JP2001152884A - Variable valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the variable valve system of an internal combustion engine, capable of changing the opening/closing timing of an intake valve and/or exhaust valve, through the use of oil pressure and preventing deterioration in the engine starting characteristics, the rate of fuel consumption, and drop in the output of the engine. SOLUTION: This variable valve system of internal combustion engine is equipped with changeable acting angle for a cam shaft and its rotation phase relative to a crankshaft, where the acting angle of the cam shaft minimizes and its rotation phase is most retarded, when a sufficient driving force for the valve device is not obtained, and the minimum acting angle of the cam shaft is arranged, so that the closing timing of the intake valve lies near the lower dead point of the suction stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating device for an internal combustion engine mounted on an automobile or the like, and more particularly to a variable valve operating device that changes a valve opening characteristic of a valve operating mechanism.

[0002]

2. Description of the Related Art In recent years, as a valve operating mechanism of an internal combustion engine mounted on an automobile or the like, a variable valve operating device capable of changing the opening / closing timing of an intake valve and / or an exhaust valve has been proposed.

[0003] As a variable valve operating device, for example, a cylindrical housing integrally formed with a timing pulley, between a timing pulley connected to a crank pulley via a belt and a camshaft; By interposing a vane body fixed to the end and rotatably housed in the housing, by rotating the vane body in an arbitrary direction in the housing,
2. Description of the Related Art There is known a vane-type variable valve apparatus that changes a rotation phase of a vane body relative to a housing, in other words, a rotation phase of a camshaft relative to a timing pulley.

[0004] In the vane type variable valve apparatus configured as described above, when the vane body is rotated with respect to the housing in the rotation direction of the timing pulley, the rotation phase of the cam shaft with respect to the timing pulley is advanced. When the vane body is rotated with respect to the housing in a direction opposite to the rotation direction of the timing pulley, the rotation phase of the cam shaft with respect to the timing pulley is retarded.

[0005] By the way, in the vane type variable valve apparatus, the rotation of the vane body is performed by utilizing the pressure of the lubricating oil of the internal combustion engine. Is pumped from an oil pan by an oil pump driven by the oil pump to the variable valve gear and various parts of the internal combustion engine, so that the viscosity of the lubricating oil is high as in starting the internal combustion engine, and the oil pump is driven. When the force is small, it becomes difficult to apply a desired oil pressure to the vane type variable valve gear.

When the internal combustion engine is started, a crankshaft is rotated by a starter motor, and the torque is transmitted to a timing pulley via a crank pulley, a belt, or the like. While being transmitted to the camshaft via the variable valve operating device, a force for preventing rotation is applied to the camshaft due to friction of an intake / exhaust valve, a valve spring, or the like.

[0007] Therefore, unlike the start of the internal combustion engine, sufficient hydraulic pressure cannot be applied to the vane type variable valve apparatus, and a force for preventing rotation of the camshaft acts on the camshaft. In such a case, the relative position of the vane body with respect to the housing cannot be maintained at a desired position in the vane-type variable valve apparatus, and the vane body is at the most retarded position with respect to the housing.

At this time, if the camshaft is an intake-side camshaft that drives the opening and closing of the intake valve, the closing timing of the intake valve is most retarded when the internal combustion engine is started. When the closing timing of the intake valve is the most retarded and later than the intake bottom dead center (compression bottom dead center), fresh air or air-fuel mixture once drawn into the combustion chamber flows out of the intake valve due to the rise of the piston. That is, a so-called air blow-back occurs. Such a blowback of the intake air becomes remarkable when the inertial force of the intake air is small, such as when the internal combustion engine is started, and the charging efficiency in the combustion chamber is reduced.

When the efficiency of charging the air-fuel mixture in the internal combustion engine is reduced, the compression ratio of the air-fuel mixture in the combustion chamber is reduced during the compression stroke, so that the combustion energy of the air-fuel mixture is reduced.
The startability of the internal combustion engine deteriorates. In particular, during a cold start in which the friction of the internal combustion engine is large, there is a possibility that the internal combustion engine cannot be started against the friction.

To solve such a problem, a "valve timing control apparatus for an internal combustion engine" described in Japanese Patent Application Laid-Open No. H11-210424 has been proposed. The valve timing control device for an internal combustion engine described in this publication
The vane-type variable valve device includes an intermediate locking means for locking the relative position of the vane body to the housing at a desired position when the temperature or pressure of the lubricating oil is unstable.

