JP3438374B2 - Intake device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an intake system for an internal combustion engine equipped with a variable valve mechanism.

[0002]

2. Description of the Related Art As an intake device that changes a plurality of cam profiles in accordance with the operating state of an engine to change the opening / closing timing of an intake valve and the lift amount, Japanese Patent Application Laid-Open No. HEI-2 is disclosed.
No. 277923 and Japanese Patent Application Laid-Open No. 2-267323 are known. For example, a cam having a large lift amount and a long valve opening period is provided for high speed operation, while a small lift amount is used for low speed operation. A cam with a short valve opening period is provided, and a high speed cam and a low speed cam are selectively switched according to the engine speed to obtain an optimum output regardless of the operating condition.

[0003]

However, in the above-described conventional intake system for an internal combustion engine, the low speed cam intakes air in a rotation range of 600 rpm or more, that is, in an idling rotation range of an automobile internal combustion engine or the like. Since the main purpose is to perform the operation, as shown in FIG. 8, the lift amount of the intake valve 8 is higher than the intake flow rate in the extremely low rotational speed range of about 200 rpm such as cranking at the start. Is large, the flow velocity of the intake air is reduced, and a part of the fuel supplied toward the intake port 2 by the injector or the like becomes a wall flow. 8 adheres to the vicinity of the umbrella portion. For this reason, the fuel does not easily flow into the cylinder 1, and as shown in FIG. 9, a difference occurs between the fuel injection amount from the injector and the fuel flow amount actually supplied into the cylinder 1, which is relative to the injector injection amount. When the responsiveness of the fuel flow rate flowing into the cylinder deteriorates and the startability deteriorates, and the fuel flow rate flowing into the cylinder increases after the end of cranking, the exhaust emission deteriorates due to an increase in HC emission amount. was there.

Therefore, the present invention has been made in view of the above problems, and provides an intake system for an internal combustion engine capable of improving the startability and the exhaust emission by reducing the response delay due to the wall flow of the fuel flow rate flowing into the cylinder. The purpose is to provide.

[0005]

As shown in FIG. 10, the first invention is directed to an intake valve 8 disposed in an intake passage 2 and a plurality of cams by selectively switching between the intake valve 2 and the intake valve 2. In the intake system for an internal combustion engine, which comprises a variable valve mechanism 50 for changing a valve opening timing or a lift amount, and a valve drive control means 53 for switching the variable valve mechanism 50 according to an operating state of the engine, The valve mechanism 50 includes at least first and second cams 51 and 52, and the first cam 51 has a predetermined lift amount of the intake valve corresponding to the normal operation, while the second cam 52 has , Of the intake valve opening period
Suppress the lift amount in the first half when the center is set as the boundary
On the other hand, the lift amount in the latter half is increased to increase the first cover.
Profile that achieves a predetermined lift amount that is relatively smaller than the
The valve drive control means 53 selects the second cam 52 when the engine is being started, and selects the first cam 51 otherwise.

In the second aspect of the invention, as shown in FIG. 10, the intake valve 8 disposed in the intake passage 2 and a plurality of cams are selectively switched to open or close the intake valve 2. An intake system for an internal combustion engine, comprising: a variable valve mechanism 50 for changing a lift amount; and a valve drive control means 53 for switching the variable valve mechanism 50 according to an operating state of the engine,
The intake passage 2 when the engine is operating
Fuel injection timing control means 54 for changing the timing of injecting fuel into the intake valve 8 during the closing period of the intake valve 8, and the variable valve mechanism 50.
However, with the first cam 51 having a predetermined lift amount of the intake valve corresponding to the normal operation and the center of the opening period of the intake valve as a boundary.
While suppressing the lift amount in the first half when
Relative to the first cam by increasing the lift amount at
Set in a profile that achieves a predetermined small lift amount.
And a second cam 52 which is fixed, the valve driving control means 53, while selecting the second cam 52 in the case during a start of the engine, said otherwise first cam 51
Select.

