JP2002276395A - Intake device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a sufficient quantity of residual gas even in a middle load area to attain a reduction in pumping loss and an improvement in fuel consumption in an intake device capable of adjusting the inlet air quantity by drive- controlling a variable valve system and omitting a throttle valve. SOLUTION: This intake device comprises at least the variable valve system capable of changing the operating timing and closing timing of an intake valve and an ECU (control means) for drive-controlling the variable valve system to adjust the inlet air quantity. In the middle load area (b), the opening timing of the intake valve is delayed to after the closing timing of an exhaust valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an internal combustion engine used in an automobile or the like.

[0002]

2. Description of the Related Art As a conventional intake device for an internal combustion engine, Japanese Patent Application Laid-Open No. 8-334070 discloses an intake manifold connected to an intake port of an internal combustion engine in order to make the device compact and easy to manufacture and assemble. A technique has been disclosed in which an intake passage forming body) is formed of a resin material and an air cleaner is built in the intake manifold.

[0003]

However, the intake device described in this publication has the following problems. That is,
In order to obtain a desired internal EGR amount (amount of combustion gas remaining in the cylinder) in a medium load range, using a variable valve operating device capable of changing a valve lift characteristic of an intake valve or an exhaust valve, exhaust top dead center When a valve overlap is provided in which both the intake valve and the exhaust valve open before and after, high-temperature combustion gas flows back to the intake port side and directly flows into the resin-made intake manifold (intake passage forming body) or air cleaner. Spraying, which may lead to such damage and decrease in durability.

As another problem, in a general gasoline internal combustion engine in which the intake air amount is adjusted mainly by a throttle valve, as is well known, when the throttle valve is throttled, a negative pressure occurs in the intake passage downstream of the throttle valve. As a result, aperture loss occurs.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and an intake system for an internal combustion engine according to the present invention can change at least the opening timing and the closing timing of an intake valve. Variable valve operating device, and control means for controlling the drive of the variable valve operating device to adjust the amount of intake air,
In the middle load range, the opening timing of the intake valve is retarded after the closing timing of the exhaust valve.

According to the first aspect of the present invention, since the intake air amount can be adjusted by controlling the drive of the variable valve device, a throttle valve for restricting the intake passage to adjust the intake air amount is required. In addition, the configuration can be simplified, and the throttle loss, which is a problem of the internal combustion engine including the throttle valve, can be eliminated.

However, in such a throttleless internal combustion engine, since a sufficient negative pressure is not provided in the intake port, a sufficient amount of the internal EGR ( It is difficult to obtain the residual gas amount). Therefore, in the present invention, in the middle load range, the opening timing of the intake valve is retarded after the closing timing of the exhaust valve. This makes it possible to secure a sufficient amount of residual gas even in a medium load region.

Preferably, as in the invention according to claim 2,
At least a part of the intake passage forming body connected to the intake port of the engine body is made of resin mainly for the purpose of weight reduction.

More preferably, an air cleaner is incorporated in a collector constituting a part of the intake passage forming body mainly for the purpose of downsizing, as in the invention according to claim 3.

When a part of the intake passage forming member is made of resin or an air cleaner is built in the collector, the combustion gas in the cylinder flows backward through the intake passage and the resin portion of the intake passage forming member is formed. Spraying on the air cleaner or the air cleaner may cause damage or deterioration of this portion.

Therefore, preferably, in the medium load range, the closing timing of the exhaust valve is retarded from the top dead center. In this case, in the initial stage of the intake stroke in which the piston starts to descend after the top dead center, only the exhaust valve is open, and after the combustion gas once discharged to the exhaust port is again introduced into the cylinder as residual gas, the intake The port opens and fresh air is introduced into the cylinder. When the intake port is opened, the residual gas in the cylinder does not flow back to the intake port because the piston is in the downward stroke. Therefore, there is no possibility that the resin gas of the intake passage forming body or the air cleaner is damaged or deteriorated due to the backflow of the residual gas.

