JP4033115B2 - Intake control device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake air control device that controls the amount of intake air taken into a cylinder of an internal combustion engine, and more particularly to a combination of variable control of valve lift characteristics of an intake valve and so-called electronically controlled throttle valve opening control. The present invention relates to an intake air control apparatus for an internal combustion engine that achieves control of an air amount.

  In a gasoline engine, the intake air amount is generally controlled by controlling the opening of a throttle valve provided in the intake passage. As is well known, this type of system has a particularly small throttle valve opening. There is a problem that the pumping loss is large at low load. On the other hand, attempts have been made to control the intake air amount without depending on the throttle valve by changing the opening / closing timing of the intake valve and the lift amount. Similarly, it has been proposed to realize a so-called throttle-less configuration in which the intake system is not equipped with a throttle valve.

Patent Documents 1 and 2 disclose a variable valve mechanism that can be continuously and variably controlled by the lift amount and operating angle of an intake valve and the center angle of the lift previously proposed by the present applicant. According to this type of variable valve mechanism, as described above, it is possible to variably control the amount of air flowing into the cylinder without depending on the opening degree control of the throttle valve, particularly in a region where the load is small. In other words, so-called throttleless operation or operation with a sufficiently large opening of the throttle valve can be realized, and the pumping loss can be greatly reduced.
JP 2001-263105 A JP 2003-232233 A

  As described above, when the intake amount is controlled by variable control of the valve lift characteristic of the intake valve as so-called throttle-less, if no negative pressure is generated in the intake system as complete throttle-less, for example, blow-by gas, purge gas from an evaporator, etc. A new problem arises in that the existing system that recirculates air to the intake system cannot be used, and the negative pressure that is also used as a drive source for various actuators cannot be easily obtained.

  For this reason, the present applicant has studied to realize the control of the intake amount by the valve lift characteristics of the intake valve while ensuring the minimum negative pressure by providing a so-called electronically controlled throttle valve and combining it with the opening degree control. ing.

  Here, from the point of transient response from the low load range to the high load range, it is desirable that the intake pressure upstream of the intake valve is a pressure close to atmospheric pressure. It is desirable to adjust to the required intake air amount by expanding / reducing, but if the lift / operating angle is somewhat small in the partial load range, the valve overlap with the exhaust valve will be reduced or minus overlap, Internal EGR (internal exhaust gas recirculation) is reduced, which is disadvantageous in terms of fuel consumption.

The present invention relates to a first variable valve mechanism that can continuously expand and reduce the lift / operating angle of an intake valve, a second variable valve mechanism that delays the central angle of the operating angle of the intake valve, and an exhaust valve. An exhaust valve side variable valve mechanism capable of delaying at least the closing timing of the throttle valve, and an opening degree of the throttle valve so that an intake air amount sucked into the cylinder becomes a target intake air amount according to operating conditions. A control means for controlling the valve lift characteristics of the intake valve and the exhaust valve, wherein the first and second variable valve mechanisms, the exhaust valve side variable valve mechanism, and the As a control mode of the throttle valve, there is a response emphasis mode giving priority to the responsiveness of the internal combustion engine. Is prescribed And controls the opening degree of the throttle valve so that the reference negative pressure, to the load change, the intake valve side is indolent the intake valve closing timing by the scaling operation angle according to the first variable valve mechanism In addition, the exhaust valve side is characterized in that the exhaust valve closing timing is delayed at least from the top dead center so as to obtain internal exhaust gas recirculation.

  Desirably, the intake control device of the present invention emphasizes response as a control mode of the first and second variable valve mechanisms, the exhaust valve side variable valve mechanism and the throttle valve, with priority given to the response of the internal combustion engine. The mode and the fuel consumption priority mode giving priority to fuel consumption are provided, and the control as described above is performed in the response priority mode.