A third aspect of the invention is based on the first or second aspect of the invention, wherein the second cam has a lift amount capable of generating a predetermined intake flow velocity at an engine speed during start-up.

[0008]

As shown in FIG. 10, a fourth aspect of the present invention is the valve drive control means 53 according to any one of the first to third aspects, wherein the valve drive control means 53 is means 55 for detecting an engine speed. A means 56 for detecting the starting state of the engine is provided, and the second cam is selected when the engine speed is below a predetermined value and the engine is in the starting state.

[0010]

Therefore, according to the first aspect of the present invention, the valve drive control means switches the variable valve mechanism according to the operating state of the engine, and during normal operation, the first cam drives the intake valve while starting the engine. Select the 2nd cam inside, and when cranking
It may be limited to a small value so that the specified flow velocity is obtained.
At the beginning of valve opening until the specified lift amount is reached,
Since the lift amount is suppressed in the first half of the valve period, the intake valve
The flow velocity of the intake air that passes through is increased, and even when the engine speed is extremely low during startup, the intake flow velocity is increased, so that the fuel adhering to the intake passage or the intake valve can be separated and atomization can be promoted. it can.

According to a second aspect of the present invention, the valve drive control means switches the variable valve mechanism according to the operating state of the engine, and during normal operation the first cam drives the intake valve while starting the engine. Select the second cam and set the center of the intake valve opening period.
While suppressing the lift amount in the first half when it becomes the boundary,
Increase the lift amount in the latter half to make it more relative to the first cam
The intake valve is driven with a profile that achieves a predetermined smaller lift amount, and the fuel injection timing control means changes the fuel injection timing during the closing period of the intake valve if the engine is being started.
The intake air that has flowed in from the intake passage during engine startup flows into the cylinder while the intake valve is open, and at this time, the lift amount of the second cam is suppressed in the first half of the valve opening period, so the intake air is intaken.
The flow velocity of intake air passing through the valve increases, and the intake flow velocity increases even when the engine speed is extremely low during start- up, while the fuel injected during the valve closing period adheres to the intake passage or intake valve. However, the fuel is separated by the intake air whose flow velocity has increased according to the lift amount accompanying the opening of the intake valve, and the fuel flows into the cylinder while promoting atomization, and the response delay of the injected fuel is suppressed to start. And exhaust emissions can be improved.

According to the third aspect of the present invention, the lift amount of the second cam has a lift amount capable of generating a predetermined intake flow velocity at the engine speed during start, so that the crank rotates extremely during start. Even when the number is low, it is possible to secure the flow velocity of the intake air to separate and atomize the fuel adhering to the intake valve and the intake passage, and suppress the response delay of the injected fuel.

[0013]

According to a fourth aspect of the present invention, the valve drive control means selects the second cam only when the engine speed is less than or equal to a predetermined value and the engine is in a starting state. In case of rising, it is possible to promptly switch to the first cam for normal operation, the lift amount is increased in accordance with the increase in intake air amount, and stable combustion can be continued.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where an embodiment of the present invention is applied to a 4-valve engine will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the cylinder 1 is connected to intake ports 2 and 3 and exhaust ports 4 and 5, and an injector 6 is arranged upstream of the intake ports 2 and 3, and a signal from a controller 7 is supplied. In response, the injector 6 opens the valve and injects fuel corresponding to the signal into the intake ports 2 and 3.

The controller 7 calculates the fuel injection amount according to the operating state of the engine, in order to calculate the fuel injection amount, the engine speed Ne from the speed sensor 30, the intake flow rate Q from the air flow meter 31, and the cooling from the water temperature sensor 32. Water temperature,
The start signal SSW from the start switch 33 linked to the ignition switch and the crank angle sensor 3
The angle signal from 4 is read, and the valve opening signal according to the calculated fuel injection amount is sent to the injector 6.

