JP2745955B2 - Intake device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an internal combustion engine, and more particularly to a technique for controlling the operation of an intake valve.

[0002]

2. Description of the Related Art In an internal combustion engine, an intake system for improving fuel efficiency and torque characteristics is provided with two intake valves for each cylinder, and in a low rotation speed range, one intake valve is stopped and only the other intake valve is operated. When activated, the intake swirl is generated to enhance the mixture of the air-fuel mixture, thereby improving fuel efficiency. In a high rotation range, both intake valves are activated to increase intake charging efficiency and obtain high torque. (See Japanese Patent Application Laid-Open No. 59-229008, etc.).

[0003]

However, in such a conventional intake device, when a traveling state in which the vehicle travels only at a low speed continues for a predetermined period or more, the accumulated air accumulates in the vicinity of the opening of the intake valve whose operation is stopped. When the deposit grows and then shifts to the high-speed range and opens and closes, a large amount of deposit reduces the opening area of the intake port, making it impossible to secure a sufficient amount of intake air, reducing torque, and reducing the intake valve and valve seat. In the airtightness.

The present invention has been made in view of such conventional problems, and by appropriately controlling the operation of two intake valves provided for each cylinder, it is possible to ensure good fuel economy and torque characteristics. It is an object of the present invention to provide an intake device for an internal combustion engine that solves the above problem by suppressing the growth of deposits.

[0005]

Accordingly, the present invention provides a variable valve mechanism having two intake valves for each cylinder, and changing the lift / working angle characteristics of the two intake valves in two stages. A rotational speed detecting means for detecting a rotational speed of the engine, a load detecting means for detecting a load on the engine, and an idle range. Then, the two intake valves are operated, and in the low-speed / low-load region other than the idling region, the amount is small.
At least one of the intake valves is stopped and only the other intake valve is activated, and the two intake valves are operated with the characteristics of low lift and small working angle in the low rotation and high load range, and high lift in the high rotation range. A valve mechanism control means for controlling the variable valve mechanism so as to operate with a characteristic of a large operating angle.

[0006]

In a low-rotation / low-load range other than the idling range, at least one of the intake valves is stopped and only the other is operated, so that, for example, the fuel supply amount generates at least the intake swirl and the fuel is supplied. Fuel efficiency is improved by improving the combustibility by improving the mixing property with air. In the low rotation and high load range, the two intake valves are operated in response to a high load requirement to secure an opening area of the intake port, and at the same time, since the inertia of the intake is small, the two intake valves have a low lift and a small operating angle. By operating with the characteristics described above, the intake charging efficiency is increased. At high rpm,
Since the inertia of the intake air is large, the two intake valves are operated with the characteristics of a high lift and a large operating angle to secure the intake charging efficiency and to ensure a sufficiently large maximum output. By operating the two intake valves in the idle range, the intake valves are not held in the closed state for a long time even when the low-speed running continues for a long time due to traffic congestion or the like. The deposit deposited near the valve is burned and removed in the idle region in a small amount, and the growth of the deposit is suppressed.

In the low rotation speed and high load range, two intake valves are operated in response to a demand for high load to secure an opening area of the intake port, and at the same time, since the inertia of the intake is small, the two intake valves are connected to a low lift / low load. By operating with the characteristic of a small operating angle, the intake charging efficiency is increased. In the high rotation range, the inertia of the intake air is large. Therefore, the two intake valves are operated with the characteristics of high lift and large operating angle to secure the intake charging efficiency and to ensure a sufficiently large maximum output.

In the idle range, by operating the two intake valves, the intake valves are not kept in the closed state for a long time even when the low-speed running continues for a long time due to traffic congestion. The deposits deposited near the intake valve during valve opening are burned and removed in the idle region in a small amount, and the growth of the deposits is suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 showing a configuration of an embodiment, an internal combustion engine is provided with two intake valves 1A and 1B for each cylinder, and the lift / working angle characteristics of the intake valves 1A and 1B are respectively set in two stages. It is provided with a variable valve mechanism that can change and stop the operation of one intake valve 1B.

