JP4811139B2 - Intake and exhaust valve control device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake / exhaust valve control device for an internal combustion engine.

  A technique for reducing the amount of unburned hydrocarbons (hereinafter referred to as “unburned HC”) discharged from the combustion chamber when the internal combustion engine is started is described in Patent Document 1. Here, when the internal combustion engine is started and the temperature of the internal combustion engine (hereinafter referred to as “engine temperature”) is relatively low, the closing timing of the exhaust valve is retarded from the intake top dead center and the intake valve is opened. By setting the valve timing to the intake top dead center, a period of overlap between the exhaust valve opening period and the intake valve opening period, that is, a so-called valve overlap period is provided. According to this, unburned HC discharged from the combustion chamber into the exhaust passage during the exhaust stroke is again sucked into the combustion chamber during the valve overlap period and burned during the next expansion stroke. Therefore, the amount of unburned HC discharged from the combustion chamber is reduced. That is, in the technique described in Patent Document 1, when the internal combustion engine is started, when the engine temperature is relatively low and the amount of HC that remains unburned in the combustion chamber is relatively large, the exhaust gas is discharged from the combustion chamber. The valve closing timing of the exhaust valve and the valve opening timing of the intake valve are controlled so that the unburned HC discharged into the passage is again sucked into the fuel chamber, and the unburned HC sucked into the combustion chamber is returned to the next expansion stroke. The amount of unburned HC discharged from the combustion chamber is reduced by burning the inside.

  On the other hand, in the technique described in Patent Document 1, when the combustion is stabilized, that is, when the warm-up of the internal combustion engine is completed or at least partially completed, the closing timing of the exhaust valve is set to the intake top dead center. And the opening timing of the intake valve is delayed from the opening timing of the intake valve when the internal combustion engine is started and the engine temperature is relatively low. According to this, the difference between the pressure in the combustion chamber when the intake valve is opened and the pressure in the intake passage becomes large, and air is sucked from the intake passage into the combustion chamber at a very high flow rate. The Thereby, the atomization of the fuel in the air is promoted, and as a result, the combustion is also promoted, so that the amount of HC that remains unburned in the combustion chamber is reduced. Therefore, the amount of unburned HC discharged from the combustion chamber is reduced. That is, in the technique described in Patent Document 1, when the warm-up of the internal combustion engine is completed or at least partially completed, the pressure in the combustion chamber and the pressure in the intake passage when the intake valve opens The unclosed HC discharged from the combustion chamber is controlled by controlling the closing timing of the exhaust valve and the opening timing of the intake valve so as to increase the difference between The amount of is reduced.

JP 2003-120348 A JP 2002-147272 A JP 2000-320387 A

  Incidentally, as described above, in the technique described in Patent Document 1, when the warm-up of the internal combustion engine is completed or at least partially completed, the closing timing of the exhaust valve is advanced from the intake top dead center. Horn. However, if the valve closing timing of the exhaust valve is advanced from the intake top dead center, the amount of exhaust gas remaining in the combustion chamber without being discharged from the combustion chamber into the exhaust passage increases. According to this, since the amount of air sucked into the combustion chamber is reduced by the amount of exhaust gas remaining in the combustion chamber, the fuel is not sufficiently burned in the next expansion stroke, and as a result, fuel consumption is reduced. It can get worse.

  An object of the present invention is to keep the fuel consumption as high as possible while minimizing the amount of unburned HC discharged from the combustion chamber.