Alternatively, in the medium load range, the closing timing of the exhaust valve is advanced from the top dead center, and the exhaust valve is closed for a period longer than the period from the closing timing of the exhaust valve to the top dead center. The opening timing of the intake valve is retarded from the top dead center. In this case, when the exhaust valve is closed in the latter half of the exhaust stroke in which the piston before the exhaust top dead center rises, residual gas remaining in the cylinder is sealed in the cylinder. Thereafter, when the piston enters a suction stroke in which the piston descends through the top dead center, the pressure in the cylinder, which has once risen, decreases, and a period longer than the period from the closing timing of the exhaust valve to the top dead center is after the top dead center. Over time,
The pressure in the cylinder becomes substantially negative, after which the intake valve is opened. Therefore, there is no danger that the residual gas remaining in the cylinder will flow back to the intake port side, and there is no danger that the resin flow of the intake passage forming body and the air cleaner will be damaged or deteriorated due to the backflow of the residual gas.

According to a sixth aspect of the present invention, the variable valve apparatus has an operating angle changing mechanism capable of mainly changing an operating angle of an intake valve or an exhaust valve. , A control cam provided eccentrically to the control shaft, a rocker arm rotatably fitted to the outer periphery of the control cam, and a shaft driven by rotational power transmitted from a crankshaft. A drive shaft that rotates around,
An oscillating cam that is swingably fitted to the drive shaft and presses and drives an intake valve or an exhaust valve; an eccentric cam provided eccentrically to the drive shaft; and a rotatably fitted outer periphery of the eccentric cam. A first link whose tip is rotatably connected to one end of the rocker arm; and a second link which is rotatably connected to the other end of the rocker arm and the tip of the swing cam. And a link.

Accordingly, when the drive shaft rotates around the shaft in conjunction with the rotation of the crankshaft, the first link externally fitted to the eccentric cam moves, and the movement of the first link is converted into the rocking movement of the rocker arm. Then, the swing cam swings via the second link. The oscillating cam pushes an intake / exhaust valve (an intake valve or an exhaust valve), and the intake / exhaust valve opens and closes. Further, when the control shaft is driven to rotate in accordance with the engine operating state, the center position of the control cam, which is the rocking arm of the rocker arm, changes, and the posture of the rocker arm and each link changes, and the rocking of the rocking cam changes. Dynamic characteristics change. As a result, the operating angle (and the valve lift) of the intake and exhaust valves is continuously changed.

In the operating angle changing mechanism having such a structure, the swing cam for opening and closing the intake / exhaust valve is mounted coaxially with the drive shaft, so that the shift between the swing cam and the drive shaft is caused. There is no danger, the control accuracy is excellent, and the rocker arm and each link can be integrated around the drive shaft to achieve compactness, which is excellent in engine mountability. Also, since many of the connecting parts between the members are in surface contact, such as the bearing part between the eccentric cam and the first link and the bearing part between the control cam and the rocker arm, lubrication is easy and durability is high. ， Excellent reliability. Further, even when this operating angle changing mechanism is applied to a general fixed valve train having a fixed cam and a camshaft, if the swing cam and the drive shaft are arranged at the positions of the fixed cam and the camshaft. Since the layout can be changed very little, the application is very easy.

The invention according to claim 7 is characterized in that the variable valve operating device has a phase changing mechanism capable of changing the center phase of the operating angle of the intake valve or the exhaust valve with respect to the phase of the crankshaft. I have.

Such a phase changing mechanism can be intensively arranged around one end of the drive shaft (or a camshaft of a fixed valve system) to which rotational power is transmitted from a crankshaft. It can be easily used together without interfering with the change mechanism. As described above, by applying both the phase changing mechanism and the operating angle changing mechanism to one of the intake valve and the exhaust valve, the opening timing and the closing timing of the intake valve or the exhaust valve can be adjusted independently of each other. Thus, more advanced valve timing control can be performed.

[0018]

As described above, according to the present invention, by controlling the driving of the variable valve apparatus, the amount of intake air can be adjusted without relying on the throttle valve, and a sufficient amount of residual air can be maintained even in a medium load range. A gas amount can be given, so that pumping loss can be reduced and fuel efficiency can be improved.

In particular, according to the second aspect of the present invention, at least a part of the intake passage forming member is made of resin, so that the weight and cost can be reduced.

According to the third aspect of the present invention, the air cleaner is built in the collector constituting a part of the intake passage forming body, and the size can be reduced.

According to the fourth or fifth aspect of the present invention, it is possible to reliably avoid a situation in which the residual gas in the cylinder flows backward to the intake port side to cause damage and deterioration of the resin portion of the intake passage forming body and the air cleaner. Can be.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an air intake device according to the present invention will be described.
An embodiment applied to a four-cylinder gasoline internal combustion engine will be described in detail with reference to the drawings.

