JP2000154755A - Valve system device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compact-form a valve system device by avoiding weight increase and enlargement of a locker arm, preventing increase of inertial weight of a valve system and arranging an engine valve, a locker arm shaft and a cam shaft adjacent to each other concerning the valve system device of an internal combustion engine to actuate the engine valve to open and close through a hydraulic tappet. SOLUTION: A hydraulic tappet 14 is held on a hydraulic tappet holder 13 fixed on a cylinder head 3 and a cutout 13m capable of storing a part of locker arms 21, 22 by being positioned in an oscillating range of the locker arms 21, 22 is formed on the hydraulic tappet holder 13 in a valve system device of an internal combustion engine 1 to actuate engine valves 6, 7 to open and close through the hydraulic tappet 14 by the rocker arms 21, 22 supported on rocker arm shafts 19, 20 free to oscillate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gear for an internal combustion engine, and more particularly to a valve gear for an internal combustion engine in which an engine valve is opened and closed by a rocker arm via a hydraulic tappet held in a hydraulic tappet holder. About.

[0002]

2. Description of the Related Art Conventionally, in a valve train of an internal combustion engine, in order to smoothly operate a valve train with a valve clearance of zero, an intake valve or an exhaust valve of the engine is provided via a hydraulic tappet incorporated in a rocker arm. Is known (see JP-A-59-141706).

[0003] In this conventional valve train, a hydraulic tappet that comes into contact with a valve stem end of an intake valve or an exhaust valve is assembled to one end of a rocker arm. Specifically, this hydraulic tappet has a plunger slidably inserted into a cylinder hole formed at one end of a rocker arm, and two oil chambers slidably inserted inside the plunger and inside the plunger. A valve seat is formed, and a check valve is provided in a communication hole formed in the center of the valve seat to communicate or shut off two oil chambers. The bottom of the plunger abuts on the valve stem end of the intake valve or the exhaust valve, and oil is supplied to the oil chamber from the top of the plunger through an oil passage formed in the rocker arm. .

[0004]

In the above-described conventional valve gear, the hydraulic tappet is held by the rocker arm, so that the rocker arm becomes large and the hydraulic tappet itself and the hydraulic Since the structure for holding the tappet is added to the rocker arm, the weight of the entire rocker arm increases. Therefore, the inertia weight of the valve train increases, and it becomes difficult for the intake valve or the exhaust valve to appropriately follow the movement of the operation cam, especially when the engine is rotating at a high speed.

[0005] Further, in the valve operating device of the internal combustion engine, a rocker arm includes a connection switching means for switching the engine valve between a valve closing rest state and an opening / closing operation state so as to enable the cylinder rest operation. Some are provided. Therefore, if such a connection switching unit is to be adopted in a valve train of an internal combustion engine configured to hold a hydraulic tappet on the rocker arm, a hydraulic tappet and a connection switching unit are provided on the rocker arm. The arrangement of the connection switching means is restricted. Further, since the two mechanisms are incorporated in the rocker arm, the inertial weight and the size of the rocker arm are further increased.

[0006]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks, and the invention according to claim 1 comprises an engine valve provided in a cylinder and a hydraulic tappet attached to the engine valve. A rocker arm swingably supported on a rocker arm shaft, which is operatively connected to open and close the engine valve, a hydraulic tappet holder fixed to a cylinder head and holding the hydraulic tappet, and the hydraulic tappet A notch formed in the holder and located within the rocking range of the rocker arm and capable of accommodating a part of the rocker arm.

According to the first aspect of the present invention,
Since the hydraulic tappet is held by the hydraulic tappet holder fixed to the cylinder head separately from the rocker arm, the weight of the rocker arm does not increase, and the rocker arm does not become large. Therefore,
The inertia weight of the valve train is not increased, and the rocker arm follows the movement of the operation cam well even at high engine speeds. Furthermore, the hydraulic tappet holder for holding the hydraulic tappet is formed with a notch located within the rocking range of the rocker arm, so that the cutout can accommodate a part of the rocker arm that rocks. When the engine valve is lifted, a part of the rocker arm can enter the notch without interfering with the hydraulic tappet holder. Therefore, despite the provision of the hydraulic tappet holder fixed to the cylinder head, the distance between the rocker arm shaft that rockably supports the rocker arm and the hydraulic tappet holder can be shortened. It can be located closer. As a result, the valve train can be made compact.

According to a second aspect of the present invention, a pair of engine valves provided in one cylinder are operatively connected to the pair of engine valves via hydraulic tappets and provided on a camshaft. A first and a second drive rocker arm swingably supported by a rocker arm shaft, respectively abutting against a pair of rest portions for bringing the engine valve into a valve-closing rest state, and the engine provided on the cam shaft. A first free rocker arm swingably supported on a rocker arm shaft, abutting on a first operating cam having a profile for opening and closing one of the valves, and opening and closing the other of the engine valves provided on the cam shaft Abuts a second actuation cam having a profile to actuate;
A second free rocker arm swingably supported by a rocker arm shaft, and a first connection switching provided on the first drive rocker arm and the first free rocker arm to switch between connection and disconnection of the two. Means, a second connection switching means provided on the second drive rocker arm and the second free rocker arm for switching between connection and disconnection thereof, and a hydraulic tappet fixed to a cylinder head, A hydraulic tappet holder formed with a hydraulic tappet holding portion for holding the first and second rocker arms, the first and second rocker arms being formed in the respective hydraulic tappet holding portions and located within respective swing ranges of the first and second rocker arms. And a notch capable of accommodating a part of the two-drive rocker arm.

According to the second aspect of the present invention,
The cylinder deactivated operation in which the first and second connection switching means are disconnected and the first and second drive rocker arms are brought into contact with the deactivated portion of the camshaft to close the pair of engine valves in the valve deactivated state. In a possible internal combustion engine, the inertia weight of the valve train does not increase and the rocker arm follows the movement of the operation cam well even when the engine is running at high speed. Can be.

In each of the hydraulic tappet holders of the hydraulic tappet holder, a notch is formed within a rocking range of the rocker arm, and each of the first and second drive rocker arms in which the notch rocks. When the engine valve is lifted, a part of the first and second drive rocker arms enter the notch without interfering with the hydraulic tappet holding portion, and the hydraulic tappet can be accommodated. Can be pushed down. As a result, the rocker arm shaft and the cam for swingably supporting the drive rocker arm and the free rocker arm are provided by the notch, despite the provision of the hydraulic tappet holder fixed to the cylinder head. Since the shaft can be arranged close to the hydraulic tappet holding portion, the height of the valve train can be reduced.

Further, since the hydraulic tappet is not held by the drive rocker arm but is held by the hydraulic tappet holder fixed to the cylinder head, the engine tap is switched between the valve-closing rest state and the opening / closing operation state. When the connection switching means is arranged on the drive rocker arm and the free rocker arm, the number of restrictive elements is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention described in claims 1 and 2 of the present application shown in FIGS. 1 to 9 will be described below. The internal combustion engine 1 illustrated in FIG.
A four-stroke cycle overhead valve type multi-cylinder internal combustion engine, wherein a piston (not shown) is slidably fitted to each cylinder of the cylinder block 2, and an upper surface of the cylinder block 2 is provided between the piston and the piston. Is connected to a cylinder head 3 forming a combustion chamber.

The cylinder head 3 includes, for each cylinder,
A pair of intake valve ports and a pair of exhaust valve ports are formed in the combustion chamber, and both intake valve ports communicate with an intake port 4 that opens on one side of the cylinder head 3. The head 3 communicates with an exhaust port 5 opened on the other side surface. A pair of separately operated intake valves 6 are provided at both intake valve ports so as to be openable and closable, and a pair of separately operated exhaust valves 7 are provided at both exhaust valve ports so as to be openable and closable. Have been. An intake manifold communicating with the intake port 4 is connected to one side surface of the cylinder head 3, and an exhaust manifold communicating with the exhaust port 5 is connected to the other side surface of the cylinder head 3. Here, the intake valve 6 or the exhaust valve 7 corresponds to an engine valve of the internal combustion engine 1.