In order to solve the above-mentioned problem, in the first invention, the timing for closing the fuel injection valve for injecting fuel into the intake passage and the exhaust valve and the timing for opening the intake valve can be changed. In an internal combustion engine equipped with an intake / exhaust valve opening / closing timing control device capable of performing the warm-up completion temperature when the temperature of the internal combustion engine that can be determined that the warm-up of the internal combustion engine is completed, Intake / exhaust valve control that closes the exhaust valve at a timing near exhaust top dead center and opens the intake valve at a timing near exhaust top dead center when the temperature of the internal combustion engine is higher than the warm-up completion temperature In the apparatus, the temperature of the internal combustion engine lower than the warm-up completion temperature is referred to as a first warm-up incomplete temperature, and the temperature of the internal combustion engine lower than the first warm-up incomplete temperature is referred to as a second warm-up incomplete temperature. The internal combustion machine When the temperature of the engine is lower than the second warm-up incomplete temperature, the exhaust valve is closed at a timing earlier than the exhaust top dead center and the intake valve is opened at the timing of exhaust top dead center or substantially exhaust top dead center. When the temperature of the internal combustion engine is higher than the second warm-up incomplete temperature and lower than the first warm-up incomplete temperature, the exhaust valve is closed at a timing earlier than the exhaust top dead center and the intake valve is exhausted top dead The valve opens at a timing later than the point. When the temperature of the internal combustion engine is higher than the first warm-up incomplete temperature and lower than the warm-up completion temperature, the exhaust valve is closed at the timing of exhaust top dead center or substantially exhaust top dead center and the intake valve Is opened at a timing later than the exhaust top dead center.

In the second invention, in the first invention, when the temperature of the internal combustion engine is lower than the second warm-up incomplete temperature, the fuel is injected from the fuel injection valve when the intake valve is opened or after the intake valve is opened. When the temperature of the internal combustion engine is higher than the second warm-up incomplete temperature and lower than the first warm-up incomplete temperature, fuel is injected from the fuel injection valve before the intake valve opens.

In the third invention, in the first or second invention, when the temperature of the internal combustion engine is higher than the warm-up completion temperature, the exhaust valve is closed at the timing of exhaust top dead center or substantially exhaust top dead center and the intake valve. Is opened at the timing of exhaust top dead center or substantially exhaust top dead center.

  When the temperature of the internal combustion engine is lower than the second warm-up temperature, that is, when the temperature of the internal combustion engine is very low, the fuel is difficult to atomize in the first place. Should. According to the present invention, at this time, the exhaust valve is closed at a timing earlier than the exhaust top dead center, the exhaust gas remains in the combustion chamber, and the intake valve is exhausted at an exhaust top dead center or substantially at the exhaust top dead center timing. By opening the valve, the exhaust gas remaining in the combustion chamber is discharged into the intake passage at once. According to this, since the atomization of the fuel is promoted by the exhaust gas discharged to the intake passage, the amount of unburned HC generated in the combustion chamber is reduced and the fuel consumption is also improved.

  On the other hand, when the temperature of the internal combustion engine is higher than the second warm-up incomplete temperature and lower than the first warm-up incomplete temperature, that is, when the temperature of the internal combustion engine is relatively low, the fuel is relatively easily atomized. For this reason, priority should be given to improving the mixing state of the fuel with the air in the combustion chamber rather than atomizing the fuel. According to the present invention, at this time, the exhaust valve is closed at a timing earlier than the exhaust top dead center, and the intake valve is opened at a timing later than the exhaust top dead center, thereby opening the intake valve. When this happens, the difference between the pressure in the combustion chamber and the pressure in the intake passage becomes very large. According to this, since air flows into the combustion chamber at a high flow rate, the diffusion of fuel in the air in the combustion chamber is promoted. For this reason, the fuel burns well, the amount of unburned HC generated in the combustion chamber is reduced, and the fuel efficiency is improved.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an intake port injection type spark ignition internal combustion engine. In FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a piston, 4 is a cylinder head, 5 is a combustion chamber, 6 is an intake valve, 7 is an intake port, 8 is an exhaust valve, 9 is an exhaust port, An ignition plug 11 indicates a fuel injection valve. The fuel injection valve 11 is attached to the cylinder head 4 so as to inject fuel into the intake port 7.

  The intake port 7 of each cylinder is connected to a surge tank 14 via a corresponding intake branch pipe 13. The surge tank 14 is connected to an air cleaner (not shown) via an intake duct 15 and an air flow meter 16. A throttle valve 18 driven by a step motor 17 is disposed in the intake duct 15. On the other hand, the exhaust port 9 of each cylinder is connected to a corresponding exhaust branch pipe 19. The exhaust branch pipe 19 is connected to a catalytic converter 21 containing a three-way catalyst 20.

