JP3871154B2 - Engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine control device, and more particularly, to an engine control device that can be controlled by a control means so as to strengthen the action of the engine brake when it is determined that the vehicle state requires an engine brake.
[0002]
[Prior art]
In a general gasoline engine (hereinafter simply referred to as “engine”), the output is controlled by opening and closing a throttle valve installed in an intake pipe. For this reason, when the load is low, there is a problem that the pumping loss increases due to the negative pressure on the downstream side of the throttle valve increasing. In particular, in automobiles that frequently use low loads, this is one of the major causes of fuel consumption deterioration.
[0003]
In the engine control apparatus, the present applicant provides two intake valves per cylinder, provides cams for opening and closing these intake valves, and sets one intake valve at a fixed phase with respect to the crank angle. An application for controlling the intake air amount, that is, the output by opening and closing and opening and closing the other intake valve at a phase variable on the side delayed from the crank angle has already been filed (Japanese Patent Laid-Open No. 3-88907). .
[0004]
[Problems to be solved by the invention]
By the way, in the conventional engine control device disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-88907, in the case of full load, the phase difference between the fixed phase cam and the variable phase cam is 0 degree as shown in FIG. Thus, in the case of partial load, as shown in FIG. 17, the phase of the variable phase cam is delayed and a part of the air-fuel mixture sucked into the cylinder in the compression stroke is returned to the intake pipe. Limit the amount of intake air. Therefore, non-throttle operation is possible and fuel efficiency is improved.
[0005]
However, the conventional engine control device has a disadvantage that the pumping loss is small, so that the operation of the engine brake is less than that of a normal engine.
[0006]
[Means for Solving the Problems]
Therefore, in order to eliminate the above-described disadvantages, the present invention provides at least two intake valves per cylinder in a plurality of cylinders of an engine, and these intake valves are top dead center by power transmitted from the crankshaft. Two camshafts that can be opened and closed at an angle around the crankshaft corresponding to the crank angle from (TDC) to bottom dead center (BDC), and one camshaft fixed to the crank angle In addition, a variable phase cam control mechanism for changing the phase difference between the cam shafts by making the other cam shaft variable with respect to the crank angle is provided, and the engine is controlled by the variable phase cam control mechanism and a throttle valve opened and closed by a throttle actuator. a control apparatus for an engine having a control unit for controlling the amount of intake air, during normal operation that does not require engine braking, the other cam shaft The camshaft is controlled so that the phase difference increases from the top dead center (TDC) side to the bottom dead center (BDC) side of the crank angle, and the throttle valve opening is fully opened when the accelerator pedal is depressed. When the vehicle state that requires engine braking is determined , the other camshaft is moved to a bottom dead center (crank angle) so that the cam phase difference is reduced by the variable phase cam control mechanism. with back towards top dead center (TDC) side from BDC) side, characterized in that the function of controlling so as to a small throttle opening of the throttle valve is provided in addition to the control means.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As a result of the invention as described above, when the vehicle state is determined to require engine braking, the control means shifts the other camshaft so that the cam phase difference is reduced by the variable phase cam control mechanism. At the same time, the throttle opening of the throttle valve is controlled to be small, and the action of the engine brake is strengthened.
[0008]
【Example】
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0009]
1 to 15 show an embodiment of the present invention. In FIG. 2, 2 is a control device for the engine 4 described later.
[0010]
The control device 2 includes at least two, for example, two later-described intake valves 50a and 50b per cylinder, in a plurality of cylinders (not shown) of the engine 4, and these intake valves 50a and 50b are connected to a crankshaft (not shown). The first cam for fixed phase is provided with two first and second cam shafts 6-1 and 6-2 that can be opened and closed at a crank angle that substantially extends from the top dead center to the bottom dead center. Variable phase cam control for changing the phase difference between the cam shafts by changing the second cam shaft 6-2 for variable phase to the crank angle while setting the shaft 6-1 to a cam phase fixed to the crank angle. A mechanism 8 is provided, and control means 14 for controlling the intake air amount of the engine by the variable phase cam control mechanism 8 and the throttle valve 12 opened and closed by the throttle actuator 10 is provided.
[0011]
A power transmission mechanism (not shown) of the engine 4 includes a crank pulley (not shown) provided at one end of the crankshaft, and a first pulley 16-1 as a cam timing pulley provided at one end of the first camshaft 6-1. The second pulley 16-2, which is a cam timing pulley provided at one end of the second cam shaft 6-2, and one timing belt (not shown) wound around the three pulleys. .