The intermediate locking means includes a lock pin provided on the vane body, a spring for urging the lock pin toward the housing, and a vane body on the wall surface of the housing which is positioned between the most retarded position and the most advanced position. A lock hole provided at a position aligned with the lock pin when the lock pin is at an intermediate position, and when sufficient hydraulic pressure is not obtained in the vane type variable valve apparatus, the lock pin advances by receiving the urging force of the spring. Then, when the oil pressure exceeds the urging force of the spring, the lock pin retreats and separates from the lock hole of the housing.

[0012]

In an apparatus for fixing a relative position of a vane body to a housing using a lock pin in a vane type variable valve operating apparatus, such as the above-described valve timing control apparatus for an internal combustion engine, the lock pin In some cases, the lock pin cannot be detached from the lock hole due to sticking or deterioration of lubricating oil performance. In such a case, the opening and closing timings of the intake valves and the exhaust valves cannot be set to timings commensurate with the operation state of the internal combustion engine, which may cause a decrease in the output of the internal combustion engine or a deterioration in the fuel consumption rate. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is directed to an internal combustion engine having a variable valve operating device capable of changing the opening / closing timing of an intake valve and / or an exhaust valve using hydraulic pressure. It is another object of the present invention to provide a technique for preventing the deterioration of the startability of the internal combustion engine, the deterioration of the fuel consumption rate, and the reduction of the output of the internal combustion engine.

[0014]

The present invention employs the following means to solve the above-mentioned problems. That is, a variable valve train of an internal combustion engine according to the present invention is formed so that a plurality of operating angles can be selected, and a camshaft that opens and closes an intake valve of the internal combustion engine by receiving a rotational force of a crankshaft; A variable valve train for an internal combustion engine, comprising: a rotation phase changing means for changing a rotation phase of the camshaft with respect to a rotation angle; and a working angle switching means for changing a working angle of the camshaft. Is characterized in that when the rotational phase of the camshaft is most retarded with respect to the crankshaft, the closing timing of the intake valve is formed near the intake bottom dead center.

In the variable valve apparatus for an internal combustion engine having the above-described structure, when the driving force of the rotation phase changing means and the operating angle switching means can be obtained stably as in the case where the internal combustion engine is in a normal operation state. The rotation phase changing means changes the rotation phase of the camshaft so that the opening / closing timing of the intake valve matches the operating state of the internal combustion engine, and the operating angle changing means sets the opening / closing timing of the intake valve and / or the lift amount. The operating angle of the camshaft is switched so as to make the timing suitable for the operating state of the internal combustion engine.

Further, in the variable valve operating device for an internal combustion engine, when the driving force of the rotation phase changing means and the operating angle switching means cannot be sufficiently obtained as at the time of starting the internal combustion engine, the cam for the crankshaft is not provided. The rotational phase of the shaft becomes the most retarded state, and the minimum operating angle is selected from a plurality of operating angles of the camshaft.

At this time, the minimum working angle of the camshaft is formed such that the closing timing of the intake valve is near the intake bottom dead center when the rotational phase of the camshaft with respect to the crankshaft is the most retarded state. Therefore, when the intake valve is in the open state, fresh air once sucked into the combustion chamber is discharged from the intake valve. There is no.

As a result, in the combustion chamber of the internal combustion engine, the compression ratio does not decrease due to the decrease in the charging efficiency of the intake air, and the startability of the internal combustion engine does not deteriorate.
The driving force of the rotation phase changing means and the working angle changing means according to the present invention can be exemplified by the pressure of the lubricating oil of the internal combustion engine. Next, in the variable valve operating device for an internal combustion engine according to the present invention, the minimum operating angle of the camshaft is determined when the rotational phase of the camshaft is most retarded with respect to the crankshaft. The valve opening timing may be formed so as to be after the intake top dead center. Preferably, the opening timing of the intake valve is after the intake top dead center and there is no overlap with the exhaust valve. It may be formed as follows.

In this case, after each cylinder of the internal combustion engine has shifted from the exhaust stroke to the intake stroke, the intake valve is opened after the exhaust valve is closed. Here, in the cylinder in the intake stroke, since the piston moves from the top dead center to the bottom dead center, if the exhaust valve and the intake valve are closed at that time, a negative pressure is generated in the cylinder. . When the intake valve is opened in the state where the negative pressure is generated in the cylinder, the intake air flows into the cylinder with a good momentum, and the flow velocity of the intake air increases.

When the flow velocity of the intake air is increased, the atomization of the fuel injected from the fuel injection valve is promoted, so that a favorable mixture suitable for combustion is formed in the cylinder. As a result, the air-fuel mixture easily burns, and the startability of the internal combustion engine is improved.