  According to the present invention, during the transition from the low load range to the high load range, the lift / operating angle of the intake valve is increased by the first variable valve mechanism while the suction negative pressure is maintained at the predetermined reference negative pressure. As a result, the intake air amount increases, so that the transient response is excellent, and at the same time, the internal EGR is increased by delaying the closing timing of the exhaust valve, so that the fuel efficiency is improved.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration explanatory view showing the system configuration of an intake control device for an internal combustion engine according to the present invention. The internal combustion engine 1 has an intake valve 3 and an exhaust valve 4, and the valve of the intake valve 3 is operated. As a mechanism, a first variable valve mechanism 5 capable of continuously expanding / reducing the lift / operating angle of the intake valve 3 and a second adjustable mechanism capable of continuously delaying the central angle of the operating angle. A variable valve mechanism 6 is provided. Further, as the valve operating mechanism of the exhaust valve 4, an exhaust valve side variable valve operating mechanism 14 capable of continuously delaying the opening / closing timing of the exhaust valve 4 is provided.

  The mechanical configuration of the first variable valve mechanism 5 and the second variable valve mechanism 6 is known, and for example, has the same configuration as the devices described in Patent Documents 1 and 2 described above. . The exhaust valve side variable valve mechanism 14 has a known configuration similar to that of the second variable valve mechanism 6. Therefore, detailed description of these variable valve mechanisms is omitted.

  The intake passage 7 is provided with an electronically controlled throttle valve 2 whose opening degree is controlled by an actuator such as a motor. Here, the throttle valve 2 is provided in the intake passage 7 for the purpose of generating a slight negative pressure (for example, −50 mmHg) required for blow-by gas processing and the like. Is adjusted by changing the lift characteristics of the intake valve 3 by the first and second variable valve mechanisms 5 and 6. Note that the amount of intake air flowing into the cylinder is mainly determined by the opening / closing timing of the intake valve 3 under a condition where the lift amount of the intake valve 3 is large to some extent, whereas the lift amount is mainly determined under a condition where the lift amount is sufficiently small. The amount of intake is determined by the amount.

  A fuel injection valve 8 is disposed in the intake passage 7, and an amount of fuel corresponding to the intake air amount adjusted by the intake valve 3 or the like as described above is injected from the fuel injection valve 8. Therefore, the output of the internal combustion engine 1 is controlled by adjusting the intake air amount by the first and second variable valve mechanisms 5 and 6 and the throttle valve 2.

  The control unit 10 includes an accelerator opening signal APO from an accelerator opening sensor 11 provided on an accelerator pedal operated by a driver, a rotation speed signal Ne from an engine rotation speed sensor 12, and an intake air amount sensor. 13, and based on these signals, the target throttle valve opening, fuel injection amount, ignition timing, intake valve side operating angle target value and central angle target value, exhaust valve side Calculate the advance amount. The fuel injection valve 8 and the spark plug 9 are controlled so as to realize the required fuel injection amount and ignition timing, and a control signal for realizing the target valve lift characteristics of the intake valve 3 and the exhaust valve 4 is obtained. It outputs to the actuators of the first variable valve mechanism 5, the second variable valve mechanism 6, and the exhaust valve side variable valve mechanism 14, respectively, and controls the opening degree of the throttle valve 2.

  Next, the control of the opening / closing timing of the intake valve 3 and the exhaust valve 4 and the opening degree of the throttle valve 2 will be described.

  In this embodiment, as control modes of the first and second variable valve mechanisms 5 and 6, the exhaust valve side variable valve mechanism 14 and the throttle valve 2, a response emphasis mode giving priority to the responsiveness of the internal combustion engine, And priority is given to the fuel efficiency mode. These response emphasis modes and fuel efficiency emphasis modes are, for example, a switch change by the driver, an automatic discrimination based on a change pattern (for example, acceleration / deceleration frequency) of the accelerator opening signal APO, an automatic transmission It can be selectively switched according to switching between the sport mode and economy mode.

  First, the fuel efficiency mode will be described with reference to FIG. In this fuel efficiency mode, as shown in FIG. 2, the region A on the high load side and the high speed side is set as the valve control region, and the region B on the low speed and low load side is set as the internal EGR priority region. ing. Furthermore, a region C of very low speed and low load including idle is set as a lift limiting region.

