JP4385585B2 - Internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine mounted on an automobile or the like, and relates to an internal combustion engine provided with a valve mechanism that independently controls the opening timing and closing timing of intake and exhaust valves.
[Prior art]
[0002]
Conventionally, by changing the length and cross-sectional area of the intake passage according to the engine speed, the intake efficiency is improved in various engine speed ranges by utilizing the pressure fluctuation in the intake passage, and the output is improved. Is known (see, for example, Patent Document 1).
[0003]
In other words, pressure oscillations occur in the intake passage due to intermittent intake as the internal combustion engine operates. Therefore, if the positive pressure wave of the pressure wave is introduced into the cylinder at an appropriate timing, the intake Efficiency can be increased. And since the timing for introducing the positive pressure wave into the cylinder can be adjusted by the length of the intake passage, by changing the length of the intake passage according to the change of the operating state of the engine, in various operating regions, The so-called dynamic effect of intake due to the above phenomenon, that is, the inertial effect and pulsation effect can be effectively used to increase the intake efficiency. Note that such dynamic effect of intake air can be adjusted by changing the cross-sectional area of the intake passage.
[0004]
Conventionally, in this type of apparatus, the opening and closing timing of the intake valve is constant, and the intake valve is closed when it is delayed by a predetermined timing from the bottom dead center of the piston. Under such conditions, even if tuning is performed to increase the dynamic effect by the positive pressure wave as much as possible by adjusting the length or the cross-sectional area of the intake passage, the operating state of the internal combustion engine, for example, with a change in the engine speed Due to the change in the characteristics of the cylinder pressure, the cylinder pressure rises before the intake valve is closed at low revolutions, and blows back. At high revolutions, the cylinder pressure is low and intake can still be introduced. Since the intake valve is closed in a state, it is difficult to enhance the dynamic effect of the intake air over a wide rotational speed range.
[0005]
On the other hand, as a means for improving the intake efficiency when the length and cross-sectional area of the intake passage are fixed, there is a method of adjusting the opening / closing timing of the intake valve, particularly the closing timing, according to the operating state of the internal combustion engine. In this method, if at least the closing timing of the intake valve is controlled according to the operating state of the internal combustion engine so that the intake valve is closed when the pressure in the cylinder and the pressure in the intake passage immediately before the intake valve become equal. Good. However, in this case, due to the relationship between the length and the cross-sectional area of the intake passage, the tuning state in which the positive pressure wave generated in the intake passage is most effectively used is limited to a specific operation region. In the region, the dynamic effect due to the positive pressure wave is reduced. Therefore, there is a limit to improving the intake efficiency even by adjusting the opening / closing timing of the intake valve.
[0006]
Therefore, in Patent Document 2, both the length and the cross-sectional area of the intake passage are adjusted in accordance with the operating state of the internal combustion engine, and the valve closing timing of the intake valve is controlled in accordance with this, so that the intake inertia effect is reduced. We are making further improvements.
[0007]
On the other hand, there is also known a technique for quickly exhausting the combustion chamber using the exhaust pulsation effect by changing the length and cross-sectional area of the exhaust passage according to the operating state (see, for example, Patent Document 3 and Patent Document 4). It has been.
[0008]
Further, a technique that combines a mechanism for adjusting both the length and the cross-sectional area of the exhaust passage according to the operating state of the internal combustion engine and a valve mechanism that makes the opening / closing timing of the exhaust valve variable (for example, Patent Documents) 5) is also known.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 48-58214 [Patent Document 2]
JP-A-60-164610 [Patent Document 3]
Japanese Utility Model Publication No. 58-49381 [Patent Document 4]
Japanese Patent Laid-Open No. 11-107789 [Patent Document 5]
Japanese Patent Laid-Open No. 3-9026 [Problems to be Solved by the Invention]
[0010]
In an internal combustion engine, in order to improve intake efficiency and promote exhaust, when the pressure in the intake passage immediately before the intake valve is higher than the pressure in the exhaust passage immediately after the exhaust valve, the closing timing of the exhaust valve and the opening of the intake valve By adjusting the timing, it is preferable to have an overlapping state in which both the intake valve and the exhaust valve are opened.
