JP2011038439A - Internal combustion engine having variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a torque variation by restraining a variation in the air-fuel ratio of a spitting air-fuel mixture to an intake passage, and to improve fuel economy performance by reduction in a pumping loss, by devising a valve operation characteristic of an intake valve for spitting the air-fuel mixture to the intake passage, in an internal combustion engine. <P>SOLUTION: A valve characteristic variable mechanism Aa of a valve gear V of the internal combustion engine, selects a low speed cam 21i and a decompression cam 24 as a specific cam from a plurality of cams 21i-23i and 24 for constituting a cam group 20i when an engine speed is a specific operation state of an idling engine speed or more. The low speed cam 21i controls a first intake valve 10a so as to become a valve opening state in the vicinity of the exhaust top dead center, and the decompression cam 24 controls a second intake valve 10b so as to open by a maximum lift quantity smaller than a maximum lift quantity of the first intake valve 10a, and to open over a compression stroke from the latter half of an intake stroke. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine including a variable valve operating device that changes valve operating characteristics of an intake valve in accordance with an engine operating state, and more particularly to opening / closing control of an intake valve for air-fuel mixture blowback.

In a direct injection internal combustion engine as an internal combustion engine having a variable valve operating device, when the engine operation state is a specific operation state, fuel injected from the fuel injection valve into the combustion chamber in the intake stroke is blown back into the intake passage. In addition, there is known a variable valve device that delays the opening and closing timing of the intake valve to delay the intake valve (for example, see Patent Document 1).
Further, as a variable valve operating device for an internal combustion engine, a plurality of cams for controlling opening and closing of the first and second intake valves and a specific cam for changing the valve operating characteristics of the intake valves according to the engine operating state are selected. A device having a variable valve characteristic mechanism is also known (see, for example, Patent Document 2).

JP 2002-285870 A Japanese Patent Laid-Open No. 6-93821

In a direct injection internal combustion engine, when the return of fuel from the combustion chamber to the intake passage is performed by delaying the opening / closing timing (valve timing) of the intake valve by the valve characteristic variable mechanism of the variable valve device, Since not only the valve closing timing but also the opening timing of the intake valve is retarded, the valve opening period from the opening of the intake valve to the intake bottom dead center is shortened. For this reason, in the intake stroke, the mixture time of the fuel and air in the combustion chamber (including the mixture blown back to the intake passage in the previous cycle) is insufficient, and the mixture is sufficiently homogenized. In some cases, the air-fuel mixture is blown back to the intake passage, and the air-fuel ratio of the air-fuel mixture blown back (hereinafter referred to as “blow-back air-fuel mixture”) tends to vary. Such a variation in the blowback air-fuel ratio causes a variation in the air-fuel ratio in the combustion chamber when the blow-back mixture is sucked into the combustion chamber in the next intake stroke, and the internal combustion engine has a plurality of variations. In the case of a multi-cylinder engine equipped with cylinders, variations in the air-fuel ratio between the cylinders are generated, causing torque fluctuations and emission deterioration. The same phenomenon may occur in an internal combustion engine in which fuel is injected into an intake port that is opened and closed by an intake valve.
Further, since the opening timing of the intake valve is retarded, the pumping loss increases because the intake valve is closed in the first half of the intake stroke.
Further, by switching the valve opening characteristic between a long valve opening period and a short valve opening period, in an internal combustion engine that slowly closes the intake valve, the valve overlap amount with the exhaust valve becomes large, and in a low load operation region. Is not preferred.

  The present invention has been made in view of such circumstances, and in an internal combustion engine, by devising a valve operating characteristic of an intake valve for blowing back an air-fuel mixture to the intake passage, An object of the present invention is to reduce the variation in torque by suppressing the variation in the air-fuel ratio of the blow-back mixture, and to improve the fuel efficiency by reducing the pumping loss.

According to the first aspect of the present invention, the first and second intake valves (10a, 10b) for opening and closing the first and second intake ports (7a, 7b) of the intake passage (Pi) opened to the combustion chamber (5), respectively. A predetermined number of cams (21i to 23i, 24) that respectively control the opening and closing of the first and second intake valves (10a, 10b) in synchronization with the rotation of the crankshaft (6), and the first 1, a variable valve gear (1) including a variable valve characteristic mechanism (Aa) capable of changing a valve operating characteristic of at least the second intake valve (10b) of the second intake valve (10a, 10b) according to an engine operating state. V), a fuel injection valve (12) for injecting fuel into intake air, and a control device (80) for controlling the valve characteristic variable mechanism (Aa) according to the engine operating state, Controlled by the control device (80) The valve characteristic variable mechanism (Aa) selects one or two specific cams from the predetermined number of cams (21i to 23i, 24) in order to change the valve operating characteristic according to the engine operating state. When the engine operation state is a specific operation state (R4) at an engine rotation speed equal to or higher than the idling rotation speed, the specific cams are the first specific cam (21i) and the second specific cam (24), The first specific cam (21i) controls the first intake valve (10a) to be opened near the exhaust top dead center, and the second specific cam (24) is a decompression cam (24). The second intake valve (10b) is opened with a maximum lift amount (Ld) smaller than the maximum lift amount (La) of the first intake valve (10a), and is opened from the latter half of the intake stroke to the compression stroke. To control When the engine operating state is an operating state different from the specific operating state (R4), the specific cam has a valve operating characteristic different from that of the decompression cam (24), and the first and second intake valves (10a, 10b) is an internal combustion engine that controls opening and closing.
According to the first aspect of the present invention, in the specific operation state when the engine rotational speed is equal to or higher than the idling rotational speed, the valve is opened early in the intake stroke because the valve is open near the exhaust top dead center. Since the swirl is generated in the combustion chamber by the intake air flowing into the combustion chamber through the first intake valve, homogenization of the fuel injected from the fuel injection valve is promoted. The second intake valve is opened from the second half of the intake stroke to the compression stroke by the second specific cam functioning as a decompression cam, so that the air-fuel mixture that has been homogenized in the combustion chamber passes through the intake passage from the second intake port. Blown back.
As a result, the air-fuel mixture homogenized by the swirl in the combustion chamber is blown back into the intake passage, so that the variation in the air-fuel ratio in the combustion chamber when the blow-back air-fuel mixture is sucked into the combustion chamber again in the next intake stroke is performed. When the internal combustion engine is a multi-cylinder engine, the variation in the air-fuel ratio of the blow-back mixture between the cylinders is suppressed, so that the torque fluctuation of the internal combustion engine can be reduced, and therefore the rotational fluctuation can be reduced. .
Further, the second intake valve that is in the open state in the compression stroke enables the blow-back control, reduces the pumping loss, and improves the fuel efficiency.
The invention according to claim 2 is the internal combustion engine according to claim 1, wherein the first intake valve (10a) has the maximum lift amount (La) at the center position of the intake stroke in the specific operation state (R4). The second intake valve (10b) is in a closed state throughout the fuel injection period of the fuel injection valve (12).
According to the second aspect of the present invention, when the second intake valve is in a specific operation state in which the second intake valve is opened and closed by the second specific cam functioning as a decompression cam, the first intake valve has its maximum lift amount at the center position of the intake stroke. While the valve is opened with a lift amount of ½ or more, the second intake valve is kept closed throughout the fuel injection period of the fuel injection valve, so that it opens relatively large early in the intake stroke. Since the swirl generated by the air sucked into the combustion chamber through the valved first intake valve can be strengthened, the air-fuel mixture in the combustion chamber can be homogenized before the second intake valve is opened. Can be promoted, and thus the blow-back mixture can be homogenized.
According to a third aspect of the present invention, in the internal combustion engine according to the first or second aspect, the second specific cam (24) includes the second intake valve (10b) and the maximum lift amount (Ld) in a compression stroke. The valve is opened as follows.
According to the third aspect of the present invention, since the lift amount of the second intake valve is maximized in the compression stroke, the air-fuel mixture in the combustion chamber is swirled before the second intake valve is opened with the maximum lift amount. Since the homogenization of the air-fuel mixture proceeds, the homogenization of the blown-back mixture is improved.
According to a fourth aspect of the present invention, in the internal combustion engine according to any one of the first to third aspects, the control device (80) sets the fuel injection timing by the fuel injection valve (12) to the engine operating state. Accordingly, in the specific operation state (R4), the control device (80) ends the fuel injection before the second specific cam (24) opens the second intake valve (10b). Is.
According to the fourth aspect of the present invention, since the fuel injection is completed before the second intake valve is opened, when the second intake valve is opened, the air-fuel mixture in the combustion chamber is homogenized by the swirl. Since it is progressing, homogenization of the blown-back mixture is improved.
The invention according to claim 5 includes a plurality of service cylinders (C1, C4) that are always operated, and cylinders (C2, C3) that can be stopped depending on the engine operation state and can be switched between an operation state and a suspension state. 5. The cylinder according to claim 1, further comprising cylinders (C1 to C4), wherein the resting cylinders (C2, C3) are in a resting state when the engine operation state is a predetermined operation state (R3). In the internal combustion engine, the variable valve mechanism (V) including the variable valve characteristic mechanism (Aa) is provided for the service cylinders (C1, C4), and the specific operation state (R4) is the predetermined operation. This is a partial operation state of the state (R3).
According to the fifth aspect of the present invention, the air-fuel ratio of the blow-back mixture is reduced in the cylinder-cylinder operation when the intake air amount per one cylinder and the generated torque are large compared with the operation of all cylinders in which all the cylinders are in operation. Torque fluctuation caused by variation is reduced.
According to a sixth aspect of the present invention, in the internal combustion engine according to any one of the first to fifth aspects, the variable valve gear (V) is driven by the predetermined number of cams (21i to 23i, 24). Is provided with a rocker arm group (30i) composed of a plurality of rocker arms (31i to 33i, 34), and the predetermined number of cams (21i to 23i, 24) are arranged via the rocker arm group (30i). Connection switching for controlling the opening and closing of the first and second intake valves (10a, 10b) and for controlling the connection and release of the rocker arms (32i, 34; 31i to 33i). It is a mechanism.
According to the sixth aspect of the present invention, the use of a connection switching mechanism that controls connection and release of connection between the rocker arms constituting the rocker arm group, and the valve operating characteristics for reducing the compression pressure in the specific operation state, and the specific operation state It is possible to easily switch the valve operating characteristic of the second intake valve to another valve operating characteristic in a different operating state.