Valve guides 8 for each intake valve 6 and each exhaust valve 7
An oil seal 9 is provided at the upper end of the
The valve spring retainer 10 is attached to a and 7a via a cotter. The valve spring receiving portion 1 of the cylinder head 3
A valve spring 12 is interposed between the valve spring 1 and the valve spring retainer 10, and the intake valve 6 and the exhaust valve 7 always close the intake valve port and the exhaust valve port, respectively, by the spring force of the valve spring 12. Is being biased. The detailed configuration of the oil seal 9, the valve spring retainer 10, and the valve spring receiving portion 11 will be described later.

A hydraulic tappet holder 13 is integrally attached to the cylinder head 3 by a bolt 70 (FIG. 3) for each cylinder. A hydraulic tappet 14 is mounted on a hydraulic tappet holding portion 13a of each hydraulic tappet holder 13. ,
The respective stem ends 6 of the corresponding intake valve 6 and exhaust valve 7
a, 7a with the lower end of the hydraulic tappet 14 in contact with
It is slidably fitted. The detailed configurations of the hydraulic tappet holder 13 and the hydraulic tappet 14 will be described later.

As shown in FIG. 1, between each intake valve 6 and the intake camshaft 15, an intake valve driving device 17 for converting the rotational movement of the intake camshaft 15 into the opening and closing movement of the intake valve 6 is provided. Provided between each exhaust valve 7 and the exhaust cam shaft 16.
An exhaust valve driving device 18 for converting the rotational movement of the exhaust cam shaft 16 into the opening and closing movement of the exhaust valve 7 is provided. The intake valve driving device 17 includes an intake rocker arm 21 swingably supported by an intake rocker arm shaft 19, and the exhaust valve driving device 18 includes an exhaust rocker swingably supported by an exhaust rocker arm shaft 20. A rocker arm 22 is provided.
The intake rocker arm shaft 19 and the exhaust rocker arm shaft 20 pass through a rocker arm shaft holder 23 attached to the cylinder head 3 and are fixed. Also,
Intake rocker arm 21 and exhaust rocker arm 22
, An intake cam shaft 15 and an exhaust cam shaft 16 are rotatably supported between a rocker arm shaft holder 23 and a cam shaft holder 24, respectively.

In the cylinder head cover 25, the screw portion of the bolt 26 is formed lower than the rocker arm shaft holder 23 so as to follow the outer shapes of the rocker arm shaft holder 23 and the two cam shaft holders 24 and at a small interval. The screw 27 is pressed against the cylinder head 3 by the urging force of the coil spring 28 by being screwed to the head of the bolt 27 located at the central portion.

Next, a drive mechanism of the intake valve 6 and the exhaust valve 7 will be described with reference to FIGS. Journal portions (not shown) rotatably supported between the rocker arm shaft holder 23 and the cam shaft holder 24 are provided on the intake camshaft 15 at intervals in the axial direction thereof. From FIG. 3, in FIG.
In order from the top, the first intake valve operating cam 31 and the intake valve pause section 3
0, a third intake valve operation cam 33, an intake valve pause section 30, and a second intake valve operation cam 32 are provided integrally. Similarly, the exhaust camshaft 16 has a first exhaust valve operating cam 31 ′, an exhaust valve pause section 30 ′, and a third exhaust valve operating cam 33.
′, Exhaust valve pause section 30 ′ and second exhaust valve operating cam 32
'Are provided integrally.

The first intake valve operating cam 31 has a profile for opening and closing the intake valve 6, and has an arcuate base circle centered on the axis of the intake camshaft 15 and a radially outward portion from the base circle. And a cam nose part protruding therefrom. The second intake valve operating cam 32 is provided with the first intake valve operating cam 3.
It has the same profile as 1. Further, the third intake valve operating cam 33 also has an arcuate base circular portion centered on the axis of the intake camshaft 15 and a cam nose portion protruding radially outward from the base circular portion to open and close the intake valve 6. And a profile consisting of However, the cam nose portion is set higher than the respective cam nose portions of the first intake valve operating cam 31 and the second intake valve operating cam 32. The intake valve rest portion 30 of the intake camshaft 15 has the same radius as the base circle portion of the first intake valve operating cam 31, and
It is formed as a circle centered on five axes. Further, the operation cam for the exhaust valve 7 has basically the same configuration as the operation cam for the intake valve 6.

The intake valve driving device 17 shown in FIGS. 1 and 2 includes the first and second intake valve driving rocker arms 3.
4, 35 (see FIG. 3), first, second and third intake valve free rocker arms 36, 37, 38 (see FIG. 3);
Each of the rocker arms 34, 35, 36, 37, and 38 is swingably supported, and has an intake rocker arm shaft 19 fixed to the rocker arm shaft holder 23 at a position obliquely below the intake cam shaft 15.

The intake rocker arm shaft 19 has a hole with a circular cross section, and three pipe members 39 are inserted into the hole.
Are integrally inserted and attached. Each pipe member 39 has the same cross-sectional shape in the axial direction, and both the outer shape and the cross-sectional shape of the hollow portion are substantially fan-shaped.
The three pipe members 39 are cylindrically fitted so that their outer circumferences are circular, and are inserted into the holes with their outer circumferences in contact with the peripheral walls of the holes in the intake rocker arm shaft 19. These three pipe members 39 are connected to first, second and third connection switching means 4 to be described later, respectively.
A switching hydraulic pressure supply passage 40 for supplying hydraulic pressure to 1, 42, and 43 is configured. That is, each passage 40 has the first
Communication passages 54, 55, 56 formed in the intake valve free rocker arm 36, the second intake valve free rocker arm 37, and the second intake valve drive rocker arm 35, respectively.
Via (see FIG. 4), it is always in communication with the hydraulic chambers (see FIG. 4) of the first, second and third connection switching means 41, 42, 43. The switching hydraulic pressure supply passage 40 is connected to a hydraulic pressure source via a control valve (not shown). The control valves operate in an engine operating range determined based on a cylinder deactivation command signal or a signal from a means for detecting an engine speed, an engine load, an intake air amount, and the like of the operating internal combustion engine 1, for example, a small intake air amount operation. It is controlled by control means (not shown) according to the region, the medium intake amount operation region, and the large intake amount operation region.

As shown in FIG. 3, one end of each of the first and second intake valve drive rocker arms 34, 35 is provided with a contact portion that contacts the upper end surface of the hydraulic tappet 14 of the intake valve 6. The other end is provided with a contact portion that comes into contact with the intake valve pause portion 30. The first intake valve free rocker arm 36 is rotatably supported by a roller 36 a that is in rolling contact with the first intake valve operating cam 31, and the second intake valve free rocker arm 37 is in rolling contact with the second intake valve operating cam 32. Roller 37a is rotatably supported, and roller 38a that is in rolling contact with third intake valve operating cam 33 is rotatably supported on third intake valve free rocker arm 38. The first intake valve free rocker arm 36, the first intake valve drive rocker arm 34, the third intake valve free rocker arm 38, the second intake valve drive rocker arm 35, and the second intake valve free rocker arm 37 are connected to the intake camshaft 15. The first intake valve operation cam 31, the intake valve pause section 30, the third intake valve operation cam 33, the intake valve pause section 30, and the second intake valve operation cam 32 formed in
Corresponding to the positions of the intake rocker arm shafts 19, respectively.
Are located in

Springs 44 (see FIG. 2) are provided between the first, second and third intake valve free rocker arms 36, 37 and 38 and the cylinder head 3, respectively. , The second and third intake valve free rocker arms 36, 37, 38 are urged to always contact the first, second and third intake valve operating cams 33, respectively.

In the intake valve drive device 17, the first intake valve drive rocker arm 34 and the first intake valve free rocker arm 36 are provided with first connection switching means 41 for switching between connection and disconnection of both. The second intake valve driving rocker arm 35 and the second intake valve free rocker arm 37 are provided with second connection switching means 42 for switching between connection and disconnection of the two, and the first intake valve driving rocker arm 34. The third rocker arm 35 and the third rocker arm 38 are provided with third connection switching means 43 for switching between connection and disconnection of the three members.

As shown in FIG. 4, the first connection switching means 41 includes a piston 4 slidably fitted in a cylinder chamber 45 formed in the first intake valve free rocker arm 36.
6, a pressing member 47 slidably fitted in the piston 46, a pressing spring 48 contracted between the piston 46 and the pressing member 47, and a cylinder chamber 45 and the first Intake valve drive rocker arm 34
A switching pin 50 slidably fitted in a cylinder chamber 49 formed on the other side;
A regulating member 51 abutting on the cylinder member 49 and slidably fitted in the cylinder chamber 49;
9 and a return spring 52 contracted between the bottoms. The set load of the return spring 52 is set to be larger than that of the pressing spring 48.