Further, when the opening timing of the intake valve is set to a timing at which no overlap with the exhaust valve occurs, the exhaust gas discharged from the combustion chamber of the internal combustion engine via the exhaust valve is drawn into the combustion chamber again. The exhaust gas does not remain in the combustion chamber and the amount of fresh air drawn into the cylinder does not decrease.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of a variable valve operating device for an internal combustion engine according to the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 are diagrams showing a schematic configuration of an internal combustion engine to which the variable valve apparatus according to the present invention is applied. FIG.
And an internal combustion engine 1 shown in FIG.
It is a cycle water-cooled gasoline engine.

The internal combustion engine 1 includes a cylinder block 1b in which a plurality of cylinders 2 and a cooling water passage 1c are formed, and a cylinder head 1a fixed on an upper portion of the cylinder block 1b.

A crankshaft 4 as an engine output shaft is rotatably supported by the cylinder block 1b. The crankshaft 4 is connected to a piston 3 slidably mounted in each cylinder 2. .

Above the piston 3, a combustion chamber 6 surrounded by a top surface of the piston 3 and a wall surface of the cylinder head 1a is provided.
Are formed. An ignition plug 7 is attached to the cylinder head 1a so as to face the combustion chamber 6.

The cylinder head 1a is formed so that the open ends of two intake ports 8 and the open ends of two exhaust ports 9 face the combustion chamber 6. Each open end of the intake port 8 is opened and closed by an intake valve 10 supported on the cylinder head 1a so as to be able to advance and retreat, and each open end of the exhaust port 9 is connected to the cylinder head 1a.
a is opened and closed by an exhaust valve 11 supported to be able to move forward and backward.

An intake camshaft 1 for opening and closing the intake valve 10 is provided on the cylinder head 1a.
5 and an exhaust-side camshaft 16 for opening and closing the exhaust valve 11 are rotatably supported.

An intake-side timing pulley 15a is attached to a base end of the intake-side camshaft 15, and an exhaust-side pulley 16a is attached to a base end of the exhaust-side camshaft 16.

The above-described intake-side timing pulley 1
The pulley 5a and the exhaust side pulley 16a are connected to a crank pulley 4a attached to a base end of the crankshaft 4 and a timing belt 17 composed of a cogged belt, and the rotational force of the crankshaft 4 is transmitted via the timing belt 17 to the intake camshaft. 15 and the exhaust-side camshaft 16.

Here, the timing pulleys 15a, 16a
And the number of teeth of the crank pulley 4a each time the crankshaft 4 makes two rotations.
And the exhaust-side camshaft 16 is set to make one rotation, and the intake valve 10 and the exhaust valve 11 are opened and closed in synchronization with the rotation of the crankshaft 4, that is, the intake stroke, compression stroke, expansion stroke, and exhaust stroke of each cylinder 2. It is supposed to.

The intake side timing pulley 15a
Is provided with a variable valve mechanism 32 that changes the rotation phase of the intake camshaft 15 with respect to the crankshaft 4 and the working angle of the cam provided on the intake camshaft 15.

A cam position sensor 18 for outputting an electric signal corresponding to the displacement angle of the intake camshaft 15 is attached to the cylinder head 1a at a position facing the intake camshaft 15.

The intake port 8 communicates with each branch pipe of an intake branch pipe 19 connected to the cylinder head 1a of the internal combustion engine 1. A fuel injection valve 23 is attached to the intake branch pipe 19 such that the injection hole faces the intake port 8 of each cylinder 2.

The intake branch pipe 19 is connected to a surge tank 20 for smoothing the pulsation of intake air, and the surge tank 20 is connected via an intake pipe 21 to an air cleaner box 22.
Is connected to

An intake pressure sensor 25 for outputting an electric signal corresponding to the pressure in the surge tank 20 is attached to the surge tank 20. In the intake pipe 21,
A throttle valve 24 for adjusting the flow rate of intake air flowing through the intake pipe 21 in conjunction with an accelerator pedal (not shown) is provided, and a throttle position sensor 26 for outputting an electric signal corresponding to the opening of the throttle valve 24 is attached. Have been.

On the other hand, the exhaust port 9 communicates with each branch pipe of the exhaust branch pipe 28 connected to the cylinder head 1a of the internal combustion engine 1. The exhaust branch pipe 28 is connected to an exhaust pipe 30 via an exhaust purification catalyst 29, and the exhaust pipe 30 is connected downstream to a muffler.