  According to the present invention, in an internal combustion engine, by controlling the opening and closing of the intake valve for returning the air-fuel mixture to the intake passage, variation in the air-fuel ratio of the air-fuel mixture returning to the intake passage is suppressed and torque fluctuations are suppressed. In addition, the fuel efficiency can be improved by reducing the pumping loss.

2 is a cross-sectional view of the internal combustion engine to which the present invention is applied, in a plane perpendicular to the axial direction of the camshaft and including the cylinder axis, and the sub-rocker arm group and the camshaft of FIG. FIG. 2 is a cross-sectional view taken along the line -I and schematically shows a part of the internal combustion engine. It is the schematic in the general II-II arrow line of FIG. FIG. 3 is an enlarged view of main parts of FIG. 2. It is a disassembled perspective view of the sub rocker arm group of the variable valve operating apparatus of the internal combustion engine of FIG. It is sectional drawing of the regular valve operating apparatus of the variable valve operating apparatus of FIG. 1, (a) is sectional drawing in the Va-Va line of FIG. 1, (b) is Vb-Vb line of FIG. FIG. It is sectional drawing in the valve operating apparatus for a pause of the variable valve apparatus of FIG. 1, (a) is a figure equivalent to FIG. 5 (a), (b) is a figure equivalent to FIG.5 (b). It is. FIG. 2 is a diagram for explaining a relationship between lift amounts and crank angles of first and second intake valves and first and second exhaust valves of the internal combustion engine of FIG. 1. FIG. 2 is a diagram for explaining the relationship between lift amounts and crank angles of first and second intake valves and first and second exhaust valves when the engine operation state of the internal combustion engine of FIG. 1 is a specific operation state. 2 is a valve operating characteristic map for setting the valve operating characteristic according to the engine operating state by the valve characteristic variable mechanism of the variable valve operating apparatus for the internal combustion engine of FIG. 1.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIGS. 1 and 2, a cylinder injection internal combustion engine E as an internal combustion engine to which the present invention is applied is fitted with four cylinders C1 to C4 as a plurality and a reciprocating motion in each of the cylinders C1 to C4. This is a multi-cylinder internal combustion engine including a piston 4 to be coupled and a crankshaft 6 connected to each piston 4 via a connecting rod, and is mounted on a vehicle as a mounting target.
In the following description, when the cylinders C1 to C4 are not distinguished, they are described as cylinders C.

An internal combustion engine E having one cycle of four strokes (see FIG. 7) of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke is a cylinder in which first to fourth cylinders C1 to C4 are arranged in series and integrated. An engine body including a block 1, a cylinder head 2 coupled to the upper end portion of the cylinder block 1, and a head cover 3 coupled to the upper end portion of the cylinder head 2 is provided.
For each cylinder C, a combustion chamber 5 is formed by each cylinder C, piston 4 and cylinder head 2 between the piston 4 and cylinder head 2 in the cylinder axial direction.
All cylinders C of the internal combustion engine E are one or more partial cylinders, and are second and third cylinders C2 that can be switched to an operation state and a stop state according to the engine operating state of the internal combustion engine E. , C3 and all the remaining cylinders, which are first and fourth cylinders C1, C4, which are service cylinders that are always in operation.

  In the embodiment, the vertical direction is a direction parallel to the cylinder axis Y of the cylinder C (that is, the cylinder axis direction), and the upper direction is the direction in which the combustion chamber 5 is located with respect to the crankshaft 6 in the cylinder axis direction. The axial direction is assumed to be a direction parallel to the rotation center line of the camshafts Si and Se of the valve gear V.

Referring also to FIG. 3, the cylinder head 2 has an intake air having two or more, here, a pair of intake ports 7 a and 7 b that open to the combustion chamber 5 for each cylinder C (that is, for each combustion chamber 5). A port 7, an exhaust port 8 having one or more exhaust ports 8 a and 8 b, which open to the combustion chamber 5, and two or more, here a pair of first ports, which open and close the intake ports 7 a and 7 b. , The second intake valves 10a, 10b, and one or more, here, a pair of first and second exhaust valves 11a, 11b that open and close the exhaust ports 8a, 8b, and the fuel injection valve 12 that faces the combustion chamber 5, respectively. And a spark plug 13 are provided.
In the following description, when a pair of intake valves 10a and 10b and a pair of exhaust valves 11a and 11b are not distinguished, they are referred to as an intake valve 10 and an exhaust valve 11, respectively.

The internal combustion engine E is further disposed in a valve operating chamber 14 formed by the cylinder head 2 and the head cover 3 and controls the opening and closing of the intake valve 10 and the exhaust valve 11 in synchronization with the rotation of the crankshaft 6. A device V, an intake device 15 attached to the intake side of the cylinder head 2 and leading intake air taken from the outside of the internal combustion engine E to the combustion chamber 5, and attached to the exhaust side of the cylinder head 2 and in the combustion chamber 5 And an exhaust device 16 that guides the combustion gas generated by the combustion of the air-fuel mixture to the outside of the internal combustion engine E as exhaust gas.
Here, the intake passage Pi that guides outside air to the combustion chamber 5 as intake air is composed of an intake port 7 and a passage formed by the intake device 15, and the exhaust passage Pe that guides exhaust gas to the outside of the internal combustion engine E is The exhaust port 8 and a passage formed by the exhaust device 16 are configured. The intake device 15 includes a throttle valve 15a that controls the flow rate of air flowing through the intake passage Pi.

The fuel injection valve 12 for injecting fuel into the intake air directly injects the fuel into the combustion chamber 5, and the injected fuel is mixed with the air sucked from the intake passage Pi in the combustion chamber 5 to produce an air-fuel mixture. Form. The ignition plug 13 is accommodated in an accommodation cylinder 17 provided in the cylinder head 2 together with an ignition coil (not shown). The spark plug 13 and the ignition coil are part of an ignition device that is controlled by the control device 80 and controls the ignition timing in accordance with the engine operating state.
The piston 4 is driven by the pressure of the combustion gas generated when the air-fuel mixture in the combustion chamber 5 is ignited and burned by the spark plug 13, and reciprocates to rotate the crankshaft 6.