First, the configuration, operation and effect common to all the embodiments will be described with reference to FIGS. The intake device of each embodiment is provided with a variable valve operating device capable of changing a valve lift characteristic (valve timing and valve lift amount) of an intake / exhaust valve (intake valve or exhaust valve) 1. As an example of such a variable valve operating device, FIG. 5 mainly shows an operating angle changing mechanism 10 capable of changing the operating angle and the valve lift amount of the intake / exhaust valve 1 and a rotational phase of a crankshaft (not shown). A phase change mechanism 20 that can change the phase (for example, the center phase) of the operating angle of the intake / exhaust valve 1 is illustrated.

The operating angle changing mechanism 10 has a drive shaft 11 and a control shaft 12 extending in the cylinder row direction in parallel with each other. The drive shaft 11 rotates around the axis by the rotational power transmitted from the crankshaft. This drive shaft 11 includes:
Swing cam 13 that can contact valve lifter 2 of intake / exhaust valve 1
Are rotatably fitted to the outside, and an eccentric cam 14 is fixed or integrally formed for each cylinder. The axis of the outer peripheral surface of the eccentric cam 14 is eccentric with respect to the axis of the drive shaft 11, and the ring-shaped first link 15 is rotatably fitted on the outer peripheral surface of the eccentric cam 14.

The control shaft 12 has a control cam 16 for each cylinder.
Are fixed or integrally formed. The axis of the outer peripheral surface of the control cam 16 is eccentric with respect to the axis of the control shaft 12,
A central portion of the rocker arm 17 is rotatably fitted on the outer peripheral surface of the control cam 16. This rocker arm 1
One end of 7 is rotatably connected to the distal end of the first link 15, and the other end of the rocker arm 17 is rotatably connected to one end of the second link 18 having a rod shape.
The other end of the second link 18 is rotatably connected to the tip of the swing cam 13.

Therefore, when the drive shaft 11 rotates around the shaft in conjunction with the rotation of the crankshaft, the first link 15 externally fitted to the eccentric cam 14 operates substantially in the translation direction, and the translation movement of the first link 15 is performed. Is converted into the rocking motion of the rocker arm 17, and the rocking cam 13 is
Swings. The oscillating cam 13 is brought into contact with and presses the valve lifter 2 of the intake / exhaust valve 1, whereby
The intake / exhaust valve 1 is driven to open and close against a reaction force of a valve spring (not shown).

The actuator 19 controls the control shaft 1.
2, the center position of the control cam 16 which is the rocking center of the rocker arm 17 changes, the postures of the rocker arm 17 and the links 15 and 18 change, and the rocking characteristics of the rocking cam 13 change. Change. As a result, both the operating angle and the valve lift of the intake / exhaust valve 1 are continuously changed. The center phase of the operating angle of the intake / exhaust valve 1 with respect to the rotational phase of the crankshaft hardly changes due to the operation of the operating angle changing mechanism 10.

The operating angle changing mechanism 10 having such a configuration is
Since the swing cam 13 for opening and closing the intake / exhaust valve 1 is coaxially mounted on the drive shaft 11, there is no possibility that the swing cam 13 and the drive shaft 11 are misaligned, and the control accuracy is excellent. And the rocker arm 17 and each link 1
By consolidating the parts 5, 18 around the drive shaft 11, the size can be reduced, and the engine can be easily mounted. Also,
Many of the connecting parts between the members are in surface contact, such as the bearing part between the eccentric cam 14 and the first link 15 and the bearing part between the control cam 16 and the rocker arm 17, so that lubrication is easy to perform, Excellent durability and reliability. Furthermore,
Even when the operating angle changing mechanism 10 is applied to a general fixed valve train having a fixed cam and a camshaft, the swing cam 13 and the drive shaft 11 are arranged at the positions of the fixed cam and the camshaft. The layout can be changed very little, and the application is extremely easy.

The phase changing mechanism 20 changes the rotational phase of the drive shaft 11 (or camshaft in the case of a fixed valve system) with respect to the rotational phase of the crankshaft to continuously maintain the central phase of the lift operating angle of the intake valve. The type using a vane, the type using a helical spline, and the like are publicly known, and a detailed description thereof will be omitted.