The valve mechanism for controlling the intake and exhaust timing is
The intake ports 2 and 3 are driven to open and close via a variable valve mechanism, and the exhaust ports 4 and 5 are driven to open and close to cams 17 and 18 connected to an exhaust camshaft 13, respectively. The exhaust valves 17 and 18 are provided, and a variable valve mechanism is provided on the intake side, while a normal valve drive mechanism is provided on the exhaust side.

The variable valve mechanism for driving the intake valves 8 and 9 is
The intake camshaft 12 is provided with normal operation cams 16 in addition to the startup cams 14 and 15 formed corresponding to the intake valves 8 and 9, respectively, and the normal operation cam 16 includes the startup cams 14 and 15 respectively. It is arranged between.

Starting cams 14 and 15 and normal operation cam 1
The profile of No. 6 is set as shown in FIGS. 3 and 4, and the normal operation cam 16 is set to a predetermined lift amount and valve opening timing capable of ensuring an optimum output in the rotation region from idling to the maximum rotation speed. On the other hand, the start cam 1
Nos. 4 and 15 are set to profiles capable of ensuring an optimum flow velocity in response to the rotation speed during cranking during starting.

That is, as will be described later, the maximum value of the lift amount of the intake valves 8 and 9 is a predetermined value for generating a flow velocity at which the fuel adhering to the vicinity of the intake valves 8 and 9 can be entrained, for example, about 2 mm. The profile is set such that the lift amount of the intake valves 8 and 9 is suppressed in the first half of the full opening period while the lift amount is increased in the latter half of the full valve opening period to achieve a predetermined lift amount. Lift amount is set higher than in the first half. The first half and the latter half of the valve opening period are roughly divided by the center of the valve opening period.

A rocker arm slidably contacting each of these three cams 14 to 16 is arranged, a first rocker arm 22 slidably contacts the starting cam 14, and a free rocker arm 24 and a starting cam 16 are slidably connected to the normal operation cam 16. Second to fifteen
The rocker arms 23 are in sliding contact with each other, and the rocker arms 22 to 24 are pivotally supported at their base ends by the rocker shafts 21, while the other ends swinging in response to the cams 14 to 16 open and close the intake valves 8 and 9. is there.

Here, the intake valves 8 and 9 are constantly in contact with the first rocker arm 22 and the second rocker arm 23, and the starting cams 14 and 15 and the normal operation cam 1 having different lift amounts.
6 is selected by a variable valve mechanism by hydraulic pressure, and the intake valves 8 and 9 are driven according to the selected cam.

A hydraulic oil passage 20 for driving the variable valve mechanism is formed on the inner periphery of a rocker shaft 21 supported by a cylinder head (not shown). The hydraulic oil passage 20 has a predetermined high pressure in response to a command from the controller 7. , Communicates with the hydraulic pressure supply means 19 for switching the low pressure.

An oil chamber 25 opened at a predetermined position facing the free rocker arm 24 is provided inside the second rocker arm 23 whose base end is supported by the rocker shaft 21.
And a piston 27 that selectively connects the second rocker arm 23 and the free rocker arm 24 is housed in the oil chamber 25.

The oil chamber 25 is opened at a predetermined position facing the free rocker arm 24, and a hole 24A is formed through the free rocker arm 24 facing the oil chamber 25 and further faces the hole 24A. A hole 22A is formed through the first rocker arm 22, and these oil chambers 25,
The hole portion 24A and the hole portion 22A are formed to have substantially the same diameter at the coaxial position.

Then, the piston 2 for connecting the free rocker arm 24 and the first rocker arm 22 to the hole 24A.
6 is accommodated in the hole 22A, and the return spring 2 biases the guide piston 28 slidingly contacting the piston 26 toward the free rocker arm 24.
9 is accommodated, and the pistons 26 and 27 have holes 22 respectively.
It is formed so that it can be fitted to A and 24A.

