JP2012193689A - Variable valve mechanism control apparatus of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an intake negative pressure during idle or deceleration/coasting and to reliably actuate accessories or a brake device by the secured intake negative pressure.SOLUTION: The variable valve mechanism control apparatus of an internal combustion engine includes a variable valve mechanism for changing the phase of an operating angle which determines lift timing of a valve, and a control unit for changing the phase of the variable valve mechanism when a predetermined operation condition is established. A temperature of the internal combustion engine, an accelerator opening, and an intake negative pressure are detected as a predetermined operation condition. When the detected temperature of the internal combustion engine is a fixed value or more which can be considered to be in warm-up state, when the detected accelerator opening is a fixed value or less which can be considered to be in idle state, and when the detected intake pressure is a predetermined value or less, the operating angle of the variable valve mechanism is changed so as to be converged to a predetermined operation angle which generates a predetermined intake negative pressure.

Description

The present invention relates to a control technique for operating auxiliary machinery and a brake device using intake negative pressure generated by an internal combustion engine.
In particular, the present invention relates to intake negative pressure control for operating accessories and brake devices in an internal combustion engine equipped with a variable valve mechanism (also referred to as “variable valve timing mechanism”, “VVT mechanism”, or simply “VVT”). .

Usually, a brake booster for increasing a braking force is combined with a brake device in an automobile.
This brake booster generally uses a negative pressure in an intake manifold (hereinafter also referred to as “intake manifold”).
For this reason, the operation of the booster mechanism of the brake booster of the brake device is performed using intake negative pressure (also referred to as “intake manifold internal pressure”).
On the other hand, in a vehicle with a variable valve mechanism, the control target value of the variable valve mechanism is set to reduce the negative pressure in order to improve fuel consumption.
Therefore, the negative pressure required for the brake may not be ensured.
Also, as the operation of the auxiliary machinery, purge operation for sucking evaporative gas from the fuel tank into the combustion chamber, blow-by gas (air mixture or combustion gas leaking from the combustion chamber of the internal combustion engine into the crankcase) into the combustion chamber The operation is performed using the intake negative pressure.
At this time, if the intake valve is an engine having a variable valve mechanism having a sufficient phase change angle, the intake negative pressure can be increased or decreased by changing the variable valve angle.
And the technique of changing a variable valve mechanism in order to ensure the intake pipe pressure required for a brake booster is known.
For example, it is disclosed in Patent Document 1 described later.
In recent gasoline engines, in order to improve fuel efficiency, an increase in intake resistance due to closing of the throttle is suppressed, and intake negative pressure at idling is reduced.

JP 2005-163635 A JP 2009-85145 A

By the way, in the conventional variable valve mechanism control device for an internal combustion engine, the booster mechanism can be operated by the capacity of the brake booster even if the intake negative pressure temporarily becomes weak, but the intake negative pressure is somewhat longer. If it becomes weaker, the operation of the booster mechanism becomes weaker depending on the frequency of use, and eventually the operation of the booster mechanism will be lost, so the brake device will be operated only by the driver's operating force, which is inconvenient is there.
Also, even if the intake negative pressure temporarily decreases, it is only necessary to stop the operation of the auxiliary equipment in the meantime, but if the intake negative pressure becomes weak for a long time, evaporative gas or blow-by gas can be discharged. This is disadvantageous in that there is a possibility that the deterioration of the lubricating oil is accelerated or the unburned gas is released into the atmosphere.
However, if the control is uniformly performed so as to reduce the intake negative pressure during idling, the necessary intake pipe pressure may not be ensured when the atmospheric pressure is low or the engine load is large.
For example, as disclosed in Patent Document 2, when the negative pressure of the brake booster is detected and the phase of the variable valve mechanism is changed, the negative pressure is reduced by using the brake operation. The purpose of increasing the pressure can be achieved, and while this control is being performed, the operation of the auxiliary equipment can be performed accompanying this.
However, if climbing in the highlands continues, phase change control of the variable valve mechanism for securing negative pressure to the brake device does not work in situations where the brake is not used frequently and negative pressure is secured in the brake booster. There is a disadvantage that the state in which the intake negative pressure is extremely small continues, and the opportunity to discharge the evaporated gas or blow-by gas is remarkably reduced.

