JP3165532B2 - Engine valve drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low-speed cam and a high-speed cam integrally formed on a cam shaft for driving a valve (an intake valve or an exhaust valve). The present invention relates to a valve drive device for an engine that drives a valve at a high-speed valve timing by a high-speed cam while driving with a high-speed cam.

[0002]

2. Description of the Related Art Conventionally, as a valve driving device for an engine of the above-described example, there is, for example, a device described in Japanese Patent Laid-Open No. 3-151510. That is, as shown in FIGS. 11 and 12, a low-speed cam 201 having a small cam profile and a high-speed cam 2 having a large cam profile are provided on a camshaft 200.
02 is integrally formed, and a low-speed rocker arm 204 that swings around a rocker shaft 203 is provided at a position corresponding to the above-described low-speed cam 201, and is provided at an intermediate portion of the low-speed rocker arm 204. A roller follower 205 that contacts the above-described low-speed cam 201 is disposed in the recessed groove portion.

On both sides of the low-speed rocker arm 204 described above, a pivot receiver 20 is provided at one end (the right end in the drawing).
6 is provided with high-speed rocker arms 208 and 208 (only one is shown in the drawing) having an HLA 207 at the other end (left end in the drawing), and the plunger 20 of the HLA 207 at the other end of the high-speed rocker arm 208 is provided.
9 is pressed against the upper end of the valve stem 211 of the valve 210, and the engagement concave portion having a semicircular cross section at the upper end on the other end side of the high-speed rocker arm 208 is configured to be able to engage with the pin 212 protruding from the low-speed rocker arm 204. On the other hand, the pivot receiver 206 at one end of the high-speed rocker arm 208 is connected to the pivot 2 at the upper end of the plunger 214 in the actuator 213.
A slipper 216 that is swingably attached to the high-speed cam 15 and that is integrally formed on the upper surface of the high-speed rocker arm 208 corresponds to the high-speed cam 202 described above.

According to this conventional apparatus, as shown in FIG. 11, when the hydraulic pressure of the actuator 213 is drained, the plunger 214 and the pivot 215 are moved downward, and the pivot receiver 206 of the high-speed rocker arm 208 is in the low position. The slipper 216 of the high-speed rocker arm 208 is separated from the high-speed cam 202 by allowing the rocker arm 208 to slant so that the movement of the low-speed cam 201 is controlled by the elements 205, 204, 212, and 20.
The valve timing at a low speed transmitted to the valve 210 via 7, 209 can be obtained.

On the other hand, when hydraulic pressure is supplied to the actuator 213 as shown in FIG. 12, the plunger 214 and the pivot 215 are moved upward, and the pivot receiver 206 of the high-speed rocker arm 208 is moved upward, so that
8 is displaced substantially horizontally, so that the high-speed rocker arm 2
08 slipper 216 is brought into contact with the high-speed cam 202,
The movement of the high-speed cam 202 is determined by the elements 216, 208, and 20.
The valve timing at the high speed transmitted to the valve 210 via 7, 209 can be obtained.

In this conventional apparatus, a high-speed rocker arm 20 is provided on both sides of a low-speed rocker arm 204.
8, 208, the valve driving reaction force is uniformly input to the bearing that supports the camshaft 200 in an apparatus having a two-valve intake or exhaust valve, and the durability of the bearing is improved. Performance can be improved.

However, in order to improve the intake / exhaust efficiency, follow-up performance during high-speed operation, and increase the allowable maximum number of revolutions, the intake / exhaust valves are increased in number, for example, to a five-valve structure having three intake valves and two exhaust valves. In the engine, when the above-described conventional device is applied to the intake three-valve side, a large amount of load acts as the number of valves increases, and a load acts at a position distant from the bearing. It is not preferable for the bearing to be disposed at a position distant from the durability of the bearing.
When two of the three intake valves are driven in common and the remaining one valve is driven independently, the valve driving reaction force is non-uniformly input to the bearing that supports the camshaft 200, and The durability of the camshaft 200 is degraded, and a large valve driving reaction force is applied to the camshaft 200 at a position deviated to one side from the center between the bearings, particularly at a high speed. There was a point.