  The electronic control unit 31 is composed of a digital computer, and is connected to a RAM (Random Access Memory) 33, a ROM (Read Only Memory) 34, a CPU (Microprocessor) 35, and an input port 36 which are connected to each other via a bidirectional bus 32. And an output port 37. The air flow meter 16 generates an output voltage proportional to the intake air amount (the amount of air sucked into the combustion chamber 5), and this output voltage is input to the input port 36 via the corresponding AD converter 38. The load sensor 41 generates an output voltage proportional to the amount of depression of the accelerator pedal 40, and this output voltage is input to the input port 36 via the corresponding AD converter 38. Further, the crank angle sensor 42 generates an output pulse every time the crankshaft rotates, for example, 30 °, and this output pulse is input to the input port 36. Further, the output port 37 is connected to the ignition plug 10, the fuel injection valve 11, and the step motor 17 through a corresponding drive circuit 39.

  Further, the internal combustion engine shown in FIG. 1 has a mechanism that can change the timing for opening and closing the intake valve, and the timing for opening and closing the exhaust valve, so-called variable valve actuation. Provide mechanism.

  Next, the timing of closing the exhaust valve 8 (hereinafter referred to as “exhaust valve closing timing”) and the timing of opening the intake valve 6 (hereinafter referred to as “intake valve opening timing”) in the present embodiment are controlled. Will be described.

  In the field of internal combustion engines, there is a demand to keep fuel consumption as high as possible. Further, unburned hydrocarbons (hereinafter referred to as “unburned HC”) discharged from the combustion chamber 5 to the exhaust passage (that is, the exhaust port 9 in the illustrated internal combustion engine) without being burned in the combustion chamber 5 can be as much as possible. There is also a request to reduce it. Here, when the temperature of the internal combustion engine (hereinafter referred to as “engine temperature”) is very low, for example, when the internal combustion engine is started when the temperature of the outside air is very low, the fuel injected from the fuel injection valve 11 Difficult to convert. That is, the ease of atomization of fuel is related to the engine temperature, and the higher the engine temperature, the easier the fuel is atomized. From this, when the engine temperature is very low, the fuel injected from the fuel injection valve 11 is difficult to atomize. For this reason, it is difficult for the fuel to burn well in the combustion chamber 5, and the fuel efficiency is lowered accordingly. As a matter of course, unburned HC discharged into the exhaust passage tends to increase. Therefore, in order to keep the fuel consumption as high as possible and reduce the unburned HC discharged from the combustion chamber 5 as much as possible when the engine temperature is very low, the atomization of the fuel injected from the fuel injection valve 11 is promoted. Should be given top priority.

  On the other hand, when the engine temperature is not very low but relatively low, for example, when starting the internal combustion engine when the temperature of the outside air is not very low but relatively low, the fuel injected from the fuel injection valve 11 Is relatively easy to atomize. Therefore, at this time, in order to maintain the fuel consumption as high as possible and to reduce the unburned HC discharged from the combustion chamber 5 as much as possible, the atomization of the fuel injected from the fuel injection valve 11 is promoted while the combustion is performed. The diffusion of atomized fuel in the air taken into the chamber 5 should also be promoted.

  Furthermore, when the engine temperature is relatively high, for example, when it can be determined that the warm-up of the so-called internal combustion engine is at least partially completed, the fuel injected from the fuel injection valve 11 is easily atomized. Therefore, at this time, in order to maintain the fuel consumption as high as possible and to reduce the unburned HC discharged from the combustion chamber 5 as much as possible, the combustion chamber is more preferable than the atomization of the fuel injected from the fuel injection valve 11. Priority should be given to the promotion of atomized fuel diffusion in the inhaled air.