[0011]
However, the valve operating mechanism with variable opening / closing timing of the intake valve described in Patent Document 2 adjusts the opening timing of the intake valve in conjunction with the closing timing. Since it cannot be arbitrarily set independently of the closing timing, the intake valve cannot be opened at the above timing, and there is a limit to improving the intake efficiency and promoting exhaust.
[0012]
Also, when the exhaust valve is opened, in order to enhance the exhaust effect and improve the intake efficiency, the exhaust negative pressure wave is synchronized in the overlap state, and the positive pressure wave due to blowdown from other cylinders is generated. It is preferable not to synchronize.
[0013]
However, the valve operating mechanism described in Patent Document 5 in which the opening / closing timing of the exhaust valve is variable is also adjusted in conjunction with the closing timing of the exhaust valve. Since it cannot be set arbitrarily, there is a limit to improving suction efficiency and promoting exhaust.
[0014]
The present invention has been made in view of such circumstances, and an object thereof is to most effectively utilize the inertia effect and the pulsation effect in the intake system and the exhaust system of the internal combustion engine.
[Means for Solving the Problems]
[0015]
In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention is an internal combustion engine provided with an intake passage shape variable mechanism that variably controls an intake passage shape. comprising a valve operating mechanism for controlling the timing independently the valve operating mechanism, the opening timing and closing timing of the intake and exhaust valves, the intake passage shape varying mechanism variably controlled intake passage shape and mutually associated by a It is characterized by control.
[0016]
In the internal combustion engine thus configured, the opening and closing timings of the intake and exhaust valves can be arbitrarily set in accordance with the shape of the intake passage that is variably controlled. Therefore, the inertia effect in the intake and exhaust systems of the internal combustion engine And the pulsation effect can be utilized most effectively.
[0017]
According to a second aspect of the present invention, there is provided an internal combustion engine having an exhaust passage shape variable mechanism that variably controls an exhaust passage shape, and an operation for independently controlling the opening timing and closing timing of a cylinder intake / exhaust valve. a valve mechanism, the valve operating mechanism is characterized in that the variable controlled exhaust passage shape and mutually associated controlled by said opening timing and closing timing of the intake and exhaust valves, the exhaust passage form variable mechanism .
[0018]
In the internal combustion engine configured as described above, the opening and closing timings of the intake and exhaust valves can be arbitrarily set in accordance with the variably controlled exhaust passage shape, so that the inertia effect in the intake system and exhaust system of the internal combustion engine can be set. And the pulsation effect can be utilized most effectively.
[0019]
According to a third aspect of the present invention, there is provided an internal combustion engine including an intake passage shape variable mechanism that variably controls an intake passage shape and an exhaust passage shape variable mechanism that variably controls an exhaust passage shape. A valve operating mechanism for independently controlling the opening timing and closing timing of the intake / exhaust valve, wherein the valve operating mechanism is an intake air in which the opening timing and closing timing of the intake / exhaust valve are variably controlled by the intake passage shape variable mechanism; is characterized in that the variable controlled exhaust passage shape and mutually associated controlled by passage shape and the exhaust passage variable shape mechanism.
[0020]
In the internal combustion engine thus configured, the opening timing and closing timing of the intake and exhaust valves can be arbitrarily set in correspondence with the intake passage shape and the exhaust passage shape that are variably controlled. The inertial and pulsating effects in the system can be used most effectively.
DETAILED DESCRIPTION OF THE INVENTION
[0021]
Hereinafter, specific embodiments of the internal combustion engine according to the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine and its intake / exhaust system according to the present embodiment. An internal combustion engine 1 shown in FIG. 1 is an in-line four-cylinder four-cycle gasoline engine having four cylinders 21.
[0023]
The internal combustion engine 1 includes a cylinder block 1b in which four cylinders 21 and a cooling water channel 1C are formed, and a cylinder head 1a fixed to the upper portion of the cylinder block 1b.
[0024]
A crankshaft 23 serving as an engine output shaft is rotatably supported on the cylinder block 1b. The crankshaft 23 is connected to a piston 22 slidably loaded in each cylinder 21.
