JP3976002B2 - Intake valve drive control device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake valve drive control device for an internal combustion engine provided with a variable lift operating angle mechanism capable of changing a valve lift amount (maximum lift amount) and an operating angle of an intake valve.

Patent Document 1 and the like disclose a lift operating angle variable mechanism previously proposed by the present applicant. The lift operating angle variable mechanism includes a control shaft having a control eccentric shaft portion, a rocker arm swingably mounted on the control eccentric shaft portion, a drive having a drive eccentric shaft portion that rotates in conjunction with the crankshaft. A shaft, a swing cam as a valve-operating cam supported swingably on the drive shaft, a first link linking the drive eccentric shaft portion and one end of the rocker arm, the other end of the rocker arm, and a swing cam The 2nd link which links | links. The intake valve is driven to open and close by a swing cam that swings as the drive shaft rotates. Then, by rotating and driving the control shaft (control eccentric shaft portion) by the actuator, the initial posture and swing range of the swing cam change, and the lift curve that is the valve lift characteristic of the intake valve, that is, the valve of the intake valve The lift amount and the operating angle are configured to increase and decrease simultaneously and continuously. By adjusting the intake air amount using such a lift operating angle variable mechanism, for example, it is possible to remarkably reduce throttle loss in a gasoline engine.
JP 2003-106176 A

  In such a lift operating angle variable mechanism, mechanically, if the angle of the control shaft is the same, that is, if the operating angle (target value) is the same, regardless of the engine speed, the engine temperature, etc. The valve lift characteristic, that is, the lift curve has the same shape, and the valve lift amount including the maximum lift amount should be uniquely determined. That is, the cam profile of the swing cam is designed so as to have a predetermined lift characteristic according to the angle of the control shaft. In practice, however, the lift curves are unavoidably different depending on the engine speed even at the same control shaft angle (operating angle target value) due to bending deformation of each link component, clearance between links, and the like. It will be a thing. For example, even if the operating angle of the intake valve is the same, the valve lift amount becomes relatively large mainly due to valve jump in the high rotation range, and the valve lift amount becomes relatively small mainly due to the deflection of the link in the low rotation range. . Due to such variations in the lift curve, especially in a gasoline engine that controls the intake air amount according to the required (load) torque, the control of the intake air amount using the lift operating angle variable mechanism is not stable, and the output for the required torque is not achieved. There is a possibility that a problem such as a large torque deviation / variation may occur. As with the engine speed, the lift characteristics may vary depending on the engine temperature such as the engine oil temperature and the engine water temperature. The present invention has been made in view of the problems uniquely found in this way.

And a lift operating angle variable mechanism that can change a valve lift amount and an operating angle of the intake valve, and a drive unit that drives the lift operating angle variable mechanism based on an operating angle command value. Based on the target intake air amount, a target operating angle value of the intake valve is calculated. An engine speed detecting means for detecting the engine speed, and an engine temperature detecting means for detecting the engine temperature, and when calculating the operating angle command value, based on the engine speed and the engine temperature , Correct the operating angle target value. Here, in the high temperature region, the operating angle target value is corrected to the lower side as the engine temperature becomes higher. In the low temperature region, the operating angle target value is corrected to the lower side as the engine temperature becomes lower.

According to the present invention, in anticipation of variations in the lift curve according to the engine speed and the engine temperature , which is a problem specific to the lift operating angle variable mechanism that can change both the valve lift amount and the operating angle of the intake valve, The operating angle target value is corrected based on the engine speed and the engine temperature . Therefore, the control accuracy of the intake air amount by the variable lift operating angle mechanism can be remarkably improved regardless of variations in the lift curve according to the engine speed and the engine temperature .

  Hereinafter, an embodiment in which the present invention is applied to a spark ignition gasoline engine for an automobile will be described. FIG. 1 is a configuration explanatory view showing a configuration of a variable valve mechanism for an intake valve of an internal combustion engine. The variable valve mechanism includes a lift operating angle variable mechanism 1 that changes both the valve lift amount (maximum lift amount) and the operating angle of the intake valve simultaneously and continuously, and a phase (not shown) of the center angle of the lift. And a phase variable mechanism 21 for advancing or retarding the phase) relative to the crankshaft. Since these mechanisms 1 and 21 are known as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2003-106176, only the outline will be described here.

