KR101136704B1 - Variable valve driving device of internal combustion engine - Google Patents

Abstract

In the variable valve drive apparatus of an internal combustion engine provided with the camshaft phase variable mechanism which changes the opening / closing time of the intake valve of an internal combustion engine, when the load L of an internal combustion engine is less than 1st predetermined value L1, the valve of an intake valve When the closing timing is advanced to the predetermined range T1 including the bottom dead center, and the load L of the internal combustion engine is greater than or equal to the first predetermined value L1, the valve closing timing of the intake valve is late than the predetermined range T1. To control the camshaft phase variable mechanism and the variable valve lift mechanism.

Variable Valve Drive, Intake Valve, Variable Valve Lift Mechanism, Engine, ECU

Description

Variable valve drive for internal combustion engines {VARIABLE VALVE DRIVING DEVICE OF INTERNAL COMBUSTION ENGINE}

The present invention relates to a variable valve driving apparatus of an internal combustion engine which can change the lift amount and the opening / closing time of an intake valve.

Background Art Conventionally, as a variable valve drive device of an internal combustion engine, a variable valve lift mechanism for changing the lift amount of an intake and exhaust valve and a variable valve timing mechanism for changing the opening and closing timing (phase) of the intake and exhaust valve are known. In recent years, in order to further improve fuel efficiency and output performance, engines provided with both of these variable valve lift mechanisms and variable valve timing mechanisms have been increasing.

As described above, in an engine equipped with a variable valve lift mechanism and a variable valve timing mechanism, the valve closing timing of the intake valve is generally accelerated at the time of low load, thereby suppressing the negative pressure in the intake manifold, reducing the pumping loss, and improving fuel efficiency. have. On the other hand, at high loads, the lift amount of the intake valve is increased to increase the intake amount to improve the output (Japanese Patent Application Laid-Open No. 2006-97647).

However, in the technique described in the above publication, the valve closing timing of the intake valve is late due to increasing the lift amount of the intake valve at high load. When the valve closing timing is late and near the bottom dead center, the actual compression ratio becomes too large, which may cause knocking. When knocking occurs in this way, there is a problem that fuel economy is lowered.

SUMMARY OF THE INVENTION An object of the present invention is a variable valve drive apparatus of an internal combustion engine having a variable valve timing mechanism and a variable valve lift mechanism, which leads to a valve closing timing of an intake valve at low loads, thereby improving fuel efficiency and at The present invention provides a variable valve driving apparatus that can improve the performance of the variable valve.

In order to achieve the above object, the present invention is a variable valve drive device of an internal combustion engine that varies the opening and closing time of the intake valve, and when the load of the internal combustion engine is less than the first predetermined value, the valve closing timing of the intake valve is a bottom dead center. Control means for controlling the opening and closing timing of the intake valve so that the valve closing timing of the intake valve is late than the predetermined range when the load of the internal combustion engine is greater than or equal to the first predetermined value. Equipped with.

Thereby, when the load of an internal combustion engine is less than a 1st predetermined value, since the valve closing timing of an intake valve is advanced-advanced, the negative pressure in an intake manifold is suppressed and a pumping loss can be reduced and fuel economy can be improved. On the other hand, when the load of the internal combustion engine is greater than or equal to the first predetermined value, the valve closing timing of the intake valve is late than the predetermined range including the bottom dead center, so that knocking is suppressed and fuel efficiency can be improved by the Miller cycle effect. have. Therefore, the shape of fuel consumption can be aimed at the low load from the high load.

Preferably, a variable valve timing mechanism for changing the phase of the crankshaft and the intake camshaft of the internal combustion engine to vary the opening and closing timing of the intake valve, and the lift of the intake valve while retarding at least the valve closing timing of the intake valve. And a variable valve lift mechanism for increasing the amount, wherein the control means controls the variable valve lift mechanism together with the variable valve timing mechanism to determine the valve closing timing of the intake valve based on the load of the internal combustion engine. It is better to advance or perceive than a predetermined range.

As a result, since the valve closing timing of the intake valve is performed by two mechanisms, the variable valve timing mechanism and the variable valve lift mechanism, the advance and perception switching is smoother than the predetermined range including the bottom dead center of the valve closing timing of the intake valve. I can do it.

Further, preferably, when the load of the internal combustion engine is less than the first predetermined value, the control means advances the valve closing timing of the intake valve by the variable valve timing mechanism and simultaneously transfers the variable valve lift mechanism to the load. Therefore, it is better to control.

