JP2632211B2 - Intake device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial Application Field The present invention relates to a first engine provided in an engine body facing a combustion chamber.
And first and second intake valves capable of opening and closing a second intake valve port are provided in the engine body, and the first and second intake valves are capable of changing the operating state between low-speed operation and high-speed operation of the engine. The present invention relates to an intake device for an internal combustion engine to which a valve gear is connected.

(2) Prior Art Conventionally, such an apparatus is known, for example, from Japanese Utility Model Publication No. 61-8184 and Japanese Patent Application Laid-Open No. 59-119021.

(3) Problems to be Solved by the Invention In the above-mentioned prior art, a swirl adjusting plate is disposed in the intake port, and the swirl intensity is adjusted by controlling the swirl adjusting plate so as to generate a strong swirl during low-speed operation of the engine. This requires a swirl control plate and control means for controlling the swirl control plate.

By the way, the intake valve generally starts to open immediately after the piston facing the combustion chamber starts descending from top dead center, but if the intake valve start timing is shifted to the retard side, the combustion chamber and It is possible to increase the swirl by opening the intake valve opening in a state where the differential pressure between the intake ports is increased and introducing the air-fuel mixture into the combustion chamber at high speed.

On the other hand, a valve gear having a function of shifting the opening timing of an intake valve in order to perform precise intake valve control according to the engine operating state has been already known, for example, from Japanese Patent Application Laid-Open No. 64-3207, When the valve opening timing of the intake valve is shifted by using such a valve operating device, the swirl intensity can be controlled without providing the swirl control valve.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide an intake device for an internal combustion engine in which the swirl intensity can be controlled by controlling the opening timing of an intake valve without disposing a member for swirl control in an intake port.

B. Configuration of the Invention (1) Means for Solving the Problems According to the present invention, the engine main body is provided with a swirl-generating intake port communicating with the first intake valve port, and is provided with a substantially linear second port.
A main intake port communicating with the intake valve port is provided, and the valve operating device sets the opening timing of the first intake valve after the top dead center while stopping or almost stopping the second intake valve during low-speed operation of the engine. It can be changed at any time after the top dead center.

(2) Operation According to the above configuration, the first intake valve is opened when the pressure difference between the combustion chamber and the intake port becomes large after the crank angle becomes higher than the top dead center during low-speed operation, and the swirl generating intake port is opened. The air-fuel mixture can flow into the combustion chamber at high speed through the first intake valve port to form a strong swirl, and the swirl strength can be increased by changing the opening timing of the first intake valve according to the operating state of the engine. Can be controlled.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, in FIGS.
In a DOHC type multi-cylinder internal combustion engine, a plurality of cylinders 2 are provided in a cylinder block 1 in series, and a cylinder head 3 coupled to an upper end of the cylinder block 1 to form an engine main body E; Combustion chambers 5 are respectively defined between the slidably fitted pistons 4.
Further, the cylinder head 3 is provided with first and second intake valve ports 6a, 6b and first and second exhaust valve ports 7a, 7b in a portion forming a ceiling surface of each combustion chamber 5. On the other hand, a swirl-generating intake port 8 and a main intake port 9 are formed in the cylinder head 3 and open on one side surface of the cylinder head 3 with an open end in common. The port 8 is spirally bent and communicates with the first intake valve port 6a, and the main intake port 9 extends substantially linearly and communicates with the second intake valve port 6b. The first and second exhaust valve ports 7a, 7b are connected to substantially linear exhaust ports 10, 11, and both of the exhaust ports 10, 11 are commonly opened on the other side surface of the cylinder head 3.

A portion corresponding to each cylinder 2 of the cylinder head 3 includes first and second intake valves 12a and 12b capable of opening and closing the first and second intake valve ports 6a and 6b, respectively, and first and second exhaust valve ports. In order to guide the first and second exhaust valves 13a and 13b capable of opening and closing the respective 7a and 7b, two pairs of guide cylinders 14 are provided.
… Are fitted and fixed respectively, and their guide tubes
Valve springs 16 are contracted between the cylinder head 3 and the flanges 15 provided at the upper ends of the intake valves 12a, 12b and the exhaust valves 13a, 13b projecting upward from the cylinder head 3, respectively. Each of the intake valves 12a and 12b and each of the exhaust valves 13a and 13b are biased upward, that is, in the valve closing direction by the valve springs 16.

