CONTROL APPARATUS FOR INTERNAL-COMBUSTION ENGINE WITH VARIABLE VALVE MECHANISM
An intake variable valve mechanism 34 is provided that allows closing timing of an air intake valve 30 to be varied. The intake variable valve mechanism 34 has a first control mode that controls IVC timing of the intake valve 30 at an angle-advancing side relative to a certain range including an air intake bottom dead center BDC, and a second control mode that controls the IVC timing of the intake valve 30 at an angle-retarding side relative to the certain range. IVC variable control (first control mode) for making the IVC timing of the intake valve 30 variable according to load is selected for operation in a region of relative low loads, and intake valve closing retardation control (second control mode) for controlling the intake valve 30 in fully retarded IVC timing is selected for operation in a region of relatively high loads.
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The present invention relates to a control apparatus for an internal-combustion engine having a variable valve mechanism.
BACKGROUND ARTPatent Document 1, for example, discloses a control apparatus for an internal-combustion engine having a variable valve mechanism to make variable the opening and closing timing of an air intake valve and the lift amount thereof. The conventional control apparatus as described in Patent Document 1 is constructed so that when knock is detected, the apparatus executes control to suppress knock and suppress changes in torque. More specifically, as an example of the control performed when knock is detected, the conventional control apparatus operates to increase the opening area of the intake valve as well as to advance the closing timing thereof.
Including the above-mentioned document, the applicant is aware of the following document as a related art of the present invention.
[Patent Document 1] Japanese Patent Laid-open No. 2002-180857
[Patent Document 2] Japanese Patent Laid-open No. 2004-116315
[Patent Document 3] Japanese Patent Laid-open No. Hei 4-246249
DISCLOSURE OF INVENTIONIn an internal-combustion engine with a variable valve mechanism for making variable the opening and closing timing of an intake valve and the lift amount thereof, as in the foregoing conventional internal-combustion engine, such intake air amount control as outlined below may take place to reduce pumping loss for improved fuel efficiency. That is to say, the intake air amount may be controlled such that: the closing timing of the intake valve is advanced by reducing the operating angle of the intake valve to limit the amount of air passed through the intake valve, and a throttle angle is correspondingly increased at the same time.
According to the above control of the intake air amount, when an operating region of the internal-combustion engine changes from a low-load region to a high-load region, pumping loss is reduced by gradually increasing the operating angle in accordance with the load required of the internal-combustion engine. As a result, an operating angle equivalent to the very timing in which the intake valve is closed near a bottom dead center will be used in a medium-load region. When the intake valve is closed near the bottom dead center, an actual in-cylinder compression ratio will increase and knock will be more likely to occur.
The present invention has been made for solving the above problem, and an object of the invention is to provide a control apparatus which can control an operating state of an internal-combustion engine while properly avoiding knock in the internal-combustion engine having a variable valve mechanism to make at least closing timing of an intake valve variable
The above object is achieved by a control apparatus for an internal-combustion engine having a variable valve mechanism which at least makes closing timing of an intake valve variable. An intake valve control means is provided with a first control mode for controlling the closing timing of the intake valve at an angle-advancing side relative to a certain range including an air intake bottom dead center, and with a second control mode for controlling the closing timing of the intake valve at an angle-retarding side relative to the certain range. The intake valve control means controls the closing timing of the intake valve in either the first control mode or the second control mode. A control mode selection means is also provided for selecting the first control mode for operation in a region of relatively low loads, and selecting the second control mode for operation in a region of relatively high loads.
In a second aspect of the present invention, at least the first control mode of the first control mode and the second control mode may be the control that determines the closing timing of the intake valve according to a load of the internal-combustion engine.
In a third aspect of the present invention, the second control mode may be the intake valve closing retardation control that determines the closing timing of the intake valve such that even under a steady state, blowback of intake air into an intake passage occurs.
In a fourth aspect of the present invention, the first control mode may be the control that determines the closing timing of the intake valve according to a load of the internal-combustion engine.
In a fifth aspect of the present invention, the intake valve closing retardation control may be used in an operating region in which the engine runs at a speed equal to or smaller than a certain value and under a load equal to or greater than a certain value.
In a sixth aspect of the present invention, the control mode selection means may select the first control mode until the load region of the internal-combustion engine has reached the higher region as engine speed increases.
