JP2783080B2 - Intake / exhaust valve actuator for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust valve operating device for an internal combustion engine for switching the opening and timing of an intake valve and an exhaust valve between a low speed operation and a high speed operation.

[0002]

2. Description of the Related Art Conventionally, lift characteristics of an intake valve or an exhaust valve are changed according to an operation state in order to achieve both a torque at a low to medium speed operation and an output at a high speed operation. Alternatively, it is known to control the intake / exhaust amount (see Japanese Patent Application Laid-Open No. 63-167003).

[0003] Such a valve operation timing control device includes a rocker arm that slides on a drive system of an intake valve and an exhaust valve and that is in sliding contact with a low speed cam having a cam profile suitable for medium to low speed operation of the engine. Another rocker arm slidably contacts with a high-speed cam having a cam profile suitable for high-speed operation of the engine. The switching between the high-speed cam and the low-speed cam is performed by controlling the operation of each rocker arm. Then, as shown in FIG. 11, the overlap between the exhaust stroke and the intake stroke is increased during high rotation.

Here, as a device for controlling the operation of the rocker arm, there is a device disclosed in Japanese Patent Application Laid-Open No. 3-43612. This device is shown in FIGS. That is, in the low-speed rocker arm 110, its main body 111
Has a cylindrical space portion 112 formed therein. In the space 112, a plunger 113 in which a large section 113a, a small section 113b, and a spring receiving section 113c are integrally formed in this order.
And a spring 114 whose one end is in contact with the spring receiving portion 113c. The space 112 has an opening 116. The intake valve 123 attached to the cylinder head 122 is always urged upward in FIG. 14 by the return spring 124, and the valve shaft of the intake valve 123 is
The tip of 125 is set so as to always contact the tappet screw 121.

On the other hand, the high-speed rocker arm 130 has a high-speed cam follower 132 formed on the upper surface of a main body 131, and the main body 131 has a main body of the low-speed rocker arm 110 on a surface opposite to the high-speed cam follower 132 side. A projection 133 that can enter the space portion 112 from the hole 116 formed in the 111 is integrally formed. In the above configuration, at the time of low-speed operation, the plunger 113 is moved by the spring 114 as shown in FIG.
Is held in the position. That is, the space 1 corresponding to the hole 116
At the position 12, the small cross section 113b of the plunger 113 is located. In this state, if the high-speed rocker arm 130 is swung by the high-speed cam 142, the projection 133 does not contact the small cross section 113b of the plunger 113, so that the high-speed rocker arm 130 may have no effect on the low-speed rocker arm 110. Absent. As a result, the low-speed rocker arm 110
Is swung according to the cam shape of the low-speed cam 141.

Next, at the time of high-speed operation, the plunger 113 moves rightward in FIG. 14 due to hydraulic pressure or the like, and a large section 113a of the plunger 113 is placed in a space 112 corresponding to the hole 116.
Is located. As a result, the projection of the high-speed rocker arm 130
133 tries to get into the space 112 through the hole 116,
Since the large cross section 113a exists, it cannot enter the space 112, and the projection 133 of the high-speed rocker arm 130 is
Pressing 113a results in pushing the free end of the low speed rocker arm 110 downward in FIG. That is, the low-speed rocker arm 110 is swung according to the cam shape of the high-speed cam 142 having a larger swing width than the low-speed cam. As a result, the movement stroke of the intake valve 123 also increases for the intake valve 123 where the tip of the valve shaft 125 is always in contact with the tappet screw 121, and the intake air flow rate and the exhaust air amount increase.

[0007]

However, in such a conventional apparatus for controlling the switching of the intake and exhaust valves of an internal combustion engine, the plunger 113 for performing the switching and the plunger 113 are housed. The space 112 is arranged below the high-speed rocker arm 130. Here, since the low-speed rocker arm 110, the high-speed rocker arm 130, and the like are members that swing at a high speed, it is necessary to ensure sufficient rigidity. Can not be extremely thin.

