtaining the jet effect. ECU 1 A stores a table associating the air density and the preferred spray particle size (target spray particle size) as shown in FIG. Therefore, the ECU 1 A specifies the target spray particle size when the air density is estimated from the outputs of the intake pressure sensor 16 and the intake temperature sensor 17 as described above. The ECU 1A controls the fuel pressure with the high-pressure pump 24 so that the spray particle diameter from the injector 21 becomes the target spray particle diameter.

[0042]

FIG. 4 is a flowchart summarizing the tumble flow enhancement processing executed by the control device for the internal combustion engine 50 realized by the ECU 1A. The ECU 1A starts this routine when the internal switch of the internal combustion engine 50 is turned on. The ECU 1A confirms the intake air pressure in the intake hold 15 from the output of the intake pressure sensor 16 in FIG. 1 and the intake air temperature from the output of the intake air temperature sensor 17 (S101). Based on these outputs, the air density in the cylinder is estimated (S102). As shown in FIG. 1, the air density in the cylinder can be estimated relatively easily by using the outputs of the intake pressure sensor 16 and the intake air temperature sensor 17 provided in the internal hold 15. However, estimating the air density in this way is only one example of confirming the air density. If an in-cylinder pressure sensor that detects the in-cylinder pressure of the internal combustion engine 50 is provided, the output may be used. Also, instead of intake hold, the intake pressure sensor 16 and the intake air temperature sensor 17 may be arranged in the surge tank 14 to detect the intake air pressure and the intake air temperature.

[0043]

Next, the ECU 1A confirms whether or not the obtained air density is changing (S103). The ECU 1A executes the above steps S101 to S103 at a predetermined cycle to periodically monitor the change in air density. Then, when the change in the air density is confirmed in step S103, the ECU 1A further confirms whether or not the air density has increased as compared to before (S104).

[0044]

If it is determined in step S104 that the air density is increasing, the ECU 1A controls the fuel pressure so that the spray particle size increases in proportion to the air density (S105). ECU 1 A controls the high pressure pump 24 that changes the fuel pressure to the injector 21 and changes the spray pressure To do. This enlarges the spray particle diameter from the injector 21 and surely strengthens the tumble flow formed in the cylinder at that time.

[0 0 4 5]

On the other hand, it is determined that the air density has not increased in step S 10 4 above when the air density has decreased. At this time, E C U 1 A controls the fuel pressure so that the spray particle size decreases (decreases) in proportion to the air density (S 1 0 6). In this case as well, E C U 1 A controls the high-pressure pump 24 that changes the fuel pressure to the injector 21 to change the spray pressure. This reduces the spray particle diameter from the injector 21 and reliably strengthens the tumble flow formed in the cylinder at that time.

[0 0 4 6]

According to the control device of the first embodiment described above, since the spray particle diameter from the injector is adjusted according to the change in the air density in the cylinder, the fuel was injected in response to the change in the internal combustion engine 50. Sometimes the tumble flow can be reliably strengthened. Therefore, an internal combustion engine that employs such a control device can be provided as an internal combustion engine that can achieve good combustion and exhaust emission. '

[0 0 4 7]

In addition, the control device of the first embodiment can reliably obtain the “jet effect” by changing the spray particle size in proportion to the change in the air density in the cylinder. Here, the low air density in the cylinder is equivalent to the low load of the internal combustion engine 50, and the high air density in the cylinder means that the internal combustion engine 50 is in a high load. May be understood to be equivalent to That is, when the internal combustion engine 50 is idling, etc., the load is light and the air density is low. Further, when the internal combustion engine 50 is at high speed, the load is high and the air density is high. Therefore, at first glance, adjusting the fuel spray particle size according to the air density in the cylinder is the same as adjusting the fuel spray particle size according to the load state of the internal combustion engine 50. It may be understood as if. However, this understanding is incorrect. The following explanation shows that this is an error.

[0 0 4 8]

The stoichiometric gasoline engine has an AZ F value of about 14.5. This means that gasoline is “1” and air is “14.5”. On the other hand, there is also known an engine that burns with a lean burn that is burned with a lean air-fuel mixture. For this lean burn engine, For example, air is “2 0” or more for “1”. Here, since the load of the internal combustion engine can be understood as gasoline weight, the stoichiometric and lean burn are almost the same load, where the gasoline weight is both “1”. Therefore, when the spray particle size of the fuel is adjusted according to the load state of the internal combustion engine, the spray particle size is not changed.

