JPH10220256A - Intake valve controller of internal combustion engine with turbosupercharger and method for controlling it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide compatibility to power performance and fuel consumption by increasing the compression ratio of an internal combustion engine provided with a turbosupercharger without deteriorating low-speed torque and responsiveness. SOLUTION: A variable valve mechanism for changing the operating angle is used for an intake valve 5, and the closing timing is variably controlled with the closing timing is held constant. The relative large A/R (the ratio of the scroll narrowest sectional area A and the distance R from the shaft center) is provided to a turbosupercharger 9 so that exhaust pressure on a turbine inlet may be equal to or not more than supercharged pressure of a compressor outlet in all load ranges before a waste gate valve is opened. Since the intake valve closing timing is controlled according to the engine speed before a waste gate valve 11 is opened and since it is controlled in the low-speed range so as to approach the bottom dead center, the intake air back flow in the initial stage of the compression stroke is prevented, and low-speed torque and responsiveness are improved even in a supercharger having the large A/R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine with a turbocharger, and more particularly to a gasoline engine used as an engine for an automobile, and more particularly, to an internal combustion engine with a turbocharger having a variable valve mechanism. The present invention relates to an intake valve control device and a control method.

[0002]

2. Description of the Related Art Turbochargers, which drive a coaxial compressor by an exhaust turbine, have been frequently used in automobile gasoline engines and the like. The characteristics of this turbocharger are based on the A / R of the turbine. As shown in FIG. 1, A is the cross-sectional area of the narrowest part of the scroll, and R is the distance from the center of the shaft. FIG. 2 shows the difference in the torque characteristics depending on the setting of the A / R. As shown in FIG. 2, when the A / R is large, the efficiency of the turbocharger increases at high speed with a large exhaust flow rate. Therefore, the maximum output performance is good, but on the other hand, the turbocharger rotation speed does not easily increase at low speeds with low exhaust flow rate, so the rise of the supercharging pressure is delayed, and the low-speed torque under steady conditions decreases. Of course, the responsiveness of the turbocharger at the time of transition, such as at the time of starting, is low, and the operability is deteriorated. Therefore, in an internal combustion engine with a turbocharger of a general automobile, the setting of the A / R of the turbocharger is set to a relatively small value that emphasizes responsiveness.

[0003] Many of the internal combustion engines with a turbocharger that are in practical use are combined with a valve operating mechanism having a fixed characteristic, and the opening and closing timing of an intake valve is always constant. Normally, the intake valve closing timing is set to about 50 ° after the bottom dead center (ABDC).

On the other hand, various types of variable valve mechanisms for variably controlling the opening / closing timing of intake valves of an internal combustion engine have been proposed in the past, and some of them have already been put to practical use. For example, by changing the phase relationship between a camshaft and a crankshaft that drives the camshaft relatively, the opening / closing timing of the intake valve is changed in the same direction, or two cams having different cam profiles are used. Follow 2
An apparatus has been put into practical use in which two rocker arms are provided, and the valve lift characteristics are switched between two types by selectively switching a rocker arm in which an intake valve is actually linked. In Japanese Patent Application Laid-Open No. 6-185321, the valve lift characteristics can be continuously variably controlled by rotating the cylindrical camshaft at an unequal speed by applying the principle of an unequal speed shaft coupling. A variable valve mechanism is disclosed.

[0005]

As described above, in many internal combustion engines with a turbocharger, the A / R of the turbine is set to be relatively small.
Is smaller, the exhaust pressure upstream of the turbine is at a high level because the inlet of the turbine is throttled. In FIG.
After the supercharging pressure reaches the target level, the wastegate valve for bypassing the exhaust gas is opened to suppress an increase in the exhaust pressure, but the exhaust pressure level at this point is already at a considerably high level (FIG. 4). reference). When the exhaust pressure level is high as described above, (1) the output decreases due to the increase in the exhaust work in the exhaust stroke, (2) the intake amount (filling rate) decreases due to the increase in the residual gas amount, and (3) the high-temperature residual There is a problem that the intake air temperature increases due to the gas, and the knock resistance deteriorates.