  The lift operating angle variable mechanism 1 includes a drive shaft 2 that is rotationally driven in conjunction with a crankshaft, a drive eccentric shaft portion 3 that is eccentrically provided on the drive shaft 2, and parallel to the drive shaft 2 in the cylinder row direction. The control shaft 12 that extends, the control eccentric shaft portion 18 provided eccentric to the control shaft 12, the rocker arm 6 that is swingably supported by the control eccentric shaft portion 18, and the drive shaft 2 can swing. And a swing cam 9 as a valve-operating cam attached thereto. The drive eccentric shaft portion 3 and one end of the rocker arm 6 are linked by the first link 4, and the other end of the rocker arm 6 and the swing cam 9 are linked by the second link 8. The first link 4 and the rocker arm 6 are connected by a connecting pin 5, and the second link 8 is connected to the rocker arm 6 and the swing cam 9 by connecting pins 7 and 17, respectively. When the drive shaft 2 rotates, the attitude of the first link 4 changes due to the cam action of the drive eccentric shaft portion 3, and the rocker arm 6 swings accordingly. The rocking motion of the rocker arm 6 is transmitted to the rocking cam 9 via the second link 8, and the rocking cam 9 rocks. The tappet 10 is pressed by the cam action of the swing cam 9, and the intake valve 11 is opened and closed.

  One end of the control shaft 12 is connected to a lift operating angle control actuator 13 as a driving means via a worm gear 15. The lift operating angle control actuator 13 is composed of a servo motor for rotating the control shaft 12 and is controlled by a control signal from the engine control unit 19. The rotation angle of the control shaft 12 is detected by the control shaft sensor 14. When the angular position of the control shaft 12 is changed via the lift operating angle control actuator 13, the initial position of the control eccentric shaft portion 18 which becomes the rocking fulcrum of the rocker arm 6 changes, and consequently the rocking range of the rocking cam 9.・ The posture changes. Since the initial position of the control eccentric shaft portion 18 can be continuously changed, the valve lift characteristic of the intake valve continuously changes accordingly. That is, the valve lift amount and the operating angle of the intake valve can be increased and decreased simultaneously and continuously. Depending on the layout of each part, for example, the opening timing and closing timing of the intake valve 11 change substantially symmetrically with the change in the lift operating angle.

  Such a lift operating angle variable mechanism 1 is compact and excellent in engine mountability because the components are concentrated around the drive shaft 2, and the drive shaft 2 and the swing cam 9 are provided. Since it corresponds to the positions of the camshaft and fixed cam of the direct acting valve system, it is easy to apply the existing direct acting valve system to the internal combustion engine. Further, since most of the connecting parts of the link component parts are in surface contact and no urging means such as a return spring is required, lubrication is easy and the durability and reliability are excellent.

  The phase variable mechanism 21 includes a sprocket 22 provided at the front end portion of the drive shaft 2 and a phase control actuator 23 that relatively rotates the sprocket 22 and the drive shaft 2 within a predetermined angle range. It is configured. The sprocket 22 is linked to the crankshaft via a timing chain or timing belt (not shown) and rotates in synchronization with the crankshaft. The phase control actuator 23 is composed of, for example, a hydraulic or electromagnetic rotary actuator, and is controlled by a control signal from the engine control unit 19. The action of the phase control actuator 23 causes the sprocket 22 and the drive shaft 2 to rotate relative to each other, thereby delaying the lift center angle in the valve lift. That is, the lift curve itself of the lift characteristic does not change, and the whole advances or retards. This change can also be obtained continuously. The control state of the phase variable mechanism 21 is detected by the drive shaft sensor 16 that responds to the rotational position of the drive shaft 2.

  The control of the lift operating angle variable mechanism 1 and the phase variable mechanism 21 is not limited to closed loop control based on the detection signals of the sensors 14 and 16, and may be simply open loop controlled according to the operating conditions. .

  An internal combustion engine equipped with such a variable valve mechanism on the intake valve side can control the intake air amount by variable control of the intake valve 11 without depending on only the throttle valve. However, in a practical engine, a slight negative pressure is applied to the intake system so that the intake air amount control can be stably performed even in a situation where the intake air amount is extremely small like an idle, or for the return of blow-by gas, etc. Therefore, an electric throttle valve 55 (see FIG. 2) is provided upstream of the intake passage, as will be described later.