The variable valve operating mechanism will be described. One end of a main rocker arm 3 is rotatably supported by a main rocker shaft 2 provided on a cylinder head (not shown). Is
A main rocker shaft roller 4 is rotatably supported by a shaft 6 fixed to the main rocker arm 3 via a ball bearing 5, and a sub rocker arm 7 is rotatably supported by a shaft 8 fixed to the main rocker arm 3. Supported. The main rocker shaft roller 4 is engaged with a low lift / small working angle characteristic cam 9 formed on a camshaft disposed in parallel with the main rocker shaft 2, and the sub rocker arm 2 is formed on the camshaft. Engaged with the high lift / large working angle characteristic cam 10.

The sub rocker arm 7 is connected to a spring 11
The plunger 12 urged in the direction of the main rocker shaft 3 by the urging force is slidably inserted and held in a hole 13 formed in the main rocker arm 3. A hole 14 penetrating in the axial direction of the main rocker shaft 2 is opened at the swinging end of the sub rocker arm 7.
Holes 15 and 16 are formed in the side wall portions opposite to each other so as to overlap with the hole 14 at a predetermined swing angle position of the sub rocker arm 7. In the state where the holes 14 and the holes 15 and 16 are superimposed, the hole 1
The first to third plungers 17, 18, and 19, which are freely slidable in the axial direction in 4, 15, and 16, and the stopper 20 with an oil drain hole are fitted into the third plunger.
A spring 21 is interposed between the concave portion on the end face of the plunger 19 and the stopper 20. Also, the main rocker arm 3
An oil passage 24 is formed between the inner end surface of the hole 15 and the insertion hole 22 of the main rocker shaft 2. The main rocker shaft 2 has an annular groove 25 communicating with the oil passage 24 and the annular groove 25. An oil passage 26 communicating with the groove 25 and extending in the radial direction is formed, and an oil passage 27 communicating with the oil passage 26 and extending in the axial direction is formed. The end of the oil passage 27 is connected to the hydraulic oil via a first switching valve 28. It is connected so as to selectively communicate with a supply source (oil pump) 29 and a low-pressure oil source (oil tank) 50.

When the first switching valve 28 is controlled to the one switching position, the oil passage 27 communicates with the low-pressure oil source 50, and the pressure oil is not supplied into the hole 15, the spring 21 expands. The second plunger 18 abuts against the end face of the hole 15, and in this state, the first to third plungers 17, 18, 19 are respectively connected to the holes 14,
The first plunger 17 is housed only in the holes 15 and 16 and in this state, the first plunger 17 can swing freely in a direction perpendicular to the axial direction of the hole 14 integrally with the sub rocker arm 7 (see FIG. 2A). . As a result, the sub rocker arm 7 engaging with the high lift / large working angle characteristic cam 10 becomes freely swingable relative to the main rocker arm 1, and the movement of the main rocker arm 3 moves to the high lift / large working angle characteristic cam 10. Is not constrained, the main rocker arm 3 is driven in accordance with the engagement with the low lift / small operating angle characteristic cam 9, and the intake valve 1A (and the intake valve 1
B) operates with characteristics that the lift amount is small and the working angle (crank angle from the start to the end of the lift) is small (shown by a solid line in FIG. 6).

When the first switching valve 28 is controlled to the other switching position and the oil passage 27 communicates with the pressure oil supply source 29, the oil passage
Pressurized oil is supplied to the hole 15 through the annular grooves 27 and 26, the annular groove 25, and the oil passage 24. As a result, the spring 21 is compressed and the first plunger 17 is fitted over the hole 14 and the hole 16. At the same time, the second plunger 18 is fitted over the hole 15 and the hole 14, and in this state, the swing of the sub rocker arm 7 is prevented and the second rocker 18 is fixed to the main rocker arm 3. As a result, the main rocker arm 3 is driven in accordance with the engagement with the high lift / large working angle characteristic cam 10, and the intake valve 1A (and the intake valve 1
B) operates with characteristics that both the lift amount and the operating angle are relatively large (shown by a chain line in FIG. 6).