[0006] The decrease in the output in (1) and the decrease in the filling rate in (2) can be compensated to some extent by increasing the supercharging pressure. However, regarding the deterioration of the knocking resistance of (3), even if an intercooler is installed, the temperature of the residual gas in the combustion chamber cannot be reduced, so there is no effect, and the knocking is prevented by setting the compression ratio low. I have to do it. This decrease in compression ratio causes deterioration of fuel efficiency.

An object of the present invention is to combine a variable valve operating mechanism capable of variably controlling the closing timing of an intake valve and a turbocharger having a large A / R of a turbine in an internal combustion engine with a turbocharger. As a result, the compression ratio of the engine can be set to be high, and the torque reduction at low speed and the deterioration of responsiveness caused by setting the A / R large are compensated for by optimizing the intake valve closing timing. The aim is to ensure both performance and fuel economy.

[0008]

In order to achieve the above object, an intake valve control device according to a first aspect of the present invention variably controls an operating angle of an intake valve to set a closing timing of the intake valve. In a turbocharged internal combustion engine equipped with a controllable variable valve mechanism and a turbocharger, the intake valve closing timing is controlled to approach the bottom dead center at low engine speed, and In the high-speed range and the high-speed full-open range, the intake valve closing timing control means delays from the bottom dead center so that the actual compression ratio decreases, and the turbocharger has a turbine in the full load range before the wastegate valve opens. The boost pressure characteristic is set so that the exhaust pressure at the inlet is substantially equal to or lower than the boost pressure at the compressor outlet.

Further, the intake valve control method according to claim 8 is
The turbocharged internal combustion engine having a variable valve actuation mechanism capable of controlling the closing timing of the intake valve by variably controlling the operating angle of the intake valve and having a turbocharger. The supercharging pressure characteristics of the compressor are set so that the exhaust pressure at the turbine inlet is substantially equal to or lower than the supercharging pressure at the compressor outlet in the full load range before the wastegate valve opens, and the intake valve It is characterized in that the closing timing is controlled so as to approach the bottom dead center when the engine is running at a low speed, while the actual compression ratio is delayed from the bottom dead center in the middle speed range and the high speed fully open range.

The above-described supercharging pressure characteristic is set, for example, by adjusting the A / R of the turbine of the turbocharger as described in claim 2.

According to a third aspect of the present invention, the supercharging pressure characteristic is set to be satisfied in the full load region under the engine steady condition.

That is, when the closing timing of the intake valve is fixedly set to, for example, about 50 ° after the bottom dead center, it is good in the medium speed range, but in the low speed range, the inertia effect of the intake is small. The intake air flows backward from inside the cylinder. On the other hand, in the present invention, the intake valve closing timing is advanced to, for example, 20 ° after the bottom dead center in the engine low speed range, and is delayed to, for example, about 40 ° to 60 ° after the bottom dead center in the middle to high speed range. . By doing so, at the time of low speed, it is possible to prevent the intake air backflow at the beginning of the compression stroke, so that the low-speed torque can be improved. In addition, the rising characteristics of the rotation speed of the turbocharger are also improved by increasing the intake air amount and thus the exhaust gas amount, so that even if the turbocharger has a large A / R of the turbine, the operability does not deteriorate.

By the way, in order to reduce the residual gas amount,
The lower the exhaust pressure, the better, and it is necessary to increase the A / R. On the other hand, if the A / R is excessively large, the A / R does not function as a supercharger, so that the A / R near the limit where knock resistance is not deteriorated It is important to select In the present invention, the supercharging pressure characteristics of the turbocharger are set such that the exhaust pressure at the turbine inlet is substantially the same as the supercharging pressure at the compressor outlet in the entire load region before the wastegate valve is opened. This results in an optimal A / R.