An ECU (engine control unit) 4 as a control means performs general engine control such as fuel injection control based on an engine operating state detected by various sensors and the like, and also controls the operating angle changing mechanism 10. The operation of the actuator 19 and the phase changing mechanism 20 (or its actuator) is controlled to change and control the valve lift characteristics of the intake / exhaust valve 1.

In each of the embodiments described below, a variable valve operating device is applied at least on the intake valve side.
The intake air amount can be adjusted. For example, the intake air amount can be reduced by advancing the closing timing of the intake valve from the bottom dead center, and the intake air amount can also be reduced by reducing the operating angle and the valve lift amount of the intake valve. . Therefore, it is possible to realize a simple structure that does not require a throttle valve for adjusting the intake air amount.

FIGS. 1 to 4 are cross-sectional views showing a schematic configuration of the intake device. As shown in FIG.
The intake ports 34 of a plurality of (four in this embodiment) cylinders constituting the cylinder row are open on the side wall 32 on the intake side of the cylinder 0, and the port openings 35 of the plurality of intake ports 34 are closed. The mounting bracket 36 covers the side wall 32 so as to cover it.
Fixed to. And, this mounting bracket 36
One of the collectors 38 is directly attached thereto, and a plurality of intake branches 40 respectively communicating with the plurality of intake ports 34 project from the collector 38.

The collector 38 is composed of two members, a collector upper divided body 42 and a collector lower divided body 44 made of a lightweight resin material. That is, for the purpose of reducing the weight mainly, the divided bodies 42 and 44 constituting a part of the formation body of the intake passage connected to the intake port 34 are made of resin. An air cleaner 46 is interposed between the two divided bodies 42 and 44. That is, as shown in FIG. 4, in a state where the air cleaner 46 and the gasket 48 are sandwiched between the collector upper divided body 42 and the collector lower divided body 44, the two divided bodies 42 and 44 are detachably fixed by the clip 50, for example. ing. In addition, in the divided bodies 42 and 44, an appropriate clip engaging portion 52 is provided in a recessed position at a clip mounting position.
In other parts, as shown by the broken line H in FIG. 4, the above-mentioned locking portion 52 is not formed.

As shown in FIG. 3, for example, as shown in FIG. 3, an upper flange portion 55 is fastened and fixed to a mounting bracket 36 by a pair of upper bolts 54. The lower flange portion 57 is fixed to the cylinder head 30 by the lower bolt 56.
Alternatively, it is fastened and fixed to the cylinder block 31 or these mounting members.

As shown in FIG. 2, a cylindrical intake port 58 is formed integrally with the upper collector section 42, and an intake pipe 62 is attached to the intake port 58 via a gasket 60. Have been. A pressure regulating valve 64 is disposed in the intake pipe 62. The pressure adjusting valve 64 is provided not for adjusting the intake air amount but for obtaining a minimum suction negative pressure required for the engine, and is used for controlling the engine operating state such as the engine speed and the accelerator opening. The drive is controlled by the ECU 4 accordingly.

At the inlet of the intake pipe 62, the filtering function is lower than that of the air cleaner 46 (coarse) so that large dust or the like does not bite into the pressure regulating valve 64.
A filter 66 is attached.

As shown in FIG. 2, the collector lower divided body 44 extends in a cylindrical shape toward the inside of the collector 38, and comprises a plurality of first branch constituting parts 68 constituting a part of the intake branch 40, and the intake port 34. Fuel injection valve 7 that injects fuel into
And a mounting plate 74 fixed to the mounting bracket 36 in surface contact.
And these parts 68, 72, 74 are integrally formed. The mounting plate portion 74 is relatively thicker than other portions in order to secure mounting rigidity.

The mounting bracket 36 is mounted on the cylinder head 3.
0, and is formed of a high-rigidity aluminum alloy or the like, and has a cylindrical second branch constituting portion 76 constituting a part of each intake branch 40 and a mounting boss portion 78 of the fuel injection valve 70.
And a mounting plate portion 80 interposed between the side wall 32 of the cylinder head 30 and the mounting plate portion 74 of the collector lower divided body 44, and these portions 76, 78, and 80 are provided.
Are integrally formed. This mounting bracket 36
Is typically fastened and fixed to the side wall 32 of the cylinder head 30 by a plurality of bolts 82 as shown in FIG.