Each intake valve 12a, 12b is connected to an intake valve side valve operating device 19 to be operated in an operation mode according to the operating state of the engine, and each exhaust valve 13a, 13b is connected to an operating state of the engine according to the operating state of the engine. The exhaust valve side valve gear 20 is connected to be operated in the operation mode.

Referring to FIG. 3 and FIG. 4 together, the intake valve-side valve operating device 19 is moved from the crankshaft (not shown) of the engine by 1 /.
2, a low-speed cam 22, a high-speed cam 23 and a pause cam 24 provided on the camshaft 21, and a rocker shaft 25 fixedly disposed in parallel with the camshaft 21. And a first drive rocker arm 26, a free rocker arm 27 and a second drive rocker arm 28 pivotally supported by the rocker shaft 25, and each rocker arm 26, 27,
And a timing changing means 30 (see FIG. 5 described later) interposed between the crankshaft and the camshaft 21 (not shown).

The camshaft 21 has a low-speed cam 22 at a position corresponding to the first intake valve 12a, a pause cam 24 at a position corresponding to the second intake valve 12b, and a high-speed cam 23 between the two cams 22, 24. Each is integrated. The low-speed cam 22 has a shape corresponding to the low-speed operation of the engine, and has a base circular portion 22a and a high-order portion 22b protruding radially outward from the base circular portion 22a. Further, the high-speed cam 23 has a shape corresponding to the high-speed operation of the engine, and has a base circular portion 23a and a protruding amount and a central angle range larger than those of the high portion 22b. A portion 23b. Further, the rest cam 24 is for resting the second intake valve 12b, and is formed to have the same outer diameter as the base circle portions 22a, 23a and a circular cross section. Moreover, the high-order portion 22b of the low-speed cam 22 has a timing in which the phase between the crankshaft and the camshaft 21 is not shifted by the timing changing means 30, and the opening timing of the first intake valve 12a is set at the top dead center (TDC). It is set to be later.

On the other hand, the rocker shaft 25 is fixed to the cylinder head 3 at a position below the camshaft 21 and has an axis parallel to the camshaft 21. The rocker shaft 25 includes a first drive rocker arm 26 linked to and connected to the first intake valve 12a, a second drive rocker arm 28 linked to and connected to the second intake valve 12b, and first and second drive rocker arms. A free rocker arm 27 disposed between 26 and 28 is pivotally supported adjacent to each other.

Tappet screws 31 are respectively screwed to the first and first drive rocker arms 26 and 28 so as to be able to advance and retreat, and these tappet screws 31 contact the upper ends of the corresponding intake valves 12a and 12b. Therefore, both intake valves 12a and 12b operate according to the swinging movement of both drive rocker arms 26 and 28.

The free rocker arm 27 is moved by a resilient biasing means B (see FIG. 1) interposed between the free rocker arm 27 and the high-speed cam.
It is resiliently biased in the direction of sliding contact with 23.

The hydraulic connection switching means 29 includes a first switching pin 32 capable of connecting between the first drive rocker arm 26 and the free rocker arm 27.
And the free rocker arm 27 and the second drive rocker arm 28
A second switching pin 33 capable of connecting between them, a regulating pin 34 for regulating movement of the first and second switching pins 32 and 33, and each of the pins 32 to 3
And a return spring 35 for urging the connection spring 4 toward the connection release side.