  An object of the present invention is to ensure intake negative pressure (intake manifold internal pressure) during idling, deceleration, and coasting, and to reliably operate auxiliary equipment and brake devices with the ensured intake negative pressure.

  In view of this, the present invention eliminates the above-described inconveniences, and changes the phase of the operating valve that determines the valve lift timing and changes the phase of the variable valve mechanism when a predetermined operating condition is satisfied. In the variable valve mechanism control apparatus for an internal combustion engine that detects the temperature, accelerator opening, and intake negative pressure of the internal combustion engine as the predetermined operating conditions, The detected temperature of the internal combustion engine is equal to or higher than a certain value that can be regarded as a warm-up state, the detected accelerator opening is equal to or smaller than a certain value that can be regarded as an idle state, and the detected intake negative pressure is When it is less than or equal to a predetermined value, the operating angle of the variable valve mechanism is changed so as to converge to a predetermined operating angle that generates a predetermined intake negative pressure.

As described above in detail, according to the present invention, the variable valve mechanism that changes the phase of the operating angle that determines the lift timing of the valve, and the control that changes the phase of the variable valve mechanism when a predetermined operating condition is satisfied. A variable valve mechanism control apparatus for an internal combustion engine comprising a device, the variable valve mechanism control apparatus for an internal combustion engine detecting a temperature, an accelerator opening, and an intake negative pressure of the internal combustion engine as predetermined operating conditions. The temperature of the internal combustion engine is not less than a certain value that can be regarded as a warm-up state, the detected accelerator opening is not more than a certain value that can be regarded as an idle state, and the detected intake negative pressure is not more than a predetermined value In this case, the operating angle of the variable valve mechanism is changed to converge to a predetermined operating angle that generates a predetermined intake negative pressure.
Therefore, when the internal combustion engine is warmed up and the intake negative pressure is low, the intake negative pressure is increased by changing the position of the VVT, so that the operation of the brake device and the auxiliary equipment can be ensured. In other cases, such as when the intake negative pressure is high, the position can be met to meet the demand for fuel efficiency, exhaust gas purification performance, etc., and it is possible to ensure both the operation of the brake device and the auxiliary machine and good fuel efficiency.

FIG. 1 is a flowchart for control of a variable valve mechanism control apparatus for an internal combustion engine. Example 1 FIG. 2 is a system diagram of a variable valve mechanism control apparatus for an internal combustion engine. Example 1 FIG. 3 is a diagram showing the relationship between the lift amount and the crank angle. Example 1 FIG. 4 is a system diagram of a variable valve mechanism control apparatus for an internal combustion engine. (Example 2)

  Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 3 show a first embodiment of the present invention.
In FIG. 2, reference numeral 1 denotes a variable valve mechanism control device for an internal combustion engine (not shown).
As shown in FIG. 2, the variable valve mechanism control apparatus 1 is a variable valve mechanism (also referred to as “variable valve timing mechanism” or “VVT mechanism”) 2 that changes the phase of the operating angle that determines the lift timing of the valve. And a control device 3 that changes the phase of the variable valve mechanism 2 when a predetermined operating condition is satisfied.
At this time, the control device 3 has a VVT control function for changing the phase of the variable valve mechanism 2 when various signals are input and a predetermined operating condition is satisfied.
Further, the variable valve mechanism control device 1 includes a water temperature sensor 4, a crank angle sensor 5, an intake cam angle sensor 6, a throttle / accelerator opening sensor 7, an atmospheric pressure on the input side of the control device 3. A sensor 8 and an intake pressure sensor 9 are provided.
At this time, the water temperature sensor 4 detects the temperature of the internal combustion engine by detecting the engine water temperature.
The crank angle sensor 5 detects the rotational speed from the crank angle.
The intake cam angle sensor 6 detects the phase of an intake cam (not shown).
The throttle / accelerator opening sensor 7 detects the accelerator opening.
The atmospheric pressure sensor 8 detects atmospheric pressure.
The intake pressure sensor 9 detects intake negative pressure (also referred to as “intake manifold internal pressure”).
That is, the variable valve mechanism control apparatus 1 detects the temperature of the internal combustion engine, the accelerator opening, and the intake negative pressure as the predetermined operating conditions.
The variable valve mechanism control device 1 includes the variable valve mechanism 2 on the output side of the control device 3.