[0012]
Since the engine 4 has four cycles, when the crankshaft rotates twice, the power transmission mechanism rotates the first and second camshafts 6-1 and 6-2 once.
[0013]
The variable phase cam control mechanism 8 includes a hydraulic pressure generator 8A and a drive unit 8B. A control signal for controlling the phase of the variable phase cam is output from the control means 14 to the electromagnetic valve 18 of the variable phase cam control mechanism 8.
[0014]
Further, as shown in FIG. 3, the variable phase cam control mechanism 8 adjusts the oil sent from the oil pan 22 to the oil passage 24-1 by the hydraulic pump 20 by the relief valve 26. The oil in the oil passage 24-1 acts as a force for pushing the control valve 30 to the right via the orifice 28 and the oil passage 24-2. The control valve 30 receives a leftward force by a spring 32, and the position of the control valve 30 is determined by the oil pressure of the oil passage 24-2.
[0015]
In a state where the solenoid valve 18 is not energized, the oil pressure in the oil passage 24-2 is drained, and the control valve 30 moves to the left. Then, the oil pressure in the oil passage 24-3 is drained through the oil passage 24-4, the helical spline 34 and the piston 36 are moved to the left by the return spring 38, and the phase difference is reduced.
[0016]
When the solenoid valve 18 is energized, the oil pressure in the oil passage 24-2 increases and the control valve 30 moves to the right. Then, the oil passage 24-1 and the oil passage 24-3 communicate with each other, the oil pressure in the oil passage 24-3 increases, the helical spline 34 and the piston 36 move to the right against the return spring 38, and the phase difference increases. To do.
[0017]
4, 5 and 6 show an outline of the valve train. FIG. 4 is a view as seen from above the cylinder head. FIG. 5 shows a cross section A and FIG. 6 shows a cross section B.
[0018]
The first cam shaft 6-1 for the fixed phase is connected to the first pulley 16-1 that is a camshaft timing pulley, and opens and closes the exhaust valve 44 via the cams 40a and 40b and the rocker arms 42a and 42b. The first cam shaft 6-1 for fixed phase opens and closes one intake valve 50a via the cam 46 and the rocker arm 48. The second cam shaft 6-2 for variable phase is connected to the second pulley 16-2, which is a camshaft timing pulley, and opens and closes the other intake valve 50b via the cam 52 and the rocker arm 54.
[0019]
The control means 14 includes an accelerator pedal depression amount sensor 58 that detects an accelerator pedal depression amount of the accelerator pedal 56, a crank angle, that is, a crank angle sensor 60 that detects a cam angle of a fixed phase cam and an engine speed, and a variable phase detector. Signals from a cam angle sensor 62 that detects the cam angle of the cam, a throttle sensor 64 that detects the opening of the throttle valve 12, a cranking switch 66 that detects cranking, and a water temperature sensor 68 that detects water temperature are input. The
[0020]
The control means 14 has a phase difference between the second cam shaft 6-2, which is the other cam shaft, on the delay side of the crank angle with respect to the first cam shaft 6-1, which is the one cam shaft. On the other hand, when the throttle valve 12 is moved to the fully open side when the accelerator pedal is depressed , the variable phase cam control mechanism 8 determines the cam phase difference when the vehicle state is determined to require engine braking. The second camshaft 6-2 that is the other camshaft is returned to the crank angle advance side, and a function for controlling the throttle opening of the throttle valve 12 to be small is added. And
[0021]
More specifically, the control means 14 determines that the accelerator pedal depression amount is equal to or less than a predetermined value based on a detection signal from the accelerator pedal depression amount sensor 58 and that the vehicle is in a state where engine braking is required during braking. Control to gradually change the cam phase difference and the throttle opening of the throttle valve by the variable phase cam control mechanism 8 so that the engine brake does not act suddenly when it is determined that the vehicle state needs to be braked. It is.
[0022]
The control means 14 determines that the brake pedal depression amount is equal to or less than a predetermined value based on the detection signal from the accelerator pedal depression amount sensor 58, and the vehicle condition that requires engine braking during braking is applied. when only becomes not satisfied, while slowing the return speed of the throttle opening of the cam phase difference and the throttle valve by the variable phase cam control mechanism, when the conditions other than the brake becomes not satisfied, the cam position The phase difference and the throttle opening are controlled to return to normal.
