JPH07103812B2 - Valve operating system with a function of changing the valve operating characteristics of an 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 internal combustion engine having a control function for changing the operating characteristics of an intake valve or an exhaust valve by selectively connecting and disconnecting a plurality of rocker arms according to the engine speed. The present invention relates to a valve train having a valve operating characteristic changing function.

[0002]

2. Description of the Related Art As one of the valve operating devices having the above-mentioned valve actuation characteristic changing function, one cam shaft is arranged substantially in the center of a cylinder head, and rocker shafts are provided above and to the left and right of the cam shaft, respectively. The rocker shafts are arranged in parallel, and two rocker arms on the intake side and two rocker arms on the exhaust side are arranged on the rocker shafts so that the central portions of the rocker arms are swingably supported. There is a structure in which the operating characteristics of a desired intake valve or exhaust valve are changed in accordance with the rotational state of the engine by releasing the interlocking of both.

[0003]

By the way, in an internal combustion engine for a vehicle, generally, in order to obtain a high output, the intake valve has a larger diameter than the exhaust valve and the lift amount is set larger. On the other hand, on the intake valve side and the exhaust valve side, the valve spring load on the intake side is set higher than that on the exhaust side in order to try to suppress the valve bounce to the same extent while maintaining the same engine speed. Therefore, the cam transmission force acting on the rocker arm becomes larger on the intake side.

Therefore, even in the valve operating device with the valve actuation characteristic changing function which is used by interlocking the rocker arms with each other through the pins or releasing the interlocking as described above, an unbalanced load is not applied to the rocker arms as much as possible. It is necessary to take care so that uneven wear does not occur on the slipper surface of the rocker arm or the rocker arm support portion of the rocker shaft, but at this time, it is necessary to take care not to apply an unbalanced load or the like especially to the rocker arm on the intake side.

The present invention has been made in view of the above circumstances, and a function for changing the valve operation characteristic of an internal combustion engine in which an unbalanced load is not applied to the rocker arm and uneven wear is less likely to occur in the slipper portion of the rocker arm and the rocker arm support portion of the rocker shaft. An object of the present invention is to provide a valve operating device with a valve.

[0006]

In order to achieve the above object, in the present invention, two rocker arms on the intake side are arranged adjacent to each other, and are located between the rocker shaft and the valve contact portion .
By connecting and separating the rocker arms, the above-mentioned 2
A change mechanism capable of changing one valve operating characteristic of the intake valve provided is arranged, and the intake side cam part of the cam shaft and the slipper part of the intake side rocker arm are arranged with reference to the axial direction of the rocker shaft. It characterized thereby placed substantially centrally between the intake valves, that the slipper portions of the exhaust-side cam portion and exhaust-side rocker arm of the cam shaft, arranged outside of the two exhaust valves of the axial direction of the rocker shaft as a reference I am trying.

[0007]

When both the rocker arms on the intake side are connected together (usually, they are connected during high rotation), the connected rocker arms have one end for lifting the valve from the cam shaft when the valve is operating. And the load by the valve spring is applied to the other end. At this time, since the intake side cam part of the cam shaft and the slipper part of the intake side rocker arm are arranged between both intake valves with reference to the axial direction of the rocker shaft, the load applied from the cam shaft is applied from the valve spring. It will be applied to the middle part of the load.

Therefore, an unbalanced load is unlikely to be applied to the coupled rocker arm, and uneven wear of the rocker arm supporting portion of the rocker shaft and the slipper portion of the rocker arm is prevented in advance.

An unbalanced load may be applied to the rocker arm on the exhaust side, but since the valve spring load on the exhaust side is set smaller than the valve spring load on the intake side, its influence is small. That is, the uneven wear of various members on the intake side where the valve spring load is large is preferentially prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to (a) and (b). In this embodiment, the present invention is applied to a 4-valve engine having a valve resting type valve operating characteristic changing mechanism. That is, this engine has two intake valves and two exhaust valves,
In addition, it is a type having only one cam shaft, and one of the two intake valves and one of the two exhaust valves can take a valve operating state and a valve resting state, respectively.
Moreover, the valves that switch between the rest state and the operating state are arranged so as to cross each other when viewed from above.