Further, the variable valve mechanism control apparatus 1 is configured such that the detected temperature of the internal combustion engine is equal to or greater than a certain value that can be regarded as a warm-up state, and the detected accelerator opening is equal to or less than a certain value that can be regarded as an idle state. And when the detected intake negative pressure is less than or equal to a predetermined value, the operating angle of the variable valve mechanism is changed to converge to a predetermined operating angle that generates a predetermined intake negative pressure. Yes.
More specifically, the variable valve mechanism control apparatus 1 determines that the detected temperature of the internal combustion engine is equal to or higher than a certain value that can be regarded as a warm-up state, that is, the engine water temperature T detected by the water temperature sensor 4 is an engine water temperature condition. It is determined whether or not a certain value t or more.
Further, the variable valve mechanism control apparatus 1 determines that the detected accelerator opening is equal to or less than a certain value that can be regarded as an idle state, that is, the accelerator opening A detected by the throttle / accelerator opening sensor 7 is the accelerator opening. It is determined whether or not the value is a certain value a or less.
Further, in the variable valve mechanism control apparatus 1, the detected intake negative pressure is equal to or less than a predetermined value, that is, the intake negative pressure P_A-P_I detected by the intake pressure sensor 9 is equal to or less than a predetermined value p which is a negative pressure condition. It is determined whether or not. At this time, the intake negative pressure P_A-P_I is calculated by subtracting the intake manifold internal pressure P_I from the atmospheric pressure P_A.
Then, the variable valve mechanism control apparatus 1 determines that the engine water temperature T is equal to or greater than a certain value t, the accelerator opening A is equal to or less than a certain value a, and the intake negative pressure P_A-P_I is equal to or less than a predetermined value p. The operating angle of the variable valve mechanism 2 is changed so as to converge to a predetermined operating angle that generates a predetermined intake negative pressure.
Accordingly, when the internal combustion engine is warmed up and the intake negative pressure is low, the intake negative pressure is increased by changing the position of the variable valve mechanism 2, so that the operation of the brake device and the auxiliary equipment is ensured. In other cases, such as when the intake negative pressure is high, it can be positioned to meet fuel consumption requirements and exhaust gas purification performance requirements, etc. can do.

In other words, when the variable valve mechanism 2 is operated, the intake air amount changes, and the negative pressure in the intake manifold (not shown) changes accordingly.
Usually, the control target value of the variable valve mechanism 2 is set to reduce the negative pressure in order to improve fuel consumption.
On the other hand, when the load of auxiliary equipment such as an air conditioner or an alternator is large, the brake negative pressure may be insufficient.
In order to avoid this, the brake negative pressure is ensured by changing the control target value of the variable valve mechanism 2 in accordance with the negative pressure value detected by the intake pressure sensor 9 attached to the intake manifold.