The exhaust gas purifying catalyst 29 includes, for example, hydrocarbons (HC) contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the exhaust gas purifying catalyst 29 is a predetermined air-fuel ratio near the stoichiometric air-fuel ratio. Carbon monoxide (CO), nitrogen oxides (NO
When the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 47 is a lean air-fuel ratio, nitrogen oxides (NOx) contained in the exhaust gas are stored, and the air-fuel ratio of the inflowing exhaust gas is reduced. When the stoichiometric air-fuel ratio or the rich air-fuel ratio is attained, the occlusion-reduction type NOx catalyst that reduces and purifies while releasing the stored nitrogen oxides (NOx), and the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 47 is excessive oxygen This is a selective reduction type NOx catalyst that reduces and purifies nitrogen oxides (NOx) in exhaust gas when it is in a state and a predetermined reducing agent is present, or a catalyst obtained by appropriately combining the various catalysts described above.

An air-fuel ratio sensor 31 for outputting an electric signal corresponding to the air-fuel ratio of the exhaust flowing through the exhaust branch 28, in other words, the air-fuel ratio of the exhaust flowing into the exhaust purification catalyst 29, is provided at the exhaust branch 28. Is attached.

The internal combustion engine 1 includes a crank position sensor 12 including a timing rotor 12a attached to an end of a crankshaft 4 and an electromagnetic pickup 12b attached to a cylinder block 1b near the timing rotor. And a water temperature sensor 13 for outputting an electric signal corresponding to the temperature of the cooling water flowing in the cooling water passage 1c formed in the cooling water passage 1c.

An electronic control unit (ECU) 14 for controlling the operating state of the internal combustion engine 1 is also provided in the internal combustion engine 1 configured as described above.

Various sensors such as the crank position sensor 12, the water temperature sensor 13, the cam position sensor 18, the intake pressure sensor 25, the throttle position sensor 26, and the air-fuel ratio sensor 31 are connected to the ECU 14 via electric wiring. , The output signals of various sensors are
4 is input.

The ECU 14 includes a spark plug 7, a fuel injection valve 23, a variable valve mechanism 32
And the like are connected via electric wiring, so that the ECU 14 can perform ignition control, fuel injection control, opening / closing timing control of the intake valve 10, lift amount control of the intake valve 10, etc. using output signals of various sensors as parameters. . Next, a specific configuration of the variable valve mechanism 32 according to the present embodiment will be described.

The variable valve mechanism 32 implements the rotation phase changing means and the working angle switching means according to the present invention.
As shown in FIG. 3, an intake-side timing pulley 15a rotatably supported by the cylinder head 1a and the bearing cap 38 is provided.

The intake side timing pulley 15a
Of the two side surfaces, a side surface located on the side opposite to the cylinder head 1a has an annular spacer 320 and the spacer 3 having the same outer diameter as the spacer 320 and having the same outer diameter.
A cylindrical case 321 whose end face on the 20 side is closed, and a disk-shaped end cover 322 that closes the open end of the case 321 are sequentially arranged. These spacers 32
The case 0, the case 321, and the end cover 322 are fixed to the timing pulley 15 a by a plurality of bolts 323.

As shown in FIG. 4, four partition portions 320a projecting radially toward the center are formed at equal intervals in the circumferential direction on the inner peripheral surface of the spacer 320. At this time, the four partition portions 320a are formed to have the same length from the inner wall of the spacer 320 to the tip of the partition portion 320a.

The spacer 320 is formed such that its axial length is the same as that of the spacer 320 and its outer diameter is the same as the circle passing through the tips of the four partition portions 320a. The arranged annular vane body 324 is arranged. At this time, the outer peripheral surface of the vane body 324 and the partition 3
It is assumed that it is formed so as to be slidable with respect to the tip end of 20a and to be in liquid-tight contact with each other.

On the outer peripheral surface of the vane body 324, four vanes 324a projecting in the radial direction are formed at equal intervals in the circumferential direction. Each of the vanes 324a is located in a space between the adjacent partition plates 320a, and is formed such that a tip end of each of the vanes 324a comes into contact with the inner peripheral surface of the spacer 324 in a liquid-tight and slidable manner. .

In this case, the space between the adjacent partition portions 320a in the spacer 320 is divided into two spaces 800 and 900 by the vane 324a of the vane body 324. Here, the two spaces 80 described above are used.
0, 900, the space 800 located on the rotation direction side of the intake-side timing pulley 15a with respect to the vane 324a is referred to as a retard chamber 800, and the space 800 with the rotation direction side of the intake-side timing pulley 15a with respect to the vane 324a. The space 900 located on the opposite side is referred to as an advance chamber 900.

Returning to FIG. 3, the intake camshaft 15 passes through the intake side timing pulley 15a and the axis of the case 321. The tip of the intake camshaft 15 projects into the case 321. ing.