FIG. 1 is a view of the engine with the cylinder head cover removed from above, FIG. 2 is a sectional view taken along line II--II in FIG. 1, and FIG. 3 is a sectional view taken along line III--III.

In these drawings, reference numeral 1 is a cylinder head, 2 is a cylinder head cover (see FIGS. 2 and 3), and one cam shaft 3 is rotatably supported at substantially the center of the cylinder head 2. The cam shaft 3 is the same as the cam shaft 3
It rotates in conjunction with the rotation of a crankshaft (not shown) via a sprocket 4 and a chain 5 which are screwed together.

This engine has two intake valves 6 and two exhaust valves 7, and the camshaft 3 has cam portions 3a and 3b corresponding to the intake valve 6 and the exhaust valve 7, respectively.
An intake-side rocker shaft 8 and an exhaust-side rocker shaft 9 are provided above the cam shaft 3 and supported by the cylinder head 1 so as to be parallel to the cam shaft 3 and on both left and right sides of the cam shaft 3. . The rocker shaft 8 on the intake side has a normal-acting rocker arm 10 and a switching type rocker arm 11 supported at the central portions of the rocker arm 10 so as to be swingable and adjacent to each other. The rocker arm 12 and the switchable rocker arm 13 are swingably and adjacently supported at their central portions. Further, as described above, in this engine, the intake-side normal-action rocker arm 10 and the exhaust-side normal-action rocker arm 12 are arranged so as to cross each other when viewed from above.

As shown in FIG. 2, the normal-action rocker arms 10 and 12 contact the cam portions 3a and 3b of the cam shaft 3 with the slipper portions 10a and 12a, and follow the cam portions 3a and 3b. It is swingably driven around the shafts 8 and 9 to constantly open and close the intake valve 6 and the exhaust valve 7.

Here, the intake side cam portion 3a of the cam shaft 3 and the slipper portion 10a of the intake side rocker arm 10 are arranged between the intake valves 6 and 6 with reference to the axial direction of the rocker shaft 8. In addition, the exhaust side cam portion 3b of the cam shaft 3
And the slipper portion 10b of the intake side rocker arm 10 is
Both intake valves 7, 7 with reference to the axial direction of the rocker shaft 8
Is located outside of. In FIG. 2, reference numeral 14 is a valve guide, 15 is a valve spring, 16 is a valve spring retainer, and 17 is an ignition plug arranged substantially in the center of the cylinder head.

The switching type rocker arms 11 and 13
Is operated by the control mechanism 21 in accordance with the rotation state of the engine (for example, the number of rotations), and for example, when the engine is in the high speed rotation range, it operates integrally with the rocker arms 10 and 12 of the normal motion type to drive the corresponding valve. On the other hand, when the engine is in the low speed rotation range, the engine is stopped and the corresponding valve is not driven.

The control mechanism 21 connects the switching type rocker arms 11 and 13 to the normal type rocker arm 10 via a pin.
Drive system 22 for interlocking with 12 and releasing the interlock
And a hydraulic operating system 23 for operating the drive system 22 in accordance with the engine speed.

The control mechanism 21 will be described by taking the intake side as an example. A plunger pin 24, which can be inserted into the cylindrical hole of the switching type rocker arm 11, is slidably protruded by a spring 25 on the normal motion type rocker arm 10. The locker arm 11 is biased in the direction and is housed therein. A return pin 27 that receives the force of a return spring 26 and pushes back the plunger pin 24 is housed in the switchable rocker arm 11.
The hydraulic chamber 28 formed on the back side of the rocker shaft 4 is provided with an oil passage 29 formed in the stationary rocker arm 10.
It communicates with the oil passage 30 inside. In addition, the control mechanism 21
It is located between the rocker shaft and the valve contact part of the rocker arm.
It

Here, the plunger pin 24, the pin 27, and the springs 25 and 26 constitute the drive system 22 of the control mechanism.