Next, the valve operation stopping mechanism will be described. Rod engaged with stem head of one intake valve 1A
30 is fastened to the main rocker arm 3 via a nut 31, but when the rod 32 engaging with the stem head of the other intake valve 1B swings integrally with the main rocker arm 3, A valve operation stopping mechanism is provided for switching between when the operation of the intake valve 1B is stopped as the relative movement is free in the axial direction.

That is, a spring 33 is fitted between the bottom flange of the rod 32 engaging with the stem head of the intake valve 1B and the main rocker arm 3, and the rod 32 is
The main rocker arm 3 is inserted into the main rocker arm 3 so as to slide freely in the axial direction against the urging force of 33. The peripheral wall of the rod 32 and the rod
In the part of the main rocker arm 3 facing the insertion hole 32, holes 34 and 35 are formed which overlap each other at a predetermined axial position of the rod 32 with respect to the main rocker arm 3, and these holes 34 and 35 are formed.
Inside the fourth and fifth plungers 36, 37 and spring 38
The main rocker arm 3 has an oil passage 39 communicating with the rear end face of the hole 35 and an oil passage 40 which intersects the oil passage 39 at right angles to the insertion hole of the main rocker shaft 3. The main rocker shaft 3 includes an annular groove 41 communicating with the oil passage 40, an oil passage 42 communicating with the annular groove 41 and extending in the radial direction, and an oil passage communicating with the oil passage 42 and extending in the axial direction. An oil passage 43 is formed, and an end of the oil passage 43 is connected to the pressure oil supply source 29 and the low pressure oil source 50 via a second switching valve 44 so as to be selectively communicated.

When the second switching valve 44 is controlled to one of the switching positions, the oil passage 43 communicates with the low-pressure oil source 30 and the pressure oil is not supplied into the hole 35, the spring 38 expands. As a result, the fourth plunger 36 abuts against the end face of the hole 35, and in this state, the fourth and fifth plungers 36 and 37 are accommodated only in the holes 34 and 35, respectively. Is free to slide in the axial direction. As a result, even if the main rocker arm 3 swings, the rod 32 moves relative to the main rocker arm 3 so that the operation of the intake valve 1B is stopped. Instead of completely stopping, the lift may be slightly lifted to prevent accumulation of fuel or the like (shown by a dotted line in FIG. 6).

When the oil passage 43 communicates with the pressure oil supply source 29, pressure oil is supplied to the hole 35a via the oil passage 42, the annular groove 41, and the oil passage 40, and as a result, the spring 38 is compressed. Since the fifth plunger 37 is fitted over the holes 35 and 34 and the rod 32 is fixed to the main rocker arm 3, when the main rocker arm 3 swings, the rod 32 swings integrally with the main rocker arm 3. To operate the intake valve 1B.

On the other hand, a rotation speed sensor 45 such as a crank angle sensor is detected as engine rotation speed detection means, and a throttle valve opening is detected as load detection means.
And a throttle sensor 47 provided with an idle switch 46 serving as N. A detection signal from these sensors is input to a control unit 48. control unit
48 controls the switching position of the first switching valve 28 and the second switching valve 44 based on the rotation speed and the load detection signal as described above, and thereby lifts and lifts the intake valves 1A and 1B.
The operating angle characteristic and whether or not the operation of the intake valve 1B is stopped is controlled.

The control of the operation of the intake valve by the control unit 48 in accordance with the operating state of the engine will be described below. Since the relationship between the operation of each of the intake valves 1A and 1B and the operation of each of the mechanisms for providing the operation characteristics has already been described, the relationship is omitted in the following description. Further, in the present embodiment, the air-fuel ratio control that switches and controls the lean air-fuel ratio leaner than the stoichiometric air-fuel ratio, the stoichiometric air-fuel ratio, and the rich air-fuel ratio richer than the stoichiometric air-fuel ratio in accordance with the operation range is described above. The operation is performed by controlling the injection amount of a fuel injection valve (not shown) by the control unit 48. The operation performance is further improved by combining the control of the intake valve operation with the control of the air-fuel ratio.