  In the valve control region A, the opening degree of the throttle valve 2 is controlled so that the pressure downstream of the throttle valve 2 becomes a predetermined reference negative pressure, that is, the minimum negative pressure necessary for a negative pressure source (for example, −50 mmHg). The The final intake air amount control is performed by the first and second variable valve mechanisms 5 and 6.

  In the internal EGR priority region B, even if the opening degree of the throttle valve 2 is reduced and the pumping loss is increased, the fuel consumption as a whole is improved by securing the internal EGR by increasing the operating angle of the intake valve 3. Here, the pressure downstream of the throttle valve 2 is controlled to a negative pressure stronger than the pressure (−50 mmHg) in the valve control region A. For example, the opening degree of the throttle valve 2 is controlled so that the negative pressure is about −200 mmHg to −300 mmHg. Since the valve lift characteristic of the intake valve 3 by the first and second variable valve mechanisms 5 and 6 is set on the assumption of such a negative pressure, the same negative pressure (−50 mmHg) as the negative pressure in the valve control region A is set. Compared with the case, the lift / operating angle is larger. FIG. 4 illustrates the opening / closing timing of the intake valve 3 and the exhaust valve 4 at the point b in the internal EGR priority region B. IVO is an intake valve opening timing, IVC is an intake valve closing timing, EVO is an exhaust valve opening timing, and EVC is an exhaust valve closing timing. By increasing the operating angle of the intake valve 3 in this way, a sufficient valve overlap with the exhaust valve opening period is ensured, and the internal EGR is relatively large. Thereby, a fuel consumption becomes a favorable thing. It should be noted that the opening / closing timing of the exhaust valve 4 by the exhaust valve side variable valve mechanism 14 is substantially at the maximum advanced position.

  The lift limiting region C on the low speed and low load side is a region where the lift / operating angle of the intake valve 3 by the first and second variable valve mechanisms 5 and 6 reaches a minimum. Here, the variable valve mechanisms 5 and 6 The valve lift characteristic of the intake valve 3 is maintained constant, and the required intake air amount is controlled according to the operating conditions by controlling the opening of the throttle valve 2. That is, the opening degree of the throttle valve 2 changes depending on the operating conditions, and the intake air amount and thus the engine torque are controlled by the throttle valve opening degree.

  Note that, in the full load region D of the maximum load shown as one line in FIG. 2, high filling efficiency is required, so that the opening degree of the throttle valve 2 is fully opened. In this region D, the pressure downstream of the throttle valve 2 is close to atmospheric pressure. Here, the valve lift characteristics have a large lift / operating angle so as to ensure a large charging efficiency. For example, the intake / exhaust valve opening / closing timing at the point d has the characteristics illustrated in FIG. It should be noted that the opening / closing timing of the exhaust valve 4 by the exhaust valve side variable valve mechanism 14 is substantially at the maximum advanced position.

  In such a fuel efficiency-oriented mode, the fuel efficiency is maximized, but the second variable operation is performed at the time of a transition that suddenly changes from a low load range to a high load range as indicated by an arrow T1 in FIG. The valve mechanism 6 needs to change from “most retarded position → most advanced angle position → retarded position”. In particular, the operating direction is reversed in the middle, which is disadvantageous in terms of responsiveness.

  Next, the response emphasis mode will be described with reference to FIG. In this response emphasis mode, the above-described internal EGR priority area B does not exist, and as shown in FIG. 3, almost the entire area excluding the lift limiting area C of extremely low speed and low load including idle and the fully open area D which is the maximum load. Is set as the valve control region A ′.

  The lift restriction region C on the low speed and low load side and the fully open region D of the maximum load are not particularly different from the case of the fuel consumption priority mode described above. That is, the lift restriction region C is a region in which the lift / operating angle of the intake valve 3 by the first and second variable valve mechanisms 5 and 6 reaches the minimum. Here, the intake valve by the variable valve mechanisms 5 and 6 The valve lift characteristic 3 is kept constant, and the required intake air amount according to the operating conditions is controlled by the opening degree control of the throttle valve 2. In the fully open region D, the opening degree of the throttle valve 2 is fully opened, and the valve lift characteristic has a large lift / operating angle that ensures a large filling efficiency. The intake / exhaust valve opening / closing timings in the lift restriction region C and the fully open region D are the same as those in the fuel efficiency mode. For example, the intake / exhaust valve opening / closing timing at point d in FIG. 3 has the same characteristics as those illustrated in FIG. It should be noted that the opening / closing timing of the exhaust valve 4 by the exhaust valve side variable valve mechanism 14 is at a position where the valve is advanced to the maximum as described above.