On the other hand, to explain the control mechanism operating system 23, reference numeral 31 in FIG. 3 denotes an oil passage provided in the cylinder head cover 2, and the base end side of this oil passage 31 is a discharge side (not shown) of an oil pump. Connected to a pressure oil supply source), the tip end side extends to the cam shaft bearing portion 32, and communicates with a circumferential groove 33 formed along the outer circumference of the cam shaft 3 there. Also,
Four holes 34 extending in the radial direction are provided at positions facing the circumferential groove 33 of the cam shaft 3 at intervals of 90 degrees in the circumferential direction (FIG. 3).
reference).

A governor shaft (switching valve) 35 is arranged in the cam shaft 3 so as to be rotatable relative to the cam shaft 3. A centrifugal governor 36 is connected to the end of the governor shaft 35. The arm 36a of the centrifugal governor 36
As shown in FIG. 4, when the governor weight 36b attached to the arm 36a is engaged with the notch 35a formed in the end surface of the governor shaft 35 and moves outward by the centrifugal force, the governor shaft 35 is rotated.

On the outer periphery of the governor shaft 35, as shown in FIG. 5, a circumferential groove 37 is provided at a position facing the hole 34 of the cam shaft 3.
Is formed, and four vertical grooves 38 extending from the circumferential groove 37 to the governor 36 side along the axial direction of the governor shaft 35 are provided at intervals of 90 degrees in the circumferential direction, and the vertical grooves 38 extend in the radial direction between the vertical grooves 38. A hole 39 is provided, and the return oil passage 4 communicating with the hole 39 is further provided inside the governor shaft 35.
0 is provided. The oil in the return oil passage 40 is
It is guided to the outside of the cam shaft 3 through the hollow hole 3c of the cam shaft 3 and the hole 3d formed between the cam portions 3a and 3b, and lubricates a predetermined sliding portion in the engine (see FIG. 3).

A hole (oil discharge hole) 41 extending radially is formed in the camshaft 3 at a position facing the hole 39 of the governor shaft 35 and at the same circumferential position as the hole 34.
Four holes are provided for each 0 degree, and the holes 41 are arranged and provided on the same plane orthogonal to the axis of the cam shaft 3. And, in the cam shaft bearing portion 32 of the cylinder head 1,
A circumferential groove 42 is formed so as to surround the hole 41.

As shown in FIGS. 1 and 2, the cylinder head 1 is provided with an oil passage 44 that extends linearly from the cam shaft bearing portion 32 to the rocker shaft bearing portion 43.
By the circumferential groove 42 and the oil passage 30 in the rocker shaft 8.
And are in communication.

The control mechanism operating system 23 is constituted by the oil passages 30, 31, 44, the governor shaft 35, the centrifugal governor 36, etc. described above.

In the exhaust side control mechanism, the arrangement of the plunger pin 24, the return pin 27, and the springs 25 and 26 attached to them is different from that of the intake side between the normal type rocker arm and the switching type rocker arm. Although it is different, the basic configuration is the same as that on the intake side, and here, the same components as those on the intake side are designated by the same reference numerals and the description thereof will be omitted.

Further, as shown in FIG. 2, the switching type rocker arms 11, 1 on the inner surface of the cylinder head cover 2 are provided.
At the location opposite to 3, the one end of the leaf spring 51 has a bolt 52
Is fixed by. The leaf spring 51 urges the rocker arms 11 and 13 so that the actuating portion abuts the valve stem end. Further, the leaf spring 51 is provided on the inner surface of the cylinder head cover 2 facing the other end of the leaf spring 51.
A stopper 53 is provided integrally with the cylinder head cover 2 to prevent the splashing. The stopper 53 does not have to be provided integrally with the cylinder head cover 2, but may be provided as a separate body and integrally attached to the cylinder head cover 2 by a fixing means such as a screw. The material is not limited to metal and may be non-metallic material such as hard nylon.