Further, the variable valve mechanism control apparatus 1 includes the variable valve mechanism 2 only in an intake valve (not shown).
In other words, the intake valve OCV (also referred to as “intake oil control valve”) 10 is used for the variable valve mechanism 2 in order to set the intake valve to the optimum valve timing (advance amount and retard amount), as shown in FIG. Consists of.
In addition, the variable valve mechanism control device 1 reduces the intake negative pressure due to the blow-back and increases the predetermined operating angle that generates the predetermined intake negative pressure as the operating angle of the intake valve is delayed, and the operating angle of the intake valve. Is an intermediate advance position at which the intake non-pressure increases by the balance with the decrease in intake negative pressure due to the increase in internal EGR accompanying the overlap with the exhaust valve that increases as the angle is advanced.
Therefore, regardless of the closing timing of the exhaust valve, even when the opening time during lift of the intake valve is set to be clearly larger than the crank angle of 180 degrees, the intake negative pressure is the most balanced with the balance between the blowback and the internal EGR. The operating angle can be converged to a large position.

In addition, in the internal combustion engine provided with the variable valve mechanism control device 1, the variable valve mechanism 2 is moved from the initial position as a reference to the advance side as shown in FIG.
Then, the variable valve mechanism 2 is used in which the opening time (crank angle range) during lift of the intake valve is set larger than 180 degrees corresponding to the intake stroke of the piston (for example, about 40 to 40% higher).
The internal combustion engine may be set so that the intake valve is closed late, that is, the intake valve is closed at a timing later than the bottom dead center in idle control where the accelerator opening A is equal to or less than a predetermined value a. The pumping loss is reduced by returning the intake gas into the combustion chamber at a predetermined amount to the intake manifold side during the compression stroke in which the piston rises, that is, by blowing it back. Along with this, the intake negative pressure decreases.
Then, as shown in FIG. 3, by moving the valve in the advance direction, that is, in the direction in which the intake valve is quickly closed, the blow-back is reduced and the negative pressure can be secured. That is, in order to ensure negative pressure, the operating angle of the variable valve mechanism 2 is moved in the advance direction, that is, the direction in which the intake valve is quickly closed.
On the other hand, when the advance angle advances and the opening timing of the intake valve becomes earlier than the closing timing of the exhaust valve, valve overlap occurs. When the valve overlap increases, the internal EGR (exhaust gas remaining in the combustion chamber after being re-sucked or retained) increases. Since the pressure of the exhaust gas is relatively higher than the pressure in the intake pipe, if the valve is advanced too much, the intake negative pressure decreases due to the mutual influence of the gas flow and pressure.
Here, the intake valve operating angle is closed, and the intake negative pressure decrease due to blow-back increases as the timing is delayed beyond the bottom dead center, and the exhaust valve increases as the intake valve operating angle is advanced. The intake negative pressure that is determined at the intermediate advance angle position where the intake negative pressure is determined by the balance with the decrease in the intake negative pressure due to the increase in the internal EGR due to the lap, that is, a position that is a valley between the two in a trade-off relationship, is increased. An intermediate advance position is set, and the variable valve mechanism 2 is operated so as to converge at this position.
For this reason, the amount of advance is largely dependent on the specifications of each engine. To determine the setting of the amount of advance specific to each engine, the correlation between the amount of advance and the negative pressure is experimentally determined beforehand. It is necessary to know.
When the engine temperature is low and the engine is not completely warmed up, for example, the controllability of the variable valve mechanism 2 may not be sufficiently secured, but the intake amount and fuel are reduced by fast idle control for early warming up. The injection amount is corrected to increase. For this reason, in such a situation, it is better not to perform the main control for securing the negative pressure.
The intake negative pressure becomes larger as the absolute pressure becomes closer to zero with reference to the atmospheric pressure. Therefore, the intake negative pressure P_A-P_I is equal to or lower than the predetermined value p. The intake negative pressure P_A-P_I is higher than the predetermined value p. It means close to atmospheric pressure.

  Next, the operation will be described along the control flowchart of the variable valve mechanism control apparatus 1 of the internal combustion engine of FIG.