[0023]
That is, in general, the pumping loss can be increased in order to increase the action of the engine brake. However, in order to increase the pumping loss, the throttle valve 12 is closed and the cam phase difference is reduced to reduce the intake pipe. It is necessary to increase the pressure.
[0024]
When the engine brake is required, the vehicle is decelerated, so that the accelerator pedal 56 is released.
[0025]
Further, it is unclear whether or not the driver intends to decelerate only by releasing the accelerator pedal 56. Therefore, when both conditions are satisfied by detecting whether or not the brake is operating by a brake switch or the like. Enhance the action of the engine brake.
[0026]
In this case, the change speed of the cam phase difference and the throttle opening is made small so that the engine brake does not act suddenly and the speed does not change suddenly.
[0027]
Further, even if the brake is released, if the accelerator pedal 56 is kept released, the speed of change between the cam phase difference and the throttle opening is small, so that the operation of the engine brake can be continued.
[0028]
When the accelerator pedal 56 is depressed, it is clear that the driver does not intend to decelerate, and the cam phase difference and the throttle opening are immediately returned to normal.
[0029]
The control means 14 controls the electromagnetic valve 18 according to the flowcharts shown in FIGS. Hereinafter, the operation will be described along the flowchart.
[0030]
FIG. 7 shows a flowchart for calculating the duty for energizing the electromagnetic valve 18. First, a target phase difference (target phase difference) is calculated (100) based on a signal from the accelerator pedal depression amount sensor 58 or the like.
[0031]
Next, the actual phase difference is detected from the crank angle sensor 60 and the cam angle sensor 62 (102). When these magnitudes are compared (104) and the actual phase difference is larger than the target phase difference, the duty applied to the solenoid valve 4 is decreased (106), and the actual phase difference is smaller than the target phase difference. In this case, the duty for energizing the solenoid valve 18 is increased (108).
[0032]
FIG. 8 shows a flowchart for calculating the phase difference, and FIG. 9 shows a crank angle sensor signal and a cam angle sensor signal.
[0033]
The period T is calculated in advance from the crank angle sensor signal, ΔT corresponding to the phase difference is calculated from the crank angle sensor signal and the cam angle sensor signal, and the phase difference is obtained by calculating k × ΔT / T (200). . Here, k is a constant corresponding to the number of cylinders.
[0034]
Furthermore, the control means 14 controls the throttle actuator 10 according to the flowchart shown in FIG.
[0035]
First, the target throttle opening degree is searched (300) using the target throttle opening degree map shown in FIG.
[0036]
Next, the target throttle opening is compared with the current throttle opening (302). If they are not equal, the magnitude is compared (304). If the throttle opening is smaller than the target throttle opening, the throttle opening is increased (306). If the throttle opening is larger than the target throttle opening, the throttle opening is increased. Decrease (308).
[0037]
FIG. 11 is a time chart showing the relationship between the accelerator pedal depression amount, the cam phase difference, and the throttle opening.
[0038]
In the time chart of FIG. 11, t1 to t2 are cases where the accelerator pedal is suddenly returned from a predetermined opening, and the cam phase difference gradually increases as the accelerator pedal depression amount decreases. However, the throttle opening does not change.
[0039]
t3 is a case where it is determined that the vehicle state where the engine brake is required is detected by detecting the operation state of the brake switch or the like, and the cam position is determined when the vehicle state where the engine brake is required is determined. As the phase difference gradually decreases, the throttle opening moves from the fully open state to the fully closed state, and the engine brake acts.
[0040]
At t4, the cam phase difference becomes 0 degrees and the throttle opening is fully closed.
[0041]
t5 is a case where only the brake condition is not established, and when only the brake condition is not established, the cam phase difference and the throttle opening return at a slow change rate.
[0042]
t6 is a case where conditions other than the brake are not satisfied, such as when the accelerator pedal is depressed. When conditions other than the brake are not satisfied, the cam phase difference and the throttle opening immediately return to normal as shown in t6 to t7. It becomes the change speed.
[0043]
FIG. 1 shows a flowchart for calculating the target cam phase difference.
[0044]
First, when the program is started, it is determined whether the engine speed is equal to or lower than the idling determination speed (400). If this determination (400) is YES, that is, if the engine speed is equal to or lower than the idle determination rotation speed, the routine proceeds to determination (402) on whether or not the accelerator pedal is released, and the determination (400) is NO. If this is the case, that is, if the engine speed exceeds the idle determination speed, the routine proceeds to a determination (404) of whether or not the accelerator pedal is released.