The first drive rocker arm 26 has a bottomed first guide hole 36 opened to the free rocker arm 27 side in parallel with the rocker shaft 25, and a first switching pin 32 formed in a columnar shape. The hydraulic chamber is slidably fitted in the guide hole 36 and is provided between one end of the first switching pin 32 and the closed end of the first guide hole 36.
37 is defined. In addition, a passage 38 communicating with the hydraulic chamber 37 is formed in the first drive rocker arm 26, and the rocker shaft 25
Is provided with a refueling passage 39. The oil supply passage 39 is always in communication with the hydraulic chamber 37 via the passage 38 regardless of the swinging state of the first drive rocker arm 26. Moreover, the oil supply passage 39 is connected to a hydraulic supply 41 via a control valve 40, and the control valve 40 can switch the oil pressure from the oil supply 41 to high or low and supply the oil to the oil supply passage 39, that is, the hydraulic chamber 37. It is.

A guide hole 42 corresponding to the first guide hole 36 is formed in the free rocker arm 27 so as to be parallel to the rocker shaft 25 and between both side surfaces, and one end of the first switch pin 32 abuts on the other end. The second switching pin 33 is slidably fitted in the guide hole.

A second guide hole 43 having a bottom corresponding to the guide hole 42 is opened in the second drive rocker arm 28 toward the free rocker arm 27 and formed in parallel with the rocker shaft 25.
The disc-shaped regulating pin 34 that contacts the other end of the switching pin 33 is the second
It is slidably fitted in the guide hole 43. This second guide hole
A cylindrical guide member 44 is inserted and fixed to the closed end of 43, and a rod 45 movably inserted into the guide member 44 is provided coaxially and integrally with the regulating pin 34. The return spring 35 is contracted between the closed end of the second guide hole 43 and the restricting pin 34, and the pins 32, 33, and 34, which are in contact with each other due to the spring force of the return spring 35, are connected to each other. It is urged to the hydraulic chamber 37 side.

In the hydraulic connection switching means 29, the first switching pin 32 is fitted in the guide hole 42 and the second switching pin 33 is fitted in the second guide hole 43 by increasing the hydraulic pressure in the hydraulic chamber 37. The respective rocker arms 26, 27, 28 are connected. When the oil pressure in the hydraulic chamber 37 decreases, the first force is generated by the spring force of the return spring 35.
The switching pin 32 returns to the position where the contact surface with the second switching pin 33 corresponds between the first drive rocker arm 26 and the free rocker arm 27, and the second switching pin 33 changes the contact surface with the regulating pin 34 into the free rocker arm 27. And the position returns to the position corresponding to the position between the second drive rocker arms 28, so that the connected state of the rocker arms 26, 27, 28 is released.

In FIG. 5, a camshaft 21 for opening and closing the first and second intake valves 12a and 12b is rotatably supported by the cylinder head 3, and rotational power from a crankshaft (not shown) of the engine is provided. A pulley 47 around which a timing belt 46 for transmitting the signal is wound, and the camshaft 21 are interlocked and connected via a timing changing means 30 that enables the phases of the pulley 47 and the camshaft 21 to be shifted. You.

The timing changing means 30 has a rotating shaft 48 coaxially connected to the camshaft 21, a housing 49 provided integrally with the pulley 47 and surrounding the rotating shaft 48 coaxially, and a hydraulic chamber 50 facing one axial end. A piston 52 is disposed coaxially with the housing 49 and the rotary shaft 48 while being biased to one side in the axial direction by a spring 51, a servo valve 53 for regulating the amount of movement of the piston 52, and an axial movement of the piston 52. A phase adjusting mechanism 54 for interlocking and connecting the piston 52, the housing 49, and the rotating shaft 48 to change the rotational phase of the pulley 47 and the rotating shaft 48 accordingly.