A disk-shaped piston 153 having an outer diameter substantially equal to the inner diameter of the case 321 is fixed to a tip end of the intake-side camshaft 15 by a bolt 154. Outer peripheral surface of the piston 153 and the case 32
The inner wall 1 is slidably and liquid-tightly contacted.

In this case, the space in the case 321 is
The two spaces 500 and 600 are formed by the piston 153.
It will be divided into. In the following, the piston 15
The space 500 located on the base end side of the intake side camshaft 15 with respect to the piston 3 is referred to as a biasing chamber 500, and the space 600 located on the distal end side of the intake side camshaft 15 with reference to the piston is a hydraulic chamber 600. Shall be called.

The urging chamber 500 includes the piston 15
3 and a coil spring 7 for urging the intake camshaft 15 toward the hydraulic chamber 600 along the axial direction.
00 is provided.

The intake side camshaft 15
An annular projection 151 is formed in a portion of the vane body 324 located in the hollow portion. As shown in FIG. 5, flat teeth 151a are formed on the outer peripheral surface of the annular projection 151 along the axial direction. Correspondingly, on the inner peripheral surface of the vane body 324, a spur tooth 324b meshing slidably in the axial direction with the spur tooth 151a of the annular projection 151 is provided.
The vane body 324 and the intake camshaft 15 are integrally rotatable by engagement of the spur teeth 151a and the spur teeth 324b.

On the other hand, as shown in FIG. 6, the intake camshaft 15 is formed with the same number of three-dimensional cams 150 as the number of intake valves 8 whose operating angle continuously changes in the axial direction. The operating angle of the three-dimensional cam 150 is formed so as to be larger at a portion of the intake camshaft 15 closer to the intake timing pulley 15a. Next, a first oil passage 33 communicating with the advance chamber 900 in the spacer 320 is formed in the vane body 324, the intake-side timing pulley 15a, and the cylinder head 1a.

A second oil passage 34 communicating with the retard chamber 800 in the spacer 320 is formed in the spacer 320, the intake-side timing pulley 15a, and the cylinder head 1a.

Further, the above-mentioned bolt 154, intake side camshaft 15, intake side timing pulley 1
5a and the cylinder head 1a,
A third oil passage 39 communicating with the hydraulic chamber 600 in 1 is formed.

The first to third oil passages 33, 3
Reference numerals 4 and 39 communicate with the oil control valve 35. The oil control bubble 35 is connected to an oil pump 36 that uses the rotational force of the crankshaft 4 as a driving source, and is also connected to an oil pan 37 that stores the lubricating oil of the internal combustion engine 1.

The oil control bubble 35 supplies the lubricating oil pressure-fed from the oil pump 36 to the variable valve mechanism 32 and leaks the lubricating oil supplied to the variable valve mechanism 32 to By returning the oil to the oil pan 37, the hydraulic pressure applied to the variable valve mechanism 32 is controlled.

In the variable valve mechanism 32 configured as described above, the rotational force transmitted from the crank pulley 4a to the intake-side timing pulley 15a is transmitted from the intake-side timing pulley 15a to the spacer 320.

The torque transmitted to the spacer 320 is transmitted from the partition plate 320a of the spacer 320 to the vane 324a via the lubricating oil in the advance chamber 900, and then transmitted from the vane 324a to the vane body 324.

The rotational force transmitted to the vane body 324 is transmitted from the spur teeth 324 b of the vane body 324 to the spur teeth 151 a of the annular projection 151 of the intake camshaft 15,
Next, the power is transmitted from the spur teeth 151 a to the annular projection 151 and the intake camshaft 15.

At this time, by adjusting the hydraulic pressure of the advance chamber 900 and the retard chamber 800 in the spacer 320,
The rotation phase of the vane body 324 with respect to the spacer 320 changes, and as a result, the intake-side timing pulley 15a
, The rotational phase of the intake camshaft 15 can be changed.

For example, when the first oil passage 33 communicates with the oil pump 36 and the second oil passage 34 communicates with the oil pan 37 in the oil control bubble 35, the lubrication discharged from the oil pump 36 The pressure of the oil is controlled by the variable valve mechanism 32 via the first oil passage 33.
And the variable valve mechanism 3
The hydraulic pressure in the second retard chamber 800 leaks to the oil pan 37 via the second oil passage 34.

When the pressure in the advance chamber 900 becomes higher than the pressure in the retard chamber 800 in the variable valve mechanism 32, the vane 324 a of the vane body 324 moves from the advance chamber 900 side to the retard chamber 800 side in the spacer 320. And the rotation phase of the vane body 324 advances with respect to the spacer 320, and as a result, the rotation phase of the intake camshaft 15 with respect to the intake timing pulley 15a advances.