  In view of such circumstances, in the present embodiment, the following intake / exhaust valve control is executed in order to keep the fuel consumption as high as possible and reduce the unburned HC discharged from the combustion chamber 5 as much as possible, particularly when starting the internal combustion engine. To do. That is, the engine temperature when the so-called warm-up of the internal combustion engine is completed is referred to as a “warm-up completion temperature”, which is a temperature lower than the warm-up completion temperature, and the so-called warm-up of the internal combustion engine is at least partially completed. The engine temperature at which it can be determined is called “first warm-up incomplete temperature”, and the engine temperature lower than the partial warm-up completion temperature (for example, so-called normal temperature) is called “second warm-up incomplete temperature”. When the engine temperature is lower than the second warm-up incomplete temperature, that is, when the engine temperature is extremely low, the valve closing timing of the exhaust valve 8 is set to the exhaust as shown in FIG. The timing is set to a timing advanced from the dead center TDC, and the valve opening timing of the intake valve 6 is set to the exhaust top dead center or substantially exhaust top dead center timing. According to this, since the exhaust valve 8 is closed at a timing earlier than the exhaust top dead center, the exhaust gas remains in the combustion chamber 5. Since the intake valve 6 is opened at the timing of the exhaust top dead center, the exhaust gas flows out from the combustion chamber 5 to the intake port at a relatively high flow rate. At this time, fuel atomization is promoted by the heat and kinetic energy of the exhaust gas discharged to the intake port. Therefore, since the fuel burns well in the combustion chamber 5, the fuel consumption is maintained as high as possible and the unburned HC discharged from the combustion chamber 5 is reduced as much as possible. In this case, the temperature in the combustion chamber 5 is kept high by the heat of the exhaust gas remaining in the combustion chamber 5 until the intake valve 6 is opened after the exhaust valve 8 is closed. However, the fuel burns well in the combustion chamber 5.

  On the other hand, when the engine temperature is higher than the second warm-up incomplete temperature and lower than the first warm-up incomplete temperature, that is, when the engine temperature is relatively low, as shown in FIG. The valve closing timing of the exhaust valve 8 is set to a timing advanced from the exhaust top dead center TDC, and the valve opening timing of the intake valve 6 is set to a timing retarded from the exhaust top dead center. According to this, since the exhaust valve 8 is closed at a timing earlier than the exhaust top dead center, the exhaust gas remains in the combustion chamber 5. For this reason, since the temperature in the combustion chamber 5 is maintained high by the heat of the exhaust gas remaining in the combustion chamber 5, the fuel burns well in the combustion chamber 5. Further, since the intake valve 6 is opened at a timing later than the exhaust top dead center, that is, since the intake valve 6 is opened after the piston starts to descend in the combustion chamber 5, the intake valve 6 is opened. The difference between the pressure in the combustion chamber 5 and the pressure in the intake port will be large. For this reason, the air containing fuel is sucked into the combustion chamber 5 from the intake port at a high flow rate. That is, a great turbulence occurs in the air sucked into the combustion chamber 5. Therefore, the diffusion of fuel in the air in the combustion chamber 5 is promoted. Therefore, since the fuel is burned well in the combustion chamber 5 as well, the fuel consumption is maintained as high as possible and the unburned HC discharged from the combustion chamber 5 is reduced as much as possible.

  Further, when the engine temperature is higher than the first warm-up incomplete temperature and lower than the warm-up completion temperature, that is, when the engine temperature is relatively high, as shown in FIG. 8 is set to the exhaust top dead center TDC or substantially the exhaust top dead center timing, and the valve opening timing of the intake valve 6 is set to a timing delayed from the exhaust top dead center. According to this, since the exhaust valve 8 is opened until the timing of exhaust top dead center or substantially exhaust top dead center, no or almost no exhaust gas remains in the combustion chamber 5. Thereafter, the intake valve 6 is opened at a timing later than the exhaust top dead center. That is, since the intake valve 6 is opened after the piston starts to descend in the combustion chamber 5 with no or almost no exhaust gas remaining in the combustion chamber 5, the combustion when the intake valve 6 is opened is performed. The difference between the pressure in the chamber 5 and the pressure in the intake port is greater than in the case described above. For this reason, the air containing the fuel is drawn into the combustion chamber 5 from the intake port at a very high flow rate. Therefore, the diffusion of fuel in the air in the combustion chamber 5 is greatly promoted. Therefore, since the fuel burns very well in the combustion chamber 5, the fuel consumption is maintained as high as possible and the unburned HC discharged from the combustion chamber 5 is reduced as much as possible. In this case, when the exhaust valve 8 is closed, no or almost no exhaust gas remains in the combustion chamber 5, so that the amount of air sucked into the combustion chamber 5 increases accordingly. The fuel burns well in the combustion chamber 5.