[0025]
A combustion chamber 24 surrounded by the top surface of the piston 22 and the wall surface of the cylinder head 1 a is formed above the piston 22 of each cylinder 21. An ignition plug 25 is attached to the cylinder head 1 a so as to face the combustion chamber 24, and an igniter 25 a for applying a drive current to the ignition plug 25 is connected to the ignition plug 25.
[0026]
The cylinder head 1 a is formed with the opening ends of the two intake ports 26 and the opening ends of the two exhaust ports 27 facing the combustion chamber 24, and the fuel injection valve so that the injection holes thereof face the intake port 26. 32 is attached.
[0027]
On the other hand, an intake pipe length variable mechanism 33 is attached to the intake port 26, and an exhaust pipe length variable mechanism 34 is attached to the exhaust port 27.
[0028]
Here, specific configurations of the intake pipe length variable mechanism 33 and the exhaust pipe length variable mechanism 34 will be described. Since the intake pipe length variable mechanism 33 and the exhaust pipe length variable mechanism 34 have the same configuration, only the intake pipe length variable mechanism 33 will be described as an example. An appearance of the intake pipe length varying mechanism 33 is shown in FIG. 2, and an exploded view for explaining the structure of the intake pipe length varying device 33 is shown in FIG.
[0029]
The structure of the intake pipe length varying mechanism will be described. In the figure, reference numeral 35 denotes an intake pipe in which, for example, four pipe bodies 36 are coupled in parallel in the lateral direction (direction perpendicular to the pipe length direction).
[0030]
One end of each tube 36 is connected to the intake port end, and the other end extends in a direction away from the cylinder head 1a. As shown in FIG. 3, the other end of each tube 36 is formed in a fan shape having a downward arc, and each tip is opened downward. Note that a coupling seat 36b formed by an opening peripheral wall of the fan-shaped portion 36a and a peripheral wall that forms a line object is formed in the lower portion of the tube body 36 on the opposite side across the arc center of the fan-shaped portion 36a.
[0031]
A surge tank 37 is connected to the fan-shaped portion 36a which is the other end portion of the intake pipe 35 so as to cover the opening. That is, as shown in FIG. 3, the surge tank 37 has a cross section in the longitudinal direction of the intake pipe 35 formed in a substantially semicircular shape having the same arc as that of the fan-shaped part 36a, and has an open top. This is composed of a box-shaped tank 37a closed.
[0032]
This tank 37a is combined with the other end portion of the intake pipe 35 so as to form an arc continuously with the fan-shaped portion 36 and the coupling seat 36b, and a substantially semi-cylindrical surge chamber is provided at the other end portion of the intake pipe 35. Forming.
[0033]
An intake pipe 38 connected to an air cleaner (not shown) is connected to one end wall of the tank 37a so as to be close to the coupling seat 36b, and air from the air cleaner is guided to the combustion chamber 24 of the engine through the tank 37a. It is like that.
[0034]
An auxiliary port body 39 is slidably fitted in each fan-shaped portion 36a which is the other end of the intake pipe 35 so that the effective length of the intake passage can be changed. Specifically, as shown in FIG. 3, the auxiliary port body 39 has four sliding openings having a fan shape that can be inserted into and removed from the fan-shaped portion 36a with respect to the arc center of the fan-shaped portion 36a. It is formed from the body 39a. These sliding opening bodies 39a are arranged in the lateral direction following the sector 36a.
[0035]
And the center side of these sliding port bodies 39a penetrates the circular arc center of the surge tank 37 and the fan-shaped part 36a, and is connected with the outer peripheral part of the rotating shaft 40 rotatably supported by these both end walls. .
[0036]
Thereby, each sliding mouth 39a is supported so as to be freely inserted into and removed from each fan-shaped portion 36a with the rotating shaft 40 as a fulcrum, and uses the rotational displacement of the sliding mouth 39a around the rotating shaft 40. Thus, the effective length of the intake passage can be changed.
[0037]
Further, for example, an output shaft (not shown) of the step motor 41 is connected to the shaft end of the rotary shaft 40, and according to the rotational displacement of each sliding port body 39a (auxiliary port 39) using the step motor 41 as a drive source. The effective length of the intake passage can be varied steplessly.