[0008]

SUMMARY OF THE INVENTION According to the first aspect of the present invention, in an engine having a three-valve structure on one side of an intake side or an exhaust side, valve driving of a camshaft is prevented while bending of a camshaft is prevented. Make the reaction force input almost even
And improve the durability of the bearing.
While preventing camshaft bending at high speed,
It is an object of the present invention to provide an engine valve drive device capable of forming a swirl .

According to a second aspect of the present invention, in addition to the object of the first aspect, a low-speed cam contact portion which comes into contact with the low-speed cam at a low speed which is frequently used at a high speed is provided. An object of the present invention is to provide a valve drive device for an engine that can be configured with a roller follower to reduce sliding resistance .

[0010] The invention of claim 3 wherein the this invention, together with objects of the invention according to the first aspect, the second valve common drive side and the variable valve mechanism, in a first valve independently driven side of the variable valve mechanism Provided is an engine valve drive device in which the pins for linking the high-speed swing arm and the low-speed rocker arm are provided independently of each other, so that the movements of the respective valve variable mechanisms are made different and swirl can be generated more reliably. With the goal.

[0011]

The invention according to claim 1 of the present invention is a valve drive device for an engine in which a low speed cam and a high speed cam are integrally formed on a cam shaft for driving an intake / exhaust valve. A plurality of valves disposed on one side of the intake valve and the exhaust valve have a three-valve structure, and a first valve variable mechanism for commonly driving two of the three valves;
A second valve variable mechanism for independently driving the remaining one of the valves, wherein each of the variable valve mechanisms includes a low-speed cam contact portion that contacts the low-speed cam and a high-speed cam that contacts the high-speed cam. each organic and cam abutment portion, by vertically moving the high-speed arm abutment, both the high for cams abutting portion and the high-speed cam is an actuator for changing the abutting state and separated states Each of the high-speed cam abutting portions of the respective valve variable mechanisms supports the cam shaft more than the low-speed cam abutting portion, and is disposed on a side close to bearings located on both sides with respect to each cylinder, when each cam is selectively contact with the corresponding cam contact portion, and configured such that movement of the cam is transmitted to the intake and exhaust valves through the variable valve mechanism, the second
Connect the low-speed cam corresponding to the variable valve mechanism to the first valve
Valve lift for variable speed mechanism and corresponding low speed cam
Set the cam profile large so that the volume is large,
On the same side as the low-speed cam contact part of the second valve variable mechanism
Distance between the bearing and one of the cylinders
The first valve variable mechanism and the variable mechanism side of the low-speed cam contact part of the first variable mechanism
The distance between the bearing and the bearing located on the other side of the cylinder
It is characterized in that the valve drive device of the engine is set to be short .

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, there is provided a valve driving device for an engine in which the low-speed cam contact portion is constituted by a roller follower. I do .

[0013] The invention of claim 3 wherein the this invention, in conjunction with the configuration of the invention described in claim 1, wherein said each valve varying mechanism is the low speed rocker arm, the high speed swing arm,
An engine valve drive device having a pin for linking the low-speed rocker arm and the high-speed swing arm, wherein the pin is divided into a pin on the first valve variable mechanism side and a pin on the second valve variable mechanism side. Features.

[0014]

According to the first aspect of the present invention, the two valves on the three valve side are commonly driven simultaneously by the first valve variable mechanism, and the remaining one valve on the three valve side is the first valve. Independently driven by a two-valve variable mechanism.

When the low-speed cam contact portion contacts the low-speed cam, each of the above-described variable valve mechanisms can obtain valve timing at a low speed, and the high-speed cam contact portion contacts the high-speed cam. Then, it is possible to obtain the valve timing at high speed.

Furthermore , the high-speed cam contact portions of the first and second variable valve mechanisms are arranged on the side close to the bearing, and receive a relatively large load at high speed. Is located close to the bearing,
The camshaft can be prevented from being bent, and the input of the valve driving reaction force to the bearing can be made substantially uniform, so that the durability of the bearing can be improved.

When the high-speed cam contact portion is set near the center between the bearings, a large load acts on the camshaft at high speed, causing the camshaft to bend. Thus, such a problem can be solved.

