JP4048560B2 - Engine valve control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine valve control device, and more particularly to an engine valve valve provided with a cam position moving mechanism for continuously changing valve timing and valve lift amount of a valve from a low load range to a high load range of the engine. The present invention relates to a control device.
[0002]
[Prior art]
In a valve operating device for a vehicle engine, a valve consisting of an intake valve or an exhaust valve that is always urged in a closing direction of a valve port by a valve spring is provided, and this valve is opened and closed by a cam provided on a camshaft. .
[0003]
In this engine valve operating device, the valve timing (opening / closing timing) of an intake valve or exhaust valve and the valve lift amount are continuously adjusted by moving a cam whose cam profile changes in the axial direction of the camshaft. There is one provided with a cam position moving mechanism to be changed (Japanese Patent Laid-Open No. Hei 4-187807). As described above, in the valve operating apparatus provided with the cam position moving mechanism, when the valve is an intake valve, the intake air amount can be controlled by continuously changing the valve lift amount of the intake valve. By reducing the intake resistance by eliminating the throttle valve in the intake passage, the engine output is improved, and in the low load range of the engine, the cam profile of the cam is set so that the intake valve closes quickly. Loss can be reduced, and by reducing the valve lift amount itself, mechanical loss is reduced and fuel efficiency is improved.
[0004]
In this case, the cam is continuously moved in the axial direction of the camshaft according to the engine load and the engine rotational speed. Generally, the target cam position is calculated based on the engine load and the engine rotational speed. The control amount of the control motor is feedback controlled according to the deviation between the target cam position and the actual cam position. In this feedback control, when the feedback gain is set by changing the feedback gain depending on factors such as the actual cam position and engine speed, and the feedback gain is the same value in the cam movement direction, the cam is In order to move in the direction in which the amount increases, it is necessary to move the cam against the force of the valve spring, while in order to move the cam in the direction in which the valve lift amount of the valve decreases, the valve spring Therefore, if the feedback gain is set large to ensure the responsiveness of the cam position movement in the direction in which the valve lift increases, the cam movement speed in the direction in which the valve lift decreases. Is too large and the cam passes past the target cam position, causing overshoot. Was Tsu.
[0005]
In other words, when the cam is acting on the valve, the cam needs to be moved against the force of the valve spring to move the cam in the direction in which the valve lift increases, while the cam acts on the valve. If not, a large force is not necessary to move the cam in the axial direction of the camshaft, and the force to move the cam varies greatly, particularly in the low rotation range.
[0006]
In order to solve such a problem, as shown in FIG. 8, for example, in a four-cylinder (# 1, # 2, # 3, # 4) engine, an output from a crank angle detection sensor corresponding to the rotation of the crankshaft is performed. By measuring or predicting the period during which the cam is acting on the valve at least when the engine speed is low, by limiting the period during which the cam is not acting on the valve. By moving the cam in the axial direction and improving controllability, the use of a motor with a small capacity is advantageous in terms of cost and mounting space.
[0007]
Further, such valve gears for engines are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2001-303990, 2001-90562, and 2000-227033. Japanese Patent Laid-Open No. 2001-303990 sets a target advance amount of valve timing in accordance with the operating state of the engine, and performs feedback control of the valve timing to the target advance amount. By determining the steady state and variably setting the feedback gain of the feedback control based on the determination result, the feedback gain is switched to an appropriate gain between the transient time and the steady time, and the response time of the variable valve timing control during the transient It achieves both steady-state stability. Japanese Patent Application Laid-Open No. 2001-90562 suppresses a significant increase in processing time for each predetermined crank angle position during high-speed rotation, reduces processing during high-speed rotation, and facilitates establishment of an engine control system. At the same time, the variation in the convergence time of the actual advance amount with respect to the target advance amount is reduced, the engine output is prevented from being lowered, and the like, and good valve timing control is enabled. The one described in Japanese Patent Application Laid-Open No. 2000-227033 is provided with a variable valve characteristic mechanism for controlling the cam phase in a stepless manner at the end portion of the cam shaft so that the deviation between the target cam phase and the actual cam phase converges to zero. When the deviation between the target cam phase and the actual cam phase is less than the threshold, the valve characteristic variable mechanism is feedback controlled. By controlling, responsiveness and convergence are improved regardless of the operating state of the engine.