As a result, when the load of the internal combustion engine is less than the predetermined value, the valve closing timing of the intake valve is further advanced with the decrease of the lift amount of the intake valve by the control of the variable valve lift mechanism, so that the intake flow rate increases and combustion is stabilized. At the same time, the fuel economy can be further improved by further reducing the pumping loss.

Further, preferably, when the load of the internal combustion engine is equal to or greater than the first predetermined value, the control means detects the valve closing timing of the intake valve by the variable valve timing mechanism and maximizes the variable valve lift mechanism. It is good to control so that it may become a lift amount.

As a result, when the load of the internal combustion engine is equal to or greater than the first predetermined value, the valve closing timing of the intake valve becomes the maximum perception and the lift amount becomes the maximum amount, whereby the Miller cycle effect can be exhibited to the maximum and the fuel economy can be further improved.

Preferably, the control means advances the valve closing timing of the intake valve from the maximum perception and lowers the lift amount of the intake valve from the maximum amount when the accelerator opening of the internal combustion engine is in the fully open state. It is preferable to control the variable valve timing mechanism and the variable valve lift mechanism.

Thereby, when the accelerator opening degree is fully open, the valve closing timing of the intake valve is advanced more than the maximum perception, and the lift amount of the intake valve can be lowered than the maximum amount, thereby maximizing the output performance of the internal combustion engine.

Further, preferably, the control means controls the variable valve lift mechanism so that the lift amount of the intake valve becomes larger than the minimum value when the accelerator opening of the internal combustion engine is in a completely closed state.

As a result, when the accelerator opening is completely closed, the lift amount of the intake valve is made larger than the minimum amount, so that the pressure in the intake manifold can be reduced. Therefore, the negative pressure of the brake master bag can be ensured at the time of idling or during brake operation.

Preferably, the control means advances the valve closing timing of the intake valve from the maximum perception regardless of the load of the internal combustion engine when the rotational speed of the internal combustion engine is equal to or greater than a second predetermined value, and at the same time, the intake air It is preferable to control the variable valve timing mechanism and the variable valve lift mechanism so that the lift amount of the valve is lower than the maximum amount.

As a result, when the internal combustion engine rotational speed is equal to or greater than a predetermined value, the lift amount and phase are defined regardless of the load, so that unnecessary switching of the variable valve timing mechanism is suppressed. Therefore, the operation of the actuator in the high rotational region is suppressed, so that durability can be improved.

According to the present invention, there is provided a variable valve driving apparatus of an internal combustion engine having a variable valve timing mechanism and a variable valve lift mechanism, which leads to a valve closing timing of an intake valve at low loads, thereby improving fuel economy and at the same time, even at high loads. The variable valve drive device which can aim at the improvement of this can be provided.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing.

First, the first embodiment of the present invention will be described.

FIG. 1: is a schematic block diagram of the internal combustion engine (henceforth an engine) 1 provided with the variable valve drive apparatus of this embodiment.

The engine 1 of this embodiment has a DOHC drive valve mechanism, and is mounted on a vehicle as a drive source for travel. The timing pulleys 4 and 5 are connected to the front end portions of the intake cam shaft 2 and the exhaust cam shaft 3 of the engine 1, respectively, and these timing pulleys 4 and 5 are connected via the timing belt 6. It is connected to the crankshaft 7. As the crankshaft 7 rotates, the intake shaft 2 and the exhaust cam shaft 3 are driven to rotate together with the timing pulleys 4 and 5, and the intake cam 2a provided in the intake cam shaft 2 is provided. The exhaust valve 9 is opened and closed by the exhaust cam 3a provided in the exhaust cam shaft 3 by the intake valve 8.

The variable valve drive apparatus of this embodiment is employ | adopted as the drive valve mechanism which drives the intake valve 8. The variable valve drive device is provided with the camshaft phase variable mechanism (variable valve timing mechanism) 11 and the variable valve lift mechanism 12 mentioned later.

2 is an internal structural diagram of the camshaft phase variable mechanism 11. Hereinafter, the camshaft phase variable mechanism 11 is demonstrated with reference also to FIG.

The camshaft phase variable mechanism 11 is provided between the intake camshaft 2 and the timing pulley 4 on the intake side, and is described, for example in Unexamined-Japanese-Patent No. 2000-27609 or 3846605. A vane camshaft phase shift mechanism is employed.

As shown in FIG. 2, the camshaft phase variable mechanism 11 rotatably installs the vane rotor 14 in the housing 13 provided in the timing pulley 4, and the intake cam 14 in the vane rotor 14. As shown in FIG. It is comprised by connecting the shaft (2).