The DOHC variable valve operating device V includes an intake valve operating device that controls opening and closing of the intake valve 10 and an exhaust valve operating device that controls opening and closing of the exhaust valve 11.
In the following, the structure related to the valve operating device V will be described mainly in relation to the intake valve operating device, and the description related to the exhaust valve operating device will function as components of the intake valve operating device. The same reference numerals are used in part for the corresponding component members and members related to the exhaust valve operating device, and when the terms or signs are different, they are described in parentheses as necessary. . When distinguishing between the intake valve device and the exhaust valve device, the suffixes “i” and “e” are added to the reference numerals for the intake valve device and the exhaust valve device, respectively.
Further, the valve operating device V is provided for each cylinder C as a normal valve operating device Va as a first valve operating device provided for the service cylinder and a second valve operating device provided for the restable cylinder. And a valve operating device for rest Vb.

  As shown in FIGS. 2, 3, and 5, the service valve device Va includes a cam shaft Si (Se) having an intake cam group 20 i (exhaust cam group 20 e) as an intake cam (exhaust cam), and a cam Intake cam followers 30i, 61i, 62i (exhaust cam followers 30e, 61e, 62e) driven by the group 20i (20e) to control the opening and closing of the intake valves 10 (exhaust valves 11), and the intake cam followers 30i, 61i, 62i Cam follower support members 63i, (63e), 64 that movably support the exhaust cam followers 30e, 61e, 62e) and valve springs (not shown) that bias the intake valve 10 (exhaust valve 11) in the valve closing direction. 1), and a valve characteristic variable mechanism Aa that can change the valve operating characteristic of the intake valve 10 (exhaust valve 11) according to the engine operating state. 1, includes a second connection switching mechanism 36 and 37 (see FIG. 5), and a lost motion mechanism 65.

Moreover, as shown in FIGS. 1 to 3 and FIG. 6, the stop valve gear Vb includes a cam shaft Si (Se) having an intake cam group 40 i (exhaust cam group 40 e) as an intake cam (exhaust cam). Intake cam followers 50i, 61i, 62i (exhaust cam followers 50e, 61e, 62e) that are driven by the cam group 40i (40e) to control the opening and closing of the intake valve 10 (exhaust valve 11), and the intake cam followers 50i, 61i, 62i (exhaust cam followers 50e, 61e, 62e) movably supporting cam follower support members 63i, (63e), 64, a valve spring 18 for urging the intake valve 10 (exhaust valve 11) in the valve closing direction, and intake air First and second connection switching mechanisms 56 and 57 constituting a valve characteristic variable mechanism Ab capable of changing the valve operating characteristic of the valve 10 (exhaust valve 11) according to the engine operating state (FIG. And the reference), and a lost motion mechanism 65.
2 and 3, for convenience of illustration, the cam crest positions of the cams are shown at the same position, but in actuality, the rotation of the cam shaft Si (Se) corresponds to the intake stroke for each cylinder C. In different positions.

First, with reference to FIG. 1 to FIG. 3 and FIG. 6, the stop valve gear Vb will be described.
Each cam shaft Si (Se) is inserted in the axial direction into a cam holder 9 integrally formed with a head cover 3 fixed to the cylinder head 2 with bolts 3a, and the journal portion Sij (Sej) ( By being rotatably supported in FIG. 2), the cylinder head 2 is rotatably supported via the cam holder 9.
Both camshafts Si and Se are driven by the power of a crankshaft 6 serving as a valve drive source that is transmitted via a valve drive mechanism (not shown) constituted by, for example, a winding drive mechanism having a timing chain. The rotary shaft is rotationally driven at a rotational speed that is half the rotational speed of the crankshaft 6.

The cam group 40 i (40 e) includes a plurality of third cams 41 i to 45 i (41 e to 45 e) as a plurality of third predetermined numbers for each combustion chamber 5.
In the intake cam group 40i, the first and second cams are stop cams 41i and 42i that keep the intake valves 10a and 10b closed for cylinder stop, and the third cam is a high-speed operation state R2 (FIG. 9). The high-speed cam 43i controls the opening and closing of the intake valves 10a and 10b with the high-speed lift amount in FIG. 7, and the fourth cam controls the intake valve 10a with the low-speed lift amount (see FIG. 7) in the low-speed operation state R1 (see FIG. 9). , See FIG. 8), and the fifth cam is a substantial pause 45i as a pause cam that closes the intake valve 10b. In this embodiment, from the viewpoint of preventing the intake valve 10b from sticking, the substantial rest cam 45i opens slightly to the extent that the inflow or outflow of air or air-fuel mixture into the combustion chamber 5 can be ignored (see FIG. 7). This is a cam that substantially closes the valve 10b, and as another example, a cam that does not open at all may be used.
Further, in the exhaust cam group 40e, the first and second cams are pause cams 41e and 42e similar to the pause cams 41i and 42i, and the third cam is a double exhaust valve in the high speed operation state R2 (see FIG. 9). 11a and 11b are high-speed cams 43e that control opening and closing with a high-speed lift amount (see FIG. 7), and the fourth and fifth cams use both exhaust valves 11a and 11b for low-speed operation in the low-speed operation state R1 (see FIG. 9). Low-speed cams 44e and 45e that are controlled to open and close by the lift amount (see FIGS. 7 and 8), respectively.

  1, 3, 4, and 6, intake cam followers 50 i, 61 i, 62 i (exhaust cam followers 50 e, 61 e, 62 e) of the stop valve operating device Vb are provided for each combustion chamber 5. Then, an intake sub-rocker arm group 50i (exhaust sub-rocker arm group 50e) as an intake sub-cam follower (exhaust sub-cam follower) composed of five sub-rocker arms 51i to 55i (51e to 55e) of the same number as the third predetermined number, An intake main rocker arm 61i as an intake main cam follower (exhaust main cam follower) that is driven by the rocker arm group 50i (50e) and opens and closes the first and second intake valves 10a and 10b (first and second exhaust valves 11a and 11b), respectively. , 62i (exhaust main rocker arms 61e, 62e).

  The cam follower support members 63i, (63e), 64 of the suspension valve device Vb are rocker shafts 63i, which are first support members that swingably support the first to fifth sub-rocker arms 51i-55i (51e-55e). (63e) and a pivot member 64 which is a second support member that supports the main rocker arms 61i, 62i (61e, 62e) in a swingable manner. A rocker shaft 63 i (63 e) provided in the cam holder 9 is provided in the cylinder head 2 via the cam holder 9 and the head cover 3, and the pivot member 64 is provided directly in the cylinder head 2.

The first and second sub-rocker arms 51i, 52i (51e, 52e) are paired with cam contact portions 51a, 52a made of rollers respectively contacting the first and second pause cams 41i, 42i (41e, 42e). Follower contact portions 51b and 52b that contact the main rocker arms 61i and 62i (61e and 62e), and first connection portions 51c and 52c and second connection portions provided with first and second connection switching mechanisms 56 and 57, respectively. Parts 51d and 52d.
The third sub-rocker arm 53i (53e) includes a cam contact portion 53a formed of a roller that contacts the high-speed cam 43i (43e), a connection portion 53c provided with the second connection switching mechanism 57, and a biasing force of the lost motion mechanism 65. And an action portion 53h on which.
The fourth and fifth sub-rocker arms 54i, 55i (54e, 55e) are connected to the cam contact portions 54a, 55a made of rollers respectively contacting the low speed cam 44i (44e) and the substantial rest cam 45i (45e), and the first connection. It has the connection parts 54c and 55c in which the switching mechanism 56 is provided, and the action parts 54h and 55h where the urging | biasing force of the lost motion mechanism 65 acts.

  The main rocker arms 61i, 62i (61e, 62e) are the same in the valve gears Va, Vb, and are supported by the columnar pivot member 64 that is held by the cylinder head 2 and has a lash adjuster function so as to be swingable. The The main rocker arms 61i, 62i (62e, 62e) are in contact portions 61a, 62a made of rollers with which the follower contact portions 51b, 52b abut, and both intake valves 10a, 10b (both exhaust valves 11a, 11b) and valve pressing portions 61b and 62b that abut on the valve stems and press the intake valves 10a and 10b (exhaust valves 11a and 11b) in the valve opening direction.