FIG. 3 shows a change (calculation) of the residual gas amount due to an increase in exhaust pressure (assuming that A / R is gradually reduced) when the intake pressure (supercharging pressure) is fixed. Obtained by the following method). This figure summarizes the characteristics when the valve overlap is set to 10 °, 20 °, and 30 °. When the intake pressure (supercharging pressure Pc) is fixed, the exhaust pressure Pe and the intake pressure ( Under the condition that the supercharging pressure Pc) is equal, there is no difference in the residual gas amount depending on the magnitude of the valve overlap, and in the region before and after that, the change in the residual gas amount is greatly affected by the valve overlap. The reason is that the change in the residual gas amount due to the backflow of the exhaust gas due to the differential pressure between the exhaust pressure Pe and the intake pressure is affected by the valve overlap. In the region where the exhaust pressure Pe is larger than the intake pressure (P
In the region on the right side of the line e = Pc), the residual gas amount has a characteristic of rapidly increasing. On the other hand, on the other hand, a condition in which the exhaust pressure Pe is lower than the intake pressure (region on the left side of the line of Pe = Pc) may be considered. In this case, the characteristic is such that fresh air flows from the intake system to the exhaust system. However, when a turbocharger is provided, it is theoretically unlikely that the intake pressure (supercharging pressure Pc) greatly exceeds the exhaust pressure Pe. In a normal case, the A / R of the turbine is set to be large. However, as shown in FIG. 5, the supercharging pressure Pc only slightly exceeds the exhaust pressure Pe. When A / R is small,
As shown in FIG. 4, the exhaust pressure Pe greatly exceeds the supercharging pressure Pc. For this reason, when the exhaust pressure Pe is decreased by increasing the A / R, in the region of the exhaust pressure Pe <the intake pressure (supercharging pressure Pc) in FIG. 3, the effect of the exhaust pressure Pe is limited to only the density change. The change in the residual gas amount has the characteristic shown by the solid line a regardless of the magnitude of the valve overlap.

Therefore, if the exhaust pressure level is set so as not to exceed the supercharging pressure before the waste gate valve is opened, that is, under the condition that the entire amount of exhaust gas passes through the turbine, the level of the residual gas amount is suppressed to a low level. Since the knocking resistance is improved, the compression ratio can be set to be high even in an internal combustion engine with a turbocharger.

In the high-speed region after the wastegate valve is opened, the supercharging pressure is limited to a predetermined value, so that the exhaust pressure is necessarily higher, but the A / R is increased. The more the setting is made, the more the opening operation of the wastegate valve is performed on the high-speed side, and the more the knocking does not easily occur at high speed, so the characteristics in the region until the wastegate valve opens are very important. .

An important point in the present invention is that a variable valve mechanism that changes the intake valve closing timing by variably controlling the operating angle is used. In particular, it is desirable that the intake valve opening timing be kept substantially constant, and that the intake valve closing timing relatively largely change with the variable control of the operating angle. Thus, it is possible to control the intake valve closing timing to the optimum without greatly changing the valve overlap.

The relationship shown in FIG. 5 and the like described above is for the full load region under steady-state conditions where the load, rotation speed, temperature, etc. of the engine is substantially constant. Due to the delay in the rise of the rotation speed of the feeder, the exhaust pressure level rises from the steady state, and even if the A / R is set to the characteristics described above, the exhaust pressure is supercharged at the stage where the wastegate valve does not open. A phenomenon that greatly exceeds the pressure occurs. In an actual use mode, the frequency of such a situation as starting acceleration is high as a characteristic of the internal combustion engine with a turbocharger. However, the effect of compression ratio on knocking is most severe under steady full load conditions. The reason for this is that the temperature of each part has risen to the maximum by continuing full load operation for a certain period of time, which is the most severe thermal condition. The knock resistance is most affected by the thermal conditions. Therefore, if the compression ratio is optimally provided in the entire load region under a steady condition in which the load, the number of revolutions, the temperature, and the like of the engine are substantially constant, there is no problem at the time of transient such as starting acceleration for a short time.

Further, in the invention according to claim 5, the intake valve closing timing control means determines that the actual compression ratio is equal to the actual expansion ratio in a full load region on a higher speed side than a wastegate valve opening condition of the turbocharger. The intake valve closing timing is controlled to be smaller than the ratio. That is, in the high-speed region where the supercharging pressure reaches the predetermined value, the actual compression ratio is reduced by delaying the closing timing of the intake valve more than usual. As a result, a so-called mirror cycle is achieved, and knock resistance is improved.

Further, there is provided a means for detecting a supercharging pressure on the upstream side of the intake valve, wherein the closing timing of the intake valve is controlled in accordance with engine operating conditions including the supercharging pressure. Is also good.