[0038]
That is, a variable mechanism is configured. In the present embodiment, the effective length of the intake passage is the shortest suitable for the high-speed operation region of the engine, for example, when most of the auxiliary port body 39 as shown in FIG. 4 is inserted into the fan-shaped portion 36a. On the contrary, most of the auxiliary port body 39 moves from the fan-shaped portion 36a into the surge tank 37, and becomes the longest effective length suitable for the low-speed operation region of the engine as shown in FIG. The length can be changed in the range up to L3.
[0039]
Although the intake pipe length variable mechanism 33 has been described in detail above, the same applies to the exhaust pipe length variable mechanism 34.
[0040]
On the other hand, the cylinder head 1a is provided with an intake valve 28 that opens and closes each open end of the intake port 26 so as to freely advance and retract. Each intake valve 28 is attached with an electromagnetic drive mechanism 30 (hereinafter referred to as an intake-side electromagnetic drive mechanism 30) that drives the intake valve 28 back and forth using an electromagnetic force generated when an excitation current is applied. ing.
[0041]
The cylinder head 1a is provided with an exhaust valve 29 that opens and closes each open end of the exhaust port 27 so as to freely advance and retract. Each exhaust valve 29 is attached with an electromagnetic drive mechanism 31 (hereinafter referred to as an exhaust-side electromagnetic drive mechanism 31) that drives the exhaust valve 29 forward and backward using an electromagnetic force generated when an excitation current is applied. ing.
[0042]
Here, specific configurations of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 will be described. Since the intake side electromagnetic drive mechanism 30 and the exhaust side electromagnetic drive mechanism 31 have the same configuration, only the exhaust side electromagnetic drive mechanism 31 will be described as an example.
[0043]
FIG. 7 is a cross-sectional view showing the configuration of the exhaust-side electromagnetic drive mechanism 31. In FIG. 7, the cylinder head 1 a of the internal combustion engine 1 includes a lower head 10 fixed to the upper surface of the cylinder block 1 b and an upper head 11 provided on the upper surface of the lower head 10.
[0044]
An exhaust port 27 corresponding to each cylinder 21 is formed in the lower head 10, and a valve seat 12 for seating a valve body 29 a of the exhaust valve 29 is formed at the opening end of each exhaust port 27 on the combustion chamber 24 side. Is provided.
[0045]
The lower head 10 is formed with a through hole having a circular cross section from the inner wall surface of each exhaust port 27 to the upper surface of the lower head 10, and the valve shaft 29 b of the exhaust valve 29 inserted through the through hole is advanced and retracted in the through hole. A cylindrical valve guide 13 that is freely held is inserted.
[0046]
The upper head 11 is provided with a core mounting hole 14 having a circular cross section into which the first core 301 and the second core 302 are fitted, and the core mounting hole 14 is located at the same axis as the valve guide 13. The lower portion of the core mounting hole 14 is formed with a large diameter, and includes an upper small diameter portion 14a and a lower large diameter portion 14b.
[0047]
An annular first core 301 and second core 302 made of a soft magnetic material are fitted in the small diameter portion 14a in series in the axial direction with a predetermined gap 303 interposed therebetween. The upper end of the first core 301 and the lower end of the second core 302 are respectively formed with a flange 301a and a flange 302a. The first core 301 is from above and the second core 302 is from below the core mounting holes. 14 and the flanges 301a and 302a abut against the edge of the core mounting hole 14, whereby the first core 301 and the second core 302 are positioned, and the gap 303 is held at a predetermined distance. It is like that.
[0048]
A cylindrical upper cap 305 is provided above the first core 301. The upper cap 305 is fixed to the upper portion of the upper head 11 by passing a bolt 304 through a flange portion 305a formed at the lower end thereof. In this case, the lower end of the upper cap 305 including the flange portion 305 a is fixed in a state where the lower end of the upper cap 305 is in contact with the peripheral edge of the upper surface of the first core 301, and as a result, the first core 301 is fixed to the upper head 11. become.
[0049]
On the other hand, a lower cap 307 made of an annular body having an outer diameter substantially the same diameter as the large-diameter portion 14 b of the core mounting hole 14 is provided at the lower portion of the second core 302. A bolt 306 passes through the lower cap 307, and is fixed to the downward step surface of the step portion of the small diameter portion 14a and the large diameter portion 14b by the bolt 306.