That is, a device for controlling the switching of the intake and exhaust valves is interposed between the high-speed rocker arm 130 and the cylinder head 122, so that it is difficult to make the parts related to the device extremely small. Here, the intake valve 123 is configured to include a return spring 124 and the like. However, since the return spring 124 always sufficiently urges the intake valve 123 upward in FIG. I have. Therefore, the low-speed rocker arm 110 and the high-speed rocker arm
There is almost no space below 130. Therefore, in a configuration in which a device that performs switching control of the intake and exhaust valves is disposed below the low-speed rocker arm 110 and the high-speed rocker arm 130, the height of the cylinder head 122 in the height direction increases. Therefore, the rocker arm 110,
The overall height of the engine is increased in order to avoid interference between 130 and the return spring 124, etc., which is disadvantageous in the layout of the engine room in which the engine is mounted. In addition, the height of the engine room is increased, so that the front projection area is increased and the influence on the overall shape of the vehicle is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and by improving the structure of a device that performs switching control of intake and exhaust valves, the overall height of the engine is suppressed, and when the engine is mounted, An object of the present invention is to provide an intake / exhaust valve operating device for an internal combustion engine that is advantageous in terms of engine room layout.

[0010]

SUMMARY OF THE INVENTION Therefore, the present invention provides a first method.
, A second cam for operating the valve with a larger lift amount or a wider valve opening period than the first cam, a main rocker shaft supported by the cylinder head, and supported swingably by the main rocker shaft. A main rocker arm for opening a valve according to the displacement of the first cam, a sub rocker shaft supported by the main rocker arm,
A sub rocker arm that swings relative to the main rocker arm so as to be rotatable with respect to the main rocker arm, and that is fixed to an end of the sub rocker shaft and swings integrally with the sub rocker arm along a side portion of the main rocker arm. An arm portion and locking means for locking and releasing the arm portion with respect to the main rocker arm are provided.

[0011]

The main rocker arm swings according to the displacement of the first cam, and the sub rocker arm moves to the main rocker arm according to the displacement of the second cam which operates the valve with a larger lift or a wider valve opening period than the first cam. It swings so that it can rotate relative to it. Here, an arm portion that swings integrally with the sub rocker arm along a side portion of the main rocker arm is fixed to an end of the sub rocker shaft. When the locking means locks the swinging operation of the arm with respect to the main rocker arm, the sub rocker arm and the arm are configured to swing integrally, so that the swinging operation of the sub rocker arm is mainly performed. Locked to rocker arm. Accordingly, the swinging motion of the sub rocker arm by the second cam is transmitted to the locking means via the arm and transmitted to the main rocker arm.
The main rocker arm and the sub rocker arm swing about the main rocker shaft.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 10 show two valves having the same function for one cylinder (intake valves and exhaust valves may be used, and the intake valves are shown as intake valves 5 and 5). An embodiment in which the present invention is applied to an internal combustion engine 1 is shown. Each cylinder is provided with a single main rocker arm 11 corresponding to the two intake valves 5 and 5. The base end of the main rocker arm 11 is swingably supported by a cylinder head (not shown) via a main rocker shaft 12 common to each cylinder, and the tip of the main rocker arm 11 is brought into contact with the stem tops of the intake valves 5 and 5. Adjusting screw 14 is nut 15
Is concluded through.

A roller follower 18 is rotatably connected to the main rocker arm 11 via a needle bearing 17 on a shaft 16, and a low speed cam 19 as a first cam is brought into rolling contact with the roller follower 18. I have. The main rocker arm 11 is formed substantially rectangular in plan view, and the main rocker arm 11 is provided with a single sub rocker arm 31 alongside the roller follower 18. A sub rocker shaft 32 is fitted to the base end of the sub rocker arm 31, and is supported so as to be rotatable relative to the main rocker arm 11. Sub rocker shaft 32 is main rocker arm 11
A lever 34 is fixed to one shaft end 33 of the sub rocker shaft 32 by, for example, a key.

The high-speed cam 36 comes into contact with the cam follower 35 of the sub-rocker arm 31, but the sub-rocker arm 31 does not have a portion that comes into contact with the intake valve 5.
Here, below the lower surface 37 of the cam follower section 35, a lost motion spring 39 receiving a pressing force of the sub rocker arm 31 by the high speed cam 36 is interposed together with a lost motion plunger 38.

That is, the sub rocker arm 31 rotates relative to the main rocker arm 11 integrally with the sub rocker shaft 32 according to the high speed cam 36. Here, in the present embodiment, the sub rocker arm 31 and the sub rocker shaft
The lever 32 and the lever 34 rotate integrally. Accordingly, the relative rotation between the main rocker arm 11 and the sub rocker arm 31 is stopped by locking the swinging operation of the lever 34 with respect to the main rocker arm 11 with reference to FIGS. 4, 6 and 10. Will be described.