The return spring 29 urges the pistons 26, 27 against the oil pressure in the oil chamber 25, that is, the free rocker arm 24 and the first and second rocker arms 22,
When the hydraulic pressure supplied to the oil chamber 25 reaches a predetermined high pressure by urging the piston 23 in a direction to release the coupling, the piston 27 extends through the pistons 26 and 28 against the return spring 29, so that the piston 27 moves. By fitting the hole 26A and the piston 26 in the hole 22A, the free rocker arm 24 is connected to the first and second rocker arms 22 and 23, and the intake valves 8 and 9 are in sliding contact with the free rocker arm 24. It is driven by the normal operation cam 16.

On the other hand, when the hydraulic pressure applied to the oil chamber 25 is lower than a predetermined value, the return spring 29 expands and the pistons 26 and 27 come out of the holes 22A and 24A, respectively, so that the guide piston 28, the piston 26 and the piston 26. And the piston 27 slide the ends into mutual contact,
Free rocker arm 24 and first and second rocker arm 2
Allowing relative displacement of 2 and 23, the intake valves 8 and 9 are opened / closed according to the start cams 14 and 15 which are in sliding contact with the first and second rocker arms.

Therefore, the cam for driving the intake valves 8 and 9 in accordance with the pressure oil from the hydraulic pressure supply means 19 in accordance with the command from the controller 7 is either the start cams 14 or 15 or the normal operation cam 16. Is set to.

Here, the profiles of the starting cams 14 and 15 are set based on the cranking rotation speed at the time of starting. When the cranking rotation speed is set to about 200 rpm, the inside of the intake ports 2 and 3 is piped. The pressure is almost atmospheric pressure.
That is, at the time of start-up, the intake air amount per cycle is equal to that at the full-open operation, and therefore the fuel injection amount per cycle must be set to be equal to or more than that at the full-open operation.

Here, considering the state where the fuel injected from the injector 6 stably flows into the cylinder 1, for example, when the fully open operation at 800 rpm is considered, the average intake air flow rate and the flow velocity in the stroke volume of 600 cc per cylinder. Is 0.6 [l] × 800 × 1/2 = 240 [l / min] (provided that the suction efficiency is 100%).

Considering the intake stroke as 1/4 cycle, the average intake flow rate is 240 [l] × 4 = 960 [l / min] = 16 × 10 ⁻³
[M ³ / sec], and the intake flow velocity at a general lift amount of 8 [mm] when the outer diameter of the intake valves 8 and 9 is Φ30 [mm], the curtain area S = 30 [mm] × π × 2 × 8 [mm] = 1508 [m
m ² ], so 16 × 10 ⁻³ [m ³ / sec] / 1508 [mm ² ] ≈ = 10.
It becomes 6 [m / S].

Therefore, if the intake flow velocity of this level can be secured, even if the fuel amount corresponding to the full opening is injected, it can stably flow into the cylinder 1. Therefore, about 200 rp
Consider the lift amount to secure an equivalent flow velocity when cranking m.

Similarly to the above, the average intake air flow rate and flow velocity in the cylinder volume 600 [cc] are 0.6 [l] × 200 × 1/2 × 4 = 240 [l / min] = 3.96 × 10 ^{− 3} [m ³ / sec] Here, if the lift amount is 2 [mm], the curtain area S
= 30 [mm] × π × 2 × 2 [mm] = 376.8 × 10 ⁻⁶
Since it is [mm ² ], 3.96 × 10 ⁻³ [m ³ /sec]/376.8×10 ⁻⁶ [mm
² ] ≈ 10.6 [m / S], and the lift amount of the intake valves 8 and 9 at the time of starting needs to be set to about 2 mm.

The variable valve mechanism constructed as described above is
Driven based on a command from the controller 7, an example of this control is shown in the flowchart of FIG. 5, and will be described in detail below based on this flowchart.

After the start signal SSW from the start switch 33 indicating the operation of a starting device such as an ignition key (not shown) is read in step S1, step S2 is performed.
Then, it is determined whether the start signal SSW is on, that is, whether the start signal is being started.