FIG. 7 shows the operation pattern of the intake valve for each operation state in the first embodiment. In the low / medium rotation / low load region (region I in the drawing) other than at the time of idling detected based on detection signals from the rotation speed sensor 45 and the throttle sensor 47, only the intake valve 1A is operated and the operation of the intake valve 1B is operated. To stop. The air-fuel ratio control is controlled to a lean air-fuel ratio. As a result, the flow of the intake air from the intake valve 1A to the combustion chamber is decentered with respect to the center of the combustion chamber, and the intake port to which the intake valve 1A is attached is formed as a spiral so-called swirl port. A strong intake swirl can be generated, thereby increasing the mixability of fuel and air even in the region where the intake air flow rate is small, so that the lean air-fuel ratio can be promoted as much as possible, and the fuel efficiency in the normal range Can be improved. The lift-operating-angle characteristic of the intake valve 1A may be enhanced as a low-lift-small-operating-angle characteristic to further enhance leaning, or as a high-lift-large-acting-angle characteristic to reduce intake pumping loss. Whichever of the cases is the best in terms of fuel economy, or the one that is more appropriate in consideration of other exhaust emission characteristics and the like may be selected.

In the low / medium rotation / high load region (region II in the drawing), both the intake valves 1A and 1B are operated with a low lift / small working angle characteristic. The air-fuel ratio is controlled to a stoichiometric air-fuel ratio or a rich air-fuel ratio. Since high load is required in this area, it is important to increase the intake charging efficiency.
The two intake valves are operated, and since the rotation speed is not high, the intake inertia is small. Therefore, a low lift and small operating angle characteristic is adopted to adapt to the inertia supercharging effect. As a result, as high a torque as possible can be generated.

In the high rotation region (region III in the drawing), the two intake valves 1A and 1B are operated with high lift and large working angle characteristics. As for air-fuel ratio control, control is performed at a stoichiometric air-fuel ratio or a rich air-fuel ratio (particularly in a high load region). In such a region, the intake speed is high due to the high rotational speed, and the intake flow velocity and flow rate also increase, so the intake effect is secured by operating with high lift and large operating angle characteristics to increase the inertia effect and increase the opening area. You do it.

By performing control according to the operating conditions as described above,
The aim is to improve practical fuel economy and torque throughout. In the idle range (1 'in the figure) detected by the idle switch 46, both the intake valves 1A and 1B are operated with characteristics of low lift and small working angle. Accordingly, even if deposits are deposited on the intake valve 1B that has been stopped in a state where the operation of one of the intake valves 1B has been stopped by the above-described control in the low-medium-speed, low-load normal region, the operation is normally performed in the normal region. During this period, the idle state is often caught, and while the deposit is in a small amount, it enters the idle state and is burned off. Therefore, a large amount of deposit is not deposited, and when the operation shifts to an operation in which the two intake valves 1A and 1B are simultaneously operated in a high-speed and high-load region, the intake is obstructed by the large amount of deposited deposit and the output is reduced. It is possible to prevent shortage and deterioration of performance due to impaired flammability. still,
Regarding air-fuel ratio control, one of lean air-fuel ratio, stoichiometric air-fuel ratio, and rich air-fuel ratio should be adopted in consideration of rotational stability and fuel efficiency when a relatively large external load is applied and when it is not. I just need.

FIGS. 8 and 9 show the operation patterns of the intake valve for each operating state in the second and third embodiments, respectively.
The difference from the first embodiment lies in the low-load, medium-load region (shown in the figure).
II ') Only whether the stoichiometric air-fuel ratio or the rich air-fuel ratio control is performed by stopping the operation of the intake valve 1B (second embodiment, see FIG. 8)
Alternatively, a lean air-fuel ratio control is performed by operating two intake valves 1A and 1B with low lift and small working angle characteristics (third embodiment, see FIG. 9). The operating characteristics of the intake valve are, for example, low lift and small operating angle characteristics. Also,
In the idle region, lean air-fuel ratio control is performed. In this manner, in the low-speed low-load region, the intake valve 1B is deactivated to control the lean air-fuel ratio. Therefore, the low-speed low-load region and the low-speed low-load region are interposed between the idle range and the low-speed low-load region. Since the switching of the air-fuel ratio and the switching of the number of actuations of the intake valves are not performed at the same time between the regions, the torque shock at the time of the switching can be reduced. In addition, in the high rotation region, the two intake valves are operated to control the stoichiometric air-fuel ratio or the rich air-fuel ratio. Therefore, the switching of the air-fuel ratio and the switching of the operation number of the intake valve are also performed between the low rotation medium load region and the high rotation region. Are not performed at the same time, and the torque shock at the time of switching can be reduced.