The rotating shaft 48 is formed in a cylindrical shape with a bottom having a shaft portion 48a integrally at a closed end thereof, and a bolt penetrating the closed end.
By screwing 55 to the camshaft 21, the shaft portion 48a is coaxially connected to the end of the camshaft 21. Further, the housing 49 is formed in a cylindrical shape with a bottom opening to the camshaft 21 side, and a pulley 47 is integrally provided on an outer end near the open end of the housing 49, that is, near the camshaft 21. At the open end of the housing 49, an annular plate-shaped end plate 56 that covers an outer edge portion on the closed end side of the rotating shaft 48 is fixed.
A seal member 57 is interposed between the inner periphery of 56 and the outer periphery of the shaft portion 48a of the rotating shaft 48. A bearing 58 is interposed between the inner surface of the housing 49 and the outer surface of the rotating shaft 48 corresponding to the portion where the pulley 47 is provided. The bearing 58 has one end of the outer ring engaged with the housing 49, and the other end of the inner ring engaged with the rotating shaft 48.
Accordingly, the housing 49 and the pulley 47 are prevented from moving in the axial direction relative to the rotation shaft 48, that is, the camshaft 21, but are allowed to rotate relatively around the axis.

A through hole 59 is formed in the center of the closed end of the housing 49, and the piston 52 is provided with a cylindrical portion 52 that slides on the inner surface of the through hole 59.
a and a ring portion 52b that slides on the inner surface of the housing 7 are connected by a dish-shaped connecting plate portion 52c. A seal member 60 that slides on the inner surface of the through hole 59 is fitted on the outer surface of the cylindrical portion 52a. A seal member 61 that slides on the inner surface of the housing 49 is fitted on the outer surface of the ring portion 52b. As a result, both seal members 60, 6
A hydraulic chamber 50 is defined between the housing 49 and one end of the piston 52 between the two, and when hydraulic pressure is supplied to the hydraulic chamber 50, the piston 52 is pressed to the other axial side.

The piston 52 is integrally provided with a support tubular portion 52d extending from the ring portion 52b to the camshaft 21 side so as to be inserted between the housing 49 and the rotary shaft 48. The rotation shaft 49 and the rotation shaft 48 are linked and connected via a phase adjustment mechanism 54.

6A and 6B, the phase adjusting mechanism 54
A guide groove 62 provided on the outer surface of the rotating shaft 48;
A guide hole 63 provided in the housing 49 corresponding to 62, a roller pin 64 pivotally supported by the support cylindrical portion 52d to fit in the guide groove 62, and a coaxial with the roller pin 64 to fit in the guide hole 63. And a roller pin 65 pivotally supported by the support cylinder 52d. Further, the guide groove 62 and the guide hole 63 are formed so as to be inclined with respect to the axis of the rotating shaft 48 and the housing 49 and to intersect with each other.
In accordance with the movement of the rotation shaft 48 and the housing 49 in the axial direction of the rotation shaft 48 and the housing 49, the roller pins 64, 65 roll in the guide groove 62 and the guide hole 63, and the rotation shaft 48 and the housing 48 It turns in the opposite direction. Accordingly, the phases of the rotating shaft 48 and the camshaft 21 and the housing 49 and the pulley 47 change. That is, when the piston 52 moves to the position closest to the camshaft 21, the circumferential relative positions of the rotating shaft 48 and the housing 49 become as shown in FIG. 6 (a), and the piston 52 is most separated from the camshaft 21. When moved to the position, the relative positions of the rotating shaft 48 and the housing 49 in the circumferential direction are as shown in FIG. 6B. In addition, the phase adjusting mechanisms 54 are arranged at a plurality of, for example, three places at equal intervals in the circumferential direction of the piston 52 corresponding to the portion where the pulley 47 is provided.

A cylindrical cover 66 is fitted around the outer periphery of the housing 49 to prevent the roller pins 65 from dropping out of the guide holes 63, and the cover 66 is fixed to the housing 49. Moreover, seal members 67 and 68 are interposed between the housing 49 and the cover 66 on both sides of the guide hole 63. Also, on the rotation shaft 48,
A breeze hole 69 communicating the inside between the rotary shaft 48 and the housing 49 is formed.