  When the engine temperature is higher than the warm-up completion temperature, that is, when the engine temperature is high, as shown in FIG. 2D, the closing timing of the exhaust valve 8 is set to approximately the exhaust top dead center TDC, In particular, it is set to a timing that is retarded from the exhaust top dead center but very close to the exhaust top dead center, and the opening timing of the intake valve 6 is set to substantially the exhaust top dead center, in particular from the exhaust top dead center. Is also set at a timing that is very close to the exhaust top dead center.

  FIG. 3 shows an example of a routine for executing the intake / exhaust valve control described above. In the routine of FIG. 3, first, at step 10, it is judged if the engine temperature T is lower than the second warm-up incomplete temperature Tlow2 (T <Tlow2). Here, when it is determined that T <Tlow2, the routine proceeds to step 11 where the intake / exhaust valve control I is executed. That is, the exhaust valve 8 is closed at a timing advanced from the exhaust top dead center, and the intake valve 6 is opened at the exhaust top dead center or substantially exhaust top dead center timing.

  On the other hand, when it is determined in step 10 that T <Tlow2 is not satisfied, the process proceeds to step 12 where the engine temperature T is equal to or higher than the second warm-up incomplete temperature Tlow2 and lower than the first warm-up incomplete temperature Tlow1 ( It is determined whether or not Tlow2 ≦ T <Tlow1). Here, when it is determined that Tlow2 ≦ T <Tlow1, the routine proceeds to step 13 where the intake / exhaust valve control II is executed. That is, the exhaust valve 8 is closed at a timing advanced from the exhaust top dead center, and the intake valve 6 is opened at a timing delayed from the exhaust top dead center.

  On the other hand, when it is determined in step 12 that Tlow2 ≦ T <Tlow1, the routine proceeds to step 14, where the engine temperature T is equal to or higher than the first warm-up incomplete temperature Tlow1 and lower than the warm-up completion temperature High (Tlow1 It is determined whether or not ≦ T <High). Here, when it is determined that Tlow1 ≦ T <High, the routine proceeds to step 15 where the intake / exhaust valve control III is executed. That is, the exhaust valve 8 is closed at the timing of exhaust top dead center or substantially exhaust top dead center, and the intake valve 6 is opened at timing delayed from the exhaust top dead center.

  On the other hand, when it is determined in step 14 that Tlow1 ≦ T <High is not satisfied, the routine proceeds to step 16 where the intake / exhaust valve control IV is executed. That is, the exhaust valve 8 is closed at substantially exhaust top dead center timing, and the intake valve 6 is opened at substantially exhaust top dead center timing.

  By the way, if the intake / exhaust valve control described above is executed, high fuel efficiency can be maintained and unburned HC discharged from the combustion chamber 5 can be reduced regardless of the timing of fuel injection from the fuel injection valve 11. However, in this embodiment, in order to maintain higher fuel efficiency and further reduce unburned HC discharged from the combustion chamber 5, the following fuel injection control is performed simultaneously with the intake and exhaust valve control described above. .

  When the engine temperature is very low, that is, when the engine temperature is lower than the second warm-up incomplete temperature, the highest priority should be given to the promotion of atomization of the fuel injected from the fuel injection valve 11 as described above. is there. At this time, in the intake / exhaust valve control described above, the exhaust valve 8 and the intake valve 6 are controlled so that the exhaust gas flows from the combustion chamber 5 to the intake port at a relatively high flow rate. In this case, if the fuel is injected from the fuel injection valve 11 as the exhaust gas flows out from the combustion chamber 5 to the intake port, the fuel injected from the fuel injection valve 11 collides with the exhaust gas flow. Therefore, atomization of fuel is further promoted. That is, rather than injecting fuel from the fuel injection valve 11 before exhaust gas flows out from the combustion chamber 5 to the intake port, the fuel injection valve 11 flows when exhaust gas flows out from the combustion chamber 5 to the intake port. The fuel atomization is promoted when the fuel is injected from the fuel. Therefore, in the fuel injection control of the present embodiment, when the engine temperature is lower than the second warm-up incomplete temperature, the timing at which fuel is injected from the fuel injection valve 11 (hereinafter referred to as “fuel injection timing”) The valve opening timing or at least a timing later than the opening timing of the intake valve 6 is set. According to this, since the combustion of the fuel is further promoted, the fuel efficiency is maintained higher, and the unburned HC discharged from the combustion chamber 5 is reduced.