  FIG. 2 shows the overall configuration of the intake system and the exhaust system in this internal combustion engine. As shown in the figure, this internal combustion engine is, for example, an in-line four-cylinder engine, and branch passages 52 are connected to intake ports of the respective cylinders 51, and upstream ends of the four branch passages 52 are connected to collectors 53. Each is connected. An intake inlet passage 54 is provided at the upstream end of the collector 53. An electrically controlled throttle valve 55 is disposed in the intake inlet passage 54. The throttle valve 55 includes a butterfly valve type valve body that is opened and closed by an actuator 56 such as a DC motor or a diaphragm type actuator, and its opening degree is controlled independently of the accelerator pedal opening degree.

  The collector 53 is provided with a pressure sensor 57 for detecting the pressure inside the collector 53 and a temperature sensor 58 for detecting the intake air temperature. The exhaust manifold 59 is provided with an air / fuel ratio sensor for detecting the exhaust air / fuel ratio. A (linear air-fuel ratio sensor or oxygen sensor) 60 is provided. In addition, a crank angle sensor 61 serving as a rotational speed detecting means for detecting engine rotational speed and crank angle position, an accelerator opening sensor 62 for detecting an accelerator pedal opening (depression amount) operated by a driver, and an intake air amount An air flow meter 63 as an intake air amount detection means for detecting the oil temperature, an oil temperature sensor 64 as an engine temperature detection means for detecting the engine oil temperature as the engine temperature, and the like are provided. These detection signals are respectively input to the engine control unit 19 described above. Based on these detection signals, the engine control unit 19 executes the control of the lift operating angle variable mechanism 1 and the phase variable mechanism 21 and the control of the throttle valve 55 described above.

  FIG. 3 is a flowchart showing a control flow of the lift operating angle variable mechanism 1. First, in S (step) 11, the required torque is calculated mainly based on the detection signal of the accelerator opening sensor 62. In S12, the target intake air amount is calculated based on the required torque and the engine speed (engine speed) obtained from the crank angle sensor 61. In S13, the target value of the operating angle of the intake valve by the variable lift operating angle mechanism 1 is calculated based on the target intake air amount.

  In the subroutine of S14, a correction process described later is performed on the operating angle target value calculated in S13 to calculate an operating angle command value. In S <b> 15, the operating angle command value is output to the lift operating angle actuator 13. Thereby, the lift operating angle variable mechanism 1 is drive-controlled toward the command value. Although not described here, the command value for the opening degree of the throttle valve 55 and the command value for the intake valve timing of the phase variable mechanism 21 are also calculated based on the target intake air amount.

  Next, the processing content of S14 which is the main part of the present embodiment will be described in detail with reference to FIGS. The lift curve, which is the valve lift characteristic of the intake valve, should be unambiguously determined mechanically and structurally by the swing range of the swing cam 9, that is, the angular position of the control shaft 12 corresponding to the operating angle target value. is there. However, actually, as shown in FIG. 5, even if the angular position of the control shaft 12, that is, the operating angle target value is the same, the lift curves L1 to L3 differ depending on the engine speed. Specifically, the higher the engine speed, the greater the inertial force and causing valve jumps, etc., so the valve lift amount is relatively large, and the lower the engine speed, the more the valve lift is mainly caused by the deflection of the link. The amount tends to be relatively small. That is, the effective opening area of the intake valve (corresponding to the area in the lift curve) varies depending on the engine speed, and the control accuracy of the intake air amount by the variable lift operating angle mechanism 1 may be reduced.

  Therefore, in S22, the operating angle target value is corrected based on the engine speed read in S21 (correcting means). Specifically, as shown in FIG. 6, using a control map or a table (not shown) set in advance so that the desired intake valve effective opening area corresponding to the operating angle target value is obtained, The operating angle target value is corrected to the lower side as the engine speed increases, and the operating angle target value is corrected to the higher side as the engine speed decreases.

  Similarly, since the friction of each link component increases or decreases according to the engine temperature such as the engine oil temperature detected by the oil temperature sensor 64, even if the same operating angle target value, the valve according to the engine temperature. The valve lift characteristic including the lift amount, that is, the intake valve effective opening area increases or decreases. Specifically, as shown in FIG. 7, in a high temperature region where the engine temperature is higher than a predetermined reference value, the effective opening area increases as the engine temperature increases, and in a low temperature region where the engine temperature is low, the engine temperature The effective opening area tends to increase with the decrease. Therefore, in S24, the operating angle target value is corrected in accordance with the engine temperature read in S23 (correction means) so as to cancel and absorb such an increase / decrease in the intake valve effective opening area due to the engine temperature. In other words, by using a preset control map or table (not shown), the target operating angle is corrected to decrease as the engine temperature increases in the high temperature region, and operates as the engine temperature decreases in the low temperature region. The angle target value is corrected to the lower side. The operating angle command value is calculated through such correction processing as S22 and S24.