  Each lost motion mechanism 65 is the same in each valve operating device Va, Vb, and includes a spring 65a as an urging member. The lost motion mechanism 65 presses the third sub-rocker arm 33i (33e) and the fourth sub-rocker arm 34 against the high-speed cam 23i (23e) and the decompression cam 24 in the valve operating device Va, respectively, 4. The fifth sub rocker arms 53i, 54i, 55i (53e, 54e, 55e) are pressed against the high-speed cam 43i, the low-speed cam 44i, and the substantial rest cam 45i (the high-speed cam 43e, the low-speed cam 44e, and the low-speed cam 45e), respectively.

Next, the normal valve operating device Va will be described with reference to FIGS.
The cam group 20i (20e) is composed of a plurality of first cams 21i to 23i and 24 (a plurality of second cams 21e to 23e as a second predetermined number) for each combustion chamber 5. Is done.
In the intake cam group 20i, the first cam controls the opening and closing of the intake valve 10a with the same lift amount (see FIGS. 7 and 8) as the low speed cam 44i of the suspension valve operating device Vb in the low speed operation state R1 (see FIG. 9). The second cam is a substantially rest cam 22i as a rest cam similar to the substantially rest cam 45i of the rest valve operating device Vb, and the third cam is a high speed of the rest valve operating device Vb. The high-speed cam 23i controls the opening and closing of the intake valves 10a and 10b with the same lift amount as that of the cam 43i (see FIG. 7). The fourth cam closes the intake valve 10b in the latter half of the intake stroke and performs the compression stroke. The decompression cam 24 is in a valve open state (see FIG. 8).
Therefore, the intake cam group 20i is one or more, low-speed cams 21i, substantial rest cams 22i and high-speed cams 23i as three main cams here, and these cams 21i to 23i are separate cams. And a decompression cam 24.
In the exhaust cam group 20e, the first and second cams control the opening and closing of the exhaust valves 11a and 11b with the same lift amount (see FIGS. 7 and 8) as the low speed cams 44e and 45e of the suspension valve operating device Vb. The low-speed cams 21e and 22e, and the third cam is a high-speed cam 23e that controls the opening and closing of the exhaust valves 11a and 11b with the same lift amount (see FIG. 7) as the high-speed cam 43e of the suspension valve operating device Vb.
As shown in FIG. 7, in each valve operating device Va, Vb, the substantially idle cams 22i, 45i slightly open the intake valve 10b during the compression stroke.

  There are a plurality of intake cam followers 30i, 61i, 62i (exhaust cam followers 30e, 61e, 62e) of the regular valve operating device Va for each combustion chamber 5, which are the same number as the first predetermined number. An intake sub as an intake sub cam follower (exhaust sub cam follower) composed of a plurality of sub rocker arms 31i to 33i, 34 (a plurality of first to third sub rocker arms 31e to 33e, here, the same number as the second predetermined number). A rocker arm group 30i (exhaust sub-rocker arm group 30e) and an intake main cam follower (exhaust main cam follower) driven by the sub-rocker arm group 30i (30e) to open and close the pair of intake valves 10a and 10b (exhaust valves 11a and 11b), respectively. As a pair of intake main rocker arms 61i, 62i (exhaust main rocker arm 6 e, consisting of 62e).

In the sub-rocker arm group 30i (30e) that is swingably supported by the rocker shaft 63i (63e), the first sub-rocker arm 31i (31e) has a first sub-rocker arm 51 (FIG. 4) except that the connecting portion 51c is not provided. The cam contact portion 31a made of a roller that contacts the low-speed cam 21i (21e), the follower contact portion 31b that contacts the main rocker arm 61i (61e), and the second connection switching mechanism 37. And a second connecting portion 31d.
The second sub-rocker arm 32i is the same as the second sub-rocker arm 52 (see FIG. 4), and includes a cam contact portion 32a composed of a roller that contacts the substantial rest cam 22i, and a follower contact portion 32b that contacts the main rocker arm 62i. And a first connecting part 32c and a second connecting part 32d provided with the first and second connection switching mechanisms 36, 37.
On the other hand, the second sub rocker arm 32e has the same shape as the second sub rocker arm 52 (see FIG. 4) except that there is no connecting portion 32c, and a cam contact portion 32a made of a roller that contacts the low speed cam 22e. And a follower contact portion 32b that contacts the main rocker arm 62e.
The third sub-rocker arm 33i (33e) is the same as the third sub-rocker arm 53 (see FIG. 4), and includes a cam contact portion 33a made of a roller that contacts the third cam 23i (23e), and a second connection switching mechanism. The connecting portion 33d is provided with a working portion 33h on which the urging force of the lost motion mechanism 65 acts.
The fourth sub-rocker arm 34 is the same as the fifth sub-rocker arm 55 (see FIG. 4), and includes a cam contact portion 34a formed of a roller that contacts the decompression cam 24, and a connection portion 34c provided with the first connection switching mechanism 36. And an action portion 34h on which the urging force of the lost motion mechanism 65 acts.

  The cam groups 20i (20e) are similarly driven via the rocker arm group 30i (30e) because both camshafts Si and Se are rotationally driven at a rotational speed that is half the rotational speed of the crankshaft 6. The cam group 40i (40e) controls the opening and closing of the first and second intake valves 10a, 10b (exhaust valves 11a, 11b) in synchronization with the rotation of the crankshaft 6 via the rocker arm group 50i (50e).

Referring to FIGS. 3 and 8, the decompression cam 24 opens the second intake valve 10b from the latter half of the intake stroke to the compression stroke, that is, the opening timing of the intake valve 10b ranges from the second half of the intake stroke to the compression stroke. Set the time within. In this embodiment, the intake valve 10b that is opened and closed by the decompression cam 24 opens near the intake bottom dead center in the intake stroke, and the latter half of the compression stroke (that is, from the center position of the compression stroke to the compression top dead center). The valve is closed at the timing), and is closed at the center position of the intake stroke (that is, the stroke position at which the intake stroke is halved) and throughout the fuel injection period by the fuel injection valve 12.
Here, the vicinity of the intake bottom dead center in the intake stroke means the time from the stroke position 3/4 of the intake stroke to the intake bottom dead center. As another example, the intake valve 10b opened and closed by the decompression cam 24 may be opened in the compression stroke.

  The decompression cam 24 has a cam shape in which the maximum lift amount Ld of the intake valve 10b is smaller than the maximum lift amount La of the first intake valve 10a by the low speed cam 44i. The timing when the lift amount of the intake valve 10b by the decompression cam 24 becomes the maximum lift amount Ld is the compression stroke after the intake bottom dead center, and more specifically, both dead ends of the intake bottom dead center and the compression top dead center. It is a time closer to the center position in the compression stroke than the point (that is, a stroke position that is ½ of the compression stroke).

On the other hand, the intake valve 10a that is controlled to open and close by the low speed cam 44i is more specifically exhaust top dead in the intake stroke in the first half of the intake stroke (that is, the timing from the center position of the intake stroke to the exhaust top dead center). The valve is open near the point. In this embodiment, the valve is opened and closed at an opening / closing timing that forms a valve overlap period between the exhaust valves 11a and 11b.
Here, the vicinity of the exhaust top dead center in the intake stroke means a period from the exhaust top dead center to a stroke position that is 1/4 of the intake stroke.

  The first intake valve 10a opened and closed by the low-speed cam 44i is in a state where the lift amount of the intake valve 10a is increased when the engine operation state is in the low-speed operation state R1 including the specific operation state R4 (see FIG. 9). At the center position of the intake stroke, the valve is opened with a lift amount larger than the maximum lift amount Ld of the intake valve 10b by the decompression cam 24 and more than 1/2 of the maximum lift amount La of the intake valve 10a.