Furthermore, the remaining one of the three valves is used alone.
Low speed cam corresponding to the second valve variable mechanism that drives upright
Is the first valve that drives two of the three valves in common
For the low speed cam corresponding to the variable mechanism, the valve lift amount
The cam profile is set to be large so that
The swirl can be surely formed.

In addition, the low speed of the second valve variable mechanism
The distance between the cam contact portion and the bearing is adjusted by a first valve variable mechanism.
Set shorter than the distance between the low-speed cam contact part and the bearing
Therefore, when the swirl is formed, the first variable valve
A second bar is applied to a predetermined portion of the camshaft corresponding to the
The camshaft corresponding to the variable lube mechanism
Load is applied, but the side on which this large load is applied is the shaft
Since the distance between the receiving short, especially at low speed (swirl
To prevent the camshaft from flexing during
There is an effect that can be done.

According to the invention described in claim 2 of the present invention,
In addition to the effect of the first aspect of the present invention, the low-speed cam contact portion that contacts the low-speed cam at the time of low speed, which is more frequently used than at the time of high speed, is constituted by a roller follower, so that sliding resistance is reduced. There is an effect that can be .

According to the invention of claim 3 wherein the this invention,
In addition to the effect of the first aspect of the present invention, the above-mentioned pin is divided into a pin on the first variable valve mechanism side and a pin on the second variable valve mechanism side, so that the first and second variable valve sections are separated. The movements of the mechanisms can be made different from each other, and the swirl can be generated more reliably.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawings show a valve driving device for an engine. In FIGS. 1, 2 and 3, a cylinder head 3 is mounted on a cylinder block 2 having a cylinder bore 1 and three cylinder heads 3 which communicate with a combustion chamber 4 as appropriate are provided. Intake ports 5, 6, 7 and two exhaust ports 8, 9 are formed.

An intake valve 10 for opening and closing the intake port 5 and an intake valve 11 for opening and closing the intake port 6
And an intake valve 12 for opening and closing the above-described intake port 7 and exhaust valves 13 and 13 for opening and closing each of the above-mentioned exhaust ports 8, 9 to form a five-valve configuration of three intake valves and two exhaust valves. ing.

Each of these valves 10 to 13 has its valve stem 1 installed in a valve guide 14 disposed on the cylinder head 3.
5 and a split collet 16 at the upper end of the valve stem 15.
, And a valve spring 19 is stretched between a lower spring retainer 18 disposed at a predetermined portion of the cylinder head 3 and the above-described upper spring retainer 17. .

On the other hand, an intake camshaft 20 and an exhaust camshaft 21 extending in the cylinder row direction are provided, and the above-described intake camshaft 20 is connected to a plurality of camshaft bearings 22, 23.
And the exhaust camshaft 21 is supported by a plurality of camshaft bearings 24 and 25. The illustration of the bearing cap attached to the upper part of each of the above-described camshaft bearings 22 to 25 is omitted.

The intake camshaft 20 has an intake 3
Low-speed cam 2 corresponding to two intake valves 10 and 11 on the valve side
6 and a high-speed cam 27, and a low-speed cam 28 and a high-speed cam 29 corresponding to the remaining one intake valve 12 on the intake 3-valve side. The two intake valves 10 and 11 are simultaneously driven in common via the same 30 and the remaining one intake valve 12 is independently driven via the second valve variable mechanism 31 by the cams 28 and 29 described above. I have. On the exhaust side, a third variable valve mechanism 32 having the same configuration as the first variable valve mechanism 30 is provided between the upper portions of the two exhaust valves 13 and 13.
(See FIG. 1), and the third valve variable mechanism 32
To simultaneously drive the two exhaust valves 13 on the exhaust side.

The specific structure of the first variable valve mechanism 30 will be described in detail below with reference to FIGS. 4, 5, 6, and 7. The first variable valve mechanism 30 is provided with a rocker shaft 33 as a swing axis parallel to the intake camshaft 20 below the intake camshaft 20, and the rocker shaft 33 has a swing support end (left end in the drawing). A swing arm 34 for high speed is pivotally supported so that the swing arm 34 for high speed extends from the swing support end on the rocker shaft 33 side to the free end on the upper end side of the valve stem 15. A concave portion 35 for disposing a roller follower is formed on the free end side of the high-speed swing arm 34, and a tappet 36 as a high-speed cam contact portion is integrally formed on the free end.