On the other hand, when the first oil passage 33 and the oil pan 37 are communicated with each other and the second oil passage 34 and the oil pump 36 are communicated with each other in the oil control bubble 35, the lubrication discharged from the oil pump 36 The pressure of the oil is controlled by the variable valve mechanism 32 via the second oil passage 34.
Of the variable valve mechanism 3
The hydraulic pressure in the second advance chamber 900 leaks to the oil pan 37 via the first oil passage 33.

In the variable valve mechanism 32, when the pressure in the retard chamber 800 becomes higher than the pressure in the advance chamber 900, the vane 324a of the vane body 324 moves from the retard chamber 800 side to the advance chamber 900 side in the spacer 320. And the rotational phase of the vane body 324 with respect to the spacer 320 is retarded. As a result, the rotational phase of the intake camshaft 15 with respect to the intake timing pulley 15a is retarded.

Therefore, by controlling the oil pressure in the retard chamber 800 and the advance chamber 900 in the variable valve mechanism 32,
A rotation phase changing unit according to the present invention is realized. Next, in the oil control bubble 35, the third oil passage 3
9 and the oil pan 37 communicate with each other, the variable valve mechanism 3
The hydraulic pressure in the hydraulic chamber 600 in the second oil passage 39
Through the oil pan 37.

When the hydraulic pressure in the hydraulic chamber 600 leaks in the variable valve mechanism 32, the hydraulic pressure in the hydraulic chamber 600 becomes lower than the urging force of the coil spring 700, and the piston 1
53 moves from the urging chamber 500 side to the hydraulic chamber 600 side, and accordingly, the intake camshaft 15 also moves to the hydraulic chamber 60 side.
It will move to the 0 side.

Here, in the intake camshaft 15 according to the present embodiment, the working angle of the three-dimensional cam 150 is
When the intake camshaft 15 moves from the urging chamber 500 side to the hydraulic chamber 600 side, the three-dimensional cam 150 comes into contact with the intake valve 10 because the intake camshaft 15 is moved from the biasing chamber 500 side to the hydraulic chamber 600 side because the portion closer to the intake side timing pulley 15 a is formed. The site is a site with a small operating angle as shown in FIG.

As a result, if the hydraulic pressure in the hydraulic chamber 600 leaks in the variable valve mechanism 32, the three-dimensional cam 150
Of working angle becomes small. On the other hand, in the oil control bubble 35, the third oil passage 39 and the oil pump 36
Is communicated, the pressure of the lubricating oil discharged from the oil pump 36 is applied to the hydraulic chamber 600 of the variable valve mechanism 32 via the third oil passage 39.

When hydraulic pressure is applied to the hydraulic chamber 600 in the variable valve mechanism 32, the hydraulic pressure in the hydraulic chamber 600 becomes higher than the urging force of the coil spring 700, and the piston 15
3 moves from the hydraulic chamber 600 side to the biasing chamber 500 side, and accordingly, the intake camshaft 15 also moves to the biasing chamber 500 side.
Will move to the side.

As described above, the intake camshaft 15
Moves from the hydraulic chamber 600 side to the biasing chamber 500 side, the contact portion of the three-dimensional cam 150 with the intake valve 10 becomes a portion having a large working angle as shown in FIG.

Therefore, by controlling the oil pressure in the hydraulic chamber 600 in the variable valve mechanism 32, the working angle of the cam on the intake camshaft 15 can be switched, and the working angle switching means according to the present invention is realized. You.

In the variable valve mechanism 32 configured as described above, when the driving force of the oil pump 36 is small and the viscosity of the lubricating oil is high as in the case of starting the internal combustion engine 1, the hydraulic chamber 600 , Retard chamber 800, and advance chamber 900
, It becomes difficult to apply a desired oil pressure.

When no hydraulic pressure is applied to the hydraulic chamber 600 in the variable valve mechanism 32, the pressure in the hydraulic chamber 600 becomes lower than the urging force of the coil spring 700, so that the piston 153 and the intake camshaft 15 As shown in FIG. 3, the piston 153 is
22 so that the three-dimensional cam 15
At 0, the portion that comes into contact with the intake valve 10 is the portion where the operating angle is the smallest.

Further, in the variable valve mechanism 32, the retard chamber 8
When no hydraulic pressure is applied to the advance chamber 900, particularly when no hydraulic pressure is applied to the advance chamber 900, the rotational force of the crank pulley 4 a is applied to the variable valve mechanism via the timing belt 17 and the intake-side timing pulley 15 a. 3
The friction of the intake valve 10 and a valve spring (not shown) is transmitted from the intake side camshaft 15 to the spur teeth 15 of the annular protrusion 151 while being transmitted to the second spacer 320.
1a and acts on the vane body 324 via the spur teeth 324b of the vane body 324.