In this case, the lower cap 307 is fixed in contact with the peripheral edge of the lower surface of the second core 302, and as a result, the second core 302 is fixed to the upper head 11.
[0050]
A first electromagnetic coil 308 is gripped in the groove formed on the surface of the first core 301 on the gap 302 side, and the groove formed on the surface of the second core 302 on the surface of the gap 303 is The second electromagnetic coil 309 is gripped. At that time, the first electromagnetic coil 308 and the second electromagnetic coil 309 are arranged at positions facing each other with the gap 303 therebetween.
[0051]
An armature 311 made of an annular soft magnetic material having an outer diameter smaller than the inner diameter of the 303 is disposed in the 303. A columnar armature shaft 310 extending in the vertical direction along the axis of the armature 311 is fixed to the hollow portion of the armature 311. The armature shaft 310 has an upper end passing through the hollow portion of the first core 301 and reaching the upper cap 305 above it, and a lower end passing through the hollow portion of the second core 302 and a large diameter portion below it. 14b, and is held by the first core 301 and the second core 302 so as to be movable back and forth in the axial direction.
[0052]
A disk-shaped upper retainer 312 is joined to the upper end of the armature shaft 310 extending into the upper cap 305, and an adjustment bolt 313 is screwed into the upper opening of the upper cap 305. An upper spring 314 is interposed between the upper retainer 312 and the adjusting bolt 313. A spring seat 315 having an outer diameter substantially the same as the inner diameter of the upper cap 305 is interposed on the contact surface between the adjustment bolt 313 and the upper spring 314.
[0053]
On the other hand, the upper end portion of the valve shaft 29b of the exhaust valve 29 is in contact with the lower end portion of the armature shaft 310 extending into the large diameter portion 14b. A disc-shaped lower retainer 29c is joined to the outer periphery of the upper end portion of the valve shaft 29b, and a lower spring 316 is interposed between the lower surface of the lower retainer 29c and the upper surface of the lower head 10.
[0054]
In the exhaust side electromagnetically driven valve mechanism 31 configured as described above, when no excitation current is applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, the exhaust side electromagnetically driven valve mechanism 31 moves downward from the upper spring 314 to the armature shaft 310. A biasing force in the direction (that is, the direction in which the exhaust valve 29 is opened) acts, and a biasing force in the upward direction (that is, the direction in which the exhaust valve 29 is closed) from the lower spring 316 to the exhaust valve 29. As a result, the armature shaft 310 and the exhaust valve 29 come into contact with each other and are elastically supported at a predetermined position, that is, maintained in a so-called neutral state.
[0055]
The urging force of the upper spring 314 and the lower spring 316 is set so that the neutral position of the armature 311 coincides with the intermediate position between the first core 301 and the core 302 in the gap 303. When the neutral position of the armature 311 deviates from the above-described intermediate position due to initial tolerance, secular change, or the like, the adjustment bolt 313 can be adjusted so that the neutral position of the armature 311 matches the above-described intermediate position. Yes.
[0056]
Further, the axial lengths of the armature shaft 310 and the valve shaft 29b are such that when the armature 311 is positioned at an intermediate position of the gap 303, the valve body 29a is fully opened and fully closed. And an intermediate position (hereinafter referred to as an intermediate position).
[0057]
In the exhaust-side electromagnetic drive mechanism 31 described above, when an excitation current is applied to the first electromagnetic coil 308, the armature 311 is placed between the first core 301, the first electromagnetic coil 308, and the armature 311. When an electromagnetic force in a direction to be displaced toward the 301 side is generated and an excitation current is applied to the second electromagnetic coil 309, the armature 311 is placed between the second core 302, the second electromagnetic coil 309, and the armature 311. An electromagnetic force is generated in a direction to be displaced toward the second core 302 side.
[0058]
Therefore, in the above-described exhaust-side electromagnetic drive mechanism 31, the exciting current is alternately applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, so that the armature 311 moves forward and backward, thereby causing the valve body. 29a is driven to open and close. At that time, the opening / closing timing of the exhaust valve 29 can be controlled by changing the excitation current application timing and the magnitude of the excitation current to the first electromagnetic coil 308 and the second electromagnetic coil 309.