A hydraulic chamber 53 is formed between one end of the piston 46 and the cylinder chamber 45. The hydraulic chamber 53 is provided with a communication passage 5 provided in the first free rocker arm 36.
4, it is always in communication with the first switching hydraulic pressure supply passage 40 in the intake rocker arm shaft 19. The pressing member 47 is
It is formed in a cylindrical shape with a bottom, and its open end is
6 is arranged in the piston 46 so as to face the closed end. The pressing spring 48 is contracted between the closed end of the piston 46 and the bottom of the pressing member 47. The switching pin 50 is
In the cylinder chamber 45 and the cylinder chamber 49, a position between the first intake valve drive rocker arm 34 and the first intake valve free rocker arm 36 and a position between the cylinder chamber 49 and the pressing member 47. The contact surface is slidable between a position located between the first intake valve drive rocker arm 34 and the first intake valve free rocker arm 36. Control member 51
Is formed in a bottomed cylindrical shape having a bottom on the side that contacts the switching pin 50, and a flange 51 a slidably in contact with the cylinder chamber 49 is formed at the open end of the regulating member 51 so as to protrude outward in the radial direction. Is done. The cylinder chamber 49 has a flange 51
a, a retaining ring 57 for restricting movement of the regulating member 51 toward the switching pin 50 is fitted.

The first connection switching means 41 has a well-known timing plate (FIG. 1) for regulating the timing of connection and disconnection between the first intake valve drive rocker arm 34 and the first intake valve free rocker arm 36. 2 has 3
Timing plate 3 of free rocker arm 38 for intake valve
8b and the timing plate 36'b of the first exhaust valve free rocker arm 36 'are shown). This timing plate is engaged with the engagement groove 46a of the piston 46 or the engagement groove 46b between the piston 46 and the switching pin 50 to restrict the movement of the piston 46, and the engagement groove 46a or the engagement groove The piston 46 is pivotally supported by a pin fixed to the first free rocker arm 36 so as to swing freely between a position where the piston 46 moves and a position where the piston 46 is allowed to move. Further, the timing plate is urged by a spring in a direction in which the timing plate engages with the engagement grooves 46a and 46b, and abuts against a stopper surface which is a flat bottom surface of a groove formed on the outer periphery of the intake rocker arm shaft 19. Thus, the swing range is regulated.

In a state where the hydraulic pressure in the hydraulic chamber 53 is released, the switching pin 50 is moved to the first position by the spring force of the return spring 52.
It is located at a position straddling the intake valve free rocker arm 36 and the first intake valve drive rocker arm 34, and connects the two rocker arms 34, 36. At this time, when the first intake valve free rocker arm 36 is in contact with the base circle portion of the first intake valve operating cam 31, the timing plate engages with the engagement groove 46b (at this time, the timing plate A slight gap is formed between the bottom surface of the engaging groove 46b and the timing plate in contact with the stopper surface.) When the first intake valve free rocker arm 36 is pushed down by the cam nose portion of the first intake valve operation cam 31, the timing plate comes into contact with the stopper,
When the swing is restricted, it is separated from the engagement groove 46b.

When a hydraulic pressure is applied to the hydraulic chamber 53, the piston 46 moves until the pressing spring 48 is compressed and comes into contact with the switching pin 50 when the timing plate is detached from the engagement groove 46b. However, when the switching pin 50 is
The switching pin 50 is located between the intake valve drive rocker arm 34 and the first intake valve free rocker arm 36.
, A force in the shearing direction acts, and the frictional force based on the force prevents the piston 46 from moving until the switching pin 50 is pushed into the first intake valve drive rocker arm 34. Then, the first intake valve free rocker arm 36 is
The piston 46 moves until the switching pin 50 is pushed into the first intake valve driving rocker arm 34 when the force in the shearing direction on the switching pin 50 decreases when the sliding pin starts to slide on the base circular portion of the intake valve operating cam 31. And both rocker arms 3
The connection states of 4, 36 are released.

The first intake valve drive rocker arm 34 and the first
In a state in which the connection with the free intake rocker arm 36 is released, the timing plate is engaged when the first free intake valve rocker arm 36 is in contact with the base circular portion of the first intake valve operating cam 31. It engages with the groove 46a. Also,
When the first intake valve free rocker arm 36 is pushed down by the cam nose portion of the first intake valve operation cam 31, the timing plate comes into contact with the stopper surface and its swing is restricted, so that the timing plate is moved from the engagement groove 46a. break away.

When the hydraulic pressure in the hydraulic chamber 53 is released and the two rocker arms 34 and 36 are connected, the first
The intake valve free rocker arm 36 is the first intake valve operating cam 3
When the timing plate is disengaged from the engagement groove 46a by being pushed down by the first cam nose portion, the piston 46 moves to a position where the volume of the hydraulic chamber 53 is minimized by the spring force of the pressing spring 48, and then the first intake valve is free. When the rocker arm 36 starts slidingly contacting the base circle portion of the first intake valve operating cam 31 and the axes of the two cylinder chambers 45 and 49 coincide with each other, the switching pin 50 causes the rocker arms 34 and 36 to move by the spring force of the return spring 52. And the two are connected.

The second connection switching means 42 for connecting and disconnecting the second intake valve drive rocker arm 35 and the second intake valve free rocker arm 37 has basically the same configuration as the first connection switching means 41 described above. have. However, when the hydraulic pressure in the hydraulic chamber is released, the switching pin has its contact surface with the pressing member between the second drive intake valve rocker arm 55 and the second intake valve free rocker arm 37. Thus, the rocker arms 35 and 37 are in the disconnected state, and when hydraulic pressure is applied to the hydraulic chamber, the switching pin becomes the second pin.
It moves to a position straddling the intake valve drive rocker arm 35 and the second intake valve free rocker arm 37, and both rocker arms 35 and 37 are connected. The hydraulic chamber is always in communication with the second switching hydraulic pressure supply passage 40 in the intake rocker arm shaft 19 via a communication passage 55 provided in the second intake valve free rocker arm 37.

The first intake valve drive rocker arm 34, the second
The third connection switching means 43 for connecting and disconnecting the three members of the intake valve drive rocker arm 35 and the third intake valve free rocker arm 38 includes a cylinder chamber 58 formed in the second intake valve drive rocker arm 35 and a third A switching pin 61 slidably fitted in a cylinder chamber 59 formed in the free rocker arm 38 of the intake valve 3;
9 and a switching pin 62 which can be slidably fitted in a cylinder chamber 60 formed in the first intake valve driving rocker arm 34 and abuts on the switching pin 61; The regulating member 63 is slidably fitted to the cylinder chamber 60 in contact with the regulating member 63, and a return spring 64 is provided between the regulating member 63 and the bottom of the cylinder chamber 60.

A hydraulic chamber 65 is formed between one end of the switching pin 61 and the cylinder chamber 58. The hydraulic chamber 65 is provided with a communication passage 5 provided in the second intake valve drive rocker arm 35.
6, it is always in communication with a third switching hydraulic pressure supply passage 40 in the intake rocker arm shaft 19. The three switching hydraulic pressure supply passages 40 of the switching hydraulic pressure supply passage 40 and the first and second switching hydraulic pressure supply passages 40, 40 of the first and second connection switching means 41, 42 are provided independently of each other. Therefore, the first, second, and third connection switching means 41, 4
2 and 43 can be switched independently of each other.

One end of the switching pin 62 abuts on the switching pin 61, and the other end thereof has a regulating member 6 formed in a bottomed cylindrical shape.
3 contacts the bottom. In addition, a flange 63 a slidably in contact with the cylinder chamber 60 is formed at the open end of the regulating member 63 so as to protrude outward in the radial direction. Further, the switching pin 6 of the regulating member 63 contacts the cylinder chamber 60 with the flange 63 a.
A retaining ring 66 for restricting movement to the second side is fitted.