A roller follower 38 is mounted on the roller follower disposing recess 35 by using a single pin 37 as a low speed cam abutting portion for rolling contact with the low speed cam 26, and the pin 37 is used. High-speed swing arm 3
The low speed rocker arms 39 and 40 are attached to both sides of 4.

Here, the low-speed roller follower 38 described above is used.
(Low-speed cam contact portion) is a low-speed cam 2 as shown in FIGS.
6 and above tappet 36 (high-speed cam contact
Parts) are located directly below the high-speed cam 37. The arc-shaped pivot portions 39a and 40a at the other ends (left ends in the drawing) of the low-speed rocker arms 39 and 40 are connected to a hydraulic shock adjuster 41 (hereinafter simply abbreviated as HLA) attached to the cylinder head 3. The low-speed rocker arms 39 and 40 abut against the upper surface of the plunger 42.
The slipper-shaped valve contact portions 39b and 40b at one end (the right end in the drawing) of each of the intake valves 10 and 11
At the upper end of the valve stem 15.

The above-mentioned low-speed rocker arms 39, 40
The low-speed rocker arms 39 and 40 are set to be shorter than the high-speed swing arm 34 so that the other end of the high-speed swing arm 34 does not overlap with the rocker shaft 33 as a swing fulcrum of the high-speed swing arm 34, while the HLA 41 is high-speed. Rocker shaft 3 arranged at the pivot of swing arm 34
3 is disposed on the inner side of the cylinder head 3.

On the other hand, the rocker shaft 33 for pivotally supporting the swing support end of the high-speed swing arm 34 is
Guide holes 43, 43 penetrating in the vertical direction are formed in both sides of the rocker shaft 33 so as to protrude outward in the width direction from both sides in the width direction of the high-speed swing arm 34. ing.

For example, guide pins 44, 44 as guide means implanted in the cylinder head 3 are inserted through the guide holes 43, 43 and the cylinder head 3
Coil springs 45, 45 as urging means are stretched between predetermined portions of the rocker shaft 33 and lower surfaces of both side portions of the rocker shaft 33.

An actuator 46 is disposed above the swing support end of the high-speed swing arm 34 so as to be substantially vertically opposed to the guide pins 44, 44 and the coil springs 45, 45. As shown in FIG. 2, this actuator 46 is of a hydraulic drive type provided solely at the swing support end of the high-speed swing arm 34 at the widthwise intermediate portion of the arm 34, and the plunger 47 is moved downward. At times, the swing support end of the high-speed swing arm 34 is pushed down.

When the swing support end of the high-speed swing arm 34 is moved down, the rocker shaft 33 is guided by the guide pins 44 and 4.
Since the swing arm 34 moves downward while being guided by 4, the swing arm 34 swing support end is moved down while securing the swing center of the high-speed swing arm 34 swing support end.

The above-described actuator 46 is configured as shown in FIGS. That is, the actuator 46 has a cylindrical body 48 and a plunger 47 slidably disposed in the body 48, and supplies hydraulic pressure into the body 48 from a port 49 facing the back surface of the plunger 47. Then, the plunger 47 moves downward from the state shown in FIG. 6 as shown in FIG. 7, and the plurality of knock pins 5 are supplied by the hydraulic pressure supplied to the oil passage 50 in the plunger 47.
.. Project into the locking hole 52 on the body 48 side to maintain the plunger 47 in the lower movement position even when the supply oil pressure is released, while the plunger 47 in the lower movement position shown in FIG. When returning to the normal position shown in FIG. 6, when hydraulic pressure is applied to a plurality of ports 53 at positions corresponding to the outer end surfaces of the knock pins 51, the knock pins 51 enter the oil passage 50, and the coil springs 45 move. , 45 so that the plunger 47 returns to the normal position shown in FIG.

In this embodiment, as shown in FIG. 6, the swing support end of the high-speed swing arm 34 is urged to the upper side on the actuator 46 side by the spring force of the coil springs 45, 45, so that the high-speed swing is achieved. When the swing support end of the arm 34 is moved upward, the high-speed tappet 36 is set at a position separated from the cam profiles of the low-speed and high-speed cams 26 and 27, and only the roller follower 38 is used for the low-speed. Since the cam 26 comes into contact with the cam profile of the cam 26, the movement of the high-speed swing arm 34, which is movable with the rocker shaft 33 as a swing fulcrum, is simultaneously transmitted to the two intake valves 10 and 11 via the respective elements 37, 39 and 40. Thus, it is possible to obtain a valve timing at a low speed with a small valve lift.