For this reason, even if the spacer 320 rotates,
Until the wall surface on the advance chamber 900 side of each vane 324a contacts the partition 320a of the spacer 320, the rotational force of the spacer 320 is not transmitted to the vane body 324. As a result, as shown in FIG. 8, the vane body 324 rotates at the most retarded state with respect to the spacer 320.
, The rotational phase of the intake camshaft 15 is most retarded.

When the rotational phase of the intake camshaft 15 with respect to the crankshaft 4 is the most retarded, the closing timing of the intake valve 10 is the most retarded.
At that time, when the closing timing of the intake valve 10 is later than the intake bottom dead center (compression bottom dead center), fresh air or air-fuel mixture once drawn into the combustion chamber flows out of the intake valve due to the rise of the piston. There is a possibility that a so-called backflow of intake air occurs, the filling efficiency of the combustion chamber decreases, and the startability deteriorates due to a decrease in compression pressure.

Thus, in the variable valve mechanism 32 according to the present embodiment, the minimum working angle of the three-dimensional cam 150 is
When the rotational phase of the intake-side camshaft 15 with respect to the crankshaft 4 is the most retarded, as shown in FIG. 9, the opening timing of the intake valve 10 is after the intake top dead center and overlaps with the exhaust valve 11. , And the valve closing timing of the intake valve 10 is set near the intake bottom dead center (preferably immediately before the intake bottom dead center).

According to the three-dimensional cam 150 formed as described above, the variable valve mechanism 32
Cannot be applied to the crankshaft 4, the rotational phase of the intake camshaft 15 with respect to the crankshaft 4 becomes the most retarded, and the three-dimensional cam 1
When the minimum operating angle is selected at 50, the closing timing of the intake valve 10 is near the intake bottom dead center, and the opening timing of the intake valve 10 is after the intake top dead center and the exhaust valve 11
It is a time when no overlap occurs.

When the internal combustion engine 1 is started, the opening timing of the intake valve 10 is after the intake top dead center and the intake and exhaust valves 10 and 11
When the valve overlap does not occur, the intake valve 10 is opened after the exhaust valve is closed in the intake stroke. That is, a period occurs in which both the intake valve 10 and the exhaust valve 11 are closed during the intake stroke of each cylinder 2.

In the cylinder 2 in the intake stroke, the piston 3 moves from the top dead center to the bottom dead center, and if the intake and exhaust valves 10 and 11 are closed at that time, the cylinder 2 Negative pressure is generated. In a state where a negative pressure is generated in the cylinder 2, the intake valve 10
Is opened, the intake air flows into the cylinder 2 in a vigorous manner, and the flow velocity of the intake air increases.

When the flow rate of the intake air is increased as described above, the atomization of the fuel injected from the fuel injection valve 23 is promoted, so that a favorable mixture suitable for combustion is formed in the cylinder 2.
As a result, the air-fuel mixture easily burns, and the startability of the internal combustion engine 1 is improved.

Further, when the opening timing of the intake valve 10 is such that the valve overlap of the intake and exhaust valves 10 and 11 does not occur when the internal combustion engine 1 is started, the combustion chamber 6 passes through the exhaust valve 11 via the exhaust valve 11. Since the discharged exhaust gas is no longer sucked into the combustion chamber 6 and remains, the charging efficiency of the intake air during the intake stroke is improved.

On the other hand, when the internal combustion engine 1 is started, the closing timing of the intake valve 10 is near the intake bottom dead center.
The fresh air or the air-fuel mixture once sucked into the air does not flow back from the intake valve due to the rise of the piston, and the charging efficiency of the intake air does not decrease.

Therefore, according to the variable valve operating apparatus according to the present embodiment, in the internal combustion engine having the variable valve operating mechanism, the lock for fixing the rotation phase of the intake camshaft to a predetermined phase in the rotation phase changing mechanism. Since the charging efficiency at the time of starting the engine can be increased without providing a mechanism, it is possible to prevent a deterioration in fuel consumption and a decrease in engine output due to a malfunction of the lock mechanism.

In this embodiment, as an embodiment of the operating angle switching means according to the present invention, a configuration including a three-dimensional cam and a mechanism for changing the axial phase of the intake camshaft has been exemplified. However, a plurality of cams having different working angles may be provided on the intake camshaft, and one of the plurality of cams may be selected to drive the opening and closing of the intake valve. A working angle switching unit configured to select any one of a plurality of working angles using a hydraulic pressure, wherein a minimum working angle is selected when a desired hydraulic pressure cannot be obtained. Any operating angle switching means may be used.