[0059]
The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 42 for controlling the operating state of the internal combustion engine.
[0060]
The ECU 42 is connected to each other by a bus 43, a ROM 44 in which programs executed by the CPU 43, tables (look-up tables, maps), constants, and the like are stored in advance, and a RAM 45 in which the CPU 43 temporarily stores data as necessary. The microcomputer includes a backup RAM 46 that stores data while the power is turned on and holds the stored data while the power is shut off, and an interface 47 that includes an AD converter.
[0061]
The interface 47 is an air flow rate measuring means and is connected to a hot-wire air flow meter (not shown) disposed in the intake pipe 35, an engine speed sensor 48, and the like, and supplies signals from these sensors to the CPU 43. It is supposed to be. The interface 47 is connected to the igniter 25a, the intake side electromagnetic drive mechanism 30, the exhaust side electromagnetic drive mechanism 31, the intake pipe length variable mechanism 33, the exhaust pipe length variable mechanism 34, the fuel injection valve 32, and the like. In response, a drive signal is sent to them.
[0062]
The hot-wire air flow meter measures the mass flow rate of the intake air passing through the intake passage and generates Gn representing the same mass flow rate. The engine speed sensor 48 detects the speed of the internal combustion engine 1, generates a signal representing the engine speed NE, and can detect the absolute crank angle of each cylinder.
[0063]
Next, the operation of the intake side electromagnetic drive mechanism 30, the exhaust side electromagnetic drive mechanism 31, the intake pipe length variable mechanism 33, and the exhaust pipe length variable mechanism 34 configured as described above will be described. The CPU 43 of the ECU 42 is configured to repeatedly execute the program shown by the flowchart in FIG. 8 every elapse of a predetermined time. Accordingly, when the predetermined timing is reached, the CPU 43 starts processing from step 100, and in step 105, takes in the air flow rate Gn as the engine speed NE and engine load from the above-described sensors.
[0064]
Next, the CPU proceeds to step 110, where a map defining the relationship between the engine speed NE and the air flow rate Gn and the intake pipe length shown in FIG. 9 and the actual engine speed NE and air flow rate Gn taken in step 105 are shown. Based on the above, the effective length of the intake passage suitable for the operating region is determined, and a command is given to the auxiliary port body 39.
[0065]
The map used in step 110 is determined so as to obtain an effective length of the intake passage that has the effect of increasing the intake efficiency over the entire operation region of the internal combustion engine.
[0066]
That is, when the ECU 42 determines from the detection signal from the hot-wire air flow meter and the engine rotation speed sensor 48 that the engine is in the high load high rotation operation region, the ECU 42 assists as shown in FIG. The port body 39 is positioned by being rotationally displaced so that most of the port body 39 is inserted into the fan-shaped portion 36a.
[0067]
Then, the effective length of the intake passage is changed to the shortest effective length L1 at which inertia supercharging can be obtained at high rotation. As a result, a large amount of air is supplied to the combustion chamber 24 via the intake pipe 38, the auxiliary port body 39, the intake pipe 35, and the intake port 26.
[0068]
Further, when the ECU 42 determines from the detection signal from the hot-wire air flow meter and the engine speed sensor 48 that the engine is in the middle load mid-rotation operation region, the auxiliary motor as shown in FIG. The port body 39 is rotationally displaced and positioned so as to protrude into the middle surge tank 37.
[0069]
Then, the effective length of the intake passage is changed to a medium effective length L2 that allows inertia supercharging in the middle rotation range. As a result, inertial supercharging suitable for the middle rotation operation region works, and a large amount of air is supplied to the combustion chamber 24 through the same path as described above.
[0070]
If it is determined from the detection signal from the hot-wire air flow meter and the engine speed sensor 48 that the engine is in the low load and low speed operation region, the auxiliary port body 39 is driven as shown in FIG. Is positioned so as to be pivoted and displaced so that most of it protrudes into the surge tank 37.
[0071]
Then, the effective length of the intake passage is changed to the longest effective length L3 that can obtain the inertia supercharging in the low rotation range. Thereby, the inertia supercharging suitable for the low-rotation operation region works, and a large amount of air is supplied to the combustion chamber 24 through the same path as described above.