Next, the operation of the valve operating device will be described. When the engine is in the low speed rotation range, the switchable rocker arms 11 and 13 are in a rest state.

That is, the centrifugal governor 36, which rotates integrally with the cam shaft 3, is in a closed state because its rotation is low, and the governor shaft 35 is as shown in FIG.
The vertical groove 38 is displaced from the position where the holes 34 and 41 are communicated with each other to block the holes 34 and 41, and the oil passage 30 in the rocker shafts 8 and 9 is surrounded by the oil passage 44 and the cam shaft bearing portion 32. The return oil passage 40 in the governor shaft 35 communicates with the groove 42, the hole 41, and the hole 39 of the governor shaft 35 overlapping the hole 41.

Therefore, the pressure oil from the oil pump (not shown) is not supplied to the hydraulic chamber 28 of the intake type normal rocker arm 10 (the switching rocker arm 13 on the exhaust side), and the pressure is released. , Plunger pin 24
Hydraulic pressure does not work on the back of the. Therefore, the plunger pin 24 is pushed back by the return pin 27, and the stationary rocker arms 10 and 12 and the switching type rocker arm 11 are moved.
Since the motions of the normally-acting rocker arms 10 and 12 that do not engage with the cam portions 13a and swing and rotate following the cam portions 3a and 3b are not transmitted to the switching rocker arms 11 and 13, the corresponding intake valve 6 and exhaust valve 7 is kept closed, that is, in a valve rest state.

After that, when the engine speed reaches a certain value, the governor weight 36b of the centrifugal governor 36 moves outward, and the arm 36a causes the notch 35a of the governor shaft 35 to rotate the governor shaft 35 at a predetermined angle. The vertical groove 38 of the governor shaft 35 is shown in FIG.
As shown in (a), the holes 34 and 41 formed in the cam shaft 3 are communicated with each other. Therefore, the pressure oil supplied from the main pump to the oil passage 31 is supplied to the circumferential groove 33, the hole 34,
The oil is supplied to the oil passage 44 through the circumferential groove 37, the vertical groove 38, the hole 41, and the circumferential groove 42, and then to the hydraulic chamber 28 via the oil passages 30 and 29 in the rocker shafts 8 and 9.

The leak hole 39 is displaced to a position where the hole 41 of the camshaft 3 and the return oil passage 40 do not communicate with each other.
As a result, on the intake side, the plunger pin 24 projects into the switching type rocker arm 11 (the opposite is true on the exhaust side), and the normal action type rocker arm and the switching type rocker arm are engaged. Therefore, the cam portions 3a, 3
The rocker arms 10 and 1 of the normal type that swing and rotate by b
The switching type rocker arms 11 and 13 swing and rotate integrally with 2, and all the intake valves 6 and the exhaust valves 7 are driven.

Further, in the internal combustion engine having the above-mentioned structure, when the engine is in a high rotation speed range and both the normal action type and switching type rocker arms 10 and 11 on the intake side are connected together, when the valve is operated, The connected rocker arms 10 and 11
A load for lifting the valve 6 from the cam shaft 3 is applied to one end of the above, and a load by the valve spring 15 is applied to the other end. At this time, the intake side cam portion 3a of the cam shaft 3 and the slipper portion 10a of the intake side rocker arm 10
With reference to the axial direction of the rocker shaft 8, both intake valves 6, 6
The load applied from the camshaft 3 is applied to the intermediate portion of the load from the valve springs 15, 15.