As shown in FIG.
When the swing support end of the high-speed swing arm 34 is moved downward, the high-speed swing arm 34 rotates counterclockwise in FIG. Since it is set at a position where it abuts on the cam profile of the cam 27, the movement of the high-speed swing arm 34, which moves with the rocker shaft 33 as a swing fulcrum, causes the two intake valves 10, 37 to move through the respective elements 37, 39, 40. 11, the valve timing at a high speed with a large valve lift can be obtained.

Incidentally, the above-described second valve variable mechanism 31
Drives the remaining one intake valve 12 of the three intake valve sides, and the first variable valve mechanism 30 is provided on both sides of the high-speed swing arm 34 with the low-speed rocker arms 39 and 4.
0, the second variable valve mechanism 3
Numeral 1 is provided with one low-speed rocker arm 54 on one side of the high-speed swing arm.

That is, as shown in FIG. 2, the second variable valve mechanism 31 has a low-speed roller follower 38 at a position corresponding to the low-speed cam 28, and a high-speed swing arm 34 at a position corresponding to the high-speed cam 29. The low-speed rocker arm 5 is provided at a position corresponding to the intake valve 12.
4 is provided so that the above-described three members of the low-speed rocker arm 54, the high-speed swing arm 34, and the low-speed roller follower 38 are swingably and integrally linked with the pin 37.

The low speed cam 28 corresponding to the second variable valve mechanism 31 has a larger valve lift than the low speed cam 26 corresponding to the first variable valve mechanism 30. The cam profile is set to be large, and a swirl S is formed at a low speed as shown in FIG.

Further, the distance between the low-speed roller follower 38 as the low-speed cam contact portion of the second variable valve mechanism 31 and the camshaft bearing 23 is reduced by the low-speed cam of the first variable valve mechanism 30. The distance between the low-speed roller follower 38 as the contact portion and the camshaft bearing 22 is set to be short.

Furthermore, the tappets 36, 36 as the high-speed cam contact portions of the first and second variable valve mechanisms 30, 31, respectively, are camshaft bearings 22, 23 for supporting the intake camshaft 20. And is located on the side close to. That is, the tappet 36 of the first variable valve mechanism 30 for common drive of the two valves is connected to one of the camshaft bearings 2.
The tappet 36 of the second variable valve mechanism 31 for independently driving one valve is disposed on the side close to the other camshaft bearing 23.

The pins 37, 37 of the first and second variable valve mechanisms 30, 31 are, as apparent from FIG. 2, the pins 37 on the first variable valve mechanism 30 side.
And a pin 37 on the second variable valve mechanism 31 side.

Since the other points of the second variable valve mechanism 31 are the same as those of the first variable valve mechanism 30, the second variable valve mechanism 31 of FIG. The same sign is used for the part that works
Numbers are attached and detailed explanations are omitted. In FIG. 2, reference numeral 55 denotes a plug hole for disposing an ignition plug, and in FIGS. 1, 6, and 7, reference numerals 26BC and 27BC denote base circles of the corresponding cams 26 and 27, respectively.

FIG. 8 shows a control circuit of the valve drive device of the engine. The CPU 60 controls the valve via the actuator 46 in accordance with a program stored in the ROM 61 based on necessary inputs such as the engine speed Ne and the engine load CE. Drive control of the variable mechanisms 30, 31, 32,
The RAM 62 stores necessary data and maps such as a map as shown in FIG.

Here, the above-mentioned CPU 60 does not directly drive the actuator 46, but drives the above-mentioned actuator 46 via an electromagnetic solenoid valve provided on a hydraulic supply line, but is schematically shown in FIG. ing.

In the map shown in FIG. 9, the horizontal axis represents the engine speed Ne and the vertical axis represents the engine load CE.
High load high rotation region α for driving the actuator 46
And a low-load low-rotation region β in which the actuator 46 is not driven.