In order to realize the above-described variable control of the intake valve closing timing, the intake valve control device according to claim 7 is
As the variable valve mechanism, a drive shaft that rotates in synchronization with the rotation of the engine, a cam shaft that is disposed coaxially with the drive shaft and has a cam that drives an intake valve on the outer periphery, One flange portion provided at an end portion and having an engagement groove formed in the radial direction, and provided on the drive shaft side so as to face the one flange portion, and engaged along the radial direction. The other flange portion in which the mating groove is formed, an annular disk slidably disposed between the two flange portions, and projecting in opposite directions on both side portions of the annular disk to form the two flange portions. And a drive mechanism for swinging the annular disk according to the operating state of the engine.

In this configuration, when the center of rotation of the annular disk is concentric with the centers of the drive shaft and the camshaft, the drive shaft and the camshaft rotate at a constant speed, and the annular disk is at an eccentric position. In such a case, the two rotate unequally. Therefore, the valve lift characteristic of the intake valve changes continuously according to the position of the annular disk, and the opening / closing timing and operating angle of the intake valve change. In addition, if the same phase point where the phase of the drive shaft and the phase of the camshaft always coincide with each other is matched with the valve lift start timing, as in claim 4,
The intake valve opening timing is always constant.

[0023]

As described above, according to the present invention, in an internal combustion engine with a turbocharger, it is possible to use a turbocharger in which the A / R of the turbine is set large, and the knock resistance is improved. This makes it possible to set the compression ratio of the engine high. The reduction in torque at low speeds and the deterioration in responsiveness caused by setting the A / R of the turbine large can be compensated for by optimizing the intake valve closing timing. As a whole, it is possible to secure power performance and improve fuel efficiency. Can be compatible.

According to the fifth aspect, knock resistance can be further improved as a so-called mirror cycle.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 6 shows an embodiment of an internal combustion engine with a turbocharger according to the present invention. A plurality of cylinders 2 are arranged in series in a cylinder block 1 and a piston is provided in each cylinder 2. 3 are slidably fitted. An intake port 6 opened and closed by an intake valve 5 and an exhaust port 8 opened and closed by an exhaust valve 7 are formed in the cylinder head 4 covering the top of the cylinder 2. On the upstream side of an intake passage connected to the intake port 6, a turbocharger 9, specifically, a compressor 9a thereof is provided. Exhaust turbine 9b driving this compressor 9a
Is disposed in an exhaust passage downstream of the exhaust port 8. An exhaust bypass passage 10 is provided between the outlet side and the inlet side of the exhaust turbine 9b, and an electronically controlled wastegate valve 11 is interposed in the exhaust bypass passage 10. Further, a supercharging pressure sensor 12 for detecting a supercharging pressure is disposed on the outlet side of the compressor 9a, that is, on the upstream side of the intake port 6.

The wastegate valve 11 is opened on the high-speed side of the engine so as to keep the supercharging pressure at a predetermined characteristic, and is controlled by a control unit 13 in detail. The control unit 13 receives detection signals such as the engine speed, load, cooling water temperature, lubricating oil temperature, and supercharging pressure by the supercharging pressure sensor 12, and sets the supercharging pressure according to the engine operating conditions. Is controlled.

The turbocharger 9 has a turbine 9 b
A / R is set to a relatively large value. This makes it possible to set the compression ratio of the engine high.
Specifically, the supercharging pressure characteristics, specifically, A, are set so that the exhaust pressure at the turbine inlet is substantially the same as the supercharging pressure at the compressor outlet in the full load region before the wastegate valve 11 is opened. / R is set. The exhaust pressure at the turbine inlet may be set to be slightly lower than the supercharging pressure at the compressor outlet.

The exhaust valve 7 is opened and closed with a fixed valve timing by an exhaust side camshaft (not shown). On the other hand, the closing timing of the intake valve 5 can be variably controlled together with the operating angle by a variable valve mechanism described later.

The above variable valve mechanism is disclosed in Japanese Patent Laid-Open No. 6-1853.
As disclosed in Japanese Patent No. 21365 and US Pat. No. 5,365,896, the cylindrical camshaft 22 of each cylinder is rotated at a non-constant speed by applying the principle of a non-constant speed shaft coupling. Thus, the valve lift characteristics can be continuously variably controlled.