[0045]
In the determination (402) of whether or not the accelerator pedal is released, if the determination (402) is NO, the process proceeds to the determination (404) of whether or not the accelerator pedal is released and the determination (402). ) Is YES, it is determined that the vehicle is in an idle state, and the following processing is performed. That is, as shown in FIG. 13, the basic target phase difference set as a water temperature table is searched (406).
[0046]
Next, it is determined whether or not the fluctuation of the engine speed is smaller than the allowable value (408). If the determination (408) is YES, that is, if the fluctuation of the engine speed is smaller than the allowable value, feedback correction is performed. When the value is increased (410) and the determination (408) is NO, that is, when the fluctuation of the engine speed is not less than the allowable value, the feedback correction value is decreased (412) and the feedback correction value is added to the basic target phase difference. Then, the target phase difference is calculated (414), and the end.
[0047]
If the determination (404) is YES after shifting to the determination (404) of whether or not the accelerator pedal is released, the determination shifts to (416) whether or not the brake is operating. If (404) is NO, the emblem flag is set to 0 (418).
[0048]
If the determination whether the brake is operating (416) is YES, the emblem flag is set to 1 (420), and the basic target phase difference is obtained by subtracting the target phase difference decrease from the previous value ( 422) If the determination whether the brake is operating (416) is NO, a determination is made as to whether the emblem flag is “0” or “1” (424).
[0049]
In the determination (424), when the emblem flag is “1”, a basic target phase difference is obtained by adding the target phase difference increase width to the previous value (426), and in the determination (424), the emblem flag is “ In the case of “0” and after the process of setting the emblem flag to 0 (418), as shown in FIG. 14, the basic target phase difference set as the accelerator pedal depression amount table is searched (428).
[0050]
After obtaining the basic target phase difference by the processing (422, 426, 428), as shown in FIG. 15, the water temperature correction value set as the water temperature table is searched (430), and the water temperature correction is performed from the basic target phase difference. The value is reduced to a target phase difference (432). At this time, if the subtraction result is a negative value, the target phase difference is set to zero.
[0051]
The feedback correction value is set to 0 (434), and the end is set.
[0052]
As a result, the second camshaft 6-2 that is the other camshaft is made to increase in phase difference on the delay side of the crank angle with respect to the first camshaft 6-1 that is one camshaft, When the accelerator pedal is depressed, the throttle valve 12 moves so as to be fully open, and when the vehicle state is determined to require engine braking, the control means 14 causes the variable phase cam control mechanism 8 to change the cam phase difference. The second camshaft 6-2 as the other camshaft is returned to the leading side of the crank angle so as to be small, and the throttle opening of the throttle valve 12 is controlled to be small so that the action of the engine brake is strengthened. This is practically advantageous.
[0053]
Further, it is determined by the detection signal from the accelerator pedal depression amount sensor 58 that the accelerator pedal depression amount is equal to or less than a predetermined value, and the control means 14 determines that the vehicle is in a state where engine braking is necessary during braking, and the engine brake is necessary. When it is determined that the vehicle is in a bad state, the control means 14 controls the variable phase cam control mechanism 8 so as to gradually change the cam phase difference and the throttle opening of the throttle valve. It does not act, can improve safety, and can improve usability.
[0054]
Further, after the control means 14 determines that the vehicle state requires engine braking, when only the brake condition is not satisfied, the cam phase difference by the variable phase cam control mechanism and the throttle opening of the throttle valve are determined. while slow the return speed of, when the conditions other than the brake becomes not satisfied, by controlling so as to normally return the cam phase difference and the throttle opening, giving trouble to the operation control other than the deceleration There is no fear.
[0055]
The present invention is not limited to the above-described embodiments, and various application modifications are possible.
[0056]
For example, in the embodiment of the present invention, the water temperature correction of the target phase difference is performed by subtraction. However, instead of the water temperature correction value, a water temperature correction coefficient may be set and multiplied.
[0057]
【The invention's effect】
As described above in detail, according to the present invention, when it is determined that the vehicle state that requires engine braking is established, the other camshaft is operated with the crank angle so that the control means reduces the cam phase difference by the variable phase cam control mechanism. In addition, the throttle opening of the throttle valve is controlled to be small, and the action of the engine brake can be strengthened, which is practically advantageous.