When the control program of the variable valve mechanism control device 1 is started (101), the detected temperature of the internal combustion engine is equal to or higher than a certain value that can be regarded as a warm-up state, that is, the engine water temperature T detected by the water temperature sensor 4 is increased. The process proceeds to determination (102) of whether or not the value is equal to or greater than a certain value t.
If the determination (102) as to whether or not the engine water temperature T detected by the water temperature sensor 4 is equal to or higher than a predetermined value t is NO, the control program for the variable valve mechanism control device 1 described later is stopped ( Also referred to as “end”) (106).
If the determination (102) as to whether or not the engine water temperature T detected by the water temperature sensor 4 is equal to or greater than a certain value t is YES, the detected accelerator opening is equal to or less than a certain value that can be regarded as an idle state, that is, Then, the process proceeds to a determination (103) as to whether or not the accelerator opening A detected by the throttle / accelerator opening sensor 7 is equal to or less than a predetermined value a.
If the determination (103) as to whether or not the accelerator opening A is equal to or smaller than the predetermined value a is NO, the process proceeds to the stop (106) of the control program of the variable valve mechanism control apparatus 1.
If the determination (103) as to whether or not the accelerator opening A is equal to or less than the predetermined value a is YES, the detected intake negative pressure is equal to or less than a predetermined value, that is, detected by the intake pressure sensor 9. The process proceeds to determination (104) as to whether or not the intake negative pressure P_A-P_I is equal to or less than a predetermined value p.
When the determination (104) of whether or not the intake negative pressure P_A-P_I detected by the intake pressure sensor 9 is equal to or less than the predetermined value p is NO, the control program for the variable valve mechanism control apparatus 1 The process proceeds to the stop (106).
When the determination (104) of whether or not the intake negative pressure P_A-P_I detected by the intake pressure sensor 9 is equal to or less than a predetermined value p is YES, the variable valve mechanism control device 1 sets the target VVT. The operation angle is changed, that is, the control signal is output from the control device 3 to the variable valve mechanism 2, and the process proceeds to the process (105) in which the intake OCV 10 is operated to change the valve timing. Later, the program shifts to the stop (106) of the control program of the variable valve mechanism control apparatus 1.

FIG. 4 shows a second embodiment of the present invention.
In the second embodiment, portions that perform the same functions as those of the first embodiment will be described with the same reference numerals.

  The second embodiment is characterized in that the variable valve mechanism 12 of the variable valve mechanism controller 11 of the internal combustion engine is provided in each of the intake valve and the exhaust valve.

That is, as shown in FIG. 4, the variable valve mechanism control device 11 includes, on the input side of the control device 13, a water temperature sensor 4, a crank angle sensor 5, an intake cam angle sensor 6, and a throttle / accelerator opening. In addition to a sensor 7, an atmospheric pressure sensor 8, and an intake pressure sensor 9, an exhaust cam angle sensor 14 is provided.
The exhaust cam angle sensor 14 detects the phase of an exhaust cam (not shown).
Further, as shown in FIG. 4, the variable valve mechanism 12 has an intake OCV (also referred to as “intake oil control valve”) 10 for setting the intake valve to an optimal valve timing (advance amount and retard amount). And an exhaust OCV (also referred to as “exhaust oil control valve”) 15 for setting the intake valve to an optimal valve timing (advance amount and retard amount).
In the variable valve mechanism control device 11, the predetermined operating angle for generating a predetermined intake negative pressure is reduced by internal EGR due to an overlap with the intake valve that decreases as the operating angle of the exhaust valve is advanced. The exhaust valve operating angle at which the negative pressure increases is the most advanced position.
Therefore, even if the intake OCV 10 is variously changed by the variable valve mechanism 12, the intake negative pressure can be increased almost stably without being affected by the control state.
Further, since only the exhaust OCV 14 is controlled by the variable valve mechanism 12, the control is simple, the calculation load is small, and the control stability can be ensured even during the transition.