Since this mechanism itself is known, it will be briefly described with reference to FIGS.
Is a drive shaft to which rotational force is transmitted from an unillustrated engine crankshaft via the timing chain 14, and 22 is the drive shaft 21
Is a hollow cylindrical camshaft rotatably fitted on the outer periphery of the camshaft. The camshaft 22 is divided for each cylinder.

The camshaft 22 is rotatably supported by a cam bearing at the upper end of the cylinder head 4 and has a pair of cams 26 formed on the outer periphery thereof to open the pair of intake valves 5 of each cylinder. . Also, the camshaft 22
Is divided into a plurality of pieces as described above, and a first flange portion 27 is provided at one of the divided ends. A sleeve 28 and an annular disk 29 are arranged between the ends of the plurality of divided camshafts 22, respectively. The first flange portion 27 is formed with an elongated engagement groove extending in the radial direction.

The sleeve 28 is fixed to the drive shaft 21. The sleeve 28 has a second flange 32 facing the first flange 27. The second flange portion 32 is also formed with an elongated engagement groove along the radial direction.

The annular disk 29 located between the flange portions 27 and 32 has a substantially donut shape, has an annular gap with the outer peripheral surface of the drive shaft 21, and has an inner peripheral surface of the disk housing 34. It is rotatably held on a surface. Further, a pair of pins 36 and 37 projecting to opposite sides are provided at opposite positions on diameter lines different from each other by 180 °, and the pins 36 and 37 are engaged with the respective engagement grooves.

The disk housing 34 has a substantially triangular shape. The circular disk 29 is held in the circular opening, and the first cam fitting hole 38 and the second cam A fitting hole 39 is formed through.

In the first cam fitting hole 38 and the second cam fitting hole 39, the circular cam portions 41a and 43a of the first eccentric cam 41 and the second eccentric cam 43 are rotatably fitted. I agree.

As shown in FIG. 5, the second eccentric cam 43 is composed of a cylindrical shaft portion 43b and a circular cam portion 43a which are eccentric with respect to each other by a predetermined amount. Have been. The circular cam portion 43a is prevented from coming off by the snap ring 30. Shaft 4
3b is press-fitted and fixed to the partition wall of the frame 33 as shown in FIG.

The first eccentric cam 41 has a control camshaft 42 continuous over a plurality of cylinders along the engine front-rear direction.
And a plurality of circular cam portions 41a fixed to the camshaft 42 corresponding to the respective cylinders, and both are eccentric by a predetermined amount. The circular cam portion 41a of each cylinder is eccentric at a predetermined angular position of the cam shaft 42. The control cam shaft 42 is rotatably held by the frame 33 via a cam bracket 35. At one end of the control camshaft 42 located at one end of the engine, a rotary hydraulic actuator 46 is attached as a drive mechanism. A control camshaft 42 located at the front of the internal combustion engine
A rotary potentiometer 47 for detecting the rotational position of the control cam shaft 42, that is, the phase of the circular cam portion 41a, is attached to the other end of the rotary cam.

In the above variable valve mechanism, the eccentric position of the annular disk 29 is variably controlled via the first eccentric cam 41, whereby the camshaft 22 rotates at an irregular speed,
A phase difference occurs between the drive shaft 21 and the drive shaft 21 in accordance with the amount of eccentricity. For example, as shown in FIG. 8A, when the center Y of the annular disk 29 and the center X of the drive shaft 21 coincide with each other, the camshaft 22 rotates synchronously with the drive shaft 21 at a constant speed. The valve lift characteristic along the cam profile as shown by the solid line (a) in FIG. 9 is obtained. On the other hand, as shown in FIG. 9B, when the center Y of the annular disk 29 is eccentric to one side, a phase difference corresponding to the amount of eccentricity occurs, and the dashed line (b) in FIG. The valve lift characteristics shown in ()) are obtained.

Note that a positive phase difference and a negative phase difference occur during one rotation of the drive shaft 21, and the same phase point exists in the middle of the phase difference. In this embodiment, the starting point of the cam lift substantially coincides with the in-phase point. Therefore, even if the center of the annular disk 29 is eccentric and the valve operating angle increases or decreases, as shown in FIG. 9, the opening timing hardly changes and only the closing timing changes.