FIG. 10 shows an example of changes in the valve timing and the valve lift by the variable valve mechanism. The first and second variable valve mechanisms 30 and 31 on the intake side are switched to a low speed mode as shown in FIG. When the first and second variable valve mechanisms 30 and 31 are switched to the high-speed mode as shown in FIG. 7, the intake and exhaust overlap period becomes longer. .

The illustrated embodiment is configured as described above, and the operation will be described below. When the CPU 60 determines that the operating state of the engine is in the low-load low-rotation region β shown in FIG. 9, the actuator 46 maintains the state shown in FIG. 6, so that the swing support end of the high-speed swing arm 34 is in the upper position. , And the tappet 36 is separated from the high-speed cam 27, so that the two intake valves 10 and 11 are connected to the first valve variable mechanism 30.
, And is driven by the low-speed cam 26.

On the other hand, when the CPU 60 determines that the operation state of the engine is in the high-load high-rotation region α shown in FIG. 9, the swing support end of the high-speed swing arm 34 is pushed down by driving the actuator 46. The swing support end of the high-speed swing arm 34 is located at the lower position as shown in FIG. 7, and the tappet 36 (high-speed cam contact portion) contacts the high-speed cam 27. , 11 are driven by a high speed cam 27 via a first variable valve mechanism 30.

That is, the above-described high-speed swing arm 3
When the fourth tappet 36 (high-speed cam contact portion) is at a position away from the high-speed cam 27 (see FIG. 6), the movement of the low-speed cam 26 is controlled by the low-speed roller follower 38 (low-speed cam contact).
) And low-speed valve timing transmitted to the intake valves 10 and 11 via the low-speed rocker arms 39 and 40, while the high-speed swing arm 3 described above can be obtained.
When the fourth tappet 36 (high-speed cam contact portion) is in a position where it contacts the high-speed cam 27 (see FIG. 7), the high-speed cam 2
7 is transmitted to the intake valves 10 and 11 via the high-speed swing arm 34 and the low-speed rocker arms 39 and 40, so that high-speed valve timing can be obtained.

The operation of the first variable valve mechanism 30 for simultaneously driving the two intake valves 10 and 11 of the three intake valves is described above.
The function of the second variable valve mechanism 31 for independently driving the second valve 2 is substantially the same.

Further, the tappets 36, 31 in the first and second variable valve mechanisms 30, 31 are used.
36 (high-speed cam abutting portion) with the camshaft bearings 22 and 23
Since the tappets 36, 36 (high-speed cam contact portions) that receive a relatively large load at high speed are located close to the camshaft bearings 22, 23, the intake camshaft 20 is prevented from bending. Be able to
There is an effect that the input of the valve driving reaction force to the camshaft bearings 22 and 23 is made substantially uniform, and the durability of the camshaft bearings 22 and 23 can be improved.

The above tappets 36, 36 (high-speed cam)
When the contact portion is set near the center between the camshaft bearings 22 and 23, a large load acts on the intake camshaft 20 at high speed, and the intake camshaft 2
Although bending occurs at 0, such a problem can be solved by the above configuration.

Further, the remaining one of the three intake valves is provided.
12 corresponds to the second valve variable mechanism 31 that independently drives
The low speed cam 28 is connected to two of the three intake valves 10 and 1.
1 corresponding to the first variable valve mechanism 30 that drives the
With respect to the speed cam 26, the valve lift amount is increased.
The cam profile is set large, so swirl is assured
S can be formed .

In addition, the second variable valve mechanism 31
Roller follower 38 (low-speed cam contact part) and camshaft shaft
The distance between the first valve variable mechanism 30 and the
Lafollower 38 (low-speed cam contact part) and camshaft bearing 2
2 is set shorter than the distance between
When forming the valve S, the suction corresponding to the first variable valve mechanism 30 is performed.
A second valve is available for a predetermined portion of the air camshaft 20.
A predetermined portion of the intake camshaft 20 corresponding to the changing mechanism 31
Large load acts on this, but this large load acts
The side has a short separation distance from the camshaft bearing 23.
Especially at low speeds (while swirling)
There is an effect that bending of the shaft 20 can be prevented.