A hole 26 into which the sub rocker shaft 32 is fitted is formed on one side surface 20 of the main rocker arm 11.
26 and a cam follower portion 35 with respect to the hole 26.
On the opposite side, a hole 21 is formed for slidably fitting the plunger 50. Here, as shown in FIG. 10, the plunger 50 is formed in a cylindrical shape with one end 51 closed and the other end 52 opened, and a groove 55 through which the fixing pin 54 is inserted is formed in the side surface 53. A return spring 56 that urges the closed end 51 of the plunger 50 so that the open end 52 does not protrude from one side surface 20 of the main rocker arm 11 is interposed between the closed end 51 and the fixing pin 54. ing.

The plunger 50 is operated by hydraulic pressure. That is, an oil chamber 22 is defined in the hole 21 behind the plunger 50, a main passage 23 in the main rocker shaft 12, and a branch portion 24 having a large opening area at a location facing the oil chamber 22. There is also a main rocker arm
A communication passage 25 that connects the branch portion 24 and the oil chamber 22 is provided in the inside 11. Then, at the time of high-speed operation, hydraulic oil introduced from an oil pump (not shown) is guided to the oil chamber 22 via the main passage 23, the branch portion 24, and the communication passage 25.

When the hydraulic oil is led to the oil chamber 22, the closed end 51 of the plunger 50 is pressed by hydraulic pressure. Fixing pin
The plunger 50 moves until the abutment with the one end surface of the groove 55, the open end 52 of the plunger 50 protrudes from one side surface 20 of the main rocker arm 11, and the plunger 50 abuts on the lever. Thus, the relative rotation of the lever 34 with respect to the main rocker arm 11 is locked, and the main rocker arm 11 and the sub rocker arm 31 are integrated.

Low-speed cam 19 and high-speed cam adjacent thereto
36 are formed integrally with a common camshaft (not shown), and have different shapes (similar shapes having different sizes) so as to satisfy the valve lift characteristics required when the engine is running at a low speed and at a high speed. Including). Here, the high-speed cam 36 has a profile that makes the valve lift larger than the low-speed cam 19. That is, high-speed cam
36 is a second cam.

Next, the operation of the above configuration will be described.
When the engine is in a predetermined low-speed operation state, the main rocker arm 11 swings according to the profile of the low-speed cam 19,
Each intake valve and exhaust valve are driven to open and close. At this time, although the sub-rocker arm 31 is swung by the high-speed cam 36, the sub-rocker arm 31, the sub-rocker shaft 32 and the lever 34 only move relative to the main rocker arm 11 and hinder the movement of the main rocker arm 11. There is no. Further, the energy of the movement of the sub rocker arm 31 at this time is absorbed by the lost motion plunger 38 and the lost motion spring 39.

On the other hand, when switching from the low-speed cam 19 to the high-speed cam 36, the operating oil pressure is guided to the oil chamber 22, and the two rocker arms 11, 31 are integrated as described above. Rocks. Here, the high speed cam 36 is replaced with the low speed cam 19
When the swing is integrated with the sub rocker arm 31, the roller 18 of the main rocker arm 11 rises from the low speed cam 19, and the intake valve and the exhaust valve Is driven to open and close according to the profile of the high-speed cam 36, and the lift amount is increased.

That is, when the main rocker arm 11 and the sub rocker arm 31 swing by the high speed cam 36, the swing motion of the sub rocker arm 31 by the high speed cam 36 is caused by the lever 34 and the plunger via the sub rocker shaft 32. Transmitted to the main rocker arm 11 and sub rocker arm
31 swings with the main rocker shaft 12 as the swing center.

Since the lever 34 and the plunger 50 are provided on the side opposite to the cam follower portion 35 with respect to the sub rocker shaft 32, the lever 34 and the plunger 50 do not interfere with the sub rocker arm 31 and the main rocker arm
Spaces 60 and 61 are vacant below the 11 and on both sides of the lost motion plunger 38 to avoid interference between the main rocker arm 11 and the return spring 62, thereby effectively utilizing the space, and the lever 34 is moved from the low speed cam 19 to the high speed Cam36
It does not interfere with others etc., it is advantageous in layout,
The total height of the internal combustion engine 1 can be reduced, which is advantageous in terms of engine room layout when the internal combustion engine 1 is mounted.