  Depending on the size of the operating angle target value itself, the effective opening area may vary. Therefore, preferably, the correction amount by the correction processing in S22 and S24 is changed (correction amount changing means) according to the magnitude of the operating angle target value. For example, as shown in FIGS. 6 and 7, a plurality of nonlinear maps (or tables) are set and stored in advance according to the magnitude of the operating angle target value, and are appropriately set according to the magnitude of the operating angle target value. A non-linear map may be selected, and correction processing based on the engine speed and the engine temperature may be performed with reference to the selected map.

  In S25, the intake air amount detected by the air flow meter 63 is read. In S26, learning control processing for the correction processing in S22 and S24 is performed based on the actual intake air amount detected in this way (learning control means). The learning control itself is well known and will be briefly described. For example, the deviation between the target intake air amount calculated in S12 and the intake air amount detected / read in S23 is calculated, and the learning value is calculated from the deviation. The learning value may be calculated and reflected in the correction processing in S22 and S24 after the next time. By performing such learning control, it is possible to cope with variations in lift curves caused by deterioration of valve operating components over time, and stable control can be performed over a long period of time.

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, the operating angle target value correction process based on the engine speed in S22 may be performed only in a high engine speed range where variations in the effective opening area tend to appear greatly.

The perspective view which shows the lift operating angle variable mechanism in the intake valve drive control device of the internal combustion engine which concerns on one Example of this invention. FIG. 2 is an explanatory diagram illustrating the overall configuration of an intake system and an exhaust system of the internal combustion engine. The flowchart which shows the flow of control of the lift operating angle variable mechanism which concerns on a present Example. The subroutine which shows the operating angle command value calculation process in S14 of FIG. Explanatory drawing which shows the dispersion | variation in the lift curve by engine speed. Explanatory drawing which shows the dispersion | variation in the intake valve effective opening area by an engine speed and an operating angle. Explanatory drawing which shows the dispersion | variation in the intake valve effective opening area by engine temperature and an operating angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lift working angle variable mechanism 2 ... Drive shaft 9 ... Swing cam (valve cam)
19 ... Engine control unit 61 ... Crank angle sensor (rotational speed detection means)
63 ... Air flow meter (intake air amount detection means)
64. Oil temperature sensor (engine temperature detecting means)

Claims (5)

A lift operating angle variable mechanism capable of changing the valve lift amount and operating angle of the intake valve;
Drive means for driving the lift operating angle variable mechanism based on an operating angle command value;
A target value calculating means for calculating a working angle target value of the intake valve based on the target intake air amount;
A rotational speed detection means for detecting the engine rotational speed;
Engine temperature detecting means for detecting the engine temperature;
When calculating the working angle command value, based on the above engine speed and engine temperature, have a, a correction means for correcting the operation angle target value,
This correction means corrects the operating angle target value to the lower side as the engine temperature increases in the high temperature region, and corrects the operating angle target value to the lower side as the engine temperature decreases in the low temperature region. Control device.   The intake of the internal combustion engine according to claim 1, wherein the correction means corrects the target operating angle to a lower side when the engine speed is high and corrects the target operating angle to an increase side when the engine speed is low. Valve drive control device. The intake valve drive control device for an internal combustion engine according to claim 1 or 2 , further comprising a correction amount changing means for changing a correction amount by the correction means based on the operating angle target value. An intake air amount detection means for detecting an intake air amount;
Based on a deviation between the intake air amount and the target intake air amount detected by the intake air amount detecting means, any claim 1-3 having a learning control means for learning control of the correction by the correction means An intake valve drive control device for an internal combustion engine according to claim 1. The variable valve mechanism includes a valve cam for operating an intake valve, a drive shaft that rotates in conjunction with a crankshaft, and a plurality of links that link the valve cam and the drive shaft. The intake valve drive control device for an internal combustion engine according to any one of claims 1 to 4 , wherein both the valve lift amount and the operating angle of the engine are changed simultaneously and continuously.

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