In the third connection switching means 43, the hydraulic chamber 6
5 is released, the contact surface between the switching pin 61 and the switching pin 62 is located between the second intake valve driving rocker arm 35 and the third intake valve free rocker arm 38, and the switching pin 62 and the regulating pin are restricted. The contact surface with the member 63 is the third
The three rocker arms 34, 35, and 38 are located between the free rocker arm 38 of the intake valve and the first rocker arm 34 for driving the first intake valve. When hydraulic pressure is applied to the hydraulic chamber 65, the switching pin 61 moves to a position where the other end is fitted into the cylinder chamber 59, and the switching pin 62 is moved to a position where the other end is fitted to the cylinder chamber 60. , These three rocker arms 34, 3
5, 38 are connected.

Since the exhaust valve driving device 18 has basically the same configuration as the above-described intake valve driving device 17, the description of the configuration will be omitted.

Next, the hydraulic tappet holder 13 for holding the hydraulic tappet 14 will be described. 5 to 7
As shown in FIG.
A total of four mounting feet 13b, 13c, and four hydraulic tappet holding parts 1 for slidably holding each hydraulic tappet 14
3a, a cylindrical ignition plug holding portion 13d, and a mounting leg 13
b, 13c and the hydraulic tappet holding portion 13a are integrally connected to each other.
f, 13g, 13h and the intake valve 6 of the spark plug holding portion 13d.
A connecting portion 13i located on the side and connecting the two mounting legs 13b to each other, the hydraulic tappet holding portion 13a, the mounting legs 13b and 13c, the ignition plug holding portion 13d, and the frame portions 13e and 1
3f, 13g, 13h and a thin portion 13j formed between the connecting portion 13i. And a frame portion 13 for connecting both hydraulic tappet holding portions 13a for the intake valve 6.
e and the frame portion 13h connecting the two hydraulic tappet holding portions 13a for the exhaust valve 7 have the same thickness as the thin portion 13j, and are continuous with the thin portion 13j while being curved (FIG. 2). reference). The frame portions 13f and 13g connecting the mounting leg 13b and each hydraulic tappet holding portion 13a are inclined downward toward the hydraulic tappet holding portion 13a. The spark plug holding portion 13d has an insertion hole 13k into which a pipe for receiving the spark plug 29a is inserted. The spark plug holding portion 13d allows the spark plug 29a to be inserted through the pipe 29b.
Is held by the cylinder head 3.

On the side surface of the hydraulic tappet holding portion 13a for the intake valve 6 on the side of the intake rocker arm shaft 19, a part of the intake valve 6 of the first and second intake valve drive rocker arms when the intake valve 6 is opened. A notch 13m is formed to accommodate the side, and a hydraulic tappet holding portion 13a for the exhaust valve 7 is formed.
A notch 13m is formed on the side surface of the exhaust rocker arm shaft 20 side in which a part of the exhaust valve side of the first and second exhaust valve driving rocker arms 34 'and 35' is accommodated when the exhaust valve 7 is opened. Have been. The first and second intake valve drive rocker arms 34, 35 and the first and second exhaust valve drive rocker arms 34 ', 35' in which the width of the notch 13m in the axial direction of each rocker arm shaft 19, 20 are accommodated.
Are slightly larger than the widths of the respective rocker arm shafts 19 and 20 in the axial direction, and the depth thereof is shown in the drawing.
The cylindrical hydraulic tappet holding portion 13a reaches just before the central position in the axial direction, but its depth is the maximum lift amount of the intake valve 6 or the exhaust valve 7 and the hydraulic tappet in the hydraulic tappet holder 13 at the time of the maximum lift. 14 is determined as appropriate from the viewpoint of stable maintenance.

The notches 13m are swingably supported by the first and second intake valve driving rocker arms 34 and 35, which are swingably supported by the intake rocker arm shaft 19, and the exhaust rocker arm shaft 20. The hydraulic tappet holding portion 13a is located within the swing range of each of the first and second exhaust valve drive rocker arms 34 ', 35'.
An intake rocker arm shaft 19 and intake cam shaft 15 and an exhaust rocker arm shaft 20 and exhaust cam shaft 16 are arranged (see FIG. 1). Therefore, the first, second and third intake valve free rocker arms 36 and 3 which are swung by the first, second and third intake valve operation cams 31, 32 and 33, respectively.
First and second intake valve driving rocker arms 34 and 35 connected to the first and second intake valve driving cams 31 ′, 32 ′ and 33 ′. 2nd and 3rd exhaust valve free rocker arms 36 ',
When the first and second exhaust valve drive rocker arms 34 ', 35' connected to 37 ', 38' swing, a part of the drive rocker arms 34, 35, 34 ', 35' are notched. 13m is accommodated. Here, notch 1
3m, the first and second intake valve drive rocker arms 3
4 and 35, and the fact that the first and second exhaust valve driving rocker arms 34 'and 35' are accommodated in the axial direction of the crankshaft (the direction orthogonal to the plane of FIG. 1 or FIG. 2).
, The state in which the hydraulic tappet holding portion 13a and the drive rocker arms 34, 35, 34 ', 35' are overlapped.

As a result, when the intake valve 6 and the exhaust valve 7 are lifted, the first and second intake valve driving rocker arms 3 are lifted.
4, 35, and a part of the first and second exhaust valve drive rocker arms 34 ', 35' can enter the notch 13m and press down the hydraulic tappet 14 without interfering with the hydraulic tappet holding portion 13a. As a result, notch 13
m, the intake rocker arm shaft 19 and the intake cam shaft 15 and the exhaust rocker arm shaft 20 and the exhaust cam shaft 16 approach the hydraulic tappet holding portion 13a toward the intake valve port and the exhaust port, respectively. Since it can be arranged, the height of the valve train can be reduced.

The four drive rocker arms 34, 35, 34 ', respectively accommodated in the notches 13m,
35 'is a member which directly abuts on the cam shaft without a roller, and which has a width smaller than that of a free rocker arm provided with a roller. Since the size can be reduced correspondingly, the rigidity of the hydraulic tappet holding portion 13a due to the formation of the notch 13m can be reduced little.

Further, between the cylindrical ignition plug holding portion 13d and the hydraulic tappet holding portion 13a for the exhaust valve 7, an exhaust valve is formed on the upper surface of the thin portion 13j and extends radially from the ignition plug holding portion 13d. 7 is formed with a reinforcing rib 13p connected to the hydraulic tappet holding portion 13a for
The strength of the hydraulic tappet holding portion 13a due to the formation of the pressure drop is prevented. On the other hand, between the ignition plug holding portion 13d and the hydraulic tappet holding portion 13a for the intake valve 6, the ignition portion is formed on the lower surface of the thin portion 13j, like the reinforcing rib 13p of the hydraulic tappet holding portion 13a for the exhaust valve 7. Plug holder 1
Reinforcing rib 13q extending radially from 3d and connected to hydraulic tappet holding portion 13a for intake valve 6 (see FIG. 7)
Are formed.

On the other hand, the hydraulic tappet holder 13 is fixed to the cylinder head 3 by passing through the bolt hole 13r and screwing into the cylinder head 3 in the cylinder head 3 on the extension line below the bolt hole 13r of the hydraulic tappet holder 13. A bolt hole 71 through which a bolt 70 (see FIG. 3) is formed is formed. The openings of the left and right bolt holes 71 arranged on both sides of the rocker arm shaft holder 23 other than the rocker arm shaft holder 23 adjacent to the cam chain chamber 72 are V-shaped oil communication passages formed in the cylinder head 3. They are communicated with each other via 73.

Bolt hole 13 provided in mounting leg 13b
r is a frame formed to have a larger diameter than the bolt 70 so as to allow oil supplied through an oil communication hole 74 described later to pass therethrough and extending obliquely downward from the bolt hole 13r toward each hydraulic tappet holding portion 13a. An oil communication passage 13t is formed in each of 13f and 13g, and an oil communication passage 13u which passes through the oil communication passage 13t on the intake valve 6 side.
Is formed on the coupling portion 13i. Also, the oil communication passage 13
Oil is supplied into each hydraulic tappet 14 from an oil supply path 13w provided at the end of t.