The seventh aspect of the present invention may include a torque control means for controlling a torque of the internal-combustion engine in addition to controlling the closing timing control of the intake valve via the intake valve control means. A torque control change means may be provided for, when the second control mode is selected by the control mode selection means, changing the torque control performed by the intake valve control means, to the torque control performed by the torque control means.
In an eighth aspect of the present invention, the torque control means may be a throttle valve that controls an intake air amount. And the torque control means may adjust an open position of the throttle valve in accordance with at least the closing timing of the intake valve, of the closing timing and operating angle of the intake valve existing when the first control mode is changed to the second control mode.
The ninth aspect of the present invention may include an ignition timing change means for changing ignition timing of the internal-combustion engine in synchronization with the control mode change between the first control mode and the second control mode.
In a tenth aspect of the present invention, the ignition timing change means may determine an advancing amount of the ignition timing in accordance with a valve overlapping period existing when the control mode change between the first control mode and the second control mode is performed.
According to the first aspect of the present invention, the intake valve can be prevented from being closed near the bottom dead center, since the first control mode or the second control mode is selected, depending on a particular load state of the internal-combustion engine.
According to the invention, therefore, it is possible to appropriately control the operating state of the internal-combustion engine while properly avoiding knock.
According to the second aspect of the present invention, improvement of fuel efficiency by reduction of pumping loss can be realized while properly avoiding knock.
According to the third aspect of the present invention, the intake valve control appropriate for improving fuel efficiency can be realized in the high-load region while properly avoiding knock.
According to the fourth aspect of the present invention, while properly avoiding knock, the intake valve control appropriate for improving fuel efficiency can be selected depending on the load state of the internal-combustion engine.
According to the fifth aspect of the present invention, while properly avoiding knock, the intake valve control appropriate for improving fuel efficiency can be realized in a low-speed high-load region that is a region in which knock is most likely to occur.
According to the sixth aspect of the present invention, the appropriate control mode can be selected so that the intake valve control optimal in terms of fuel efficiency is used more reliably in accordance with current engine speed.
According to the seventh aspect of the present invention, operation in which the intake air amount is controlled by the certain torque control means while the closing timing of the intake valve is being fully retarded using the intake closing retardation control is possible in the high-load region where the second control mode is selected.
According to the eighth aspect of the present invention, the angle of the throttle valve can be appropriately set when the throttle valve is used as the torque control means in the second control mode.
According to the ninth aspect of the present invention, changes in torque, coupled with the selection of the first control mode or the second control mode, can be appropriately suppressed.
According to the tenth aspect of the present invention, changes in torque due to deterioration of combustion during the control mode selection can be properly suppressed.
An air flow meter 20 is installed near the inlet of the air intake passageway 16 to output a signal representing the flow rate of the air taken into the air intake passageway 16. A throttle valve 22 is installed downstream of the air flow meter 20. The throttle valve 22 is an electronically controlled throttle valve that can control an open position of the throttle valve independently of an open position of an accelerator. A throttle position sensor 24 that detects an open position TA of the throttle is disposed near the throttle valve 22.
A fuel injection valve 26 for injecting a fuel into an air intake port is disposed downstream with respect to the throttle valve 22. At cylinder head of the internal-combustion engine, an ignition plug 28 is mounted for each cylinder in such a form as to project from an upper section of the combustion chamber 14 into the combustion chamber 14. An intake valve 30 and an exhaust valve 32 are provided at the air intake port and an exhaust port, respectively. The intake valve 30 establishes continuity or discontinuity between the combustion chamber 14 and the air intake passageway 16, and the exhaust valve 32 establishes continuity or discontinuity between the combustion chamber 14 and the exhaust passageway 18.
The intake valve 30 and the exhaust valve 32 are driven by an intake variable valve mechanism 34 and an exhaust variable valve mechanism 36, respectively. The detailed configurations of the intake variable valve mechanism 34 and the exhaust variable valve mechanism 36 will be described later with reference to
The system shown in
As shown in
The intake variable valve mechanism 34A includes an electric motor (hereinafter referred to as a motor) 50A, which serves as a driving source, a gear train 52A, which serves as a mechanism for transmitting the rotary motion of the motor 50A, and a camshaft 54A, which converts the rotary motion transmitted from the gear train to a linear open/close motion of the intake valve 30. Similarly, the intake variable valve mechanism 34B includes a motor 50B, a gear train 52B, and a camshaft 54B.