In addition, depending on the specifications of the internal combustion engine and the operation state of the variable valve mechanism 12 at idle, it may be possible to ensure a negative pressure by moving the exhaust OCV 14. In the second embodiment, an example of an internal combustion engine provided with the intake OCV 10 and the exhaust OCV 15 as one intake / exhaust VVT is shown.
Further, the exhaust OCV 15 of the variable valve mechanism 12 is moved from the reference initial position to the retard side. This is opposite to the intake OCV 10 of the variable valve mechanism 12 that moves from the initial position of the reference to the advance side. If the internal combustion engine is moving toward the retard side due to reasons such as fuel efficiency requirements, the negative pressure can be increased by advancing it so as to return it to the initial position direction.
Further, in the case of this internal combustion engine, the negative pressure is the highest at the most advanced angle (initial position) of the exhaust OCV 15 of the variable valve mechanism 12. What is necessary is just to search and set the VVT position where the negative pressure specific to the internal combustion engine is generated. When there are a plurality of positions, the position may be set in consideration of responsiveness when shifting from VVT control based on other conditions.

  The present invention is not limited to the first and second embodiments described above, and various application modifications can be made.

For example, in the case of a vehicle that does not employ a pressure sensor, a special configuration that uses a model intake manifold pressure estimated from an actual flow rate measured by an air flow sensor may be employed.
Further, by adopting a special configuration in which the change of the target value of the variable valve mechanism is limited to only the idle, it is possible to satisfy both the fuel efficiency requirement during traveling and the negative pressure requirement required during idle.
Furthermore, in a vehicle capable of measuring the brake booster pressure, the VVT target value can be changed only to the brake requirement by adopting a special configuration that uses the brake booster pressure instead of the intake manifold internal pressure.

DESCRIPTION OF SYMBOLS 1 Variable valve mechanism control apparatus of internal combustion engine 2 Variable valve mechanism 3 Control apparatus 4 Water temperature sensor 5 Crank angle sensor 6 Intake cam angle sensor 7 Throttle / accelerator opening sensor 8 Atmospheric pressure sensor 9 Intake pressure sensor 10 Intake OCV (" Also referred to as “intake oil control valve”.)

Claims (3)

  A variable valve mechanism control device for an internal combustion engine comprising: a variable valve mechanism that changes a phase of an operating angle that determines a valve lift timing; and a control device that changes the phase of the variable valve mechanism when a predetermined operating condition is satisfied In the variable valve mechanism control apparatus for an internal combustion engine that detects the temperature, accelerator opening, and intake negative pressure of the internal combustion engine as the predetermined operating condition, the detected temperature of the internal combustion engine is a warm-up state. When the detected accelerator opening is equal to or less than a certain value that can be regarded as an idle state and the detected intake negative pressure is equal to or less than a predetermined value, the variable valve mechanism A variable valve mechanism control apparatus for an internal combustion engine, wherein the operating angle is changed to converge to a predetermined operating angle that generates a predetermined intake negative pressure.   The variable valve mechanism is provided only in the intake valve, and the predetermined operating angle that generates a predetermined intake negative pressure is a decrease in intake negative pressure due to blow-back that increases as the operating angle of the intake valve is delayed, and the operation of the intake valve. 2. An intermediate advance position in which an intake non-pressure determined by a balance with a decrease in intake negative pressure due to an increase in internal EGR accompanying an overlap with an exhaust valve that increases as the angle is advanced is increased. 2. A variable valve mechanism control apparatus for an internal combustion engine according to 1.   The variable valve mechanism is provided in each of the intake valve and the exhaust valve, and the predetermined operating angle that generates a predetermined intake negative pressure is accompanied by an overlap with the intake valve that decreases as the operating angle of the exhaust valve is advanced. The exhaust valve operating angle at which the intake negative pressure increases as the internal EGR decreases is set to the most advanced position. The variable valve mechanism control apparatus for an internal combustion engine according to claim 1.

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