  On the other hand, in the valve control area A ′, as in the valve control area A in the fuel consumption priority mode, the pressure downstream of the throttle valve 2 is a predetermined reference negative pressure, that is, the minimum negative pressure necessary for a negative pressure source (for example, −50 mmHg). ), The opening of the throttle valve 2 is controlled. The final intake air amount control is performed by the first and second variable valve mechanisms 5 and 6, but the setting of the intake / exhaust valve opening / closing timing at this time is different from that in the fuel consumption priority mode. .

  FIG. 6 illustrates the opening / closing timing of the intake valve 3 and the exhaust valve 4 at the point a in the valve control region A ′. At this point a, since the load is relatively small, the operating angle is small. As shown in the figure, the intake valve opening timing IVO is after top dead center, and the intake valve closing timing IVC is before bottom dead center. In particular, the central angle of the operating angle is substantially the same as the central angle in the case of maximum load. Therefore, as shown by an arrow T2 in FIG. 3, when the load changes from a low load to a high load, the central angle by the second variable valve mechanism 6 hardly changes, and the operation by the first variable valve mechanism 5 does not change. The corner simply changes from “small to large”. Therefore, the response is excellent at the time of a transient in which the load increases rapidly. Moreover, as compared with the internal EGR priority region B in the fuel efficiency priority mode, the pressure immediately before the intake valve 3 (that is, the pressure downstream of the throttle valve 2) is higher than the atmospheric pressure. The rise of the torque accompanying the change in the frequency becomes even better, and from this point, the response is excellent.

  On the other hand, in the valve control region A ′ in this response-oriented mode, the exhaust valve side variable valve mechanism 14 is controlled to the retard side, and the exhaust valve closing timing EVC is from the top dead center as illustrated in FIG. It is in a state of being greatly retarded. Thus, by extremely retarding the exhaust valve closing timing EVC, exhaust gas is sucked back into the cylinder from the exhaust port and a large amount of internal EGR is made, so that fuel efficiency is improved. The delay of the exhaust valve closing timing EVC is performed up to the limit at which combustion can be established except in the vicinity of the fully open region D where high charging efficiency is required. Specifically, the maximum retardation state is obtained in the medium load region where the combustion is stable, and the retardation amount is smaller than this in the low load region where the combustion is likely to become unstable. On the high load side, the retard amount is set to be small in order to improve the charging efficiency.

  Thus, in the response emphasis mode, a change in the intake amount at the time of transition can be obtained with higher responsiveness compared to the control in the fuel efficiency emphasis mode. And in this invention, the deterioration of the fuel consumption by setting it as this response emphasis mode becomes the minimum.

  The intake valve opening / closing timing (specifically, the target value of the lift / operating angle and the target value of the central angle) and the exhaust valve opening / closing timing (specifically, the target advance amount of the exhaust valve side variable valve mechanism 14) in each mode are respectively It is given in the form of a control map and is stored in the control unit 10. As described above, the map is switched according to the driving pattern of the driver.

1 is a system configuration diagram of an intake control device for an internal combustion engine according to the present invention. Explanatory drawing which shows the control area | region of fuel consumption priority mode. Explanatory drawing which shows the control area | region of response emphasis mode. The valve timing chart which shows the intake / exhaust valve opening / closing timing of the point b of FIG. The valve timing chart which shows the intake / exhaust valve opening / closing timing of the point d of FIG. 2 and FIG. The valve timing chart which shows the intake / exhaust valve opening / closing timing of the point a of FIG.