Next, an oil supply system to the hydraulic tappet holder 13 will be described with reference to FIG. Oil discharged from an oil pump (not shown) connected to a crankshaft of the internal combustion engine 1 and passed through an oil filter (not shown) is supplied to a main gallery (not shown) extending in a direction parallel to the crankshaft. From the end near the cam chain chamber 72 to the cam chain chamber 7 in the cylinder head 3
It is supplied to one of the bolt holes 75 on the second side. As shown in FIG. 5, the bolt 27 is formed on the rocker arm shaft holder 23 adjacent to the cam chain chamber 72.
A bolt hole 76 is formed in the cylinder head 3 at a position below a bolt hole (not shown) extending therethrough. An oil communication hole 74 is formed from a bolt hole 78 through which a bolt 77 for fixing the cylinder head 3 to the cylinder block 2 passes to an opening of the bolt hole 76. Further, an oil communication passage 79 is formed from the oil communication hole 74 to the opening of the bolt hole 71 adjacent to the cam chain chamber 72. Further, the intake camshaft 1 is
An oil communication hole (not shown) is formed toward the bearing portion of the exhaust camshaft 5 and the exhaust camshaft 16.

Next, the positional relationship between the first, second and third intake valve free rocker arms 36, 37 and 38 and the hydraulic tappet holder 13 will be described. As shown in FIGS. 2 and 8, at the tip of a frame portion 13 e provided between the two hydraulic tappet holding portions 13 a for the intake valve 6, the tip end of the intake rocker arm shaft 19 side is the hydraulic pressure The upper end of the circular shape of the tappet holding portion 13a is in contact with a vertical plane passing through the center of the circle, and the uppermost end of the tip portion is near the center of the cylindrical hydraulic tappet holding portion 13a in the axial direction. Accordingly, a cutout 13x is formed in the hydraulic tappet holder 13 by the two hydraulic tappet holding portions 13a for the intake valve 6 and the tip of the frame portion 13e on the intake rocker arm shaft 19 side. Then, the notch 13x is located within the swing range of the third intake valve free rocker arm 38 swingably supported by the intake rocker arm shaft 19 so that the hydraulic tappet holder 13 and the intake rocker arm shaft 19 Are arranged (see FIG. 2). Therefore, when the third intake valve free rocker arm 38 swings by the third intake valve operation cam 33, the roller 38a of the third intake valve free rocker arm 38 is notched 13
x. Here, the fact that the roller 38a of the third intake valve free rocker arm 38 is accommodated in the notch 13x means that the hydraulic pressure is viewed from the axial direction of the crankshaft (a direction perpendicular to the plane of FIG. 1 or FIG. 2). Tappet holder 13
a and the roller 38a overlap each other.

The relationship between the state in which the roller 38a is accommodated in the notch 13x and the swing position of the third intake valve free rocker arm 38 may be as follows. That is, when the roller 38a of the third intake valve free rocker arm 38 is in sliding contact with the base circle portion of the third intake valve operating cam 33, the roller 38a may be accommodated in the notch 13x,
Further, when the third intake valve free rocker arm 38 comes into sliding contact with the cam nose portion of the third intake valve operating cam 33 and the third intake valve free rocker arm 38 swings by a predetermined angle, the roller 38a is housed in the notch 13x. May be performed. In any case, the roller 38a may be accommodated in the notch 13x in at least a part of the swing range of the third intake valve free rocker arm 38.
Therefore, the roller 38a can be positioned with a slight gap in the vicinity of the leading end of the frame when the intake valve 6 is at the maximum lift.

Further, the hydraulic tappet holder 13 includes:
The two mounting legs 13b are provided at an interval larger than the interval between the two hydraulic tappet holding portions 13a for the intake valve 6 and parallel to the crankshaft axis. The outer surface of the frame portion 13f connected to the mounting leg 13b and the hydraulic tappet holding portion 13a for the intake valve 6 is higher than a plane contacting both cylindrical side surfaces of the cylindrical mounting leg 13b and the cylindrical hydraulic tappet holding portion 13a. Are also located near the center of the hydraulic tappet holder 13. Therefore, a pair of notches 13y are formed in the hydraulic tappet holder 13 by the mounting leg 13b, the two hydraulic tappet holding portions 13a for the intake valve 6, and the outer surface of the frame portion 13f. The pair of notches 13y are provided on the first and second intake valve free rocker arms 3 which are swingably supported by the intake rocker arm shaft 19.
The hydraulic tappet holder 13 and the intake rocker arm shaft 19 are arranged so as to be located within the swing ranges of 6, 37 (see FIG. 2). Therefore, when the first and second intake valve free rocker arms 36, 37 swing by the first and second intake valve operation cams 31, 32, respectively, the rollers 36a, 3 of the two intake valve free rocker arms 36, 37 are rotated.
7a are respectively accommodated in the notches 13y.

Here, the rollers 36a, 3 of the first or second intake valve free rocker arms 36, 37 are inserted into the notches 13y.
Meaning that 7a is accommodated, and notch 13
The relationship between the state in which the rollers 36a and 37a are housed in the y and the swinging positions of the first and second intake valve free rocker arms 36 and 37 is that both the notch 13x and the third intake valve free rocker arm 38. In this case, the meaning of being accommodated and the relationship between the accommodated state and the rocking position of the rocker arm are the same.

On the other hand, with respect to the exhaust valve 7, the arrangement relationship between the hydraulic tappet holder 13 and the exhaust rocker arm shaft 20 and each exhaust valve free rocker arm 36 ', 37', 3
The accommodation mode of the 8 'rollers 36'a, 37'a, 38'a is basically the same as that of the intake valve 6 described above, and is formed between a pair of hydraulic tappet holding portions 13a for the exhaust valve. The roller of the rocker arm of the third exhaust valve is accommodated in the cutout 13x, and the mounting leg 13c and the exhaust valve 7
The rollers 36'a, 37'a of the first and second exhaust valve free rocker arms 36 ', 37' are accommodated in a pair of notches 12z formed between the hydraulic tappet holding portions 13a for use.

As described above, the first, second and third intake valve free rocker arms 3 are provided on the hydraulic tappet holder 13.
6, 37, 38 and the notches 13x, 13y, 13z are formed in the swing range of the first, second and third exhaust valve free rocker arms 36 ', 37', 38 '. Compared to the case where the notches 13x, 13y, 13z are not formed, the hydraulic tappet holder 13
The intake rocker arm shaft 19 and the intake cam shaft 15
Since the exhaust rocker arm shaft 20 and the exhaust cam shaft 16 can be arranged closer to the hydraulic tappet holder 13, the valve train can be made compact.

Next, the structure of the hydraulic tappet 14 on the intake valve 6 side will be described. The structure of the hydraulic tappet 14 on the exhaust valve 7 side is basically the same as that on the intake valve 6 side. As shown in FIG. 8, the hydraulic tappet 14
Hydraulic tappet holder 13a of hydraulic tappet holder 13
A cylindrical cylinder 14a slidably inserted into a holding hole formed at the upper end and having a bottom at an upper end;
A cylindrical plunger 14b slidably inserted into the inside and having a bottom at the lower end, and a cylindrical valve body 14c slidably inserted into the plunger 14b and in contact with the bottom inner surface of the cylinder 14a. Have.

An oil supply groove 14d communicating with the oil supply passage 13w within a range of reciprocation of the cylinder 14a in the holding hole is provided in a cylindrical portion forming a side portion of the cylinder 14a in sliding contact with the hydraulic tappet holding portion 13a. An oil supply hole 14f formed on the moving surface and communicating the oil supply groove 14d with the cylinder chamber 14e is formed in the radial direction. On the other hand, on the bottom outer surface of the cylinder 14a,
When viewed from above in the valve axial direction of the intake valve 6, a long and thin engagement groove 14g is formed in a direction orthogonal to the axis of the intake rocker arm shaft 19. The first and second intake valve drive rocker arms 34 and 35 are fitted into the engagement grooves 14g, respectively, so that the bottom surface of the engagement groove 14g and one end of the first or second intake valve drive rocker arms 34 and 35 are always in contact. It comes into contact. The width of the engagement groove 14g in the direction orthogonal to the axis of the intake rocker arm shaft 19 is smaller than the outer diameter of the cylinder 14a. Intake rocker arm shaft 1 with engagement groove 14g
9, the width in the direction parallel to the axial direction is slightly larger than the width in the axial direction of the intake rocker arm shaft 19 of the corresponding intake valve drive rocker arm. Engages, the cylinder 14a of the hydraulic tappet 14 caused by the rotation of the intake valve 6 around the valve axis caused by the opening / closing operation of the intake valve port.
Is determined to prevent the rotation of. This engagement groove 14
g and the rocker arm of the intake valve driving mechanism cooperate to prevent the cylinder 14a from rotating.
A communication state between the oil supply passage 13w and the oil supply passage 13w is ensured, the oil can be reliably supplied to a first oil chamber 14p, which will be described later, and the hydraulic tappet holding portion 13a has one of the first and second intake valve driving rocker arms 34, 35. The oil in the cylinder chamber 14e or a first oil chamber 14p described later is supplied to the oil supply hole 1 in spite of the formation of the notch 13m for accommodating the portion.
There is no leakage from the notch 13m through the groove 4f or the oil supply groove 14d.