Further, since the plunger 50 can be disposed close to the main rocker shaft 12, the distance r between the plunger 50 and the main rocker shaft 12 can be reduced, and the length of the lever 34 can be reduced. It can be shortened and can be used more effectively. Further, in this embodiment, the distance r between the plunger 50 and the main rocker shaft 12 can be reduced, so that the rotational inertia mass at the time of the swing can be reduced. Even if the movement is performed at a high frequency, the occurrence of fluttering or the like is avoided, and the variable valve mechanism can respond to high-speed rotation.

Further, in this embodiment, the plunger 50 is provided on the opposite side of the cam follower 35 away from the rear end 40 of the sub rocker arm 32 from the rear end 40 of the sub rocker arm 31, so that the plunger 50 interferes with the sub rocker arm 31. Therefore, the length of the plunger 50 can be made sufficiently long, the diameter of the plunger 50 can be made sufficiently large, the rigidity can be increased, and the durability can be improved.

When hydraulic fluid is introduced into the oil chamber 22 from the oil pump and the plunger 50 is moved toward the open end 52, the distance r between the plunger 50 and the main rocker shaft 12 is reduced. In addition, the length of the communication passage 25 is reduced, the responsiveness of hydraulic pressure switching is improved, and loss of switching timing can be prevented. Further, since the opening area of the branch portion 24 is formed larger than the communication passage 25, even if the main rocker arm 11 provided with the communication passage 25 swings, the main passage 23 in the main rocker shaft 12 and the communication passage 25 always remain. The communication prevents the supply of hydraulic oil from being cut off.

[0027]

As described above, according to the present invention, the first rocker shaft is supported by the main rocker shaft so as to be swingable.
A main rocker arm for opening the valve according to the displacement of the cam, a sub rocker shaft supported by the main rocker arm, and a second cam for operating the valve with a larger lift amount or a wider valve opening period than the first cam. A sub rocker arm swingably rotatable relative to the main rocker arm, an arm fixed to an end of the sub rocker shaft and swinging integrally with the sub rocker arm along a side of the main rocker arm; And locking means for locking and releasing the arm with respect to the main rocker arm, so that the locking means can be provided on the side of the main rocker arm, and a space is provided below the main rocker arm. In this way, the interference between the main rocker arm and the return spring of the valve can be avoided, thereby reducing the overall height of the internal combustion engine. Can. Therefore, when the internal combustion engine is mounted, it is advantageous in terms of engine room layout.

[Brief description of the drawings]

FIG. 1 is a plan view of a valve train showing an embodiment of the present invention.

FIG. 2 is a front view of a valve train showing the embodiment.

FIG. 3 is a side view of the valve train according to the embodiment, taken along the arrow X in FIG. 1;

FIG. 4 is a side view of the valve train according to the embodiment as viewed in the direction of arrow Y in FIG. 1;

FIG. 5 is a longitudinal sectional view taken along line AA in FIG. 1;

FIG. 6 is a transverse sectional view taken along the line BB in FIG. 4;

FIG. 7 is a longitudinal sectional view along the line CC in FIG. 1;

FIG. 8 is a longitudinal sectional view taken along line DD in FIG. 1;

9 is a longitudinal sectional view taken along line EE in FIG.

FIG. 10 is a perspective view showing a configuration of a plunger in the embodiment.

FIG. 11 is a characteristic diagram showing valve switching timing in a conventional valve operation timing control device.

FIG. 12 is a plan view of a valve train showing a conventional example.

13 is a longitudinal sectional view taken along line FF in FIG.

14 is a longitudinal sectional view taken along the line GG in FIG.

[Explanation of symbols]

 5 Intake valve 11 Main rocker arm 12 Main rocker shaft 18 Roller follower 19 Low speed cam 22 Oil chamber 31 Sub rocker arm 32 Sub rocker shaft 34 Lever 35 Cam follower 36 High speed cam 50 Plunger

Claims (1)

(57) [Claims] 1. A first cam, a second cam for operating a valve with a larger lift amount or a wider valve opening period than the first cam, a main rocker shaft supported by a cylinder head, and a main rocker shaft. Swingably supported first
A main rocker arm that opens a valve according to the displacement of the cam, a sub rocker shaft supported by the main rocker arm, and a sub rocker arm that swings relative to the main rocker arm according to the second cam so as to be rotatable relative to the main rocker arm. An arm fixed to an end of the sub rocker shaft and swinging integrally with the sub rocker arm along a side portion of the main rocker arm; a locking means for locking and releasing the arm with respect to the main rocker arm; And an intake / exhaust valve operating device for an internal combustion engine.