[0008]
[Problems to be solved by the invention]
By the way, in the conventional valve operating apparatus provided with the cam position moving mechanism, when the control motor is feedback-controlled according to the deviation between the target cam position and the actual cam position, the change in the thrust force of the rotating cam and the cam The cam is moved in the axial direction of the camshaft between the period when the cam is acting on the valve against the force of the valve spring and the period when the cam is not acting on the valve. As shown in FIG. 9, when the cam is moved to the target cam position, the actual cam position deviates from the target cam position and exceeds the cam movement particularly in the low engine speed range. There is a disadvantage that a chute occurs and the cam does not reach the target cam position.
[0009]
[Means for Solving the Problems]
Therefore, in order to eliminate the above-described disadvantage, the present invention is a cam that continuously changes the valve timing and the valve lift amount of the valve by moving the cam whose cam profile changes in the axial direction of the camshaft by the control motor. In an engine valve control apparatus provided with a position moving mechanism, an engine for detecting an engine rotational speed is provided by providing a cam position detecting means for detecting an actual cam position of the cam, an engine load detecting means for detecting an engine load. A rotational speed detection means is provided, a target cam position is calculated based on the engine load and the engine rotational speed, a feedback control amount is calculated according to a deviation between the target cam position and the actual cam position, and at least the actual cam calculating a feedforward control amount based on the position and the engine rotational speed, the feedback A feedback gain used in a direction in which the valve lift amount increases and a feedback gain used in a direction in which the valve lift amount decreases and a feedback gain used in a direction in which the valve lift amount decreases. Is set to a value smaller than the feedback gain used in the direction in which the valve lift amount increases, and the motor control amount is calculated by adding the calculated feedback control amount and the calculated feedforward control amount. Means is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention, in the low rotation region of the engine rotational speed, when moving the cam to the target cam position, to improve the followability to the target cam position of the cam, prevents the overshoot occurs in the movement of the cam The cam can reliably reach the target cam position.
[0011]
【Example】
Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 to 7 show an embodiment of the present invention. In FIG. 6, 2 is an engine mounted on a vehicle (not shown), 4 is a cylinder head, 6 is a combustion chamber, 8 is an intake port, and 10 is a valve operating device. The valve operating apparatus 10 is provided with an intake valve 14 as a valve for opening and closing an intake port 12 that is a valve port communicating with the combustion chamber 6 below the cylinder head 4. A cam shaft 18 to which the cam 16 is attached is pivotally provided. The camshaft 18 rotates in synchronization with the rotation of a crankshaft (not shown) of the engine 2.
[0012]
The intake valve 14 includes a valve body 14A that contacts and separates from the intake port 12, and a valve stem 14B that is connected to the valve body 14A. The valve stem 14B is slidably held by a stem guide 20 attached to the cylinder head 4. A spring retainer 22 is fixedly provided on the distal end side of the valve stem 14B. Further, between the spring retainer 22 and the spring support 24 of the cylinder head 4, the intake valve 14 is fitted to the valve stem 14 </ b> B of the intake valve 14 to constantly urge the intake valve 14 in the closing direction (upward) of the intake port 12. A valve spring 26 is interposed. A tappet 28 is integrally provided on the spring retainer 22. An upper curved surface 30 that is in contact with the cam surface 16 </ b> A of the cam 16 is formed in the upper portion of the tappet 28.
[0013]
The valve gear 10 is provided with a cam position moving mechanism 32. In the cam position moving mechanism 32, a shaft spline 34 having a predetermined length is provided in a part of the outer peripheral surface of the camshaft 18 in the axial direction, and the cam 16 is provided on the guide spline 34 so as to be movable in the axial direction. . The cam 16 has a variable cam profile, is formed in a cylindrical shape with a predetermined length in the axial direction, and a cam spline (not shown) on the inner peripheral surface engages with a shaft spline 34 of the camshaft 18. is doing. The cam surface 16A of the cam 16 includes a basic circular surface portion 16B parallel to the axis of the camshaft 18, a protruding inclined surface portion 16D that is inclined with respect to the axial center of the camshaft 18 by an inclined protrusion 16C, Side surface portions 16E and 16E are formed to continue the base circular surface portion 16B and the protruding inclined surface portion 16D. In FIG. 6, the protruding inclined surface portion 16D gradually increases in size from the L direction of the left end portion 16-1 to the R direction of the right other end portion 16-2 on the outer peripheral surface of the inclined protrusion portion 16C. It is formed to be inclined.