If the engine is starting, the routine proceeds to step S3, where the engine speed Ne is read from the engine speed sensor 30,
In step S4, it is determined whether the rotation speed Ne is a predetermined rotation speed or less, in this case, 400 rpm or less. If the rotation speed Ne is 400 rpm or less, it is determined that the cranking is being performed, and in step S5, the hydraulic oil supply unit 19 supplies the pressure oil below the predetermined pressure to the oil chamber 25 of the variable valve mechanism to intake the intake valve. 8 and 9 are switched to drive by the starting cams 14 and 15.

On the other hand, in step S4, the rotation speed Ne is 400.
After the cranking exceeding rpm, the process proceeds to step S6, the hydraulic pressure of the oil chamber 25 is switched to a predetermined high pressure, and the intake valves 8 and 9 are driven by the normal operation cam 16.

The steps S1 to S6 are carried out at predetermined time intervals.
For example, it is executed every 10 msec, the ignition key or the like is operated, the start switch 33 is turned on, and at the same time cranking is started.

Since the engine speed is less than the predetermined value, the controller 7 judges the cranking at the time of starting and switches the hydraulic pressure supply means 19 to the low pressure side, and as described above, the piston is driven by the urging force of the return spring 29. 25, 26 is prevented from fitting into the holes 24A, 22A to allow relative displacement of the first and second rocker arms 22, 23 with respect to the free rocker arm 24, and the intake valves 8, 9 are started. It is driven by cams 14 and 15.

At the same time, the controller 7 sets the fuel injection amount and the fuel injection timing to predetermined values according to the start. As the fuel injection amount, an incremental value for starting is calculated from the water temperature detected by the water temperature sensor 32 or selected from a map,
The fuel injection timing is changed based on a signal from the crank angle sensor 34 so that the injector 6 injects a predetermined fuel into the intake ports 2 and 3 during the closing period of the intake valves 8 and 9. The signal detected by the crank angle sensor 34 is composed of a Ref signal (top dead center or a predetermined crank angle) and a Pos signal (every predetermined crank angle, for example, every 1 degree). The fuel injection timing is set to a predetermined crank angle during the closing period of the intake valves 8 and 9, that is, before the predetermined angle from the valve opening start position of the intake valves 8 and 9.

Here, the fuel injected from the injector 6 during the closing period of the intake valves 8 and 9 flows toward the cylinder 1 together with the intake air, and immediately before the opening of the intake valves 8 and 9, these intake valves 8 and 9 are opened. , 9 in the vicinity of the intake ports 2 and 3 to form a wall flow.

The intake cams 8, 15 are driven by the starting cams 14, 15.
When the valve 9 is opened, intake air and fuel in the intake ports 2 and 3 flow into the cylinder 1. At this time, the starting cam 1
As described above, the lift amounts 4 and 15 apply to the intake valves 8 and 9 are limited to a small value that provides a predetermined flow velocity during cranking, and the initial valve opening until the predetermined lift amount is reached. That is, in the first half of the above-described valve opening period, the lift amount is suppressed, so that the flow velocity of intake air passing through the intake valves 8 and 9 further increases.

Therefore, as shown in FIG. 6, the intake valve 8,
The wall flow Fa adhering to the vicinity of 9 flows into the cylinder 1 together with high-speed intake air (Fb in the figure), and at this time, the fuel separated from the intake ports 2 and 3 and the intake valves 8 and 9 promotes atomization. Therefore, the startability can be improved by improving the ignitability at the time of starting.

Further, when the starting cams 14 and 15 rotate to enter the latter half of the valve opening period, the lift amount of the intake valves 8 and 9 is relatively higher than that in the first half. Even at a very low speed, the lift amount of the intake valves 8 and 9 increased compared to the first half makes it possible to secure the intake amount required for starting.

Therefore, the fuel injection amount of the injector 6 caused by the wall flow and the fuel flow rate actually flowing into the cylinder 1 are as shown in FIG. 7, which is higher than that of the conventional example shown in FIG. The responsiveness of the fuel inflow amount of the cylinder 1 to the fuel injection amount from the injector 6 is improved, and the excessive fuel inflow due to the wall flow is suppressed, so that the fuel flow rate and the intake air amount necessary for the start are reliably ensured. As a result, it is possible to improve the startability and reduce the amount of HC emission, so that it is possible to achieve the improvement of the startability and the reduction of the exhaust emission at the same time, and further, the fuel increase correction amount at the time of the start is reduced. This makes it possible to promote the reduction of fuel consumption and exhaust emission.