The motors 50A, 50B are servomotors whose rotation speed and rotation amount of the motors 50A, 50B are controllable. A DC brushless or like motor is preferably used as the motors 50A, 50B. The motors 50A, 50B include a resolver, rotary encoder, or other built-in rotation angle sensor that detects their rotation position (rotation angle). The rotation speed and rotation amount of the motors 50A, 50B are controlled by ECU 40.
A cam drive gear 56 and a cam 58 are installed on the periphery of the camshafts 54A, 54B, respectively. The cam drive gear 56 and cam 58 both rotate together with the camshafts 54A, 54B.
The gear train 52A may be configured so that the motor gear 62A, which is installed over an output shaft 60 of the motor 50A, and camshaft 54A rotate via an intermediate gear 64A at the same speed or configured so that the cam drive gear 56 rotates at a higher speed or at a lower speed than the motor gear 62A. Similarly, the gear train 52B transmits the rotation of a motor gear 62B, which is installed over an output shaft of the motor 50B, to the cam drive gear 56 on the camshaft 54B via an intermediate gear 64B (not shown in
As shown in
As shown in
When the rotary motions of the motors 50A, 50B are transmitted to the camshafts 54A, 54B through the gear trains 52A, 52B, the cam 58 rotates together with the camshafts 54A, 54B. The valve lifter 66 is pressed downward as the nose 58a climbs over the valve lifter 66. The intake valve 30 then opens/closes against the force of the valve spring.
In the normal rotation drive mode, the operating angle of the intake valve 30 is controlled by controlling the rotation speed of the cam 58. In the swing drive mode, the operating angle and lift amount of the intake valve 30 can be controlled by controlling the rotation speed of the cam 58 and swing angle range of the cam 58. In this way, according to the intake variable valve mechanism 34, the intake valve 30 can be driven while the operating angle and lift amount (valve-opening characteristics) are optimized in accordance with the operating state.
In the thus-constructed system of the present embodiment, the operating angle of the intake valve 30 can be varied in the normal rotation drive mode by changing the rotation angle of the cam 58 per revolution thereof, more specifically, by changing the rotation speed of the motor 50A, 50B so as to change a period during which the cam 58 is lifting the intake valve 30. In the normal rotation drive mode, a desired operating angle of the intake valve 30 is set in the ECU 40 according to the operating state of the internal-combustion engine 10. The ECU 40 controls the operation of the motor 50A, 50B so that the appropriate motor speed for the desired operating angle can be achieved.
In the swing drive mode, the operating angle and maximum lift amount of the intake valve 30 can be varied by changing the rotation speed and rotation amount of the motor 50A, 50B so as to change the rotation speed of the cam 58 and the angle range in which the cam 58 rocks. In the swing drive mode, a desired operating angle of the intake valve 30 and a desired maximum lift amount thereof are set in the ECU 40 according to the operating state of the internal-combustion engine 10. The ECU 40 controls the operation of the motor 50A, 50B so that the appropriate rotation speed and rotation amount of the motor 50A, 50B according to the desired operating angle and desired maximum lift amount of the intake valve 30 can be achieved.
Feature Portions of the First EmbodimentIn the system of the present embodiment, the above-described intake variable valve mechanism 34 and the throttle valve 22 can both be used as an intake air amount controller. The present embodiment controls the intake air amount primarily by controlling the valve-opening characteristics of the intake valve 30 via the intake variable valve mechanism 34.
More specifically, the system of the present embodiment controls the intake air amount as follows to improve fuel efficiency by reducing pumping loss: the IVC timing is advanced by reducing the operating angle of the intake valve 30 to limit the amount of air passed through the intake valve 30, and at the same time, a throttle angle TA is correspondingly increased.
To this end, the desired operating angle of the intake valve 30 is determined according to a load factor requirement and engine speed of the internal-combustion engine 10, and after the determination of the desired operating angle, the opening/closing timing of the intake valve 30 is determined to achieve the determined operating angle in an appropriate valve-opening phase. Controlling the intake air amount in this manner renders the operating angle variable according to the load (load factor) and engine speed of the internal-combustion engine 10, thus controlling the IVC timing of the intake valve 30. More specifically, as shown in
The control performed in this way to make the IVC timing of the intake valve 30 variable and adjust the intake air amount according to the load is termed “IVC variable control” hereinafter.