3 and 5, in the normal valve operating device Va, the first connection switching mechanism 36 provided in the intake sub-rocker arm group 30i includes a pair of sub-rocker arms that are adjacent to each other in the axial direction in accordance with the engine operating state. Connection members 36a and 36c for connecting and releasing 32i and 34 to each other, and a position control unit that enables connection and release of the pair of sub rocker arms 32i and 34 by changing the positions of the connection members 36a and 36c. 36d, 36f, and 36g.
The connecting members 36a and 36c include a connecting pin 36a that selectively occupies a connecting position arranged over both the sub rocker arms 32i and 34 and a connecting release position arranged only in the fourth sub rocker arm 34, and a second sub And a connection release pin 36c disposed only on the rocker arm 32i.
The position control units 36d, 36f, and 36g are disposed in the second sub-rocker arm 32i to move the connection pin 36a to the connection release position, and disposed in the hydraulic chamber 36d to release the connection pin 36a. A spring 36g that is biased toward the connection release position via the pin 36c, and a hydraulic chamber 36f that is provided on the fourth sub-rocker arm 34 and moves the connection pin 36a to the connection position.

The second connection switching mechanism 37 provided in the sub rocker arm group 30i (30e) is a connecting member 37a, 37b that connects and disconnects the three sub rocker arms 31i to 33i that are adjacent to each other in the axial direction in accordance with the engine operating state. , 37c, and position control units 37f, 37g that enable connection and release of the sub rocker arms 31i to 33i by changing the positions of the connection members 37a, 37b, 37c.
The connection members 37a, 37b, and 37c alternatively occupy a connection position that is disposed across a pair of axially adjacent sub rocker arms 31i and 33i and a connection release position that is disposed only on the sub rocker arm 31i. The second connecting pin that occupies alternatively the first connecting pin 37a, the connecting position arranged across a pair of adjacent sub rocker arms 32i, 33i, and the connecting release position arranged only in the sub rocker arm 33i. 37b and a connection release pin 37c disposed only on the sub rocker arm 32i.
The position control units 37f and 37g are provided in the sub rocker arm 31i to move the first and second connecting pins 37a and 37b to the connecting position, and the sub rocker arm 32i is provided in the both connecting pins 37a and 37g. A spring 37g for urging 37b toward the connection release position via the connection release pin 37c.

Referring to FIGS. 3, 4, and 6, in the stop valve operating device Vb, the first connection switching mechanisms 56 provided in the sub rocker arm group 50 i (50 e) are adjacent to each other in the axial direction according to the engine operating state. A pair of sub-rocker arms 51, 54 and a pair of sub-rocker arms 52, 55 are connected to and disconnected from each other, and the positions of the connecting members 56a, 56c are changed to change the position of the pair of sub-rocker arms 51, 54 Position control units 56d, 56f, and 56g that enable connection and disconnection between the rocker arms 51 and 54 and the pair of sub-rocker arms 52 and 55 are provided.
The connection members 56a and 56c alternatively select a connection position disposed across the sub-rocker arms 51 and 54 and the sub-rocker arms 52 and 55 and a connection release position disposed only on the sub-rocker arms 54 and 55. The connecting pin 56a occupies and the connection release pin 56c disposed only on the sub rocker arms 51 and 52.
The position control units 56d, 56f, and 56g are provided in the sub rocker arms 51 and 52 to connect the connection pin 56a to the hydraulic chamber 56d for moving the connection pin 56c to the connection release position and the sub rocker arms 54 and 55, respectively. A hydraulic chamber 56f for moving to a position and a spring 56g disposed in the hydraulic chamber 56f and biasing the connecting pin 56a toward the connecting position are provided.

The second connection switching mechanism 57 includes connection members 57a, 57b, and 57c that connect and release the three sub rocker arms 51 to 53 that are adjacent to each other in the axial direction according to the engine operating state, and the connection members 57a and 57b. , 57c, and position control units 57f, 57g that enable connection and release of the sub-rocker arms 51-53 by changing the positions of the sub-rocker arms 51-53.
The connecting members 57a, 57b, and 57c alternatively occupy a connecting position that is arranged across a pair of sub rocker arms 51 and 52 that are adjacent in the axial direction and a connecting release position that is arranged only on the sub rocker arm 51. The second connecting pin that occupies the first connecting pin 57a, the connecting position arranged across the pair of adjacent sub rocker arms 52, 53, and the connecting release position arranged only in the sub rocker arm 53 57b and a connection release pin 57c disposed only on the sub rocker arm 52.
The position control units 57f and 57g are provided in the sub rocker arm 51 to move the first and second connection pins 57a and 57b to the connection position, and are provided in the second sub rocker arm 52 and both connection pins. And a spring 57g for urging 57a and 57b toward the connection release position via the connection release pin 57c.

  1, 4, and 5, the internal combustion engine E includes a hydraulic control system as a control system for controlling the regular valve characteristic variable mechanism Aa and the stop valve characteristic variable mechanism Ab. The hydraulic control system for supplying a part of the oil discharged from the oil pump 19 of the lubrication system included in the internal combustion engine E to the connection switching mechanisms 36, 37, 56, 57 as the working oil is the operation discharged from the oil pump 19. An oil supply passage 70 through which oil is guided and one or more, here, a plurality of first to fifth control oil passages 71a to 75a (a plurality of three first oil passages 71a to 75a) formed inside the rocker shaft 63i (63e). 1 to the third control oil passages 71a to 73a) and one or more, five in this case, provided in the sub rocker arm groups 50i and 30i and opened to the hydraulic chambers 56f, 56d, 57f, 36d, 36f, and 37f. One or more, in this case multiple, openings provided in the first to fifth end oil passages 71b to 75b and the sub rocker arm groups 50e and 30e and open to the hydraulic chambers 56f, 56d, 57f and 37f. The first to fifth hydraulic control valves 71v to 75v attached to the cylinder head 2 and controlling the supply of hydraulic oil in the oil supply passage 70 to the control oil passages 71a to 75a. And a hydraulic control valve group 76 composed of

  The hydraulic control valves 71v to 75v controlled by the control device 80 in accordance with the engine operating state are used for hydraulic oil in the oil supply passage 70 through the control oil passages 71a to 75a and the end oil passages 71b to 75b. 57f, 36d, 36f, and 37f are supplied to the hydraulic chambers 56f, 56d, 57f, 36d, 36f, and 37f through the end oil passages 71b to 75b and the control oil passages 71a to 75a. The oil is discharged into the valve chamber 14 and the oil pressure in each of the oil pressure chambers 56f, 56d, 57f, 36d, 36f, and 37f is controlled to a high oil pressure and a low oil pressure.

Referring to FIGS. 1, 5, and 6, the internal combustion engine E includes a control device 80 that controls the fuel injection valve 12 and the hydraulic control valves 71 v to 75 v in accordance with the engine operating state. The control device 80 controls the valve characteristic variable mechanisms Aa and Ab including the connection switching mechanisms 36, 37, 56 and 57 via the hydraulic control valves 71v to 75v.
The control device 80 controls the operation of the engine state detection means 82 for detecting the state of the internal combustion engine E, and the operation of the fuel injection valve 12 and the hydraulic control valves 71v to 75v according to the engine state detected by the engine state detection means 82. An electronic control unit (hereinafter referred to as “ECU”) 81.
The ECU 81 includes a computer including a storage device that stores an input / output interface, a central processing unit, various control programs, various maps, and the like. In the map, a valve operating characteristic map for setting valve operating characteristics of the first and second intake valves 10a and 10b (first and second exhaust valves 11a and 11b) by the valve characteristic variable mechanisms Aa and Ab (see FIG. 9). ) Is included.

  The engine state detection means 82 is a rotation speed detection means for detecting the engine rotation speed N (see FIG. 9) of the internal combustion engine E, and an engine load D (that is, a required torque amount by the driver based on the accelerator operation amount by the driver). ), A crank angle detecting means for detecting the crank angle that is the rotational position of the crankshaft 6 (see FIG. 1), and the opening degree is controlled by the control device 80 based on the accelerator operation amount. And an intake air amount detecting means for detecting an intake air amount whose flow rate is controlled by the throttle valve 15a.

  The ECU 81 sets the fuel amount injected from the fuel injection valve 12 and the injection timing thereof according to the engine rotational speed N and the intake air amount as the engine state, and sets the fuel injection valve 12 based on the fuel amount and the injection timing. The hydraulic control valves 71v to 75v are controlled according to the engine operating state.