[0072]
Next, the CPU proceeds to step 115, and similarly to the intake pipe length varying mechanism 33, the map that defines the relationship between the engine speed NE and the air flow rate Gn and the exhaust pipe length shown in FIG. Based on the actual engine speed NE and the air flow rate Gn, an exhaust pipe length suitable for the operating region is determined, and a command is given to an auxiliary port body (not shown) of the exhaust pipe length variable mechanism 34.
[0073]
Next, the CPU proceeds to step 120, where a map defining the relationship among the intake pipe length and exhaust pipe length, engine speed NE, air flow rate Gn, and intake / exhaust valve opening / closing timing shown in FIG. Based on the actual engine speed NE and air flow rate Gn, the intake pipe length, the exhaust pipe length, and the intake / exhaust valve opening / closing timing VT suitable for the operating region are determined, and the intake side electromagnetic drive mechanism 30 and the exhaust side electromagnetic drive are determined. A command is given to the mechanism 31, and the routine proceeds to step 125 and this routine is terminated.
[0074]
The map used in step 120 takes into account changes in the cylinder pressure corresponding to the intake pipe length, the exhaust pipe length, and the operation region over the entire operation region of the internal combustion engine, and the inertia effect in the intake system and the exhaust system of the internal combustion engine. In addition, the intake / exhaust valve opening / closing timing at which the pulsation effect can be most effectively used is determined.
[0075]
In other words, the characteristics of the cylinder pressure change with changes in the intake pipe length and the exhaust pipe length. Therefore, for each combination of the intake pipe length and the exhaust pipe length, the intake / exhaust valve opening / closing timing VT, the engine speed NE, and the air flow rate Gn A map that defines the relationship is used.
[0076]
Thereby, even if the intake pipe length and the exhaust pipe length change, the intake valve is closed when the pressure in the cylinder and the pressure in the intake passage immediately before the intake valve become equal, so that the intake efficiency is improved.
[0077]
Further, as shown in FIG. 12, even when the intake pipe length and the exhaust pipe length change, when the pressure in the intake passage immediately before the intake valve is higher than the pressure in the exhaust passage immediately after the exhaust valve, both the intake valve and the exhaust valve The overlap state opens, improving the intake efficiency and promoting exhaust.
[0078]
Furthermore, even if the intake pipe length and the exhaust pipe length change, the exhaust valve is opened so that the exhaust negative pressure wave is synchronized in the overlap state, and the positive pressure wave due to blowdown from other cylinders is not synchronized, The scavenging effect and the suction supercharging effect can be enhanced.
[0079]
Since the intake pipe length and the exhaust pipe length change slowly compared to the change in the intake and exhaust pipe opening and closing timing, the intake and exhaust pipe opening and closing timing is gradually changed in accordance with the changes in the intake pipe length and the exhaust pipe length as shown in FIG. Thus, the intake / exhaust valve can be opened and closed at an optimum time even during a transition in which the intake pipe length and the exhaust pipe length change.
[0080]
As described above, according to the above-described embodiment, the intake and exhaust valves are opened and closed at the optimal time according to the change in the cylinder internal pressure that changes with the change in the intake pipe length and the exhaust pipe length. Inertia effects and pulsation effects in the exhaust system can be utilized most effectively.
[0081]
In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, although the above embodiment includes both the intake passage shape variable mechanism and the exhaust passage shape variable mechanism, it may be an internal combustion engine provided with only one of them.
[0082]
【The invention's effect】
The inertial effect and pulsation effect in the intake system and exhaust system of the internal combustion engine can be utilized most effectively.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of an internal combustion engine according to the present invention. FIG. 2 is a perspective view showing an external appearance of an intake pipe length variable mechanism. FIG. 3 is an exploded perspective view for explaining the structure of the intake pipe length variable mechanism. FIG. 4 is a cross-sectional view showing a case where the effective length of the intake passage is determined by the intake pipe length variable mechanism to a length suitable for a high-load high-rotation operation region. FIG. 6 is a cross-sectional view showing a case where the length is determined to be suitable for a medium-load / medium-rotation operation region. FIG. FIG. 7 is a sectional view showing the configuration of the exhaust side electromagnetic drive mechanism. FIG. 8 is a control of the intake pipe length variable mechanism, the exhaust pipe length variable mechanism, the intake side electromagnetic drive mechanism, and the exhaust side electromagnetic drive mechanism. FIG. 9 is a flowchart showing a routine. Map defining the relationship between the number and air flow rate and the intake pipe length [FIG. 10] Map defining the relationship between the engine speed and air flow rate and the exhaust pipe length [FIG. 11] FIG. Map that defines the relationship between the intake and exhaust valve opening and closing timings. Fig. 12 Changes in intake and exhaust valve opening and closing timings and changes in the intake and exhaust passage pressures of the internal combustion engine with changes in the intake and exhaust pipe lengths. FIG. 13 is an explanatory diagram showing the temporal relationship between changes in the intake and exhaust pipe lengths and changes in the opening and closing timing of the intake and exhaust valves.