The servo valve 53 includes a cylindrical sleeve 70 slidably fitted to the rotating shaft 48, and a cylindrical spool 71 slidably fitted in the sleeve 70. A spring 51 is contracted between the sleeve 70 and the closed end of the rotating shaft 48,
Due to the spring force of the spring 51, one end of the sleeve 70 is urged in a direction in which it comes into contact with the connecting plate portion 52c of the piston 52. Therefore, the piston 52 is also urged to one side in the axial direction against the hydraulic pressure of the hydraulic chamber 50. Is done.

A supporting member 72 is fixed to the cylinder head 3 so as to cover the timing changing means 30. The supporting member 72 has an electric driving means coaxial with the timing changing means 30.
The drive shaft 74 of the electric drive means 73 is connected to the spool 71. Further, a cap 75 that covers the through hole 59 is fixed to the closed end of the housing 49, and the drive shaft 74 passes through the center of the cap 75 so as to be movable in the axial direction, and between the drive shaft 74 and the cap 75. Seal member
76 will be interposed.

The electric drive means 73 is for driving the drive shaft 74 to an arbitrary position in the axial direction according to the input electric signal,
For example, a DC or AC servomotor, a stepping motor, a linear motor, an electric cylinder, a linear solenoid, a rotary solenoid, a piezoelectric motor, a laminated piezoelectric actuator, and the like are used.

The cylinder head 3 is provided with a first hydraulic supply passage 77 connected to the hydraulic supply source 41, and the camshaft 21 is provided with an annular groove 78 communicating with the first hydraulic supply passage 77 on the outer surface thereof. A second hydraulic supply passage 79 leading to 78 is drilled. In addition, a third hydraulic supply path 80 that is always in communication with the second hydraulic supply path 79 is formed in the rotary shaft 48, and an annular groove 81 that is in communication with the third hydraulic supply path 80 is provided on the inner surface of the rotary shaft 48. Camshaft 21
A pair of annular seal members 82 and 83 are interposed between the camshaft 21 and the cylinder head 3 so as to sandwich the annular groove 78 therebetween, and second and third hydraulic supply paths are provided between the camshaft 21 and the rotary shaft 48. An annular seal member 84 for maintaining the communication between 79 and 80 is interposed.

The sleeve 70 is provided with an oil hole 85 constantly communicating with the annular groove 81 irrespective of the axial position with respect to the rotary shaft 48, and a position adjacent to the inner surface open end of the oil hole 85 on the camshaft 21 side. Is formed with an annular groove 86 in the inner surface thereof. Further, an oil passage 87 is formed in the sleeve 70 and the connecting plate portion 52c in contact with the sleeve 70 so as to allow the annular groove 86 to communicate with the hydraulic chamber 50. Further, a hydraulic release path 89 communicating with an oil tank 88 is formed in the bolt 55 and the camshaft 21.

An annular groove 90 is bored in the outer surface of the spool 71, and the width of the annular groove 90 along the axial direction of the spool 71 is set so that the oil groove 85 and the annular groove 86 can communicate with each other by the annular groove 90. You.
The spool 71 has a blocking position that allows only the oil hole 85 to communicate with the annular groove 90, a supply position that communicates between the oil hole 85 and the annular groove 86 via the annular groove 90, and a connection between the annular groove 86 and the hydraulic release passage 89. It is movable between three axial relative positions with a release position to be communicated. Further, a stopper 91 projecting outward in the radial direction is integrally provided at an end of the sleeve 70 on the camshaft 21 side, and the stopper 91 abuts on the spool 71 to restrict relative movement in the axial direction.