In the engagement groove 14g, the cylinder 14 opposing the oil supply hole 14f at the bottom of the cylinder 14a is provided.
a through a small hole 14h formed along the side of
Part of the oil supplied from the oil supply passage 13w into the cylinder chamber 14e accumulates, and lubrication is performed on a sliding portion between the drive rocker arm and the bottom surface of the engagement groove 14g. Through the small holes 14h, air bubbles accumulated in the cylinder chamber 11e can be released to the outside. Further, a communication groove 14i that connects the cylinder chamber 14e and a first oil chamber 14p described later is formed in a part of the bottom inner surface of the cylinder 14a in contact with the valve body 14c. Further, the cylinder 14
The stop ring 14 for preventing the plunger 14b from moving in the direction of the intake valve 6 is provided on the peripheral wall of the cylinder chamber 14e near the open end of the cylinder a.
j is provided.

The lower end surface, which is the bottom outer surface of the plunger 14b, is provided with a contact piece 14k that contacts the shaft end 6a of the intake valve 6.
The reciprocating motion of the plunger 14b, that is, the reciprocating motion of the hydraulic tappet 14 is transmitted to the intake valve 6 via the contact piece 14k.

The cylindrical valve body 14c has a partition wall 14n having a communication hole 14m formed at the center, closer to the bottom of the plunger 14b than the center position in the axial direction, and the plunger is formed by the partition wall 14n. 14b,
It is divided into a first oil chamber 14p formed by the bottom of the cylinder 14a and the valve body 14c, and a second oil chamber 14q formed between the bottom of the plunger 14b and the valve body 14c. A spherical valve element 14r that can open and close the communication hole 14m of the partition wall 14n is disposed in the second oil chamber 14q, and the first oil chamber 14p is formed by the partition wall 14n and the valve element 14r.
A check valve is configured to allow the flow of oil from the second oil chamber 14q to the second oil chamber 14q, but to prevent the flow of oil from the second oil chamber 14q to the first oil chamber 14p. Further, the second oil chamber 14
Within q, a spring receiver 14s having a function of preventing the valve body 14r from moving more than a predetermined amount when the check valve is opened, and the valve body 14c and the plunger 14b are separated from each other via the spring receiver 14s in a direction away from each other. A biasing coil spring 14t is provided.

The hydraulic tappet 14 configured as described above
Performs the same operation as the conventional hydraulic tappet. That is, the first oil chamber 14p and the second oil chamber 14q extend from the oil supply passage 13w to the oil supply groove 14d,
f, the cylinder chamber 14e, the communication groove 14i, and the oil supplied through the communication hole 14m when the check valve is opened. Then, when the valve clearance occurs and the oil pressure in the second oil chamber 14q decreases, the check valve opens and oil flows from the first oil chamber 14p to the second oil chamber 14q, so that the valve clearance is constantly maintained. Is set to zero, the intake valve 6 is opened and closed by the first, second, and third intake valve operating cams 31, 32, and 33.

Next, the oil seal 9, the valve spring retainer 10 and the valve spring receiving portion 11 employed for the intake valve 6 will be described. The exhaust valve 7 has basically the same configuration.

As shown in FIG. 8, a bowl-shaped recess 10a is formed on the upper surface of the valve spring retainer 10 opposite to the hydraulic tappet 14, and the plunger 14b is formed in the recess 10a. The lower part and the contact piece 14k are always located. Therefore, the contact surface between the contact piece 14k and the valve stem end 6a is always located in the recess 10a. Further, when the intake valve 6 is closed,
The lower part of the hydraulic tappet holder 13 is also located in the recess 10a.

As a result, the positions of the hydraulic tappet 14 and the hydraulic tappet holder 13 can be made closer to the intake valve port as compared with the case where the concave portion 10a is not formed on the upper surface of the valve spring retainer 10, and the position of the valve rod end 6a Can be lowered. As a result, the length of the valve stem can be shortened by the same amount, and the intake rocker arm shaft 19 and the intake cam shaft 15 can be arranged closer to the intake valve port. Can be lowered.
The recess 10a has a damper function because oil that leaks from the inside of the hydraulic tappet 14 through its sliding surface accumulates and the accumulated oil enters the contact surface between the valve rod end 6a and the contact piece 14k. None, the contact noise between both can be reduced. Further, the lubricating property of the contact surface can be improved.

On the other hand, the portion where the valve stem of the intake valve 6 comes out of the valve guide 8 provided on the cylinder head 3 is shown in FIG.
As shown in FIG. 1, an oil seal 9 for sealing oil for lubricating a sliding portion between the valve guide 8 and the valve rod is provided. In the oil seal 9, a metal retaining ring 9a is fitted to a small diameter portion above the resin body portion, and a metal cylindrical body 9b is adhered to a large diameter skirt portion below the resin body portion. And the strength is improved.

An annular gap 11b is formed between the inner peripheral edge 11a of the valve spring receiving portion 11 and the outer peripheral surface of the valve guide 8 projecting from the cylinder head 3 and exposed.
1b, the lower part of the cylindrical body 9b of the oil seal 9 enters, and the lower end of the cylindrical body 9b abuts on the upper seat of the seat 3a of the cylinder head 3, so that the exposed portion of the valve guide 8 is exposed. Is covered.

As a result, the oil seal 9 can be mounted through the hole of the valve spring receiving portion 11 mounted on the upper surface of the cylinder head 3, so that the length of the exposed portion of the valve guide 8 can be shortened, 9 can be lowered. And when the mounting position of the oil seal 9 is lowered,
Since there is a margin in the clearance between the lower end of the valve spring retainer 10 and the upper end of the oil seal 9, which is determined by the maximum lift amount of the intake valve 6, the positions of the valve spring retainer 10 and the valve rod end 6a are adjusted by the extra margin. It is possible to lower it. Therefore, the intake rocker arm shaft 19
In addition, the intake camshaft 15 can be arranged closer to the intake valve port, and in this regard, the height of the valve gear can be reduced.

The operation and effect of the embodiment of the present invention described above will be described. When the internal combustion engine 1 is operating, the control means controls the control valve for controlling the hydraulic pressure of the switching hydraulic pressure supply passage 40 based on the cylinder deactivation command signal, and the first, second, and third valves of the intake valve driving device 17 are controlled. All the third connection switching means 41, 42, and 43 are brought into the disconnected state, and similarly, all three connection switching means of the exhaust valve driving device 18 are brought into the disconnected state. Therefore, the first and second intake valve drive rocker arms 34,
35 and first and second exhaust valve drive rocker arms 34
'And 35' are in contact with the resting portions of the intake camshaft 15 and the exhaust camshaft 16, respectively, so that the two intake valves 6 and both exhaust valves 7 of one cylinder are substantially in a valve-closing rest state,
The cylinder is at rest.