For example, for a change from the low-load region to the high-load region during the variable IVC timing control described above, while the throttle angle TA is being basically maintained at a relatively large angle, the IVC timing of the intake valve 30 can be retarded (e.g., during a change from the stage of
Accordingly, the present embodiment provides two control modes. One is the first control mode in which the control system basically controls the intake air amount by controlling the IVC timing of the intake valve 30 according to the load by use of the IVC variable control, and then controls the IVC timing of the intake valve 30 at the timing-advancing angle position with respect to the certain angle range inclusive of the bottom dead center BDC of air intake. The other is the second control mode in which the control system controls the IVC timing of the intake valve 30 at the timing-retarding angle position with respect to the above certain angle range inclusive of the bottom dead center BDC of air intake. The first control mode is selected in a region relatively low in load, and the second control mode is selected in a region relatively high in load.
Next in step 102, the first control mode or the second control mode depending on the current operating state is selected on the basis of the current load factor and the engine speed. Following this step, step 104 is executed to judge whether the selected current control mode is the first control mode.
If it is judged in step 104 that the current control mode is the first control mode, it is next judged in step 106 on the basis of an accelerator opening and an accelerator opening change rate whether a load-increasing request (speed-up request) for a higher load is present. If, as a result, such a load-increasing request is judged to be present, it is judged in step 108 whether the load-increasing request relates to increasing the load from a valve timing region in which knock is likely.
Internal-combustion engines are prone to knock in a low engine speed region, especially, in the load region where the load factor exceeds about 60%. In step 108, therefore, when the IVC variable control is applied, a region (see
If it is judged in step 108 that the current load-increasing request does not relate to increasing the load from the knock-prone valve timing region, continued use of the first control mode that is the current control mode is determined in step 110. In this case, therefore, the IVC timing of the intake valve 30 is controlled according to the load so as to obtain the intake air amount appropriate for the load.
Conversely if it is judged in step 108 that the current load-increasing request relates to increasing the load from the knock-prone valve timing region, the first control mode that is the current control mode is instantly changed to the second control mode in step 112. More specifically, the intake variable valve mechanism 34 instantly performs a mode change from the first control mode for which the operating angle is set to reach, for example, about 150° CA., to the second control mode for which the operating angle is set to reach, for example, about 210° CA. In that case, throttle angle TA and the ignition timing are next adjusted in step 114 to adjust torque so that the control mode change does not cause a difference in torque.
In the routine of
If it is judged in step 118 that the current load-reducing request does not relate to load reduction from the knock-prone valve timing region, continued use of the second control mode that is the current control mode is determined in step 120. In this case, therefore, the IVC timing of the intake valve 30 is controlled according to the load so as to obtain the intake air amount appropriate for the load.
Conversely if it is judged in step 118 that the current load-reducing request relates to load reduction from the knock-prone valve timing region, the second control mode that is the current control mode is instantly changed to the first control mode in step 122. More specifically, the intake variable valve mechanism 34 instantly performs a mode change from the second control mode for which the operating angle is set to become about 210° CA., for example, to the first control mode for which the operating angle is set to become about 150° CA., for example. In that case, throttle angle TA and the ignition timing are next adjusted in step 124 to adjust torque so that the control mode change does not cause a difference in torque.
According to the above-described routine of
In the first embodiment, which has been described above, the “intake valve control means” according to the first aspect of the present invention is implemented when the ECU 40 performs step 110, 112, 120, or 122; the “control mode selection means” according to the first aspect of the present invention is implemented when the ECU 40 performs step 102, 108, or 118.