The timing changing unit 30 inputs an electric signal to the electric driving unit 73 to move the driving shaft 74 to a desired position. For example, in FIG. 5, when the drive shaft 74 is fully extended, the relative position of the sleeve 70 and the spool 71 in the axial direction is at the cut-off position where only the annular groove 90 communicates with the oil hole 95, and the phase adjustment mechanism 54 Is in the state shown in FIG. 6 (a).
Then, when the drive shaft 74 is contracted and the spool 71 is moved to one side in the axial direction (left side in FIG. 5), the annular groove 86 is set to the release position where the annular groove 86 communicates with the hydraulic release path 89. Therefore, the oil pressure in the hydraulic chamber 50 is released, the sleeve 70 and the piston 52 move in one axial direction by the spring force of the spring 51, and the rotation shaft 48 and the housing 49 are relatively rotated by the phase adjustment mechanism 54.
In addition, in response to the movement of the sleeve 70 in one axial direction, the spool 71 moves relative to the other side in the axial direction with respect to the sleeve 70, and the relative positions of the spool 71 and the sleeve 70 in the axial direction become the shut-off position. Accordingly, the amount of movement of the piston 52 is determined according to the amount of axial movement of the spool 71, and accordingly, the camshaft 21 with respect to the phase of the crankshaft is determined.
The amount of advance or delay of the phase is determined.
The phase shift can be steplessly controlled in accordance with the amount of movement of 71.

When the servo valve 53 is at the shut-off position, the drive shaft 74 is moved to the other axial side by the electric drive means 73, and the spool 71 is relatively operated from the shut-off position to the other axial side, via the annular groove 90. The oil hole 85 and the annular groove 86 communicate with each other, and the hydraulic pressure from the hydraulic pressure supply source 41 is applied to the hydraulic chamber 50.
, The piston 52 is pressed and driven to the other side in the axial direction against the spring force of the spring 51. And that piston
The rotation of the rotary shaft 48 and the housing 49 is relatively rotated by the operation of the phase adjusting mechanism 54 in accordance with the movement of the 52 to the other side in the axial direction, so that the phase of the camshaft 21 changes with respect to the crankshaft. Moreover, the sleeve 70 is moved in accordance with the axial movement of the piston 52.
Also moves, so that the relative positions of the spool 71 and the sleeve 70 in the axial direction are the blocking positions. Therefore, the amount of movement of the piston 52 is determined according to the amount of movement of the spool 71, and the phase shift is controlled steplessly. In addition, the back pressure between the piston 52 and the rotating shaft 48 is quickly released by the breathing hole 69 provided in the rotating shaft 48, so that the operation of the piston 52 can be made faster.

Exhaust-side valve gear 20, the low-speed cam is used instead of the cam for rest 24, except that no timing changing means is provided between the crankshaft and the camshaft,
It has basically the same configuration as the intake side valve gear 19 described above.

Next, the operation of this embodiment will be described. When the engine is running at a low speed, the control valve 40 keeps the hydraulic pressure in the hydraulic chamber 37 of the hydraulic connection switching means 29 low. In this state, the intake side valve gear 19 moves the second intake valve 12b to the cam 2
The suspension state is set by 4 and the first intake valve 12a is opened and closed in a manner corresponding to the low-speed operation of the engine according to the shape of the low-speed cam 22. Further, the phase of the camshaft 21 with respect to the crankshaft is shifted to the retard side by the timing changing means 30. As a result, when the first intake valve 12a does not cause a phase shift, the valve opening timing is set at a certain time after the top dead center (TDC) as shown by a chain line in FIG. The valve is opened at a position shifted to the retard side as indicated by a curve L indicated by a solid line in the drawing. When the valve is opened, the swirl-generating intake port 8 passes through the first intake valve port 6a into the combustion chamber 5. The air-fuel mixture is inhaled.

On the other hand, the moving speed of the piston 4 in the axial direction is as shown in FIG. 8, and the moving speed increases as it descends from the top dead center (TDC). After reaching the maximum speed, the bottom dead center (BDC)
The movement speed decreases until the speed reaches. Also the first
The differential pressure between the combustion chamber 5 and the swirl-generating intake port 8 with the intake valve port 6a kept closed becomes as shown in FIG. 9, and increases as the piston 4 descends from the top dead center. Become. Accordingly, when the first intake valve 12a is shifted and opened as shown by the curve L in FIG. 7, the air-fuel mixture is introduced into the combustion chamber 5 from the swirl generation intake port 8 with a large differential pressure. That is, the air-fuel mixture is introduced into the combustion chamber 5 at high speed from the swirl generation intake port 8 through the first intake valve port 6a, and the swirl generation in the combustion chamber 5 is promoted. Moreover, since the swirl generation intake port 8 is spirally connected to the first intake valve port 6a, the air-fuel mixture is introduced into the combustion chamber 5 at a high speed while swirling. Swirl occurs. Therefore, it is possible to improve the combustibility in a fuel-lean state when the engine is running at a low speed, and to reduce the fuel consumption.