The oil control valve (hereinafter referred to as OCV) 15 is connected to the camshaft phase variable mechanism 11 via a flow path formed in the intake camshaft 2, and the hydraulic oil supplied from the oil pump 16 of the engine 1 is supplied. Is supplied to the oil chamber 17 formed between the vane rotor 14 and the housing 13 in accordance with the switching of the OCV 15 to rotate the vane rotor 14, so that the intake cam shaft for the timing pulley 4 is rotated. The phase angle of (2), that is, the opening and closing timing of the intake valve 8 can be continuously adjusted.

Moreover, the camshaft phase variable mechanism 11 is equipped with the lock pin 18 and the spring 19 (pressing means). The lock pin 18 has a function of restricting the rotation of the vane rotor 14 by inserting it into the fitting hole 20 formed in the vane rotor 14 and setting the most advanced angle position of the vane rotor 14. The spring 19 is provided between the housing 13 and the vane rotor 14 to press the vane rotor 14 in the forward direction.

3 is a schematic structural diagram of the variable valve lift mechanism 12. Hereinafter, with reference to FIG. 1, the structure of the variable valve lift mechanism 12 is demonstrated.

The structure of the variable valve lift mechanism 12 is described, for example in Japanese Patent Application Laid-Open No. 2005-299536, and the detailed structure is omitted, but as shown in FIG. 3, the intake cam shaft 2 and In addition to the rocker arm 30 which drives the intake valve 8, the center rocker arm 31 and the swing cam 32 are provided. And when the rocker arm 30 is driven up and down by the rotational drive of the intake cam shaft 2, the rocker shaft 34 is rotated by the electric motor 33, and the position of the support point of the center rocker arm 31 is adjusted. By moving, the maximum lift amount of the intake valve 8 can be changed, and the valve closing timing is advanced with the reduction of the lift amount while keeping the valve opening timing almost constant up to the maximum lift amount and the minimum lift amount. That is, the variable valve lift mechanism 12 is a single mechanism in which the center rocker arm 31 and the swing cam 32 are combined with the intake cam shaft 2 and the rocker arm 30, and the lift amount of the intake valve 8 is increased. And the valve opening period has a function to continuously uniquely vary.

The ECU 40 includes an input / output device (not shown), a storage device such as a ROM, a RAM, a central processing unit (CPU), a timer counter, and the like, and performs overall control of the engine 1.

On the input side of the ECU 40, a crank angle sensor 41 for detecting the crank angle of the engine 1, a throttle sensor 42 for detecting the opening degree of a throttle valve (not shown), and an amount of stepping of the accelerator by the driver are detected. Various sensors, such as the accelerator position sensor 46, are connected. In addition to the OCV 15 and the electric motor 33, a fuel injection valve 43, a spark plug 44, and the like are connected to the output side of the ECU 40. The ECU 40 determines the ignition timing, the fuel injection amount, and the like based on the detection information from each sensor, drives the ignition plug 44 or the fuel injection valve 43, and controls the OCV 15 and the electric motor ( 33 controls the drive control, that is, the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12.

4 is a map used for setting the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12 in the first embodiment of the present invention.

As shown in FIG. 4, the ECU 40 selects and controls the variable valve lift mechanism 12 and the camshaft phase variable mechanism 11 in accordance with the engine rotation speed N and the load L. As shown in FIG. The engine rotation speed N is measured from the transition of the crank angle detected by the crank angle sensor 41, while the load L is calculated from the stepping amount of the accelerator detected by the accelerator position sensor 46. do.

When the load L is less than the first predetermined value L1, the ECU 40 controls the camshaft phase variable mechanism 11 to set the intake valve 8 to the most advanced angle, and at the same time, the variable valve lift mechanism 12. ) Is set to the minimum lift amount corresponding to the load L (area 1 in the drawing).

When the load L is equal to or larger than the first predetermined value L1, the camshaft phase variable mechanism 11 is controlled at the lowest angle, and the lift amount is set to the maximum value by the variable valve lift mechanism 12 (in the drawing). Zone 2).

When the load L is at the maximum region, specifically, when the accelerator is fully opened, the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12 are controlled so that the output of the engine 1 is maximized as much as possible. In the engine 1 of the present embodiment, the valve closing timing is slightly advanced than the maximum angle, and the lift amount is slightly smaller than the maximum value so that the output is maximized (area 3 in the drawing).

When the load L is in a very small area, specifically, when the accelerator is completely closed, such as in an idle state or deceleration, the variable valve lift mechanism 12 is smaller than the minimum lift amount while the camshaft phase variable mechanism 11 is controlled at the most advanced angle. Large control (area 4 in the drawing).