[0 0 4 9]

However, when comparing the stoichiometric state with the lean burn state based on the air density, the lean burn clearly has a higher air density. Therefore, when the state changes from stoichiometric to lean burn, the spray particle size increases in proportion to the change in air density. That is, in this case, the control device of the first embodiment described above functions and adjusts the fuel pressure so that the spray particle diameter is expanded according to the air density. From this explanation, it is understood that the method according to the first embodiment is different from adjusting the spray particle size in accordance with the load state of the internal combustion engine.

Example 2

[0 0 5 0]

Furthermore, a control device according to Embodiment 2 applied to a spark ignition internal combustion engine will be described. In Example 1, the spray particle size was changed in accordance with the change in air density. The second embodiment is configured to change the fuel injection pattern to cope with the change in the air density in the cylinder and to reliably obtain the jet effect. More specifically, in the control device of Example 1, the spray particle size was changed to be proportional to the air density, but in the control device of Example 2, the number of sprays increased as the air density decreased. Take action to make it happen. The present inventor confirmed that changing the number of sprays of the injector 21 also can assist the tumble flow by coping with the change in the air density in the cylinder as in the case of changing the spray particle size. It is a thing. Therefore, in the second embodiment, the response to the air density change executed by the ECU which is the control device is merely changed from the adjustment based on the spray particle size to the adjustment based on the number of sprays. Therefore, the hardware configuration as the control device is the same as in the first embodiment even in the second embodiment. Therefore, the second embodiment will be described with reference to FIGS. However, the control contents executed by ECU are different between the case of the first embodiment and the case of the second embodiment. Therefore, it is distinguished as E C U 1 A in Example 1 and E C U 1 B in Example 2.

[0 0 5 1]

FIG. 5 is a diagram schematically showing the relationship between the air density in the cylinder during fuel injection and the number of fogs suitable for obtaining the jet effect. In Fig. 5, spraying is performed once when the air density is high (close to the atmosphere), but the number of sprays increases as the air density decreases (as the pressure decreases). It is set to be added. Note that increasing the number of sprays here is not an increase in the same injection amount as in one fog, but an operation in which the injection amount for one injection is divided into a plurality of injections in small amounts. The ECU 1 B stores a table associating the air density in the cylinder as shown in FIG. 5 with a preferable number of sprays at that time (target number of sprays) in a ROM or the like. Therefore, the ECU 1 B specifies the target number of sprays when the air density is estimated from the outputs of the intake pressure sensor 16 and the intake temperature sensor 17. Then, the ECU 1 B executes the valve opening operation of the indicator 21 with the target number of sprays.

[0052]

FIG. 6 is a flowchart summarizing the tumble flow enhancement processing executed by the control device realized by the ECU 1B. The ECU 1B starts this routine when the ignition switch of the internal combustion engine 50 is turned on. The ECU 1 B checks the intake pressure in the intake hold 15 from the output of the intake pressure sensor 16 in FIG. 1 and the intake air temperature from the output of the intake temperature sensor 17 (S 201). To estimate the air density (S 202). Furthermore, ECU 1 B confirms whether or not the air density is changing (S 203). If the air density changes, the ECU 1 B determines whether or not the air density has increased compared to before. Check (S204). Steps S201 to S204 so far are the same as those in the first embodiment, but the subsequent processing is different.

[0053]

If it is determined in step S204 above that the air density has increased, ECU 1B decreases the number of sprays as opposed to the increased air density change (S205). The ECU 1 B controls the valve opening operation of the injector 21 to reduce the number of sprays, and reliably assists and strengthens the tumble flow formed in the cylinder at that time. However, even when the number of sprays is reduced the most, one fuel injection is performed (see Fig. 5).

[0054]

On the other hand, it is determined in step S204 that the air density has not increased when the air density has decreased. At this time, the ECU 1 B increases the number of sprays contrary to the change in the air density (S 206). In this case as well, the ECU 1 B controls the valve opening operation of the injector 21 to increase the number of sprays, and reliably assists the tumble flow formed in the cylinder at that time.

[0055]

According to the control device of the embodiment 2 described above, it is possible to cope with the change in the air density in the cylinder. Since the number of fogs is changed, it is possible to reliably obtain the jet effect while coping with changes in the state of the internal combustion engine 50.