  On the other hand, when the engine temperature is relatively low, that is, when the engine temperature is higher than the second warm-up incomplete temperature and lower than the first warm-up incomplete temperature, the intake / exhaust valve control described above is mainly performed by the fuel The exhaust valve 8 and the intake valve 6 are controlled so as to promote the diffusion of fuel in the air in the combustion chamber 5 by sucking the air containing the air into the combustion chamber 5 at a high flow rate. Here, if the fuel is injected from the fuel injection valve 11 before the air is sucked into the combustion chamber 5, the fuel is sucked into the combustion chamber 5 together with the air when the air starts to be sucked into the combustion chamber 5. The diffusion of fuel in the air in the combustion chamber 5 can be further promoted. That is, rather than injecting fuel from the fuel injection valve 11 after air begins to be inhaled into the combustion chamber 5, it is better to inject fuel from the fuel injection valve 11 before air begins to be inhaled into the combustion chamber 5. The diffusion of fuel in the air in the combustion chamber 5 is promoted. Therefore, in the fuel injection control of the present embodiment, when the engine temperature is higher than the second warm-up incomplete temperature and lower than the first warm-up incomplete temperature, the fuel injection timing is set to be higher than the valve opening timing of the intake valve 6. Set to early timing. According to this, since the fuel of the fuel is further promoted, the fuel efficiency is maintained higher, and the unburned HC discharged from the combustion chamber 5 is reduced.

  Further, when the engine temperature is relatively high, that is, when the engine temperature is higher than the first warm-up incomplete temperature and lower than the warm-up completion temperature, air containing fuel is introduced into the combustion chamber 5 at a very high flow rate. Thus, the exhaust valve 8 and the intake valve 6 are controlled so as to promote the diffusion of fuel in the air in the combustion chamber 5 by sucking in at once. Therefore, at this time, for the same reason as described above, rather than injecting fuel from the fuel injection valve 11 after the air starts to be sucked into the combustion chamber 5, the fuel injection valve is started before the air starts to be sucked into the combustion chamber 5. When the fuel is injected from 11, the diffusion of the fuel in the air in the combustion chamber 5 is promoted. Therefore, in the fuel injection control of the present embodiment, when the engine temperature is higher than the first warm-up incomplete temperature and lower than the warm-up completion temperature, the fuel injection timing is set to a timing earlier than the opening timing of the intake valve 6. Set. According to this, since the combustion of the fuel is further promoted, the fuel efficiency is maintained higher, and the unburned HC discharged from the combustion chamber 5 is reduced.

  In the present embodiment, when the engine temperature is higher than the warm-up completion temperature, the fuel injection timing is set earlier than the opening timing of the intake valve 6.

  FIG. 4 shows an example of a routine for executing the above-described intake / exhaust valve control and fuel injection control. In the routine of FIG. 4, first, at step 20, it is judged if the engine temperature T is lower than the second warm-up incomplete temperature Tlow2 (T <Tlow2). When it is determined that T <Tlow2, the routine proceeds to step 21, where the intake / exhaust valve / fuel injection control I is executed. That is, the exhaust valve 8 is closed at a timing advanced from the exhaust top dead center, and the intake valve 6 is opened at the exhaust top dead center or substantially exhaust top dead center timing. Along with this, fuel is injected from the fuel injection valve 11 at a timing later than the opening timing of the intake valve 6 or at least later than the opening timing of the intake valve 6.

  On the other hand, when it is determined in step 20 that T <Tlow2, the routine proceeds to step 22, where the engine temperature T is equal to or higher than the second warm-up incomplete temperature Tlow2 and lower than the first warm-up incomplete temperature Tlow1 ( It is determined whether or not Tlow2 ≦ T <Tlow1). If it is determined that Tlow2 ≦ T <Tlow1, the routine proceeds to step 23 where the intake / exhaust valve / fuel injection control II is executed. That is, the exhaust valve 8 is closed at a timing advanced from the exhaust top dead center, and the intake valve 6 is opened at a timing delayed from the exhaust top dead center. Along with this, fuel is injected from the fuel injection valve 11 at a timing earlier than the opening timing of the intake valve 6.