5A to 5E are graphs showing the setting state and the engine state of the variable valve lift mechanism 12 and the camshaft phase variable mechanism 11 according to the load. (a) is the valve closing timing of the intake valve 8, (b) is the phase of the intake valve 8 which is varied by the camshaft phase variable mechanism 11, (c) is by the variable valve lift mechanism 12 The lift amount of the variable intake valve 8, (d) represents the pressure in the intake manifold, and (e) represents fuel economy, and the values according to the load of the engine 1 are respectively shown. In the figure, o indicates a value when the valve closing timing of the intake valve 8 is the fastest, while o indicates a value when the valve closing timing of the intake valve 8 is the slowest.

As shown in FIG. 5, in the region 1 where the load L is less than the first predetermined value L1, the valve closing timing of the intake valve 8 is earlier, so that the negative pressure of the intake manifold is reduced (pressure). Can be raised). Therefore, pumping loss can be reduced and fuel economy can be improved.

In the region 2 in which the load L is equal to or larger than the first predetermined value L1, the camshaft phase variable mechanism 11 is controlled at the extreme angle, and the lift amount is set to the maximum value by the variable valve lift mechanism 12 to thereby intake air. The valve closing timing of the valve 8 is slowest. Thereby, by making the valve closing timing of the intake valve 8 slower than the predetermined range T1 containing a bottom dead center, knocking can be suppressed and fuel economy can be improved by the Miller cycle effect.

In the accelerator fully open view region 3, the valve closing timing of the intake valve 8 is advanced more than the maximum angle, and the lift amount is less than the maximum value, thereby maximizing the output performance of the engine 1.

In the accelerator fully closed visual recognition area 4, by setting the valve lift amount slightly larger than the minimum value, the pressure in the intake manifold can be lowered to sufficiently secure the negative pressure for the brake master bag.

As mentioned above, in this embodiment, in the engine provided with both the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12, in the low load area | region, the negative pressure in an intake manifold is reduced, and pumping loss is reduced. In the high load region, the valve closing timing of the intake valve 8 can be perceived more than near the bottom dead center to suppress knocking and improve fuel efficiency by the Miller cycle effect. Therefore, fuel economy performance can be improved in the whole area | region from a low load area to a high load area.

In addition, since the valve closing timing of the intake valve 8 can be changed by both the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12, it is advancing through the predetermined range T1 containing a bottom dead center. It is possible to smoothly switch the over-perception, and to control the time for which the valve closing timing of the intake valve 8 stays in the predetermined range T1 including the bottom dead center during the switching control transient. In addition, since the camshaft phase shift mechanism 11 is hydraulic and the variable valve lift mechanism 12 is electric, and it uses a different drive system, it is the same drive system, for example, and it suppresses the malfunction, such as a hydraulic shortage or a power shortage, by using the same drive system. can do.

In addition, the variable valve lift mechanism can be electrically controlled to precisely control the lift amount even when the oil temperature is lowered as in cold start or when the oil pressure is not sufficiently raised as at low rotation. Therefore, the fuel economy can be improved even at low temperature and low rotation.

In addition, since the lift amount of the valve is largely related to the air amount, the variable valve lift mechanism requires a very high variable responsiveness, and the motorization is suitable.

In addition, when the load is extremely small, such as when the accelerator is completely closed, the reduction of the negative pressure in the intake manifold is alleviated to secure the negative pressure for the brake master bag. This eliminates the need for a negative pressure pump in order to secure the negative pressure of the brake master bag, and can suppress an increase in component cost.

In the case of the maximum load such as when the accelerator is fully open, the valve closing timing of the intake valve 8 is not the maximum angle and the lift amount as the maximum value, but is slightly advanced than the maximum angle and the lift amount is slightly smaller than the maximum amount. By doing so, the output of the engine 1 is controlled to obtain the most output. Therefore, since the performance of an engine can be exhibited to the maximum as needed, the acceleration performance of a vehicle can be improved.

In addition, in the high load region, even when the intake valve 8 is controlled at the extreme angle, it may be set so that an overlap in which both the intake valve 8 and the exhaust valve 9 are in a valve-open state is formed. In this way, since the pumping loss is reduced in the initial stage of the intake stroke, fuel economy can be further improved.

Next, a second embodiment of the present invention will be described.

6 is a map used for setting the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12 in the second embodiment of the present invention.

In the second embodiment, the switching control of the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12 is not only dependent on the load as in the first embodiment, but also switched according to the engine rotation speed N. FIG.

In detail, when the engine rotational speed N is less than the 2nd predetermined value N1, control of the area | region 1-the area | region 4 is selected according to load similarly to 1st Embodiment. In this embodiment, when the engine rotational speed N is more than 2nd predetermined value N1, the camshaft phase variable mechanism 11 and the variable valve so that the output performance of an engine can be exhibited to the maximum like the area | region 3 regardless of load. The lift mechanism 12 is controlled.