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 26 ... Intake port 27 ... Exhaust port 28 ... Intake valve 29 ... Exhaust valve 30 ... Intake side electromagnetic drive mechanism 31 ... Exhaust side electromagnetic drive mechanism 33 ... Intake pipe length variable mechanism 34 ... Exhaust pipe length variable mechanism 42 ... ECU
48 ... Engine speed sensor

Claims (8)

In an internal combustion engine provided with an intake passage shape variable mechanism that variably controls an intake passage shape based on a relationship defined in advance between an engine speed and / or an operating region determined from an intake air flow rate ,
Provided with a valve mechanism that independently controls each of the opening timing and closing timing of the cylinder intake and exhaust valves,
The valve mechanism has a relationship defined in advance between the intake passage shape and the operating region in which the intake and exhaust valve opening timing and closing timing are variably controlled by the intake passage shape variable mechanism. An internal combustion engine controlled based on the control. In an internal combustion engine having an exhaust passage shape variable mechanism that variably controls an exhaust passage shape based on a relationship defined in advance between an engine speed and / or an operating region determined from an intake air flow rate ,
Provided with a valve mechanism that independently controls each of the opening timing and closing timing of the cylinder intake and exhaust valves,
The valve operating mechanism has a relationship defined in advance between the exhaust passage shape and the operation region in which the opening timing and the closing timing of the intake and exhaust valves are variably controlled by the exhaust passage shape variable mechanism. An internal combustion engine controlled based on the control. An intake passage shape variable mechanism that variably controls the intake passage shape based on a predetermined relationship between the engine speed and / or the operating range determined from the intake air flow rate, and the engine speed and / or intake air flow rate. In an internal combustion engine provided with an exhaust passage shape variable mechanism that variably controls an exhaust passage shape based on a predetermined relationship with a fixed operating region ,
Provided with a valve mechanism that independently controls each of the opening timing and closing timing of the cylinder intake and exhaust valves,
The valve mechanism includes an intake passage shape in which each of the opening timing and the closing timing of the intake and exhaust valves is variably controlled by the intake passage shape variable mechanism, and an exhaust passage in which the exhaust passage shape variable mechanism is variably controlled. An internal combustion engine controlled based on a shape and a relationship defined in advance between the operating region and the shape.   The valve operating mechanism controls the opening timing of the intake valve so that the intake valve and the exhaust valve are both opened when the pressure in the intake passage is higher than the pressure in the exhaust passage. The internal combustion engine according to any one of claims 1 to 3.   The valve operating mechanism controls the closing timing of the intake valve so that the intake valve is closed when the cylinder internal pressure and the intake passage internal pressure become equal. An internal combustion engine according to claim 1.   The valve operating mechanism controls the opening timing of the exhaust valve so that the exhaust valve is opened in synchronization with the exhaust negative pressure wave in the exhaust passage. An internal combustion engine described in 1.   The valve mechanism controls the closing timing of the exhaust valve so that when the pressure in the exhaust passage is lower than the pressure in the intake passage, a valve overlap state is established in which both the intake valve and the exhaust valve are open. The internal combustion engine according to any one of claims 1 to 6.   When the internal combustion engine has a plurality of cylinders, the valve mechanism opens the exhaust valve without synchronizing the opening timing of the exhaust valve of one cylinder with the positive pressure wave due to blowdown from the other cylinders. The internal combustion engine according to claim 1, wherein the internal combustion engine is controlled to be

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