Thus, the lift amount in the early stage of opening the valve is small and the lift amount in the latter stage of the valve opening is reliable while reducing the wall flow and the fuel injection amount at the time of starting by the cams 14 and 15 capable of giving a predetermined flow velocity to the intake air. After the engine is started, the controller 7 switches the hydraulic pressure from the hydraulic pressure supply means 19 to a predetermined high pressure and extends the pistons 25 and 26 on condition that the engine speed Ne exceeds a predetermined value. Free rocker arm 24 and first and second rocker arms 2
The intake valves 8 and 9 are connected to the normal operation cam 16 by connecting the valves 2 and 23.
The intake valves 8 and 9 are driven by the lift amount increased as compared with the starting cams 14 and 15 during the normal operation in which the intake amount is increased compared to at the time of starting, that is, in the operating range of idling rotation or more. By doing so, the output during normal operation can be secured in the same manner as in the conventional case, and the controller 7 changes the fuel injection timing and the fuel injection amount to values corresponding to normal operation, and changes the fuel amount according to the intake air amount. Is supplied to the cylinder 1.

[0049]

As described above, according to the first aspect of the invention, the second cam is selected while the engine is being started, and the second cam is opened in the first half of the valve opening period.
The flow velocity of the intake air that passes through the intake valve because the amount of shift is suppressed.
In addition, the intake flow velocity is increased even when the engine speed is extremely low during engine startup, so that fuel adhering to the intake passage or intake valve can be separated and atomization can be promoted. The response delay of the flow rate of fuel flowing into the cylinder due to the fuel can be reduced to improve the startability, and the emission amount of HC can be reduced to improve the exhaust emission.

In the second aspect of the invention, the second cam is selected while the engine is starting and the lift amount is suppressed in the first half of the valve opening period.
Therefore, while increasing the flow velocity of the intake air that passes through the intake valve , the fuel injection timing is changed during closing of the intake valve, and the intake flow velocity is increased even when the engine speed is extremely low during engine start, Fuel that has been injected during valve closing and that has once adhered to the intake passage or intake valve can be separated, and atomization can be promoted, and the response delay between the injected fuel flow rate and the fuel flow rate flowing into the cylinder can be reduced to improve startability. And the exhaust emission can be improved by reducing the HC emission amount.

Further, in the third aspect of the invention, the lift amount of the second cam has a lift amount capable of generating a predetermined intake flow velocity at the engine speed during starting, so that it is extremely difficult to perform cranking during starting. Even if the engine speed is low, the flow velocity of the intake air can be secured to separate and atomize the fuel adhering to the intake valve and the intake passage, and the response delay between the injected fuel flow rate and the fuel flow rate flowing into the cylinder can be reduced. It is possible to improve the startability by reducing the amount of HC emission, improve the exhaust emission by improving the emission amount of HC, and improve the responsiveness of the flow rate of the fuel flowing into the cylinder. It is possible to reduce the fuel consumption as compared with the conventional one, and the fuel consumption and the exhaust emission can be further improved.

[0052]

According to a fourth aspect of the invention, the valve drive control means selects the second cam only when the engine speed is equal to or lower than a predetermined value and the engine is in a starting state, so cranking during engine starting is performed. When the rotation speed increases in response to the end, the first cam for normal operation can be quickly switched to, and the engine speed can be smoothly switched from cranking to idling or higher to continue stable combustion.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an internal combustion engine showing an embodiment of the present invention.

FIG. 2 is a sectional view of the main part of the variable valve mechanism.

FIG. 3 is a sectional view of the cam.

FIG. 4 is a characteristic diagram of the cam.

FIG. 5 is a flowchart showing an example of control.