When the internal combustion engine 1 is operated in a small intake air amount operation range such as a low rotation speed and a low load, the control valve is controlled by the control means. While the switching means 41 is in the connected state, the second and third connection switching means 42 and 43 are in the disconnected state, while the first connection switching means in the exhaust valve driving device 18 is in the connected state. The second and third connection switching means are set in the disconnected state, and the first intake valve driving rocker arm 34 is connected to the first intake valve free rocker arm 3.
6 while the first exhaust valve drive rocker arm 34
'Is connected to a first exhaust valve free rocker arm 36'. For this reason, the first intake valve driving rocker arm 34 and the first exhaust valve driving rocker arm 34 ′ are connected by the first intake valve operating cam 31 of the intake cam shaft 15 and the first exhaust valve operating cam 31 ′ of the exhaust cam shaft 16. Each driven, 1
The one intake valve 6 and one exhaust valve 7 of the cylinder have a smaller valve opening lift than the third intake valve operation cam 33 and the third exhaust valve operation cam 33 ', respectively, according to the profile of each operation cam. Opening and closing operation,
The second intake valve driving rocker arm 35 and the second exhaust valve driving rocker arm 35 ′ are configured such that the other intake valve 6 and the other exhaust valve 7 of the cylinder are substantially separated by the rest portions of the intake cam shaft 15 and the exhaust cam shaft 16. The valve is in a closed state. Therefore, only one intake valve 6 is opened and closed,
A vortex, for example, a swirl, can be formed in the combustion chamber, so that the combustibility is improved, a large amount of exhaust gas can be circulated in a low-speed region of the engine or a low-load region of the engine, and lean combustion can be performed, thereby improving emission and fuel efficiency. .

When the internal combustion engine 1 is operated in a medium intake amount operation range such as a medium rotation speed and a medium load, the control means controls the control valve, and the intake valve driving device 17 The second connection switching means 41 and 42 are connected, and the third connection switching means 43 is disconnected. On the other hand, in the exhaust valve driving device 18, the first and second connection switching means are connected. And the third
When the connection switching means 43 is released, the first and second intake valve driving rocker arms 34 and 35 are connected to the first and second intake valve free rocker arms 36 and 37, respectively, while the first and second intake valve free rocker arms 36 and 37 are connected. The two exhaust valve drive rocker arms 34 ', 35' are connected to the first and second exhaust valve free rocker arms 36 ', 37', respectively. For this reason, the first and second intake valve drive rocker arms 34, 3
5 is driven by first and second intake valve operation cams 31 and 32 of the intake camshaft 15, respectively, and the first and second exhaust valve drive rocker arms 34 ′ and 35 ′ are connected to the first And the second exhaust valve operating cam 31, '32
, And one of the intake valves 6 and one of the exhaust valves 7 of one cylinder operate the third intake valve in accordance with the profiles of the first intake valve operating cam 31 and the first exhaust valve operating cam 31 ′, respectively. The cam 33 and the third exhaust valve operating cam 33 'are respectively opened and closed with a smaller valve lift than the cam 33' and the other intake valve 6 and the other exhaust valve 7 are connected to the second intake valve operating cam 32 and the second exhaust valve, respectively. Depending on the profile of the operating cam 32 ', the third intake valve operating cam 33
The opening and closing operation is performed with a valve opening lift amount smaller than that of the third exhaust valve operation cam 33 '. Accordingly, in the middle intake air amount operation region of the internal combustion engine 1, the two intake valves 6 are opened and closed with a small valve opening lift amount. The engine output in the engine operating range can be improved.

When the internal combustion engine 1 is operated in a large intake air amount operation range such as a high rotation speed and a high load, the control means controls the control valve so that the intake valve driving device 17 The switching means 43 is connected, while the third connection switching means in the exhaust valve driving device 18 is connected, and the first and second intake valve driving rocker arms 3 are connected.
4 and 35 are connected to a third intake valve free rocker arm 38 while the first and second exhaust valve drive rocker arms 34 are connected.
', 35' are connected to a third exhaust valve free rocker arm 38 '. Therefore, the first and second intake valve driving rocker arms 34 and 35 are driven by the third intake valve operating cam 33 of the intake camshaft 15, and the first and second exhaust valve driving rocker arms 34 'and 35' are driven by the exhaust cam. Driven by a third exhaust valve operating cam 33 ′ of the shaft 16, the two intake valves 6 and both exhaust valves 7 of one cylinder are respectively the profiles of the third intake valve operating cam 33 and the third exhaust valve operating cam 33 ′. , The valve is opened and closed with a large valve opening lift amount. Therefore, a required engine high output can be obtained in the large intake air amount operation range of the internal combustion engine 1. At this time, the first and second connection switching means may be in a connected state or in a disconnected state. However, when the first and second connection switching means are in the disconnected state, the first and second intake valve free rockers are provided. Arm 34,3
Fifth and first and second exhaust valve free rocker arms 34
Since 'and 35' are separated from the drive systems of the intake valve 6 and the exhaust valve 7, respectively, the weight of the rocker arm for driving the valves 6 and 7 is reduced, and the limit rotational speed can be increased.

When the first, second, or third connection switching means 41, 42, 43 is connected, the intake valve 6
The hydraulic tappet 14 abuts one end of the first or second intake valve driving rocker arms 34, 35 integrated with the first, second or third intake valve free rocker arms 36, 37, 38 that swing. The hydraulic tappet 14 is held by a hydraulic tappet holder 13 fixed to the cylinder head 3 and separate from the first and second intake valve drive rocker arms 34 and 35. The weight of the rocker arm does not increase, and the rocker arm does not become large. Therefore, the inertial weight of the valve operating system is not increased, and the intake rocker arm 21 follows the movement of the intake valve operating cam well even at high engine speeds. Further, first, second or third connection switching means 41, provided on the first and second intake valve driving rocker arms 34, 35 and the first, second and third intake valve free rocker arms 36, 37, 38, respectively. 4
2 and 43 are different from the prior art in that the hydraulic tappet 14
Can be placed on those rocker arms without any restrictions. Such operations and effects are the same for the exhaust valve 7.

On the other hand, the intake camshaft 15 and the exhaust camshaft 1
6 rotates, and the first and second intake valve operating cams 31, 3
2 and first and second exhaust valve operating cams 31 ', 32'
The first and second intake valve free rocker arms 36 and 37 and the first and second exhaust valve free rocker arms 36 ′ and 37 ′, which oscillate, respectively, even when the rocker arms 36 ′ and 37 ′ are closest to the hydraulic tappet holder 13. Rollers 36a, 27 of arms 36, 37, 36 ', 37'
a, 36'a, 37'a are notches 13y, 13z between the mounting legs 13b, 13c and the hydraulic tappet holding portion 13a.
Intake rocker arm 21 for each cylinder
The size of the exhaust rocker arm 22 in the axial direction of the rocker arm shaft can be reduced, and the distance between the hydraulic tappet holding portion 13a and the intake rocker arm shaft 19 and the exhaust rocker arm shaft 20 can be reduced. Further, the third intake valve free rocker arm 38 and the third exhaust valve free rocker arm 38 ′ that swing by the third intake valve operating cam 33 and the third exhaust valve operating cam 33 ′, respectively, come closest to the hydraulic tappet holder 13. Roller 38a, 38 'of these free rocker arms 38, 38'
a can be accommodated in the notch 13x between the hydraulic tappet holding portions 13a, the distance between the hydraulic tappet holding portion 13a and the intake rocker arm shaft 19 and the exhaust rocker arm shaft 20 can be reduced, and both can be arranged at a closer position. . As a result, the valve train can be made compact, and the degree of freedom in the layout of the valve train components within a limited valve train chamber increases.

Further, in a state where the first and second intake valve driving rocker arms 34, 35 are connected to the first, second or third intake valve free rocker arms 36, 37, 38,
First, second or third intake valve operating cams 31, 32, 33
, The drive rocker arms 34 and 35 are partially accommodated in the notches 13m of the hydraulic tappet holding portion 13a within the swing range of the lift amount of the intake valve 6 or more. Similarly, with respect to the exhaust valve 7, a part of the first and second exhaust valve driving rocker arms 34 'and 35' is disengaged from the hydraulic tappet holding portion 13a within a swing range equal to or more than a predetermined lift amount of the exhaust valve 7. Since it is accommodated in the notch 13m, the intake valve 6
When the exhaust valve 7 is lifted, the first and second intake valve driving rocker arms 34, 35 and a part of the first and second exhaust valve driving rocker arms 34 ', 35' interfere with the hydraulic tappet holding portion 13a. Without this, the hydraulic tappet 14 can be pushed down by entering the notch 13m.
As a result, the intake rocker arm shaft 19 and the intake cam shaft 15 and the exhaust rocker arm shaft 20 and the exhaust cam shaft 16 are held by the hydraulic tappet toward the intake valve port and the exhaust valve port, respectively, by the provision of the notch 13m. Part 13
a, the height of the valve train can be reduced.