The intake branch 40 is a cylindrical body that forms an intake passage from a port opening 35 of the intake port 34 to a bell mouth-shaped branch opening 84 that opens into the collector 38. Then gasket 8
The first branch component 68 and the second branch component 76 that are fitted through the second branch component 6.

As described above, the collector 3 is mounted on the mounting bracket 36 mounted on the side wall 32 of the cylinder head 30.
8, the support rigidity of the collector 38 is improved as compared with a case where the collector is attached to a protruding end of an intake branch (or an intake manifold) that protrudes from the cylinder head in the engine width direction, for example. ,
The vibration input acting on the collector 38 is also reduced. Also,
Since the collector 38 is arranged close to the side wall 32 of the cylinder head 30 and the intake branch 40 is substantially built in the collector 38, the intake device is made compact and the engine mountability is improved. .

In order to realize such a layout, it is required to shorten the intake branch 40 and increase the capacity of the collector 38. To shorten the intake branch 40 and increase the capacity of the collector 38, This can be achieved by using a system that adjusts the amount of intake air by changing the valve lift characteristics of the valve 1. That is, the layout of the intake device as shown in FIGS. 1 to 4 can be realized by using a variable valve operating device (see FIG. 5) capable of adjusting the intake air amount.

Considering further this point, if the capacity of the collector decreases, the full-open output decreases. Therefore, it is desired to increase the collector capacity in terms of output performance. However, in the conventional configuration in which the intake air amount is adjusted mainly by the throttle valve, the intake responsiveness decreases as the collector capacity increases. For example, even if the throttle valve is opened when acceleration is desired, if the volume of the collector disposed downstream of the throttle valve is large, the time required for the pressure (intake flow rate) near the intake valve to increase becomes longer, and as a result, the engine The time required for the torque to increase also increases. The same applies to deceleration.With the increase in collector capacity, the time from closing the throttle valve until the pressure in the collector decreases becomes longer, for example, the time from when the engine torque decreases to when the engine brake works is effective. It will be long. On the other hand, when the intake air amount is adjusted by changing the valve lift characteristics of the intake valve 1 closer to the combustion chamber than the collector, even if the collector capacity is increased, the above-described decrease in the intake response is caused. There is no. That is, the collector capacity can be sufficiently increased without concern about a decrease in the intake response.

Referring again to FIG. 1, the collector 38 has a dimension in the engine vertical direction (vertical direction in FIG. 1) substantially along the side wall 32 of the cylinder head 30.
The length is set to be longer than the dimension in the engine width direction (the left-right direction in FIG. 1) that is substantially orthogonal to 2. That is, the collector 38
It has a vertically long shape along the engine vertical direction (cylinder axis direction). For this reason, the amount of protrusion of the collector 38 in the engine width direction is suppressed, and the dead space below the cylinder head 30 can be used effectively, and the collector 3
8, the support rigidity and engine mountability are further improved.

Further, an air cleaner 46 is interposed between the detachable upper collector section 42 and the lower collector section 44, and a part of the intake branch 40 (the first branch forming section) is attached to the lower collector section 44. 68) is formed, and the air cleaner 46 is disposed above the branch opening 84 of the intake branch 40. Therefore, by removing the upper collector 42, the lower collector 44 constituting a large part of the collector volume is removed. There is also a merit that the air cleaner 46 can be easily replaced without removing the air cleaner 46 from the cylinder head 30 which is the engine body.

In each of the embodiments described later, the opening and closing timing of the intake and exhaust valves is set so that the combustion gas does not flow backward from the cylinder to the intake port 34. If the air flows back to the air cleaner and is directly applied to the air cleaner, the air cleaner may be damaged or deteriorated. Therefore, as shown in FIG. 1, a position deviated from the projecting direction of the intake branch 40 from which the combustion gas is discharged,
Specifically, the air cleaner 46 is disposed substantially at right angles to the protruding direction.

Next, with reference to FIG. 6, the structure and operation and effect of the intake device according to the first embodiment will be described. In this embodiment, only the operating angle changing mechanism 10 is applied to the intake valve side and only the phase changing mechanism 20 is applied to the exhaust valve side as a variable valve operating device. In order to obtain the operation and effect described later, the center phase of the operating angle of the intake valve (the center phase between the opening timing and the closing timing) is set to a phase delayed by about 100 ° from the exhaust top dead center. Further, for the purpose of improving the maximum output, the operating angle of the exhaust valve is set to a large value exceeding 180 ° which is the period of the exhaust stroke.