[Brief description of the drawings]
FIG. 1 is a target cam phase difference calculation flowchart showing an embodiment of the present invention;
FIG. 2 is a configuration diagram of an engine control device.
FIG. 3 is a hydraulic circuit diagram of an engine control device.
FIG. 4 is a schematic view of a valve mechanism.
FIG. 5 is a schematic view of a valve mechanism.
FIG. 6 is a schematic view of a valve mechanism.
FIG. 7 is a control flowchart of cam phase difference.
FIG. 8 is a control flowchart of a cam phase difference.
FIG. 9 is a diagram showing a crank angle sensor signal and a cam angle sensor signal.
FIG. 10 is a control flowchart of a throttle actuator.
FIG. 11 is a time chart of accelerator depression amount, cam phase difference, and throttle opening.
FIG. 12 is a diagram showing an example of a target throttle opening map.
FIG. 13 is a diagram showing an example of a basic target phase difference table during idling.
FIG. 14 is a diagram illustrating an example of a basic target phase difference table other than during idling.
FIG. 15 is a diagram illustrating an example of a water temperature correction value table for a target phase difference.
FIG. 16 is a diagram showing a crank angle and a valve lift when the phase difference is zero.
FIG. 17 is a diagram showing a crank angle and a valve lift when there is a phase difference.
[Explanation of symbols]
2 Controller 4 Engine 6-1 First camshaft 6-2 Second camshaft 8 Variable phase cam control mechanism 10 Throttle actuator 12 Throttle valve 14 Control means 16-1 First pulley 16-2 Second pulley 18 Solenoid valve 20 Hydraulic pump 22 Oil pan 24-1, 24-2, 24-3, 24-4 Oil passage 26 Relief valve 28 Orifice 30 Control valve 32 Spring 34 Helical spline 36 Piston 38 Return spring 40a, 40b Cam 42a, 42b Rocker arm 44 Exhaust Valve 46 Cam 48 Rocker arm 50a One intake valve 50b The other intake valve 52 Cam 54 Rocker arm 56 Accelerator pedal 58 Accelerator pedal depression sensor 60 Crank angle sensor 62 Cam angle sensor 64 Throttle sensor 66 Cranking switch 68 Water temperature sensor Sensor

Claims (3)

At least two intake valves per cylinder are arranged in a plurality of cylinders of the engine, and the crank angle over these intake valves from the top dead center (TDC) to the bottom dead center (BDC) by the power transmitted from the crankshaft. Two camshafts that can be opened and closed at an angle around the crankshaft are provided, one camshaft is fixed to the crank angle, and the other camshaft is variable to the crank angle. An engine control apparatus having a variable phase cam control mechanism for changing a phase difference between cam shafts and having a control means for controlling an intake air amount of the engine by the variable phase cam control mechanism and a throttle valve opened and closed by a throttle actuator in, during normal operation that does not require an engine brake, the top dead center of the crank angle with respect to one of the camshaft and the other cam shaft (TDC Controls such that the phase difference toward the bottom dead center (BDC) side from the side is increased, while moving the opening of the throttle valve so that the full-opening during depression accelerator pedal, and the required vehicle condition engine braking When the determination is made , the other camshaft is returned from the bottom dead center (BDC) side to the top dead center (TDC) side of the crank angle so as to reduce the cam phase difference by the variable phase cam control mechanism. the control device for an engine, wherein a function to control so as to a small throttle opening of the throttle valve is provided in addition to the control means.   The control means determines that the accelerator pedal depression amount is equal to or less than a predetermined value based on a detection signal from an accelerator pedal depression amount sensor that detects an accelerator pedal depression amount, and a vehicle state that requires engine braking during braking is applied. 2. The engine control device according to claim 1, wherein when the vehicle state is determined to require a brake, control is performed so as to gradually change the cam phase difference and the throttle opening of the throttle valve by the variable phase cam control mechanism.   The control means determines that the accelerator pedal depression amount is a predetermined value or less by a detection signal from an accelerator pedal depression amount sensor that detects an accelerator pedal depression amount, and a vehicle state that requires engine braking during braking, When only the brake condition is not satisfied, the return speed of the cam phase difference and the throttle opening of the throttle valve by the variable phase cam control mechanism is slowed, while when the condition other than the brake is not satisfied 2. The engine control device according to claim 1, wherein the control is performed to immediately return the cam phase difference and the throttle opening to normal.

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