Second EmbodimentA second embodiment of the present invention will now be described with reference to
The system according to the second embodiment is implemented by adopting the hardware configuration shown in
The IVC timing here of such an extent that the blowback of the intake air intentionally occurs refers to IVC timing in which the intake air is blown back under a steady state obtained after the engine has reached a desired operating state with the intake valve controlled to be closed in the particular IVC timing. More specifically, the above IVC timing refers to the IVC timing retarded more than the IVC timing (e.g., 30° to 40° CA. ABDC) that is adopted for high-speed high-load operation to ensure that desired output is obtained in a general internal-combustion engine. Even more specifically, the above IVC timing refers to, for example, IVC timing of 80° to 100° CA. ABDC being inclusive of 90° CA. ABDC shown in
Hereinafter, the above second control mode used in the present embodiment, that is, the IVC timing control of the intake valve 30 that aims at achieving Atkinson-cycle engine performance based on delayed closing of the intake valve 30 is also termed the “intake valve closing retardation control”. More specifically, during execution of the intake valve closing retardation control, the IVC timing of the intake valve 30 is controlled to the certain IVC timing fully retarded in the foregoing manner, and then the intake air amount is controlled by the throttle valve 22. In addition, the IVC timing of the intake valve 30 during the execution of the intake valve closing retardation control may not be fixed. Instead, the IVC timing may be made variable according to the load, engine speed, and/or other parameters concerning the operating state.
Differences between the intake valve closing retardation control and the IVC variable control in the foregoing first embodiment are defined below. The IVC variable control is a technique for controlling the intake air amount by, while fully increasing the throttle angle TA, controlling the IVC timing of the intake valve 30 so that the intake valve 30 is closed at a right timing when a desired intake air amount is judged to be obtainable according to the load and/or engine speed. In the first embodiment using the IVC variable control as the first control mode and as the second control mode, therefore, under a transient state existing immediately after the mode change from the first control mode to the second control mode has been performed following receipt of a load-increasing request, the blowback of the intake air may temporarily occur, even during the use of the IVC variable control. The IVC variable control, however, will differ from the intake valve closing retardation control intended to blow back the intake air during a steady state.
Conversely, in regions other than the hatched region in
As shown in
In the present embodiment, in a region of medium engine speeds higher than the above certain engine speed, that is, if a knock-prone region extends down to a load side lower than the region in which the intake valve closing retardation control excels in fuel efficiency, the control mode is also changed from the IVC variable control to the intake valve closing retardation control, in accordance with knock avoidance request as necessary. More specifically, the IVC timing and IVO timing of the intake valve 30 are instantly changed over so that the IVC timing that has been controlled to such an extent that the operating angle becomes, for example, 280° CA. (about 80° CA. ABDC) can be obtained immediately after the IVC timing has been controlled to such an extent that the operating angle becomes, for example, 160° CA. (about 20° CA. BBDC).
In the routine of
In the routine of
If, in step 202, the load-increasing request is judged not to be a request for a load increase toward the region in which the intake valve closing retardation control excels in fuel efficiency, whether the current load-increasing request is a request for a load increase from the knock-prone valve timing region is next discriminated in step 108. As a result, if the judgment criterion in step 108 does not hold, the use of the first control mode which is the current control mode is continued intact in step 110.
If the judgment criterion in step 108 holds, the first control mode that is the current control mode is changed to the second control mode instantly in step 204. More specifically, the intake variable valve mechanism 34 instantly performs a mode change from the first control mode for which the operating angle is set to become about 160° CA., for example, to the second control mode for which the operating angle is set to become about 280° CA., for example. In that case, torque control with the throttle valve 22 is selected and the ignition timing is changed in synchronization with the control mode change. Also, throttle angle TA and the ignition timing are adjusted in step 206 to adjust torque so that the control mode change does not cause a difference in torque.
If, in step 202, the load-increasing request is judged to be a request for a load increase toward the region in which the intake valve closing retardation control excels in fuel efficiency, the first control mode that is the current control mode is changed to the second control mode instantly in step 208. More specifically, the intake variable valve mechanism 34 instantly performs a mode change from the first control mode for which the operating angle is set to become about 140° CA., for example, to the second control mode for which the operating angle is set to become about 280° CA., for example. In that case, torque control with the throttle valve 22 is selected and the ignition timing is changed in synchronization with the control mode change. Also, throttle angle TA and the ignition timing are adjusted in step 210 to adjust torque so that the control mode change does not cause a difference in torque.
In the routine of
If, in step 212, the current load-decreasing request is judged to be a request for load reduction to the region in which the intake valve closing retardation control excels in fuel efficiency, the use of the second control mode which is the current control mode is continued intact in step 214.