The hydraulic pressure supplied to the hydraulic actuator 46 is controlled via a hydraulic control valve (not shown) based on a control signal from the control unit 13 described above.
Various signals indicating the engine operating conditions are input to the control unit 13 as described above, and the closing timing of the intake valve 5 is variably controlled based on these signals.

FIG. 10 is a flowchart showing the flow of control of the closing timing of the intake valve 5 executed by the control unit 13. First, in step 1, a control map of the intake valve closing timing (IVC) is read. The control map includes a map for normal operation, an example of which is shown in FIG. 11, a map for high supercharging and low compression ratio, which shows an example of the characteristic in FIG. 12, and a map for cold operation (not shown). Are set in advance. Next, in step 2, the cooling water temperature tw
Is a predetermined reference temperature (a temperature at which warm-up is considered to be completed) t
0, and if it is less than or equal to t0, step 3
Proceed to. In step 3, a target value of the intake valve closing timing corresponding to the load and the engine speed at that time is determined by using a control map for cold time (not shown). Further, when the warm-up is completed and the cooling water temperature tw is higher than the reference temperature t0,
Proceed to step 4. In step 4, it is determined whether or not the oil pressure in the lubrication system of the engine is equal to or higher than the reference oil pressure p0 based on a signal from an unshown oil pressure sensor. The reference oil pressure p0 is set to a level at which the above-described variable valve mechanism can be normally controlled. When the oil pressure is equal to or lower than the reference oil pressure p0, for example, immediately after starting, the oil pressure is sufficiently increased. Wait until. If the oil pressure is higher than the reference oil pressure p0, the process proceeds to step 5, where it is determined whether the supercharging pressure Pc is higher than a predetermined reference level Pc0. This reference level Pc0 substantially corresponds to the supercharging pressure when the wastegate valve 11 in the turbocharger 9 starts to open. That is, it is determined whether or not the entire amount of exhaust gas is being introduced into the turbine 9b. Instead of the determination of the supercharging pressure, the open / close state of the wastegate valve 11 may be determined.

In step 5, the supercharging pressure Pc is changed to the reference level Pc.
If it is lower than 0, the routine proceeds to step 6, where the target value of the intake valve closing timing is determined according to the engine operating conditions at that time, mainly the engine speed, using the control map for normal operation shown in FIG. I do. Similarly, if the supercharging pressure Pc is higher than the reference level Pc0 in step 5, the process proceeds to step 7, and FIG.
Using the control map for the high supercharging / low compression ratio shown in (1), the engine operating conditions at that time, in particular, the target value of the intake valve closing timing corresponding to the supercharging pressure is determined.

Then, the process proceeds to a step S8, wherein the hydraulic actuator 46 is driven according to the target value of the closing timing.
In step 9, the actual rotational position of the control camshaft 42 is detected by the potentiometer 47, and the hydraulic actuator 46 is closed-loop controlled.

In this embodiment, as shown in FIG. 11, the intake valve closing timing is advanced to about 20 ° after the bottom dead center in the engine low speed range, so that the intake backflow at the beginning of the compression stroke can be prevented. Low speed torque is improved. In addition, the rising characteristics of the rotation speed of the turbocharger 9 are also improved by increasing the intake air amount and, consequently, the exhaust gas amount, so that the responsiveness is improved. That is,
Even if the turbocharger 9 has a large A / R of the turbine 9a, the operability does not deteriorate.

At the time of high supercharging when the waste gate valve 11 is open, as shown in FIG. 12, the intake valve closing timing is increased from the bottom dead center so that the actual compression ratio becomes smaller than the actual expansion ratio. Be late. This realizes a so-called Miller cycle.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of A / R of a turbocharger.

FIG. 2 is a fully open torque characteristic diagram of an engine showing a difference in torque characteristics depending on the setting of A / R.

FIG. 3 is a characteristic diagram showing a change in residual gas due to exhaust pressure.

FIG. 4 is a characteristic diagram showing a relationship between a supercharging pressure Pc and an exhaust pressure Pe when A / R is small.

FIG. 5 is a characteristic diagram showing a relationship between a supercharging pressure Pc and an exhaust pressure Pe when A / R is large.

FIG. 6 is a configuration explanatory view showing one embodiment of an internal combustion engine with a turbocharger according to the present invention.

FIG. 7 is a perspective view of a main part showing a configuration of the variable valve mechanism.