In the above embodiment, the combination of the intake valve operation control and the different air-fuel ratio control is shown. In these devices, the driving performance can be enhanced as much as possible by the synergistic effect of both controls. However, the effect of the intake valve operation control according to the present invention can be sufficiently exhibited even when applied to a simple air-fuel ratio control in which the air-fuel ratio is kept constant regardless of operating conditions. The invention of the present application is also based on two intake valves of a cylinder.
And the exhaust valves (two in the case of two) are deactivated, so-called
To an internal combustion engine that puts some cylinders into idle operation
Is also possible.

[0026]

As described above, according to the present invention, the lift / lift of the two intake valves for each cylinder according to the operating range.
By controlling the working angle characteristic and the operation of one of the intake valves, it is possible to improve the practical fuel consumption and the torque characteristic of the entire region as much as possible. In the idle region, the two intake valves are simultaneously operated, The growth of deposits that accumulate near the intake valve when the operation is stopped can be suppressed, and the deposits increase the intake resistance and cause a decrease in output, or poor combustion properties cause a decrease in performance (including deterioration of exhaust emission characteristics). Can be prevented.

[Brief description of the drawings]

FIG. 1 is a bottom view showing an intake valve operating mechanism of an intake device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line YY of FIG.

FIG. 3 is a sectional view taken along the line ZZ of FIG. 1;

FIG. 4 is a sectional view taken along line XX of FIG. 1;

FIG. 5 is a sectional view taken along the line AA of FIG. 1;

FIG. 6 is a diagram showing lift-operating angle characteristics of two intake valves of the embodiment.

FIG. 7 is a table and an operation region diagram showing an example of an operation characteristic of an intake valve and an air-fuel ratio control pattern for each operation region in the embodiment.

FIG. 8 is a table and an operation region diagram showing another example of the operation characteristics of the intake valve and the pattern of the air-fuel ratio control in each operation region.

FIG. 9 is a table and an operating region diagram showing still another example of the operating characteristics of the intake valve and the pattern of the air-fuel ratio control in each operating region.

[Explanation of symbols]

 1A, 1B Intake valve 3 Main rocker arm 7 Sub rocker arm 9 Low lift / small working angle characteristic cam 10 High lift / large working angle characteristic cam 17 First plunger 24, 26, 27 Oil passage 25 Annular groove 28 First switching valve 32 Rod 36 4th plunger 37 5th plunger 39, 40, 42, 43 Oil passage 41 Annular groove 44 Second switching valve 45 Rotation speed sensor 46 Idle switch 47 Throttle sensor 48 Control unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02B 31/02 F02B 31/02 L F02D 41/02 320 F02D 41/02 320 (56) References JP-A-5-118209 (JP) JP-A-4-187853 (JP, A) JP-A-1-61411 (JP, U) JP-A-62-1117235 (JP, U) JP-A-4-13381 (JP, Y2) JP-A 4-47371 (JP, Y2)

Claims (1)

(57) [Claims] An intake system for an internal combustion engine having two intake valves for each cylinder, a variable valve mechanism for changing the lift / working angle characteristics of each of the two intake valves in two stages, and one intake valve. A valve operation stop mechanism for stopping the operation of the engine, a rotation speed detection means for detecting a rotation speed of the engine, a load detection means for detecting a load on the engine, and operating the two intake valves in an idle range. In the low-speed / low-load range other than the idling range, at least one of the intake valves is stopped and only the other intake valve is operated.
The variable valve mechanism and the valve operation stop mechanism are controlled so that the two intake valves operate with the characteristics of low lift and small working angle in the high load range, and operate with the characteristics of high lift and large working angle in the high rotation range. And an intake device for an internal combustion engine.