[0014]
The one end portion 16-1 and the other end portion 16-2 of the cam 16 are respectively provided with holding portions 38-1 and 38- on both sides of the horizontal portion 38 of the pushing arm 36 arranged in the axial direction of the camshaft 18. 2 is sandwiched between the two. A screw hole 42 oriented in the axial direction of the camshaft 18 is formed in the protruding portion 40 protruding upward at the central portion of the horizontal portion 38 of the push arm 36. A screw shaft 44 disposed in the axial direction of the camshaft 18 is screwed into the screw hole 42. A control motor 46 is connected to one end portion of the screw shaft 44.
[0015]
Therefore, in the cam position moving mechanism 32, the cam 16 having the cam surface 16A whose cam profile changes is moved in the axial direction of the camshaft 18 by the control motor 46, so that the cam 2 moves according to the operating state of the engine 2. The valve timing and the valve lift amount of the intake valve 14 are continuously changed. When the screw shaft 44 is rotated by the control motor 46, the push arm 36 moves in the axial direction of the camshaft 18 (see FIG. 6). L direction or R direction), the cam 16 is moved on the shaft spline 34, and the intake valve 14 is opened and closed by the cam surface 16A on which the cam profile changes. Therefore, when the cam 16 acts on the intake valve 14 due to the rotation of the cam 16 accompanying the camshaft 18, that is, when the protruding inclined surface 16D is in contact with the upper curved surface 30 of the tappet 28, the intake valve 14 is On the other hand, when the cam 16 is not acting on the intake valve 14, that is, when the basic circular surface portion 16B is in contact with the upper curved surface 30 of the tappet 28, the intake valve 14 is opened (see FIG. 7A). Is closed (see FIG. 7B). As shown in FIG. 6, when the cam 16 is moved in the R direction by driving the cam position moving mechanism 32, the projecting inclined surface 16 </ b> D on the one end portion 16-1 side with a small projecting amount becomes the upper curved surface 30 of the tappet 28. , The amount of air lifted into the combustion chamber 6 decreases, and conversely, when the cam 16 is moved in the L direction, the other end portion 16-2 having a large protrusion amount. The projecting inclined surface 16D on the side contacts the upper curved surface 30 of the tappet 28, the valve lift amount of the intake valve 14 increases, and the amount of air taken into the combustion chamber 6 increases.
[0016]
The control motor 46 communicates with a control means (ECU) 48 and is driven and controlled by a control signal (control amount) from the control means 48. The control means 48 includes a cam position detection sensor 50 which is a cam position detection means for detecting the movement of the protrusion 40 of the push arm 36 as an actual cam position of the cam 16, and detects the operating state of the engine 2. Thus, a crank angle detection sensor 52 as an engine rotation speed detection means for detecting a crank angle signal by rotation of the crankshaft and calculating an engine rotation speed, and an engine load detection means for detecting an engine load requested by the driver. A certain engine load detection sensor 54, a coolant temperature detection sensor 56 that is a coolant temperature detection means for detecting engine coolant temperature, and an accelerator opening degree in a depressed state of an accelerator pedal (not shown) by a driver are detected. An accelerator opening sensor 58 is in communication.
[0017]
As shown in FIG. 5, the control means 48 includes an engine rotation speed calculation unit 58 that calculates the engine rotation speed by measuring the period of the crank angle signal detected by the crank angle detection sensor 52, and the engine rotation speed calculation unit 58. A target cam position calculation unit 60 that calculates a target cam position according to a value output from the engine load detection sensor 54, and a value output from the target cam position calculation unit 60 and the cam position detection sensor 50. A deviation calculation unit 62 that calculates a deviation, a feedback control amount calculation unit 64 that calculates a feedback (F / B) control amount according to the deviation calculated by contacting the deviation calculation unit 62, and the engine rotation speed calculation Unit 58, the target cam position calculation unit 60, and the cam position detection sensor 50 calculate a feedforward (F / F) control amount. A forward control amount calculation unit 66, a control amount addition setting unit 68 that sets the calculated feedback control amount and the feedforward control amount to set a control amount to the control motor 46, and an intake valve based on the crank angle signal There is provided a control amount switching section 70 for outputting the control amount of the control motor 46 switched between the period during which 14 is operating and the period during which it is not operating to the control motor 46 of the cam position moving mechanism 32. Further, the control means 48 sets a target cam position map (see FIG. 2) for setting a target cam position according to the accelerator opening, and a feedforward control amount 1 according to the cam position (actual cam position). A first feedforward control amount map (see FIG. 3) and a second feedforward control amount map (see FIG. 4) for setting the feedforward control amount 2 in accordance with the engine speed are incorporated. .