During this low-speed operation, the second intake valve 12b is in the rest state, so that the generation of swirl in the combustion chamber 5 is not adversely affected. Moreover, by stopping the second intake valve 12b,
The driving force can be reduced accordingly.

Further, the swirl intensity can be controlled by changing the opening timing of the first intake valve 12a according to the operating state of the engine.

During high-speed operation of the engine, high hydraulic pressure is applied to the hydraulic chamber 37 of the hydraulic connection switching means 29 by the control valve 40, and the intake-side valve operating device is operated.
The 19 rocker arms 26, 27, 28 are integrally connected, and the timing changing means 30 returns the phase of the camshaft 21 to the crankshaft. As a result, the intake valves 12a and 12b open and close in a manner corresponding to the shape of the high-speed cam 23 as shown by the curve H in FIG. And high output can be achieved.

As described above, the phase shift of the camshaft 21 with respect to the crankshaft can be controlled by the intake-side valve operating device 19 to adjust the swirl strength in the combustion chamber 5. The means 30 is not used only for controlling the swirl strength, but is used for each intake valve 12.
The operation mode of the a and 12b can be appropriately controlled to an appropriate one according to the operating state of the engine.In an internal combustion engine including the valve operating device 19 including the timing changing means 30, a special The swirl strength can be adjusted without adding any means.

As another embodiment of the present invention, when the engine is running at a low speed, the seventh
As shown by the curve L 'in the figure, the second intake valve 12b may be opened to the extent that the second intake valve 12b is substantially considered to be at rest. Can be changed.

C. Effects of the Invention As described above, according to the present invention, the engine body has a swirl-generating intake port that communicates with the first intake valve port, and a main intake port that substantially linearly communicates with the second intake valve port. The valve gear is arranged to set the opening timing of the first intake valve after the top dead center while stopping or almost stopping the second intake valve during low-speed operation of the engine, and at any time after the top dead center. Because the pressure difference between the combustion chamber and the intake port is large during low-speed operation, the first intake valve is opened to introduce a mixture into the combustion chamber from the swirl-generating intake port, thereby producing a strong swirl. Can be formed, and the swirl intensity can be controlled by changing the opening timing of the first intake valve according to the operating state.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine, FIG. 2 is a view taken along the line II-II of FIG.
FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1, and FIG.
FIG. 5 is a longitudinal sectional side view showing a part of the valve gear, FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5, and FIG. 7 is opening of the intake valve with respect to crank angle. FIG. 8 is a diagram showing timing, FIG. 8 is a diagram showing piston moving speed, and FIG. 9 is a diagram showing a change in differential pressure between the combustion chamber and the intake port. 5 Combustion chamber, 6a First intake valve port, 6b Second intake valve port, 8 Swirl generation intake port, 9 Main intake port, 12a First intake valve, 12b … Second intake valve, 19 ……
Valve train, E ... Engine body

Claims (1)

(57) [Claims] 1. A first engine provided on an engine body facing a combustion chamber.
And first and second intake valves capable of opening and closing a second intake valve port are provided in the engine body, and the first and second intake valves are capable of changing the operating state between low-speed operation and high-speed operation of the engine. In an intake device for an internal combustion engine to which a valve gear is connected, a swirl generating intake port communicating with a first intake valve port and a main intake port communicating with a second intake valve port in a substantially linear manner are provided in the engine body. The valve train is provided during the low speed operation of the engine.
An intake valve for the internal combustion engine, wherein the intake valve is opened or almost stopped while the opening timing of the first intake valve is set to be after the top dead center and can be changed to any timing after the top dead center. apparatus.