[0089]

According to the variable valve operating apparatus for an internal combustion engine according to the present invention, when the driving force of the rotation phase changing means and the operating angle switching means cannot be sufficiently obtained as at the time of starting the internal combustion engine, the crank is required. The rotational phase of the camshaft with respect to the shaft becomes the most retarded state, and the minimum operating angle is selected from a plurality of operating angles of the camshaft.

At this time, the minimum working angle of the camshaft is formed such that the closing timing of the intake valve is near the intake bottom dead center when the rotational phase of the camshaft with respect to the crankshaft is the most retarded state. Therefore, when the intake valve is in the open state, the fresh air once sucked into the combustion chamber does not cause a blowback of the intake air discharged from the intake valve,
The charging efficiency of the intake air does not decrease.

As a result, in the variable valve apparatus for an internal combustion engine according to the present invention, when the internal combustion engine is started, the compression ratio does not decrease due to the decrease in the charging efficiency of the intake air. The property does not deteriorate.

Therefore, according to the variable valve mechanism of the internal combustion engine according to the present invention, in the internal combustion engine provided with the rotation phase changing mechanism, the rotation phase of the camshaft with respect to the crankshaft is fixed at a desired phase when the internal combustion engine is started. Because it is possible to improve the startability without providing a mechanism to perform
The deterioration of the fuel consumption and the decrease of the engine output due to the malfunction of the mechanism for fixing the rotation phase of the camshaft are prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an internal combustion engine to which a variable valve device according to the present invention is applied.

FIG. 2 is a perspective view showing a schematic configuration of a valve train of an internal combustion engine to which the variable valve train according to the present invention is applied;

FIG. 3 is a sectional view showing a configuration of a variable valve mechanism.

FIG. 4 is a cross-sectional view showing a configuration inside a spacer.

FIG. 5 is a perspective view showing the configuration of an annular projection formed on the intake camshaft;

FIG. 6 is a perspective view showing a configuration of a cam.

FIG. 7 is a diagram (1) for explaining the operation of the variable valve mechanism;

FIG. 8 illustrates the operation of the variable valve mechanism (2).

FIG. 9 is a view for explaining the operating angle of the three-dimensional cam according to the embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 4 ... Crankshaft 4a ... Crank pulley 10 ... Intake valve 11 ... Exhaust valve 15 ... Intake side camshaft 15a ... Intake side timing pulley 16 ... Exhaust camshaft 32 Variable valve mechanism 33 First oil passage 34 Second oil passage 35 Oil control bubble 36 Oil pump 37 Oil pan 39 ..The third oil passage 150..the three-dimensional cam 153..the piston 320..the spacer 321..the case 322..the end cover 324..the vane body 500..the urging chamber 600..the hydraulic chamber 700..the coil spring 800 ・ ・ Timing room 900 ・ ・ Advancing room

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 3G018 AB07 AB16 BA04 BA33 BA34 CA19 DA03 DA73 EA21 EA32 GA11 3G084 BA23 CA01 CA02 DA01 DA02 DA09 FA33 FA38 3G092 AA11 BA08 BB01 DA04 DA06 DA09 DA12 DG05 EA04 FA01 FA24 FA31 FB01 GA01 HA06Z HA12Z HD04Z HE04Z HE08Z

Claims (3)

[Claims] 1. A camshaft which is formed so that a plurality of operating angles can be selected, and which receives opening torque of a crankshaft to open and close an intake valve of an internal combustion engine, and changes a rotation phase of the camshaft relative to the crankshaft. A variable valve apparatus for an internal combustion engine, comprising: a rotation phase changing unit; and a working angle switching unit that switches a working angle of the camshaft. The minimum working angle of the camshaft is such that the rotation phase of the camshaft is A variable valve train for an internal combustion engine, wherein the valve closing timing of the intake valve is formed near the intake bottom dead center when the crankshaft is most retarded. 2. The minimum operating angle of the camshaft is such that when the rotational phase of the camshaft is the most retarded with respect to the crankshaft, the opening timing of the intake valve is the intake top dead center. The variable valve gear of an internal combustion engine according to claim 1, wherein the variable valve gear is formed so as to be as follows. 3. The minimum working angle of the camshaft is such that when the rotation phase of the camshaft is most retarded with respect to the crankshaft, the opening timing of the intake valve is the intake top dead center. 3. The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein the variable valve operating apparatus is formed so as to be at a time after which no overlap with the exhaust valve occurs.