Referring to FIGS. 1, 3, 5, 6, and 9, the valve characteristic variable mechanisms Aa and Ab including the connection switching mechanisms 36, 37, 56, and 57 include the connection switching mechanisms 36, 37, 56, and 57. Depending on the connection and release of the sub rocker arm groups 30i, 50i (30e, 50e) by the control, at least the valve operating characteristics of the first and second intake valves 10a, 10b are controlled in each cylinder C. In this embodiment, the valve operating characteristics of the first and second intake valves 10a and 10b (first and second exhaust valves 11a and 11b) are controlled to be changeable.
More specifically, the connection switching mechanisms 36, 37, 56, and 57 are controlled by the ECU 81 via the hydraulic control valves 71v to 75v, so that the valve characteristic variable mechanisms Aa and Ab differ depending on the engine operating state. In order to control the opening and closing of the intake valves 10a and 10b (exhaust valves 11a and 11b) with the valve operating characteristics, the valve operating characteristics are set to the following low speed mode M1, high speed mode M2, idle cylinder mode M3 and decompression mode according to the engine operating state. Set to M4.

(1) Low speed mode M1 as the first operation mode
In the regular valve operating device Va, the hydraulic oil in the hydraulic chamber 36d becomes high hydraulic pressure, and the hydraulic oil in the hydraulic chambers 36f, 37f becomes low hydraulic pressure, so that the second and fourth sub-rocker arms 32i, 34 are disconnected, The first to third sub rocker arms 31 to 33 are disconnected from each other. Further, in the suspension valve operating device Vb, the hydraulic oil in the hydraulic chamber 56f becomes a high hydraulic pressure, and the hydraulic oil in the hydraulic chambers 56d and 57f becomes a low hydraulic pressure, so the first and fourth sub rocker arms 51 and 54 are connected. The second and fifth sub rocker arms 52i and 55 are connected, and the first to third sub rocker arms 51 to 53 are disconnected from each other.
For this reason, in all cylinders C of the internal combustion engine E, the first intake valve 10a (both exhaust valves 10) is provided by the low speed cams 21i, 44i (21e, 22e, 44e, 45e), and the second intake valve 10b is provided by the substantially rest cam. Opening and closing control is performed by 22i and 45i, respectively, and swirls that are eddy currents of air are generated in the respective combustion chambers 5 by the air sucked from the intake passage Pi.

(2) High speed mode M2 as the second operation mode
In the service valve device Va, the hydraulic oil in the hydraulic chambers 36d and 37f becomes high hydraulic pressure, and the hydraulic oil in the hydraulic chamber 37f becomes low hydraulic pressure, so that the second and fourth sub-rocker arms 32i and 34 are disconnected, 1st-3rd sub rocker arms 31-33 are connected. In the stop valve device Vb, the hydraulic oil in the hydraulic chambers 56f and 57f becomes high hydraulic pressure, and the hydraulic oil in the hydraulic chamber 56d becomes low hydraulic pressure, so that the first and fourth sub rocker arms 51 and 54 are connected to each other. The second and fifth sub rocker arms 52 and 55 are connected, and the first to third sub rocker arms 51 to 53 are connected.
For this reason, in all the cylinders C, both intake valves 10a and 10b (both exhaust valves 11a and 11b) are controlled to open and close by the high-speed cams 23i and 43i (23e and 43e).

(3) Rest cylinder mode M3 as the third operation mode
In the service valve device Va, the hydraulic oil in the hydraulic chamber 36f becomes high hydraulic pressure, and the hydraulic oil in the hydraulic chambers 36d and 37f becomes low hydraulic pressure, so that the second and fourth sub-rocker arms 32i and 34i are disconnected and The first to third sub rocker arms 31 to 33 are disconnected. In the suspension valve operating device Vb, the hydraulic oil in the hydraulic chamber 56d becomes high hydraulic pressure, and the hydraulic oil in the hydraulic chambers 56f, 57f becomes low hydraulic pressure, so that the first and fourth sub rocker arms 51, 54 are disconnected, The second and fifth sub rocker arms 52 and 55 are disconnected, and the first to third sub rocker arms 51 to 53 are disconnected.
Therefore, in the first and fourth cylinders C1 and C4, the intake valve 10a (both exhaust valves 11a and 11b) is controlled to be opened and closed by the low speed cam 21i (21e and 22e), and the intake valve 10b is controlled by the substantially idle cam 22i. Is done. Further, in the second and third cylinders C2 and C3, both the intake valves 10a and 10b (both exhaust valves 11a and 11b) are closed, and both the cylinders C2 and C3 are deactivated.

(4) Decompression mode M4 as the fourth operation mode
In the regular valve operating device Va, the hydraulic oil in the hydraulic chamber 36f becomes high hydraulic pressure, and the hydraulic oil in the hydraulic chamber 36d becomes low hydraulic pressure, so that the second and fourth sub rocker arms 32i and 34 are connected to each other. The three sub rocker arms 31 to 33 are disconnected. In the stop valve device Vb, the connection state of the sub-rocker arms 51 to 55 is the same as that in the idle cylinder mode M3.
Therefore, in the first and fourth cylinders C1 and C4, the intake valve 10a (both exhaust valves 11a and 11b) is controlled to open and close by the low speed cam 21i (21e and 22e), and the intake valve 10b is controlled by the decompression cam 24, respectively. Further, the second and third cylinders C2 and C3 are in a resting state.

  As described above, the variable valve characteristic mechanisms Aa and Ab including the connection switching mechanisms 36, 37, 56 and 57 are controlled by the control device 80, and at least the second intake air of the first and second intake valves 10a and 10b. In order to change the valve operating characteristics of the valve 10b, in this embodiment, the valve operating characteristics of the first and second intake valves 10a and 10b and the first and second exhaust valves 11a and 11b according to the engine operating state, In the sub rocker arm groups 30i, 50i (30e, 50e), the first to third predetermined number of cams 21i-23i, 24, 41i-45i (21e-23e, 41e-45e) (or each cam group 20i). , 40i (20e, 40e)), one or two specific cams are selected according to the engine operating state.

In this embodiment, the specific cams are the low-speed cams 21i, 44i (21e, 22e, 44e, 45e) and the substantially pause cams 22i, 45i in the low-speed mode M1, and the high-speed cams 23i, 43i ( 23e, 43e), in the idle cylinder mode M3, the low speed cam 21i (21e, 22e), the substantially idle cam 22i and the idle cams 41i, 42i (41e, 42e), and in the decompression mode M4, as the first specific cam The low-speed cam 21i, the decompression cam 24 as the second specific cam, the low-speed cams 21e and 22e as the third specific cam, the substantial pause cam 22i and the pause cams 41i and 42i (41e and 42e) as the fourth specific cam.
In the valve train V, the connection switching mechanisms 56 and 57 constitute a cylinder resting mechanism that switches the second and third cylinders C2 and C3 between an operating state and a resting state according to the engine operating state.

Referring to FIG. 9, when the engine operating state of the internal combustion engine E is divided into a low speed operating state R1 and a high speed operating state R2 with respect to the engine rotational speed N, the engine rotational speed N Further, by controlling the hydraulic control valves 71v to 75v in accordance with the engine operating state determined based on the engine load D, the valve characteristic variable mechanisms Aa and Ab are controlled based on the valve operating characteristic map shown in FIG. , 10b (exhaust valves 11a, 11b), the connection switching mechanisms 36, 37, 56, 57 are controlled so as to set the valve operating characteristics.
The boundary rotational speed Nb changes according to the engine load D. The larger the engine load D, the smaller the engine rotational speed N becomes constant near the maximum load Df.

  Therefore, the valve characteristic variable mechanisms Aa and Ab are controlled by the ECU 81, and when the engine operating state is the low speed operating state R1 including the boundary rotational speed Nb, the valve operating characteristics are determined according to the engine rotational speed N and the engine load D. Is set to any one of the low speed mode M1, the cylinder deactivation mode M3, and the decompression mode M4, and when in the high speed operation state R2, the valve operating characteristic is set to the high speed mode M2.