As described above, in the second embodiment, the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12 are not subjected to unnecessary switching control at the time of high rotation where the influence on the practical fuel economy is small, so that the camshaft phase is not performed. The durability of the variable mechanism 11 and the variable valve lift mechanism 12 can be improved.

In addition, although this invention applies this invention to the engine provided with both the camshaft phase variable mechanism 11 and the variable valve lift mechanism 12 in this embodiment, it is not limited to this, but the valve of the intake valve 8 is carried out. Applicable to an engine having a function of varying the closing timing. In this case, when the load L is greater than or equal to the first predetermined value L1, the valve closing timing of the intake valve 8 is perceived more than the predetermined range T1 including the bottom dead center, so that at least the fuel consumption in the high load region is reduced. Improvement can be aimed at.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic structural diagram of the engine provided with the variable valve drive apparatus which concerns on one Embodiment of this invention.

2 is a structural diagram of a camshaft phase variable mechanism;

3 is a structural diagram of a variable valve lift mechanism.

4 is a map used for setting the camshaft phase variable mechanism and the variable valve timing mechanism in the first embodiment.

5 (a) to 5 (e) are graphs showing setting states and engine states of the camshaft phase variable mechanism and the variable valve lift mechanism according to the load;

6 is a map used for setting the camshaft phase variable mechanism and the variable valve lift mechanism in the second embodiment.

<Explanation of symbols for the main parts of the drawings>

1: engine

8: intake valve

11: camshaft phase variable mechanism

12: variable valve lift mechanism

40: ECU

Claims (7)

It is a variable valve drive device of an internal combustion engine that varies the opening and closing timing of the intake valve, When the load of the internal combustion engine is less than the first predetermined value, the valve closing timing of the intake valve is advanced to a predetermined range including a bottom dead center, while when the load of the internal combustion engine is greater than or equal to the first predetermined value, the intake valve Control means for controlling the opening and closing time of the intake valve so that the valve closing time of A variable valve timing mechanism controlled by the control means and changing a phase of the crank shaft and the intake cam shaft of the internal combustion engine to vary the opening and closing timing of the intake valve; And a variable valve lift mechanism controlled by the control means and increasing the lift amount of the intake valve while retarding at least a valve closing timing of the intake valve, When the load of the said internal combustion engine is less than a 1st predetermined value, the said control means makes the valve closing timing of the intake valve closest by the said variable valve timing mechanism, and controls the said variable valve lift mechanism according to a load, When the load of the internal combustion engine is equal to or greater than the first predetermined value, the variable valve timing mechanism controls the valve closing timing of the intake valve to be the maximum lift amount and controls the variable valve lift mechanism to be the maximum lift amount, When the accelerator opening of the engine is in the fully open state, the variable valve timing mechanism and the variable valve lift are advanced to advance the valve closing timing of the intake valve from the maximum perception and to lower the lift amount of the intake valve from the maximum amount. A variable valve drive of an internal combustion engine that controls the mechanism. It is a variable valve drive device of an internal combustion engine that varies the opening and closing timing of the intake valve, When the load of the internal combustion engine is less than the first predetermined value, the valve closing timing of the intake valve is advanced to a predetermined range including a bottom dead center, while when the load of the internal combustion engine is greater than or equal to the first predetermined value, the intake valve Control means for controlling the opening and closing time of the intake valve so that the valve closing time of A variable valve timing mechanism controlled by the control means and changing a phase of the crank shaft and the intake cam shaft of the internal combustion engine to vary the opening and closing timing of the intake valve; And a variable valve lift mechanism controlled by the control means and increasing the lift amount of the intake valve while retarding at least a valve closing timing of the intake valve, When the load of the said internal combustion engine is less than a 1st predetermined value, the said control means makes the valve closing timing of the intake valve closest by the said variable valve timing mechanism, and controls the said variable valve lift mechanism according to a load, When the load of the internal combustion engine is equal to or greater than the first predetermined value, the variable valve timing mechanism controls the valve closing timing of the intake valve to be the maximum lift amount and controls the variable valve lift mechanism to be the maximum lift amount, When the rotational speed of the engine is equal to or greater than the second predetermined value, the valve closing timing of the intake valve is advanced from the maximum perception and the lift amount of the intake valve is lowered than the maximum amount regardless of the load of the internal combustion engine. Variable of an internal combustion engine controlling the variable valve timing mechanism and the variable valve lift mechanism Valve drive. delete delete delete delete delete

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