Explanation of symbols

2 ... Electronically controlled throttle valve 5 ... First variable valve mechanism 6 ... Second variable valve mechanism 10 ... Control unit 14 ... Exhaust valve side variable valve mechanism

Claims (7)

A throttle valve that is interposed in the intake passage of the internal combustion engine and whose opening is controlled by a control signal;
A first variable valve mechanism capable of continuously expanding and reducing the lift and operating angle of the intake valve;
A second variable valve mechanism for delaying the central angle of the operating angle of the intake valve;
An exhaust valve side variable valve mechanism capable of delaying at least the closing timing of the exhaust valve;
Control means for controlling the opening degree of the throttle valve and the valve lift characteristics of the intake valve and the exhaust valve so that the intake air amount sucked into the cylinder becomes a target intake air amount according to operating conditions;
An intake control device for an internal combustion engine comprising:
As the control mode of the first and second variable valve mechanisms, the exhaust valve side variable valve mechanism and the throttle valve, there is a response emphasis mode giving priority to the response of the internal combustion engine,
In this response-oriented mode, in the valve control region including a predetermined partial load region, the throttle valve opening is controlled so that the suction negative pressure downstream of the throttle valve becomes a predetermined reference negative pressure, and the load In response to the change, the intake valve side delays the intake valve closing timing by expanding and reducing the operating angle by the first variable valve mechanism, and the exhaust valve side sets the exhaust valve closing timing so that internal exhaust gas recirculation is obtained. At least later than top dead center,
As a control mode of the first and second variable valve mechanisms, the exhaust valve side variable valve mechanism and the throttle valve, there is a fuel consumption priority mode in which fuel priority is given priority over the response priority mode,
An intake device for an internal combustion engine, wherein the operating angle of the intake valve is made larger than that in the response priority mode so that the intake valve opening timing is before bottom dead center in the partial load range in the fuel efficiency priority mode . A throttle valve that is interposed in the intake passage of the internal combustion engine and whose opening is controlled by a control signal;
A first variable valve mechanism capable of continuously expanding and reducing the lift and operating angle of the intake valve;
A second variable valve mechanism for delaying the central angle of the operating angle of the intake valve;
An exhaust valve side variable valve mechanism capable of delaying at least the closing timing of the exhaust valve;
Control means for controlling the opening degree of the throttle valve and the valve lift characteristics of the intake valve and the exhaust valve so that the intake air amount sucked into the cylinder becomes a target intake air amount according to operating conditions;
An intake control device for an internal combustion engine comprising:
As the control mode of the first and second variable valve mechanisms, the exhaust valve side variable valve mechanism and the throttle valve, there is a response emphasis mode giving priority to the response of the internal combustion engine,
In this response-oriented mode, in the valve control region including a predetermined partial load region, the throttle valve opening is controlled so that the suction negative pressure downstream of the throttle valve becomes a predetermined reference negative pressure, and the load In response to the change, the intake valve side delays the intake valve closing timing by expanding / reducing the operating angle by the first variable valve mechanism without changing the center angle by the second variable valve mechanism. An intake control device for an internal combustion engine, wherein the exhaust valve side delays the exhaust valve closing timing at least from the top dead center so that internal exhaust gas recirculation is obtained.   3. The internal combustion engine according to claim 1, wherein, in the valve control region in the response-oriented mode, the exhaust valve closing timing is retarded from a low load region and a high load region in an intermediate load region where combustion is stable. Engine intake control device. As a control mode of the first and second variable valve mechanisms, the exhaust valve side variable valve mechanism and the throttle valve, there is a fuel consumption priority mode in which fuel priority is given priority over the response priority mode,
4. The operating angle of the intake valve is made larger than that in the response priority mode so that the intake valve opening timing is before bottom dead center in the partial load range in the fuel efficiency priority mode. An intake device for an internal combustion engine as described in 1.   5. The intake air of the internal combustion engine according to claim 4, wherein in the fuel consumption priority mode, the opening degree of the throttle valve is controlled so that a negative pressure larger than the reference negative pressure is obtained in the partial load region. Control device.   6. The intake control apparatus for an internal combustion engine according to claim 4, wherein the exhaust valve closing timing is retarded in the partial load region in the response priority mode than in the fuel efficiency priority mode.   The intake control device for an internal combustion engine according to any one of claims 1 to 6, wherein the valve control region in the response priority mode is a rotational load region excluding a very low speed low load region and a fully open region.

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