  Specifically, referring to FIG. 3 and FIG. 9, a predetermined operation state including a specific operation state R4, which will be described later, including the start operation state in which the internal combustion engine E is driven by the start device and the idling operation state. When in the low speed operation state R1 other than R3, the internal combustion engine E is operated in a state where the valve characteristic variable mechanisms Aa and Ab are in the low speed mode M1. For this reason, the second intake valve 10b is in a closed state (see FIG. 7). In the first to fourth cylinders C1 to C4, which are all cylinders C, the intake passage Pi (FIG. 1) passes through the first intake valve 10a. The air that flows into the combustion chamber 5 from the reference) generates a swirl in the combustion chamber 5, and this swirl promotes the mixing of the fuel and air injected from the fuel injection valve 12, thereby improving the homogeneity of the air-fuel mixture. To do. As a result, the combustibility is improved and the engine torque is increased.

Further, the engine operation state is the low speed operation state R1, and the engine rotation speed N is in the range between the first rotation speed N1 set in advance and the second rotation speed N2 larger than the first rotation speed N1. When the engine load D is in the predetermined operation state R3 (that is, the low speed rotation / low load operation state or the cylinder deactivation operation state) equal to or lower than the first load D1 set in advance, the valve characteristic variable mechanisms Aa, Ab are The cylinder rest mode M3 is set. For this reason, the internal combustion engine E is operated in a cylinder-free operation in which the second and third cylinders C2 and C3 are in a stopped state and the first and fourth cylinders C1 and C4 are in an operating state.
At this time, in the first and fourth cylinders C1 and C4, the intake air amount and generated torque per cylinder are larger than those in the all-cylinder operation in which all the cylinders C1 to C4 are operating, and the second intake air is generated. Since the valve 10b is substantially in a closed state, the air sucked into the combustion chamber 5 from the first intake valve 10a generates a strong swirl as compared with the operation in the low speed mode M1, so that the combustion chamber 5 Mixing of fuel and air inside is promoted, and high combustibility is maintained. And the fuel efficiency performance of the internal combustion engine E improves by this idle cylinder driving.

Further, the engine operating state is a part of the predetermined operating state R3, the engine rotational speed N is greater than the first specific rotational speed N3, which is greater than the first rotational speed N1, and the first specific rotational speed N3. The specific operation state R4 (or decompression operation) when the engine load D is equal to or smaller than the second load D2 smaller than the first load D1 when the engine load D is in the range of the second specific rotation speed N4 smaller than the second rotation speed N2. In the state), the variable valve characteristic mechanisms Aa and Ab are in the decompression mode M4.
Here, the first specific rotation speed N3 is an engine rotation speed N equal to or higher than the first rotation speed N1, which is an engine rotation speed N equal to or higher than the idling rotation speed, and is higher than the first rotation speed N1 in this embodiment.
The first and second loads D1 and D2, which are preset loads, change according to the engine speed N, and become larger as the engine speed N increases. Further, hysteresis characteristics may be imparted to the first and second loads D1, D2.

When the engine operating state is the specific operating state R4, the ECU 81 starts fuel injection in the intake stroke as shown in FIG. 8 in order to improve the homogenization of the air-fuel mixture in the combustion chamber 5, and The fuel injection timing of the fuel injection valve 12 is set so that the fuel injection ends preferably in the first half of the intake stroke so as to end before the opening timing of the second intake valve 10b by the decompression cam 24.
Even in this specific operation state R4, in the first and fourth cylinders C1 and C4, the air sucked into the combustion chamber 5 from the first intake valve 10a (the air-fuel mixture in the combustion chamber 5 in the compression stroke of the previous cycle). Is blown back into the intake passage Pi including the intake port 7, the blown-back air-fuel mixture is also included.) Produces a swirl in the combustion chamber 5, and the fuel injected from the fuel injection valve 12 by this swirl Mixing with air is promoted, and the air-fuel mixture in the combustion chamber 5 is homogenized. Then, the air is homogenized in the combustion chamber 5 through the intake port 7 through the second intake port 7b opened by the second intake valve 10b that is open from the latter half of the intake stroke to the first half of the compression stroke. The mixture is blown back. Further, in the compression stroke, since the compression pressure in the combustion chamber 5 is reduced by the second intake valve 10b being in the open state, the pumping loss due to the piston 4 is reduced.

Further, when the internal combustion engine E is in the high speed operation state R2, regardless of the engine load D, the valve characteristic variable mechanisms Aa and Ab are in the high speed mode M2, and the first to fourth cylinders C1 to C4 are shown in FIG. Thus, the intake valves 10a and 10b are greatly opened at the maximum lift amount, and the engine torque increases.
Here, as the engine operation state, the operation state other than the specific operation state R4 in the low speed operation state R1 and the high speed operation state R2 are all operation states different from the specific operation state R4. In the other operating state, the second intake valve 10b is controlled to open and close with a valve operating characteristic different from the valve operating characteristic of the decompression cam 24 by the low speed cam 21i, the substantial rest cam 22i or the high speed cam 23i other than the decompression cam 24. The

Next, operations and effects of the embodiment configured as described above will be described.
In the direct injection internal combustion engine E, the valve operating characteristics of the first and second intake valves 10a and 10b (first and second exhaust valves 11a and 11b) are changed according to the engine operating state under the control of the control device 80. The variable valve characteristics variable mechanisms Aa and Ab of the variable valve operating apparatus V are cams 21i to 23i constituting cam groups 20i and 40i (20e and 40e) in order to change the valve operating characteristics according to the engine operating state. When one or two specific cams are selected from 24, 41i to 45i (21e to 23e, 41e to 45e) and the engine operation state is the specific operation state R4, the regular valve characteristic varying mechanism Aa The low-speed cam 21i and the decompression cam 24 are selected as specific cams from the plurality of cams 21i to 23i, 24 constituting the 20i, and the low-speed cam 21i raises the first intake valve 10a on the exhaust side. The decompression cam 24 opens the second intake valve 10b with a maximum lift amount Ld smaller than the maximum lift amount La of the first intake valve 10a and controls the intake stroke in the intake stroke. When the engine is controlled to open from the latter half to the compression stroke, and the engine operating state is an operating state different from the specific operating state R4, the specific cam selected by the valve characteristic variable mechanism Aa is the low-speed cam 21i other than the decompression cam 24. The first and second intake valves 10a and 10b are controlled to open and close with a valve operating characteristic different from the valve operating characteristic of the decompression cam 24.
With this structure, in the specific operation state R4 in which the engine rotation speed N exceeds the idling rotation speed, the valve is opened near the exhaust top dead center, so that the first intake valve 10a is opened early in the intake stroke. Since the swirl is generated in the combustion chamber 5 by the intake air flowing into the combustion chamber 5, the homogenization of the fuel injected from the fuel injection valve 12 in the intake stroke is promoted. The second intake valve 10b is opened by the decompression cam 24 from the latter half of the intake stroke to the compression stroke, so that the air-fuel mixture that has been homogenized in the combustion chamber 5 passes from the second intake port 7b to the intake passage Pi. Blown back.
As a result, the air-fuel mixture homogenized by the swirl in the combustion chamber 5 is blown back to the intake passage Pi, so that the blow-back air-fuel mixture is again sucked into the combustion chamber 5 in the intake stroke of the next cycle. The variation in the air-fuel ratio in the engine is suppressed, and the variation in the air-fuel ratio of the blow-back mixture between the cylinders C1 and C4 is suppressed. Therefore, the torque fluctuation of the internal combustion engine E can be reduced, and therefore the rotation fluctuation can be reduced.
Further, the second intake valve 10b that is in the open state in the compression stroke enables the blow-back control, reduces the pumping loss, and improves the fuel efficiency.
In this way, in the internal combustion engine E, by controlling the opening and closing of the intake valve 10b for returning the air-fuel mixture to the intake passage Pi, variation in the air-fuel ratio of the air-fuel mixture returning to the intake passage Pi is suppressed. Torque fluctuations can be reduced, and pumping loss can be reduced to improve fuel efficiency.

  In the center position of the intake stroke in the specific operation state R4, the first intake valve 10a is opened with a lift amount equal to or greater than ½ of the maximum lift amount La, and the second intake valve 10b is driven by the fuel injection valve 12. When the second intake valve 10b is in the specific operation state R4 in which it is opened and closed by the decompression cam 24 due to the valve closing state throughout the fuel injection period, the first intake valve 10a has its maximum lift at the center position of the intake stroke. The second intake valve 10b is kept closed during the fuel injection period of the fuel injection valve 12 while the valve is opened with a lift amount that is 1/2 or more of the amount La. Since the swirl generated by the air sucked into the combustion chamber 5 through the first intake valve 10a that is relatively large opened can be strengthened, the combustion chamber before the second intake valve 10b is opened. It can promote the homogenization of the mixture at an internal, thus homogenized 吹返 mixed gas.