  On the other hand, when it is determined in step 22 that Tlow2 ≦ T <Tlow1, the routine proceeds to step 24 where the engine temperature T is equal to or higher than the first warm-up incomplete temperature Tlow1 and lower than the warm-up completion temperature High (Tlow1 It is determined whether or not ≦ T <High). Here, when it is determined that Tlow1 ≦ T <High, the routine proceeds to step 25 where the intake / exhaust valve / fuel injection control III is executed. That is, the exhaust valve 8 is closed at the timing of exhaust top dead center or substantially exhaust top dead center, and the intake valve 6 is opened at timing delayed from the exhaust top dead center. Along with this, fuel is injected from the fuel injection valve 11 at a timing earlier than the opening timing of the intake valve 6.

  On the other hand, when it is judged at step 24 that Tlow1 ≦ T <High, the routine proceeds to step 26 where the intake / exhaust valve / fuel injection control IV is executed. That is, the exhaust valve 8 is closed at substantially exhaust top dead center timing, and the intake valve 6 is opened at substantially exhaust top dead center timing. Along with this, fuel is injected from the fuel injection valve 11 at a timing earlier than the opening timing of the intake valve 6.

It is the figure which showed the internal combustion engine provided with the intake / exhaust valve control apparatus of this invention. It is the figure which showed the time chart for demonstrating the intake / exhaust valve control in embodiment of this invention. It is the figure which showed an example of the routine which performs the intake / exhaust valve control in embodiment of this invention. It is the figure which showed an example of the routine which performs intake / exhaust valve and fuel injection control in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 3 Piston 5 Combustion chamber 6 Intake valve 7 Intake port 8 Exhaust valve 9 Exhaust port 10 Spark plug 11 Fuel injection valve

Claims (3)

A fuel injection valve for injecting fuel into the intake passage, and an intake / exhaust valve opening / closing timing control device capable of changing the timing for closing the exhaust valve and changing the timing for opening the intake valve In the internal combustion engine, when the temperature of the internal combustion engine that can be determined as the completion of the warm-up of the internal combustion engine is referred to as the warm-up completion temperature, the temperature of the internal combustion engine becomes higher than the warm-up completion temperature. The intake valve is closed at a timing near the exhaust top dead center and the intake valve is opened at a timing near the exhaust top dead center. When the temperature of the internal combustion engine is referred to as the first warm-up incomplete temperature and the temperature of the internal combustion engine lower than the first warm-up incomplete temperature is referred to as the second warm-up incomplete temperature, the temperature of the internal combustion engine is the second warm-up incomplete temperature. When the temperature is lower than the incomplete temperature The exhaust valve is closed at a timing earlier than the exhaust top dead center, and the intake valve is opened at the exhaust top dead center or substantially exhaust top dead center timing so that the temperature of the internal combustion engine is higher than the second warm-up incomplete temperature. When the temperature is higher and lower than the first warm-up incomplete temperature, the exhaust valve is closed at a timing earlier than the exhaust top dead center and the intake valve is opened at a timing later than the exhaust top dead center .
When the temperature of the internal combustion engine is higher than the first warm-up incomplete temperature and lower than the warm-up completion temperature, the exhaust valve is closed at the timing of exhaust top dead center or substantially exhaust top dead center and the intake valve is exhausted. An intake / exhaust valve control device that opens at a timing later than the top dead center . When the temperature of the internal combustion engine is lower than the second warm-up incomplete temperature, fuel is injected from the fuel injection valve when the intake valve is opened or after the intake valve is opened, and the temperature of the internal combustion engine is increased to the second warm-up temperature. 2. The intake / exhaust valve control according to claim 1, wherein the fuel is injected from the fuel injection valve before the intake valve opens when the temperature is higher than the incomplete temperature and lower than the first warm incomplete temperature. apparatus. When the temperature of the internal combustion engine is higher than the warm-up completion temperature, the exhaust valve is closed at the exhaust top dead center or substantially exhaust top dead center timing, and the intake valve is closed at the exhaust top dead center or substantially exhaust top dead center timing. The intake / exhaust valve control device according to claim 1 or 2, wherein the valve opens.

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