In the idle state (a) at the time of starting or the like, since the required intake air amount is small, the closing timing of the intake valve is advanced from the bottom dead center. Further, in such an idling state, in order to stabilize combustion, the closing timing of the exhaust valve is set near the top dead center, and the opening timing of the intake valve is greatly delayed from the top dead center. In other words, the intake valve is opened when the negative pressure in the cylinder is increased, the intake flow speed is increased,
It promotes fuel atomization (atomization). In order to obtain the opening / closing timing of the intake valve and the exhaust valve, in the idle state (a), the operating angle of the intake valve is changed by the intake-side operating angle changing mechanism 10 to the medium load range (b) and the high load range (c ), And the center phase of the exhaust valve is advanced by the exhaust-side phase changing mechanism 20 more than the middle load range (b).

In the high load range (c) including the fully open range, the closing timing of the intake valve is delayed after the bottom dead center in order to increase the amount of intake air. Further, since the combustion state is relatively stable in such a high load region, the opening timing of the intake valve is set to almost the top dead center, and the pumping loss is reduced. In order to obtain such valve timing, a high load region (c)
Here, the operating angle of the intake valve is increased, for example, as compared with the idle state (a).

In the middle load range (b), it is desired to increase the internal EGR amount (residual gas amount) to reduce pumping loss and improve fuel efficiency. In a general conventional configuration in which the intake air amount is adjusted by a throttle valve in order to obtain such an internal EGR amount, a throttle valve is throttled to apply a negative pressure downstream of the throttle, and an intake valve is provided before and after exhaust top dead center. And a valve overlap section in which both the exhaust valve and the exhaust valve are open. As a result, near the top dead center of the exhaust gas, the combustion gas flows back from the exhaust port to the intake port side where the pressure is negative through the cylinder as the piston rises. The back-flowed combustion gas (internal EGR) is sucked into the cylinder again with fresh air after the exhaust valve is closed in the subsequent piston descending stroke (suction stroke).

However, when such a valve overlap in the middle load range is applied to the intake device having the configuration as in the present embodiment, the following problem occurs. First,
As in the present embodiment, the collector 38 is made of resin for compactness and simplification, and the air cleaner 46 is built in the collector 38, so that the high-temperature combustion gas flows backward to the intake side due to valve overlap. Then
The high-temperature combustion gas may stain, damage or deteriorate resin parts such as a collector and an air cleaner built in the collector. Secondly, in the case of a system in which the adjustment of the intake air amount is mainly performed by the opening and closing timing of the intake valve as in the present embodiment, even in the middle load region, the inside of the collector is almost at atmospheric pressure (slight negative pressure by the pressure adjusting valve 64). Is given in some cases), and even if both the intake valve and the exhaust valve are open before the top dead center, the amount of combustion gas (internal EGR amount) flowing from the cylinder to the intake port side is small. . Therefore, it is difficult to obtain a desired internal EGR amount.

Therefore, in the present embodiment, the desired internal EGR is performed without performing the valve overlap in the middle load range (b).
In order to obtain the amount, the closing timing of the exhaust valve is delayed until after the top dead center, and the opening timing of the intake valve is set after the closing timing of the exhaust valve.

Therefore, during the exhaust stroke in which the piston moves up, the exhaust valve is open and the intake valve is closed.
Immediately after the subsequent exhaust top dead center, the exhaust valve remains open, and the combustion gas once discharged to the exhaust port side is taken into the cylinder again. During this time, since the intake valve remains closed, there is no possibility that the combustion gas will flow back to the intake port side. When the internal EGR amount (residual gas amount) becomes appropriate, the exhaust valve is closed to stop taking in the combustion gas, and then the intake valve is opened to suck in fresh air. As a result, a sufficient internal EGR amount can be secured without the combustion gas returning to the intake side.

In this embodiment, since the operating angle of the exhaust valve is set to be larger than 180 °, the opening timing of the exhaust valve decreases as the exhaust valve closing timing is retarded from the top dead center. As it approaches the dead center, the expansion ratio and the thermal efficiency are improved, and the fuel efficiency is improved.