  Since the decompression cam 24 opens the second intake valve 10b so as to have the maximum lift amount Ld in the compression stroke, the lift amount of the second intake valve 10b is maximized in the compression stroke, so the second intake valve 10b Until the valve is opened with the maximum lift amount Ld, homogenization of the air-fuel mixture in the combustion chamber 5 proceeds by swirl, so that the homogenization of the blown-back air mixture is improved.

  In the specific operation state R4, the control device 80 terminates the fuel injection by the fuel injection valve 12 before the decompression cam 24 opens the second intake valve 10b, so that when the intake valve 10b is opened, combustion is performed by swirl. Since the homogenization of the air-fuel mixture in the chamber 5 is proceeding, the homogenization of the blown-back air mixture is improved.

  Provided with a plurality of cylinders C composed of cylinders C1 and C4 that are service cylinders and cylinders C2 and C3 that are cylinders that can be stopped, and when the engine operation state is a predetermined operation state R3, the cylinders C2 and C3 are in a stop state In the internal combustion engine E, the variable valve gear V including the regular valve characteristic variable mechanism Aa is provided for the cylinders C1 and C4, and the specific operation state R4 is a part of the predetermined operation state R3. . With this structure, torque resulting from variations in the air-fuel ratio of the blow-back mixture during idle cylinder operation when the intake air amount and generated torque per cylinder are large compared to during all cylinder operation when all cylinders C are in operation. Variation is reduced.

The variable valve operating device V includes a plurality of first to fourth sub rocker arms 31i to 33i, 34, each of which is controlled by the first predetermined number of cams 21i to 23i, 24. The cam 30i includes a group 30i, and these cams 21i to 23i, 24 control the opening and closing of the first and second intake valves 10a, 10b via the rocker arm group 30i and the main rocker arms (61i, 62i). And connection switching mechanisms 36 and 37 for controlling the connection and release of the second and fourth sub-rocker arms 32i and 34 and the first to third sub-rocker arms 31i to 33i.
With this structure, the use of the connection switching mechanisms 36 and 37 for controlling the connection and release of the sub-rocker arms 32i and 34 and the first to third sub-rocker arms 31i to 33i constituting the sub-rocker arm group 30i enables a specific operation state. The valve operation of the second intake valve 10b includes a valve operation characteristic for reducing the compression pressure by the decompression cam 24 at R4 and another valve operation characteristic by the cams 22i and 23i in an operation state different from the specific operation state R4. The characteristics can be easily switched.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
In addition to the direct injection internal combustion engine, the internal combustion engine may include a fuel injection valve that injects fuel into the intake port.
The valve operating apparatus includes one cam shaft disposed between an intake sub cam follower (for example, an intake sub rocker arm group) and an exhaust sub cam follower (for example, an exhaust sub rocker arm group) in an orthogonal direction. An SOHC type having an intake cam and an exhaust cam may be used.
The internal combustion engine does not have to be provided with a cylinder that can be stopped. In this case, the opening / closing control of the second intake valve by the decompression cam is performed by all or some cylinders of the internal combustion engine.
The first predetermined number of cams constituting the intake cam group may be two, one of which is a decompression cam, and the intake rocker arm group may be constituted by three rocker arms. In this case, the variable valve characteristic mechanisms Aa and Ab have two cams (that is, a decompression cam and one remaining cam) in the specific operation state R4 in order to change the valve operation characteristic according to the engine operation state. When the engine operation state different from the specific operation state R4 is selected, one cam (that is, the remaining cam) is selected, and the valve operation characteristic of only the second intake valve is the engine operation state. It will be changed according to.
The intake cam follower and the exhaust cam follower have no main rocker arm, the intake sub-rocker arm group (exhaust sub-rocker arm group) serves as the intake rocker arm group (exhaust rocker arm group), and the first and second rocker arms serve as the first and second intake air. You may have a press part which presses a valve (1st, 2nd exhaust valve). The intake cam follower (exhaust cam follower) may include a cylindrical valve lifter that is slidably supported by the cylinder head.
In addition to the connection switching mechanism, the variable valve characteristic mechanism may be a mechanism that moves the cam itself in order to change the valve operating characteristic. In this case, a part of one cam selected by the variable valve characteristic mechanism is A decompression cam that controls the opening and closing of the second intake valve with the same valve operating characteristics as the decompression cam 24 is configured.
The first rotation speed may be an idling rotation speed, and in this case, the first specific rotation speed may be an idling rotation speed.
The first and second intake ports may be openings in the combustion chamber of the first and second intake passages independent of each other.
The target on which the internal combustion engine is mounted may be a ship propulsion device such as an outboard motor having a crankshaft oriented in the vertical direction, or a power generation device, in addition to the vehicle.
The internal combustion engine may be a compression ignition engine, and may be a V-type engine or a single cylinder engine having one cylinder.

5 Combustion chamber 10a, 10b Intake valve 12 Fuel injection valve 20i, 40i Intake cam group 24 Decompression cam 30i, 30e Sub rocker arm group 36, 37 Connection switching mechanism 80 Control device E Internal combustion engine V Valve mechanism Aa, Ab Valve characteristic variable mechanism.

Claims (6)

First and second intake valves that respectively open and close the first and second intake ports of the intake passage that opens to the combustion chamber;
A predetermined number of cams that respectively control the opening and closing of the first and second intake valves in synchronization with the rotation of the crankshaft, and valve operating characteristics of at least the second intake valve of the first and second intake valves A variable valve operating apparatus comprising a variable valve characteristic mechanism that can be changed according to the engine operating state;
A fuel injection valve for injecting fuel into the intake air;
An internal combustion engine comprising: a control device that controls the valve characteristic variable mechanism according to the engine operating state;
The valve characteristic variable mechanism controlled by the control device selects one or two specific cams from the predetermined number of cams in order to change the valve operating characteristic according to the engine operating state,
When the engine operation state is a specific operation state at an engine rotation speed equal to or higher than an idling rotation speed, the specific cams are a first specific cam and a second specific cam, and the first specific cam is the first intake air The valve is controlled to be in an open state near the exhaust top dead center, and the second specific cam is a decompression cam, and the second intake valve is a maximum lift amount smaller than the maximum lift amount of the first intake valve. And the valve is controlled to open from the second half of the intake stroke to the compression stroke,
When the engine operating state is an operating state different from the specific operating state, the specific cam controls the opening and closing of the first and second intake valves with a valve operating characteristic different from that of the decompression cam. An internal combustion engine. The internal combustion engine of claim 1,
In the center position of the intake stroke in the specific operation state, the first intake valve opens with a lift amount that is 1/2 or more of the maximum lift amount;
The internal combustion engine, wherein the second intake valve is in a closed state throughout a fuel injection period of the fuel injection valve. The internal combustion engine according to claim 1 or 2,
The internal combustion engine, wherein the second specific cam opens the second intake valve so as to be the maximum lift amount in a compression stroke. The internal combustion engine according to any one of claims 1 to 3,
The control device controls the fuel injection timing by the fuel injection valve according to the engine operating state,
In the specific operation state, the control device ends fuel injection before the second specific cam opens the second intake valve. A plurality of cylinders composed of a service cylinder that is normally operated and a cylinder that can be stopped according to the engine operation state; the cylinder can be stopped when the engine operation state is a predetermined operation state; The internal combustion engine according to any one of claims 1 to 4, wherein the possible cylinder is in a resting state.
The variable valve operating device having the valve characteristic variable mechanism is provided for the service cylinder,
The internal combustion engine, wherein the specific operation state is a partial operation state of the predetermined operation state. The internal combustion engine according to any one of claims 1 to 5,
The variable valve operating apparatus includes a rocker arm group composed of a plurality of rocker arms, each of which is controlled by the predetermined number of cams.
The predetermined number of cams controls opening and closing of the first and second intake valves via the rocker arm group,
The internal combustion engine, wherein the variable valve characteristic mechanism is a connection switching mechanism for controlling connection and release of connection between the rocker arms.

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