Conversely, if it is judged in step 212 that the current load-decreasing request is not a request for load reduction to the region in which the intake valve closing retardation control excels in fuel efficiency, that is, if the current load-increasing request is judged to be a request for load reduction to the region in which the IVC variable control excels in fuel efficiency, the second control mode that is the current control mode is changed to the first control mode instantly in step 216. More specifically, the intake variable valve mechanism 34 instantly performs a mode change from the second control mode for which the operating angle is set to become about 280° CA., for example, to the first control mode for which the operating angle is set to become about 140° to 160° CA., for example, depending on the engine speed. In that case, torque control with the throttle valve 22 is selected and the ignition timing is changed in synchronization with the control mode change. Also, throttle angle TA and the ignition timing are adjusted in step 218 to adjust torque so that the control mode change does not cause a difference in torque.
According to the above-described routine of
In addition, as shown in
In the second embodiment, which has been described above, the throttle valve 22 corresponds to the “torque control means” according to the seventh aspect of the present invention; the “torque control change means” according to the seventh aspect of the present invention is implemented when the ECU 40 performs step 206, 210, or 218.
Further, in the second embodiment, which has been described above, the “ignition timing change means” according to the ninth aspect of the present invention is implemented when the ECU 40 performs step 206, 210, or 218.
Third EmbodimentA third embodiment of the present invention will now be described with reference to
The system according to the third embodiment is implemented by adopting the hardware configuration shown in
The system of the present embodiment is characterized in a technique relating to the torque adjustments performed when the control mode is instantly changed between the IVC variable control and the intake valve closing retardation control (the torque adjustments are detailed in step 300 and the like). More specifically, the present embodiment adjusts a change range of throttle angle TA on the basis of the IVC timing and operating angle of the intake valve 30 existing after the control mode change.
When the intake valve closing retardation control that uses such opening/closing timing of the intake valve 30 as shown in
In the routine of
A map (not shown) in which variations in throttle angle TA are predefined in the relationship between the IVC timing and operating angle of the intake valve 30, obtained after the control mode change has been performed is stored within the ECU 40. The ECU 40 refers to this map and adjusts the throttle angle TA existing after the control mode change. A map (not shown) in which the amount of advancement of the ignition timing is predefined in the relationship with the valve overlapping period (or the IVO timing of the intake valve 30) existing after the control mode change, is also stored within the ECU 40. The ECU 40 refers to this map and adjusts the amount of advancement of the ignition timing, obtained after the control mode change.
In the routine of
According to the above-described routine of
In the first to third embodiments described above, the cam shaft 54A, 54B is driven by the motor 50A, 50B of the intake variable valve mechanism 34 in order to drive the opening/closing of the intake valve 30 of each cylinder. However, the variable valve mechanism that at least makes the IVC timing of the intake valve variable in the present invention may not always be limited to or by such a configuration. Instead, the variable valve mechanism may employ, for example, electromagnetic driving valve actuator to drive the intake valve by electromagnetic force. Alternatively, the variable valve mechanism may be of a mechanical scheme, provided that the mechanism has a function to continuously change the IVC timing of the intake valve in at least the first control mode, and that the first control mode or the second control mode can be instantly selected by, for example, engaging or disengaging coupling of the pin.
Claims
1-3. (canceled)
4. A control apparatus for an internal-combustion engine having a variable valve mechanism which at least makes closing timing of an intake valve variable, the control apparatus comprising:
- intake valve control means with a first control mode for controlling the closing timing of the intake valve at an angle-advancing side relative to a certain range including an air intake bottom dead center, in which knock is more likely to occur, and with a second control mode for controlling the closing timing of the intake valve at an angle-retarding side relative to the certain range, wherein the intake valve control means controls the closing timing of the intake valve in either the first control mode or the second control mode; and
- control mode selection means for selecting the first control mode for operation in a region of relatively low loads, and selecting the second control mode for operation in a region of relatively high loads;
- wherein the first control mode is the control that determines the closing timing of the intake valve according to a load of the internal-combustion engine;
- wherein the closing timing of the intake valve is retarded to an angle side nearer the air intake bottom dead center as the load of the internal-combustion engine increases;
- wherein the control mode selection means changes the first control mode, if the load of the internal-combustion engine has become high until such an extent that the closing timing of the intake valve is likely to enter the certain range where knock is more likely to occur, to the second control mode that controls the closing timing of the intake valve at the angle-retarding side relative to the air intake bottom dead center and at the angle-retarding side relative to the certain range where knock is more likely to occur;
- wherein the second control mode is the intake valve closing retardation control that determines the closing timing of the intake valve such that even under a steady state, blowback of intake air into an intake passage occurs;
- wherein a load region in which the intake valve closing retardation control excels the first control mode in fuel efficiency is set, in a low engine speed region in which the engine runs at a speed equal to or smaller than a certain value, so as to extend down to a load side lower than a region in which knock is likely to occur; and
- wherein the control mode selection means changes the first control mode to the second control mode, in the low engine speed region, when it is judged that the intake valve closing retardation control excels the first control mode in fuel efficiency.