In addition, in the medium load range (b), the required intake air amount increases as compared with the idle state (a), so that it is necessary to increase the operating angle of the intake valve.
Therefore, as shown in FIG. 6 (b), the operating angle of the intake valve is made as large as possible in a range where the opening timing of the intake valve is after the closing timing of the exhaust valve. As a result, the closing timing of the exhaust valve and the opening timing of the intake valve are almost at the same time.

When the backflow of the combustion gas to the intake side is allowed to some extent, for example, when the intake passage forming body is not made of resin or when the air cleaner is not built in the collector, the exhaust gas is exhausted. It is not always necessary to set the valve closing timing after the top dead center, and if the opening timing of the intake valve is after the closing timing of the exhaust valve, that is, if the setting of minus overlap, it is possible to secure a desired internal EGR amount. it can.

More preferably, the phase changing mechanism 20 is applied to the first embodiment together with the operating angle changing mechanism 10 on the intake valve side. In this case, although the configuration is complicated as compared with the first embodiment, the charging efficiency is maximized with an increase in the engine speed while adjusting the opening timing of the intake valve in the same manner as in the first embodiment. In addition, the closing timing of the intake valve can be adjusted independently of the opening timing of the intake valve, and the output can be improved over the entire operation range.

Next, an intake device according to a second embodiment will be described with reference to FIG. In this embodiment, as in the first embodiment, only the operating angle changing mechanism 10 is applied to the intake valve side and only the phase changing mechanism 20 is applied to the exhaust valve side as a variable valve operating device. In addition, the center phase of the intake valve is set at about 100% from the top dead center of the exhaust gas, as in the first embodiment.
° The phase is set to be delayed. On the other hand, although the operating angle of the exhaust valve is equal to or greater than 180 °, the closing timing of the exhaust valve is advanced from the top dead center in the middle load range (e). It is set small.

The idle state (d) and the high load state (f)
The setting of the closing timing of the exhaust valve and the opening timing of the intake valve in
This is almost the same as the first embodiment.

In the middle load range (e), the closing timing of the exhaust valve is advanced from the top dead center, and the opening timing of the intake valve is delayed from the top dead center. The period B from the top dead center to the opening timing of the intake valve is set longer than the period A from the exhaust valve closing timing to the top dead center.

Therefore, when the exhaust valve is closed in the latter half of the exhaust stroke in which the piston rises, the combustion gas remaining in the cylinder is trapped because the intake valve has not been opened yet. That is, the internal EGR amount (residual gas amount) is adjusted according to the closing timing of the exhaust valve. This combustion gas is compressed for a period A up to the top dead center. By keeping the intake valve closed even in the first half of the intake stroke in which the piston descends after the exhaust top dead center, the residual gas in the cylinder expands and the pressure in the cylinder decreases. Then, a predetermined period B from the top dead center
After the lapse of (B> A), the pressure in the cylinder decreases to a substantially negative pressure, and thereafter the intake valve is opened. That is, during the intake stroke in which the piston descends, the combustion gas contained in the cylinder expands again, and after the pressure in the cylinder becomes equal to or less than the pressure on the intake port side, the intake valve is opened to take in fresh air. Therefore, a sufficient amount of residual gas (internal EGR) can be obtained without the combustion gas remaining in the cylinder flowing back to the intake side.
Quantity) can be obtained. Further, since the exhaust gas is closed earlier than the top dead center to confine the combustion gas, the exhaust gas passes through the opening of the exhaust valve as compared with the case where valve overlap is provided to obtain the same internal EGR amount. The pumping loss during the operation is reduced, and the fuel efficiency is improved.

However, as in the second embodiment, the opening / closing timing of the exhaust valve is adjusted only by the phase changing mechanism 20, and the operating angle of the exhaust valve is set to 180 ° or more in accordance with a request for the maximum engine output. In case, medium load area (e)
When the exhaust valve closing timing is advanced from the top dead center to gain internal EGR, the exhaust valve opening timing is inevitably advanced greatly before the bottom dead center, and the expansion ratio decreases. This leads to lower fuel efficiency. That is, when the opening / closing timing of the exhaust valve is adjusted only by the phase changing mechanism 20, it is difficult to achieve both output and fuel efficiency.