Further, the recess 10a of the valve spring retainer 10
The lower part of the plunger 14b, the contact piece 14k, and the lower part of the hydraulic tappet holder 13 in the closed state of the intake valve 6 or the exhaust valve 7 are located inside the hydraulic tappet 14 and the hydraulic tappet holder 13. The position can be brought close to the intake valve port and the exhaust valve port, and
The positions of a and 7a can be lowered. Further, since the oil seal 9 is mounted through the hole of the valve spring receiving portion 11 placed on the upper surface of the cylinder head 3, the valve guide 8
The length of the exposed portion can be shortened, and the mounting position of the oil seal 9 can be lowered. As a result, the intake rocker arm shaft 19 and the intake cam shaft 15 and the exhaust rocker arm shaft 20 and the exhaust cam shaft 16 can be arranged closer to the intake valve port and the exhaust valve port, respectively. The height of the device can be reduced.

The switching hydraulic pressure supply passage 40 is connected to the pipe member 39.
And only three pipe members 39 need to be inserted and mounted in circular cross-sectional holes in the rocker arm shaft.
Are easily formed, and cost reduction is possible. Moreover,
Each pipe member 39 has the same cross-sectional shape in the axial direction, the outer circumference and the cross-sectional shape of the hollow portion are both substantially fan-shaped, and the three pipe members 39 are cylindrical so that the outer circumference is circular. It is inserted into the hole in the shaft in a state where the outer periphery is in contact with the peripheral wall of the hole in each rocker arm shaft, so that the space of the hole can be used effectively and the necessary flow area is provided. Since the three switching hydraulic pressure supply passages 40 can be arranged compactly in the shaft, the valve train can be made compact.

In the above-described embodiment, the profile of the second intake valve operating cam 32 is the same as that of the first intake valve operating cam 31, but they may be different. It is also possible to set the valve opening timing, the valve opening period, or the valve opening lift amount differently. Similarly,
The profile of the second exhaust valve operating cam 32 'may be different from that of the second exhaust valve operating cam 31'. In the embodiment, the free rocker arms 36, 37, 38, 36 ', 37', and 38 are provided for the intake valve and the exhaust valve.
'Are rollers 36a, 37a, 38a, 36'a, 37'
a, 38'a and the rollers 36a, 37
a, 38 ', 36'a, 37'a, 38'a are accommodated in the cutouts 13x, 13y, 13z of the hydraulic tappet holder 13. In this case, the rocker arm may be provided with a notch 13 of the hydraulic tappet holder 13.
x, 13y, 13z.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a main part of a valve train of a multi-cylinder internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along the line II-II in FIG.

3 is a plan view of a main part of the multi-cylinder internal combustion engine of FIG. 1 with a cylinder head cover removed and a part of a cam shaft removed.

FIG. 4 is a schematic view of a connection switching means of the valve train of the multi-cylinder internal combustion engine of FIG. 1;

FIG. 5 is a perspective view of a main part showing an arrangement of a hydraulic tappet holder of the valve train of the multi-cylinder internal combustion engine of FIG. 1;

FIG. 6 is a plan view of the hydraulic tappet holder of FIG. 5;

FIG. 7 is a VII view of FIG. 8;

FIG. 8 is a longitudinal sectional view of a hydraulic tappet and a valve spring retainer.

FIG. 9 is a longitudinal sectional view of a valve spring receiving portion and an oil seal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Cylinder block, 3 ... Cylinder head, 3a ... Step seat, 4 ... Intake port, 5 ... Exhaust port,
Reference numeral 6: intake valve, 6a: stem end, 7: exhaust valve, 7a: stem end, 8: valve guide, 9: oil seal, 9a: retaining ring,
9b: cylindrical body 10: valve spring retainer, 10a: concave portion, 1
DESCRIPTION OF SYMBOLS 1 ... Valve spring receiving part, 11a ... Inner peripheral edge, 11b ... Gap, 1
2. Valve spring 13 Hydraulic tappet holder 13a Hydraulic tappet holder 13b, 13c Mounting legs 13d
... Ignition plug holding part, 13e, 13f, 13g, 13h ... Frame part, 13i ... Coupling part, 13j ... Thin part, 13k ... Insertion hole, 13m ... Notch, 13p, 13q ... Reinforcement rib, 13
r: bolt hole, 13t, 13u: oil communication passage, 13w
... oil supply path, 13x, 13y, 13z ... notch, 1
4 ... Hydraulic tappet, 14a ... Cylinder, 14b ... Plunger, 14c ... Valve body, 14d ... Oil supply groove, 1
4e: cylinder chamber, 14f: oil supply hole, 14g: engagement groove, 14h: small hole, 14i: communication groove, 14j: retaining ring, 14k: contact piece, 14m: communication hole, 14n: partition wall, 14p ... 1st oil chamber, 14q ... 2nd oil chamber, 14r ... valve element, 14s ... spring receiver, 14t ... coil spring, 15 ... intake camshaft, 16 ... exhaust camshaft, 17 ... intake valve drive,
18: Exhaust valve drive device, 19: Intake rocker arm shaft,
20: exhaust rocker arm shaft, 21: intake rocker arm, 22: exhaust rocker arm, 23: rocker arm shaft holder, 24: cam shaft holder, 25: cylinder head cover, 26, 27 ... bolt, 28 ... coil spring,
29a: ignition plug, 29b: pipe, 30: intake valve stop portion, 31: first intake valve operating cam, 32: second intake valve operating cam, 33: third intake valve operating cam, 34: first intake valve drive Rocker arm, 35: Rocker arm for driving the second intake valve, 36: Rocker arm for the first intake valve, 36a: Roller, 37 ... Rocker arm for the second intake valve, 37a ...
Roller, 38 ... Rocker arm with third intake valve free, 38a
.. Roller, 38b timing plate, 39 pipe member, 40 switching hydraulic pressure supply passage, 41 first connection switching means, 42 second connection switching means, 43 third connection switching means, 44 spring, 45 Cylinder chamber, 46 ... piston,
47 ... pressing member, 48 ... pressing spring, 49 ... cylinder chamber,
50: switching pin, 51: regulating member, 52: return spring, 5
3 ... Hydraulic chamber, 54,55,56 ... Communication path, 57 ... Retaining ring, 58,59,60 ... Cylinder chamber, 61,62 ... Switching pin, 63 ... Regulator, 64 ... Return spring, 65 ... Hydraulic chamber, 66: retaining ring, 70: bolt, 72: cam chain chamber, 73: V-shaped oil communication passage, 74: oil communication passage,
75, 76: bolt hole, 77: bolt, 78: bolt hole, 79: oil communication passage.

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Claims (2)

[Claims] An engine valve provided in a cylinder; a rocker arm operably connected to the engine valve via a hydraulic tappet to open and close the engine valve, the rocker arm being swingably supported on a rocker arm shaft; A hydraulic tappet holder fixed to a cylinder head and holding the hydraulic tappet; and a notch formed in the hydraulic tappet holder and located within a rocking range of the rocker arm and capable of accommodating a part of the rocker arm. A valve train for an internal combustion engine, comprising: 2. A pair of engine valves provided in one cylinder, respectively operatively connected to the pair of engine valves via hydraulic tappets, and provided on a camshaft to close the engine valves in a closed state. A first and a second drive rocker arm swingably supported by a rocker arm shaft, respectively abutting against a pair of rest portions; and a profile provided on the cam shaft for opening and closing one of the engine valves. A first free rocker arm swingably supported by a rocker arm shaft, abutting on a first operation cam having: a second operation having a profile provided on the cam shaft to open and close the other of the engine valves A second free rocker arm abutting on a cam and swingably supported on a rocker arm shaft; and a second free rocker arm provided on the first drive rocker arm and the first free rocker arm. First connection switching means for switching connection and disconnection, and second connection switching means provided on the second drive rocker arm and the second free rocker arm for switching connection and disconnection between the two. A hydraulic tappet holder fixed to the cylinder head and formed with a hydraulic tappet holding portion for holding the hydraulic tappet, respectively; and a first and second rocker arm formed on each of the hydraulic tappet holding portions. And a notch which is located within the swing range and is capable of accommodating a part of each of the first and second drive rocker arms.