[0018]
The control means 48 calculates a target cam position based on the engine load and the engine rotation speed, calculates a feedback control amount according to a deviation between the calculated target cam position and the detected actual cam position, A feedforward control amount is calculated based on at least the detected actual cam position and engine rotational speed, and the control amount of the control motor 46 is increased or decreased.
[0019]
Next, the operation of this embodiment will be described based on the flowchart of FIG.
[0020]
When the program starts in the control means 48 (step 102), the actual cam position is detected (step 104), the engine load is detected (step 106), and the engine speed is determined by measuring the period of the crank angle signal. The target cam position is calculated from the engine load and the engine speed (step 110). This target cam position is set according to the accelerator opening, for example, as shown in FIG.
[0021]
The deviation between the calculated target cam position and the actual cam position is
Deviation = target cam position−actual cam position is calculated (step 112).
[0022]
Next, it is determined whether the cam 16 is acting on the intake valve 14 and the intake valve 14 is open (step 114).
[0023]
In step 114, when it is determined that the cam 16 is acting on the intake valve 14 and the intake valve 14 is in an open state (see FIG. 7A), feedback (F) is performed based on the calculated deviation. / B) A control amount is calculated (step 116). At this time, the feedback gain (proportional gain Kp, integral gain Ki) uses values when the intake valve 14 is open. That is, the feedback (F / B) control amount is
Feedback (F / B) control amount = Kp1 * deviation + ΣKi1 * deviation.
[0024]
Next, according to the cam position, for example, based on a function as shown in FIG.
Feed forward (F / F) control amount 1 = f1 (cam position)
(Step 118).
[0025]
Also, according to the engine speed, for example, based on a function as shown in FIG.
Feed forward (F / F) control amount 2 = g1 (engine speed)
(Step 120).
[0026]
Then, by adding the calculated feedforward (F / F) control amount 1 and the feedforward (F / F) control amount 2, the final feedforward (F / F) control amount is
Feed forward (F / F) control amount = feed forward (F / F) control amount 1 + feed forward (F / F) control amount 2
(Step 122).
[0027]
Then, by adding the feedback (F / B) control amount and the feed forward (F / F) control amount, the control amount output to the control motor 46 is
Control amount = Feedback (F / B) control amount + Feed forward (F / F) control amount (Step 124).
[0028]
On the other hand, if it is determined in step 114 that the cam 16 does not act on the intake valve 16 and the intake valve 16 is in a closed state (see FIG. 7B), feedback based on the calculated deviation ( F / B) A control amount is calculated (step 126). At this time, the feedback gain (proportional gain Kp, integral gain Ki) uses values when the intake valve 16 is closed. That is, the feedback (F / B) control amount is
Feedback (F / B) control amount = Kp2 * deviation + ΣKi2 * deviation.
[0029]
Next, according to the cam position, for example, based on a function as shown in FIG.
Feed forward (F / F) control amount 1 = f2 (cam position)
(Step 128).
[0030]
Also, according to the engine speed, for example, based on a function as shown in FIG.
Feed forward (F / F) control amount 2 = g2 (engine speed)
(Step 130).
[0031]
Then, by adding the calculated feedforward (F / F) control amount 1 and the feedforward (F / F) control amount 2, the final feedforward (F / F) control amount is
Feed forward (F / F) control amount = feed forward (F / F) control amount 1 + feed forward (F / F) control amount 2
(Step 132).
[0032]
Then, by adding the feedback (F / B) control amount and the feed forward (F / F) control amount, the control amount output to the control motor 46 is
Control amount = Feedback (F / B) control amount + Feed forward (F / F) control amount (Step 134).