FIG. 6 is a cross-sectional view of the intake system showing the flow of fuel at the time of starting.

FIG. 7 is a graph showing a relationship between a fuel flow rate and a rotation speed at the time of starting and time.

FIG. 8 is a sectional view of an intake system showing a flow of fuel at the time of starting in a conventional example.

FIG. 9 is a graph showing the relationship between the fuel flow rate and the number of revolutions at the time of starting and the time in the same manner as the conventional example.

FIG. 10 is a claim correspondence diagram corresponding to any one of the first to fifth inventions.

[Explanation of symbols]

2, 3 intake ports 6 injectors 7 controller 8, 9 intake valve 12 camshaft 14, 15 Start intake cam 16 Intake cam for normal operation 19 Hydraulic pressure supply means 22 1st rocker arm 23 Second Rocker Arm 24 Free Rocker Arm 25 oil chamber 26, 27 piston 29 Return spring 30 speed sensor 31 Air Flow Meter 32 Water temperature sensor 33 Start switch 34 Crank angle sensor 50 variable valve mechanism 51 First Cam 52 Second Cam 53 Valve drive control means 54 Fuel injection timing control means 55 Engine speed detection means 56 Starting state detecting means

Continuation of front page (56) Reference JP-A-2-161154 (JP, A) JP-A-2-267323 (JP, A) JP-A-2-277923 (JP, A) JP-A-56-141030 (JP , A) JP 60-75708 (JP, A) JP 61-23815 (JP, A) JP 62-13709 (JP, A) JP 4-47142 (JP, A) 61-19605 (JP, U) JP48-1729 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01L 13/00 301 F02B 29/08 F02D 13/02 F02D 41 / 06 320 F02D 41/06 335

Claims (4)

(57) [Claims] 1. An intake valve arranged in an intake passage, a variable valve mechanism for changing a valve opening timing or a lift amount of the intake valve by selectively switching a plurality of cams, and an engine operating state. In an intake system for an internal combustion engine, comprising: a valve drive control unit that switches the variable valve mechanism in accordance with the variable valve mechanism, the variable valve mechanism includes at least first and second cams, and the first cam is usually The second cam is provided with a predetermined lift amount of the intake valve corresponding to the second cam during operation.
In the first half of the period when the center of the opening period of the intake valve is taken as the boundary.
Lift amount while controlling the lift amount
A predetermined amount that is increased to be relatively smaller than the first cam.
A profile for achieving a shift amount, wherein the valve drive control means selects the second cam when the engine is starting, while the valve drive control means selects the first cam when the engine is not starting.
Intake device for an internal combustion engine, characterized in that the cam of the above is selected. 2. An intake valve disposed in an intake passage, a variable valve mechanism for changing a valve opening timing or a lift amount of the intake valve by selectively switching a plurality of cams, and an engine operating state. In the intake system for an internal combustion engine, which is provided with a valve drive control means for switching the variable valve mechanism accordingly, when the engine is operating, the timing of injecting fuel into the intake passage is set to the closing timing of the intake valve. A fuel injection timing control unit that changes during a valve period; a first cam in which the variable valve mechanism has a predetermined lift amount of an intake valve corresponding to a normal operation; and an intake valve opening period.
Suppress the lift amount in the first half when the center of the
On the other hand, by increasing the lift amount in the latter half,
A professional who achieves a predetermined lift amount that is relatively smaller than the cam.
A second cam set to a feel, the valve drive control means selects the second cam when the engine is being started, and otherwise, the first cam is selected.
Intake device for an internal combustion engine, characterized in that the cam of the above is selected. 3. The internal combustion engine according to claim 1, wherein the second cam is provided with a lift amount capable of generating a predetermined intake air flow velocity at an engine speed during starting. Inhaler. 4. The valve drive control means detects an engine speed.
And a means for detecting the starting state of the engine.
When the engine speed is less than the specified value and the engine is in the starting state
The second cam is selected, and the second cam is not included.
An intake device for an internal combustion engine according to claim 3.
Place