Therefore, in the third embodiment shown in FIG. 8, an operating angle changing mechanism 10 is applied to the intake valve side as a variable valve operating device, and both the operating angle changing mechanism 10 and the phase changing mechanism 20 are provided to the exhaust valve side. Has been applied. As described above, when both the operating angle changing mechanism 10 and the phase changing mechanism 20 are applied to the exhaust valve side, the configuration is complicated as compared with the second embodiment, but the opening timing and the closing timing of the exhaust valve are mutually different. It can be adjusted independently. Therefore, while adjusting the closing timing of the exhaust valve and the opening timing of the exhaust valve in the high load region (i) in the same manner as in the second embodiment, the exhaust valve in the idle state (g) and the medium load region (h) is adjusted. The opening timing can be set in the vicinity of the top dead center, and the above-described output and fuel efficiency can be compatible.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an intake device for an internal combustion engine according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a schematic configuration diagram showing a mounting mode of a collector and a mounting bracket.

FIG. 4 is an explanatory view showing a mounting mode of a collector upper divided body and a collector lower divided body.

FIG. 5 is a perspective view showing an operating angle changing mechanism and a phase changing mechanism as an example of a variable valve operating device.

FIG. 6 is a characteristic diagram showing opening and closing timings of an intake valve and an exhaust valve according to the first embodiment of the present invention.

FIG. 7 is a characteristic diagram showing opening and closing timings of an intake valve and an exhaust valve according to a second embodiment of the present invention.

FIG. 8 is a characteristic diagram showing opening and closing timings of an intake valve and an exhaust valve according to a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 4 ECU 4 (control means) 10 Operating angle changing mechanism (variable valve device) 20 Phase changing mechanism (variable valve device) 38 Collector 46 Air cleaner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 35/104 F02M 35/10 102N 35/10 301R (72) Inventor Shunichi Aoyama Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa No. 2 Nissan Motor Co., Ltd. (72) Takanobu Sugiyama Inventor No. 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture F-term (reference) 3G018 AA01 AA06 AB07 AB17 BA19 BA33 BA34 CA13 DA11 EA13 EA14 EA31 EA32 FA08 FA26 GA07 3G092 AA11 DA01 DA02 DA05 DA09 DA12 DG05 EA03 EA04 EA22 FA21 FA25 FA36 FA50 GA04 GA05 GA06

Claims (7)

[Claims] A variable valve operating device that can change at least an opening timing and a closing timing of an intake valve; and control means for controlling the driving of the variable valve operating device to adjust an amount of intake air. An intake system for an internal combustion engine, wherein an opening timing of an intake valve is retarded after a closing timing of an exhaust valve in a range. 2. The intake device for an internal combustion engine according to claim 1, wherein at least a part of an intake passage forming body connected to an intake port of the engine body is made of resin. 3. The intake device for an internal combustion engine according to claim 2, wherein an air cleaner is incorporated in a collector constituting a part of the intake passage forming member. 4. The intake system for an internal combustion engine according to claim 2, wherein the closing timing of the exhaust valve is retarded from a top dead center in the medium load range. 5. In the middle load range, the closing timing of the exhaust valve is advanced from the top dead center, and the opening timing of the intake valve is set to the top dead center for a period from the closing timing of the exhaust valve to the top dead center. The intake device for an internal combustion engine according to claim 2 or 3, wherein the intake device is retarded from a point. 6. The variable valve operating apparatus according to claim 1, further comprising an operating angle changing mechanism capable of changing an operating angle of an intake valve or an exhaust valve, wherein the operating angle changing mechanism is driven to rotate in accordance with an engine operating state. A control shaft, a control cam eccentrically provided on the control shaft, a rocker arm rotatably fitted around the outer periphery of the control cam, and a drive shaft rotated about the shaft by rotational power transmitted from the crankshaft. A swing cam that is swingably fitted to the drive shaft and presses and drives an intake valve or an exhaust valve, an eccentric cam provided eccentrically to the drive shaft, and a rotatable outer periphery of the eccentric cam. A first link that is fitted outside and has a tip end rotatably connected to one end of the rocker arm; and a first link rotatably connected to the other end of the rocker arm and a tip end of the swing cam. Having a second link, An intake device for an internal combustion engine according to any of claims 1 to 5 symptoms. 7. The variable valve operating device according to claim 1, further comprising a phase changing mechanism capable of changing a center phase of an operating angle of the intake valve or the exhaust valve with respect to a phase of the crankshaft. An intake device for an internal combustion engine according to any one of the above.