FIGS. 8A and 8B are explanatory views showing the operation of the variable valve mechanism, wherein FIG. 8A is an explanatory view showing a concentric state, and FIG. 8B is an explanatory view showing an eccentric state.

FIG. 9 is a characteristic diagram showing valve lift characteristics obtained by the variable valve mechanism.

FIG. 10 is a flowchart showing a flow of control of intake valve closing timing.

FIG. 11 is a characteristic diagram showing characteristics of an intake valve closing timing control map for normal operation.

FIG. 12 is a characteristic diagram showing characteristics of an intake valve closing timing control map for high supercharging and low compression ratio.

[Explanation of symbols]

 5 ... intake valve 9 ... turbocharger 11 ... waste gate valve 12 ... supercharging pressure sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02B 39/00 F02B 39/00 D F02D 23/00 F02D 23/00 K 43/00 301 43/00 301R 301Z

Claims (8)

[Claims] 1. An internal combustion engine with a turbocharger having a variable valve operating mechanism capable of controlling the closing timing of an intake valve by variably controlling the operating angle of the intake valve and having a turbocharger. Has an intake valve closing timing control means for controlling the intake valve closing timing to approach the bottom dead center when the engine is at low speed, and delaying from the bottom dead center so that the actual compression ratio decreases in the middle speed range and the high speed fully open range. , And the turbocharger,
The supercharging pressure characteristic is set so that the exhaust pressure at the turbine inlet is approximately the same as or lower than the supercharging pressure at the compressor outlet in the entire load range before the wastegate valve opens. An intake valve control device for an internal combustion engine with a turbocharger. 2. The internal combustion engine with a turbocharger according to claim 1, wherein the supercharging pressure characteristic is set as described above by adjusting the A / R of the turbine of the turbocharger. Engine intake valve control device. 3. The intake air for a turbocharged internal combustion engine according to claim 1, wherein the supercharging pressure characteristic is set to be satisfied in a full load region under an engine steady condition. Valve control device. 4. The intake valve opening timing is maintained substantially constant, and the intake valve closing timing changes relatively largely with the variable control of the operating angle. Control device for an internal combustion engine with a turbocharger. 5. The intake valve closing timing control means according to claim 1, wherein the actual compression ratio is smaller than the actual expansion ratio in a full load region on a higher speed side than a wastegate valve opening condition of the turbocharger. The intake valve control device for an internal combustion engine with a turbocharger according to any one of claims 1 to 4, wherein the valve closing timing is controlled. 6. A system according to claim 5, further comprising means for detecting a supercharging pressure on the upstream side of the intake valve, and controlling the intake valve closing timing in accordance with engine operating conditions including the supercharging pressure. An intake valve control device for an internal combustion engine with a turbocharger according to the above. 7. A variable valve mechanism, comprising: a drive shaft that rotates in synchronization with rotation of an engine; and a cam shaft that is disposed coaxially with the drive shaft and has a cam that drives an intake valve on an outer periphery. A flange portion provided at an end of the camshaft and having an engagement groove formed in a radial direction;
The other flange portion, which is provided on the drive shaft side so as to face the one flange portion and has an engagement groove formed in the radial direction, is swingably disposed between the two flange portions. The annular disc thus formed, pins protruding from both sides of the annular disc in opposite directions to engage in respective engagement grooves of the flange portions, and the annular disc is swung according to engine operating conditions. 7. An internal combustion engine with a turbocharger according to claim 1, further comprising a drive mechanism for operating the intake valve, wherein the operating angle of the intake valve changes according to the position of the annular disk. Intake valve control device. 8. An internal combustion engine with a turbocharger having a variable valve mechanism capable of controlling the closing timing of the intake valve by variably controlling the operating angle of the intake valve and having a turbocharger. The supercharging pressure characteristics of the turbocharger are set such that the exhaust pressure at the turbine inlet is substantially equal to or lower than the supercharging pressure at the compressor outlet in the entire load region before the wastegate valve is opened. In addition, while controlling the closing timing of the intake valve to approach the bottom dead center when the engine is at low speed, the turbocharger is characterized in that the actual compression ratio is delayed by delaying from the bottom dead center in the middle speed range and the high speed fully open range. Control method for an internal combustion engine with an engine.