[0 0 5 6]

The ECU 1 A of the first embodiment described above adjusts the spray particle size in proportion to the change in air density so that the fuel mist does not penetrate the tumble flow and reach the inner wall surface of the cylinder. The tumble flow can be reliably strengthened by adjusting to. Further, ECU 1 B of Example 2 can similarly strengthen the tumble flow by increasing the number of sprays as the air density is lower. Therefore, the internal combustion engine to which the control devices of Embodiments 1 and 2 are applied can always enhance the tumble flow formed in response to the situation change in the cylinder, so that combustion and exhaust can be improved. In addition, it is good also as a control apparatus which adjusts a spray particle diameter and the frequency | count of spraying simultaneously according to the change of an air density combining the case of Example 1 and Example 2. FIG. In this case, the respective adjustment range

(Particle size and number of sprays) can be reduced.

Example 3

[0 0 5 7]

Example 1 and Example 2 described above are examples in the case where a tumble flow (vertical vortex flow) is formed in the cylinder (inside the combustion chamber 57). The same effect can be obtained by forming a swirl flow (lateral vortex flow) in the cylinder. Example 3 described below is a case where a scroll flow is formed. FIG. 7 is a diagram schematically showing an internal combustion engine system 200 including an internal combustion engine 150 to which the control device according to the third embodiment is applied. In FIG. 7, the same parts as those in FIG.

[0 0 5 8]

In the case of the internal combustion engine 150, an intake control valve 1558 for generating a swirl flow S in the combustion chamber 57 is provided in the intake port 52a. This intake control valve 1 5 8 generates a spool flow S in the combustion chamber 5 7 by deflecting the intake AR in the intake port 5 2 a under the control of the ECU 1 C. The intake control valve 15 8 is plate-shaped and is set so as to rotate about a support shaft 15 9 set on the inner wall side of the intake port 52a. In Embodiments 1 and 2 described above, the valve body is arranged so as to lie down in the intake port 5 2 a, and forms a tumble flow by forming a posture that rises obliquely. In the third embodiment, the swirl flow S is formed by the valve body coming out obliquely from the side and narrowing the inside of the intake port 52a. It should be noted that when the scale flow S is formed, it is preferable to set the fuel FE to be injected near the bottom dead center of the intake stroke. This ensures swirl flow S with the injected fuel FE. Can assist and strengthen.

[0059]

The ECU 1 C of the internal combustion engine system 200 may control the spray particle diameter from the injector in accordance with the change in the air density in the cylinder, like the ECU 1 A of the first embodiment. As with ECU1B, the number of sprays may be controlled according to changes in the air density in the cylinder. The internal combustion engine system 200 can reliably enhance the swirl flow when fuel is injected in response to changes in the internal combustion engine 150. Therefore, the internal combustion engine 150 that employs such a control device can be provided as an internal combustion engine that can realize good combustion and exhaust emission.

[0060]

In addition, Example 1 and Example 2 described above show a case where a tumble flow is formed, and Example 3 shows a case where a swirl flow is formed as an example. The present invention can be similarly applied to a case where a vortex air flow is formed by combining a tumble flow and a scale flow.

[0061]

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation · Change is possible.

Claims

The scope of the claims

[1] An air density confirmation means for confirming an air density in a cylinder into which fuel is injected, and a fuel that controls at least one of the spray particle size and the number of sprays based on the air density at the time of fuel injection An in-cylinder injection spark ignition internal combustion engine control device comprising: a spray control means.

[2] The fuel spray control means controls at least one of the spray particle size and the number of sprays so that the injected fuel does not penetrate the vortex airflow. In-cylinder injection spark ignition internal combustion engine control device.

[3] The cylinder according to claim 1, wherein the air density confirmation unit estimates the air density based on an intake pressure and an intake temperature of an intake passage that supplies intake air into the cylinder. A control device for an internal injection spark ignition internal combustion engine.

4. The control apparatus for a direct injection spark ignition internal combustion engine according to claim 1, wherein the fuel spray control means changes the spray particle size in proportion to the air density.

5. The control apparatus for a direct injection spark ignition internal combustion engine according to claim 1, wherein the fuel spray control means increases the number of sprays as the air density is lower.

[6] The vortex flow is a tumble flow,

The in-cylinder injection type according to claim 1, wherein the fuel spray control means assists and strengthens the tumble flow by injecting fuel in the vicinity of an intake bottom dead center. Control device for spark ignition internal combustion engine.

[7] The vortex flow is a swirl flow,

The in-cylinder according to any one of claims 1 to 5, wherein the fuel spray control means assists and strengthens the scroll flow by injecting fuel near an intake bottom dead center. A control device for an injection spark ignition internal combustion engine.