Further, since the low-speed cam contact portions that contact the low-speed cams 26 and 28 at low speeds which are more frequently used than at high speeds are constituted by the roller followers 38, 38, the sliding resistance can be reduced. There is an effect that can be done .

[0058] is found in addition, the pin 37 described above, since the split pin 37 of the first variable valve mechanism 30 side and the pin 37 of the second variable valve mechanism 31 side, the first above and the second The movement of each of the variable valve mechanisms 30 and 31 can be made different from each other, and the swirl S can be more reliably generated.

In correspondence between the structure of the present invention and the above-described embodiment, the three-valve structure of the present invention corresponds to the intake-side three-valve structure of the embodiment. , The high-speed cam contact portion corresponds to the tappet 36, and the bearings are the camshaft bearings 22, 2.
3, the camshaft corresponds to the intake camshaft 20, but the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a valve drive device for an engine according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an explanatory diagram showing a layout of each intake / exhaust port with respect to a cylinder bore and a swirl generation state.

FIG. 4 is a perspective view of a first variable valve mechanism.

FIG. 5 is an exploded perspective view of the first variable valve mechanism.

FIG. 6 is an explanatory diagram showing a state in which low-speed valve timing is set.

FIG. 7 is an explanatory diagram showing a state in which high-speed valve timing is set.

FIG. 8 is a block diagram of a control circuit.

FIG. 9 is an explanatory diagram of a map stored in a RAM.

FIG. 10 is an explanatory diagram showing an example of changes in valve timing and valve lift by a variable valve mechanism.

FIG. 11 is an explanatory diagram of a conventional engine valve drive device at low speed.

FIG. 12 is an explanatory diagram of a conventional engine valve drive device at high speed.

[Explanation of symbols]

10, 11, 12 ... intake valve 13 ... exhaust valve 20 ... intake camshaft (camshaft) 22, 23 ... camshaft bearing (bearing) 26, 28 ... low-speed cam 27, 29 ... high-speed cam 30 ... first valve Variable mechanism 31: second valve variable mechanism 34: high-speed swing arm 36: tappet (high-speed cam contact part) 37: pin 38: low-speed roller follower (low-speed cam contact part) 39, 40, 54: low-speed rocker arm 46 ... Actuator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01L 13/00 301 F01L 1/18 F01L 1/26

Claims (3)

(57) [Claims] 1. A valve drive device for an engine in which a low speed cam and a high speed cam are integrally formed on a cam shaft for driving an intake / exhaust valve, the valve drive device being disposed on one of the intake valve and the exhaust valve. A plurality of valves having a three-valve structure, a first variable valve mechanism for commonly driving two of the three valves, and a second variable valve mechanism for independently driving the remaining one of the three valves. the provided, each variable valve mechanism and the low-speed cam contact portion in contact with the said low-speed cam, and the high-speed cam abutting portion abuts on the high-speed cam, the high-speed
By vertically moving the cams contact portion, both the high-speed arm abutment and the high-speed cam having an actuator for changing the abutting state and separated states respectively, each of said respective variable valve mechanism High-speed cam contact part
The cam shaft is supported more than the low-speed cam contact portion, and is disposed on a side close to the bearing located on both sides of each cylinder, and each of the cams is selectively contacted with the corresponding cam contact portion. and when the low-speed cam the movement of the cam is configured to be transmitted to the intake and exhaust valves through the variable valve mechanism, corresponding to the second valve varying mechanism, the
The valve for the low speed cam corresponding to the variable first valve mechanism
Set cam profile large to increase lift
And, slow cam contact portion and the variable mechanism of the second variable valve mechanism
Between the bearing and the bearing located on one side of the cylinder
The low-speed cam contact portion and the variable mechanism of the first variable valve mechanism
The distance between the cylinder and the bearing located on the other side
Engine valve drive set shorter than this . 2. An engine valve driving device according to claim 1, wherein said low-speed cam contact portion is constituted by a roller follower. 3. The variable valve mechanism according to claim 1, wherein each of said variable valve mechanisms is a rocker for low speed.
Swing arm for high speed and rocker arm for low speed
And a pin for linking the high-speed swing arm with the first valve.
2. The valve drive device for an engine according to claim 1, wherein the valve drive device is divided into a pin on a variable mechanism side .