[0033]
After step 124 or after step 134, the program is ended (step 136).
[0034]
In the flowchart of FIG. 1, each process is repeatedly performed every certain period.
[0035]
As a result, the cam position moving mechanism 32 that moves the cam 16 in the axial direction of the camshaft 18 so as to continuously change the valve timing and the valve lift amount of the intake valve 14 from the low load range to the high load range of the engine 2. In FIG. 2, it is determined whether the intake valve 14 is open when the cam 16 is acting on the intake valve 14 and when the intake valve 14 is closed when the cam 16 is not acting on the intake valve 14. And when the intake valve 14 is closed, the control amount of the control motor 46 is increased or decreased. That is, the crank angle signal from the crank angle detection sensor 52 that is output according to the rotation of the crankshaft is input, and the period during which the cam 16 is acting on the intake valve 14 and the cam 16 is not acting on the intake valve 14. By measuring or predicting the period (feedforward control amount), and dividing the control amount of the control motor 46 into a period during which the cam 16 is acting on the intake valve 14 and a period during which the cam 16 is not acting, specifically, The cam 16 gives the intake valve 14 the feedback gain of the feedforward control amount determined according to the actual cam position and the engine rotational speed and the feedback control amount determined according to the deviation between the target cam position and the actual cam position. It is changed between a period during which the valve 16 is operating and a period during which the valve 16 is not operating, so that the valve lift amount of the cam 16 is increased and decreased. In other words, when the feedback gain in the direction in which the valve lift amount decreases is set smaller than in the direction in which the valve lift amount increases, and when moving in the direction in which the valve lift amount decreases, the actual cam position When the engine approaches a target cam position to some extent, the load for moving the cam 16 is made discontinuous by setting the feedback gain small and reducing the moving speed of the cam 16, especially in the low engine speed range. The cam 16 can be moved to the target cam position, the cam 16 can follow the target cam position, and the cam 16 can be prevented from overshooting. The cam 16 can reliably reach the target cam position.
[0036]
【The invention's effect】
As is apparent from the above detailed description, according to the present invention, when the cam is moved to the target cam position in the low engine speed range, the followability to the target cam position is improved, and the cam movement is overshot. Can be prevented, and the cam can reliably reach the target cam position.
[Brief description of the drawings]
FIG. 1 is a flowchart of valve control.
FIG. 2 is a diagram for setting a target cam position.
FIG. 3 is a diagram for setting a feedforward control amount of 1;
FIG. 4 is a diagram for setting a feedforward control amount of 2;
FIG. 5 is a block diagram of a valve operating control device.
FIG. 6 is a configuration diagram of a valve operating control device.
FIG. 7A is a schematic configuration diagram when a cam is acting on an intake valve.
(B) is a schematic block diagram when the cam is not acting on the intake valve.
FIG. 8 is a time chart of valve operating control in which a crank angle signal is conventionally input.
[Explanation of symbols]
2 Engine 4 Cylinder head 10 Valve mechanism 14 Intake valve 16 Cam 18 Cam shaft 32 Cam position moving mechanism 36 Push arm 44 Screw shaft 46 Control motor 48 Control means 50 Cam position detection sensor 52 Crank angle detection sensor 54 Engine load detection sensor

Claims (1)

In a valve operating control system for an engine provided with a cam position moving mechanism that continuously changes a valve timing and a valve lift amount of a valve by moving a cam whose cam profile changes in the axial direction of the camshaft by a control motor. The cam position detecting means for detecting the actual cam position of the cam, the engine load detecting means for detecting the engine load, the engine rotation speed detecting means for detecting the engine rotation speed, the engine load, the engine rotation speed, The target cam position is calculated based on the difference between the target cam position and the actual cam position, and the feedback control amount is calculated based on at least the actual cam position and the engine rotational speed. calculated, the valve lift amount to be used for the calculation of the feedback control amount is to increase A feedback gain for use in the direction in which the valve lift amount decreases, and a feedback gain for use in the direction in which the valve lift amount decreases. A valve operating system for an engine comprising: a control means for calculating a motor control amount by setting a value smaller than a gain and adding the calculated feedback control amount and the calculated feedforward control amount Control device.

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