5. The control apparatus for an internal-combustion engine having a variable valve mechanism according to claim 4,
- wherein the intake valve closing retardation control is used in an operating region in which the engine runs at a speed equal to or smaller than a certain value and under a load equal to or greater than a certain value.
6. The control apparatus for an internal-combustion engine having a variable valve mechanism according to claim 4,
- wherein the control mode selection means selects the first control mode until the load region of the internal-combustion engine has reached the higher region as engine speed increases.
7. The control apparatus for an internal-combustion engine having a variable valve mechanism according to claim 4, the control apparatus further comprising:
- torque control means for controlling a torque of the internal-combustion engine in addition to controlling the closing timing control of the intake valve via the intake valve control means; and
- torque control change means for, when the second control mode is selected by the control mode selection means, changing the torque control performed by the intake valve control means, to the torque control performed by the torque control means.
8. The control apparatus for an internal-combustion engine having a variable valve mechanism according to claim 7,
- wherein the torque control means is a throttle valve that controls an intake air amount,
- wherein the torque control means adjusts an open position of the throttle valve in accordance with at least the closing timing of the intake valve, of the closing timing and operating angle of the intake valve existing when the first control mode is changed to the second control mode.
9. The control apparatus for an internal-combustion engine having a variable valve mechanism according to claim 4, the control apparatus further comprising:
- ignition timing change means for changing ignition timing of the internal-combustion engine in synchronization with the control mode change between the first control mode and the second control mode.
10. The control apparatus for an internal-combustion engine having a variable valve mechanism according to claim 9,
- wherein the ignition timing change means determines an advancing amount of the ignition timing in accordance with a valve overlapping period existing when the control mode change between the first control mode and the second control mode is performed.
11. A control apparatus for an internal-combustion engine having a variable valve mechanism which at least makes closing timing of an intake valve variable, the control apparatus comprising:
- an intake valve control device with a first control mode for controlling the closing timing of the intake valve at an angle-advancing side relative to a certain range including an air intake bottom dead center, in which knock is more likely to occur, and with a second control mode for controlling the closing timing of the intake valve at an angle-retarding side relative to the certain range, wherein the intake valve control device controls the closing timing of the intake valve in either the first control mode or the second control mode; and
- a control mode selection device for selecting the first control mode for operation in a region of relatively low loads, and selecting the second control mode for operation in a region of relatively high loads;
- wherein the first control mode is the control that determines the closing timing of the intake valve according to a load of the internal-combustion engine;
- wherein the closing timing of the intake valve is retarded to an angle side nearer the air intake bottom dead center as the load of the internal-combustion engine increases;
- wherein the control mode selection device changes the first control mode, if the load of the internal-combustion engine has become high until such an extent that the closing timing of the intake valve is likely to enter the certain range where knock is more likely to occur, to the second control mode that controls the closing timing of the intake valve at the angle-retarding side relative to the air intake bottom dead center and at the angle-retarding side relative to the certain range where knock is more likely to occur;
- wherein the second control mode is the intake valve closing retardation control that determines the closing timing of the intake valve such that even under a steady state, blowback of intake air into an intake passage occurs;
- wherein a load region in which the intake valve closing retardation control excels the first control mode in fuel efficiency is set, in a low engine speed region in which the engine runs at a speed equal to or smaller than a certain value, so as to extend down to a load side lower than a region in which knock is likely to occur; and
- wherein the control mode selection device changes the first control mode to the second control mode, in the low engine speed region, when it is judged that the intake valve closing retardation control excels the first control mode in fuel efficiency.
Type: Application
Filed: Dec 17, 2007
Publication Date: Jul 15, 2010
Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHA (Toyota-shi, Aichi-ken)
Inventors: Tomohiro Shinagawa (Sunto-gun), Kimitoshi Tsuji (Susono-shi)
Application Number: 12/311,807
International Classification: F01L 1/34 (20060101);