Therefore, the rocker arm 1 in the connected state
Unbalanced loads are less likely to be applied to 0 and 11, and as a result, uneven wear of the rocker arm supporting portion of the rocker shaft 8, the slipper portion 10a of the rocker arm 10 and the like is prevented in advance.

Since the exhaust side cam portion 3b of the cam shaft 3 and the slipper portion 12a of the exhaust side rocker arm 12 are arranged outside the exhaust valves 6 and 6 with respect to the axial direction of the rocker shaft 9, the exhaust gas is exhausted. When both rocker arms 12 and 13 on the side are connected, an unbalanced load may be applied to the rocker arms. However, since the valve spring load on the exhaust side is set to be smaller than the valve spring load on the intake side, its influence is affected. Is small.

When the engine is in the low speed range and the intake side rocker arms 10 and 11 are disconnected from each other, an unbalanced load is applied to the normal action type rocker arm 10. In this case, Since the rotation is low, the impact load applied to the rocker arm 10 and the rocker shaft 8 supporting it is small,
The effect can be ignored.

Further, in the internal combustion engine having the above structure,
Since the leaf spring 51 is provided on the inner surface of the cylinder head cover 2 at a position opposed to the switching type rocker arms 11 and 13, the switching type rocker arm is affected by a frictional force from an adjacent normal motion type rocker arm while the valve is at rest. Although it receives the force to follow and shake, it does not shake.

Further, when the leaf spring 51 receives a reaction force from the rocker arm when suppressing the swing of the rocker arm, the free end side may bounce outward, but a stopper 53 is provided above the free end side of the leaf spring 51. Therefore, the leaf spring 51 can be prevented from jumping.

[0039]

As described above, according to the present invention, when both the rocker arms on the intake side are connected together, the connected rocker arms at the time of valve actuation have a valve from the cam shaft at one end thereof. The load to lift is
The load by the valve spring is applied to the other end, but the intake side cam part of the cam shaft and the slipper part of the intake side rocker arm are arranged between both intake valves based on the axial direction of the rocker shaft. The load applied from the camshaft is applied to the intermediate part of the load from the valve spring. As a result, an unbalanced load is less likely to be applied to the coupled rocker arm, and uneven wear of the rocker arm, the rocker arm supporting portion of the rocker shaft supporting the rocker arm, and the slipper portion of the rocker arm is prevented in advance. In addition, the change mechanism is a rocker axis
Since it is located between the valve contact part,
Arrangement of the slipper part without interference with the slipper part
The degree of freedom is increased, and the changing mechanism and the arrangement of slippers are changed.
Avoid placing them in the same location
Therefore, for example, comparing them when arranging them vertically
All in all, the engine can be made lighter and more compact.

[Brief description of drawings]

1 to 6 (a) and (b) show an embodiment of the present invention, FIG. 1 is a plan view showing a state in which a cylinder head cover is removed,

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

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a side view of the centrifugal governor,

FIG. 5 is a perspective view of a governor shaft,

6A and 6B are cross-sectional views taken along line VI-VI in FIG. 3, showing different states in which the governor shafts are switched.

[Explanation of symbols]

 1 Cylinder shaft 2 Cylinder head 3 Cam shaft 3a, 3b Cam part 6 Intake valve 7 Exhaust valve 8 Intake side rocker shaft 9 Exhaust side rocker shaft 10, 12 Normal type rocker arm 10a, 12a Slipper part 11, 13 Switchable rocker arm 17 Ignition Plug 21 Control mechanism (change mechanism) 22 Control mechanism drive system 23 Control mechanism operation system 35 Governor shaft 36 Centrifugal governor 52 Bolt 53 Stopper

Claims (1)

[Claims] 1. An intake cam and a substantially central portion of a cylinder head.
One cam shaft having an exhaust cam is arranged, and rocker shafts are arranged above and to the left and right of the cam shaft in parallel with the cam shaft,
Two rocker arms on the intake side and two rocker arms on the exhaust side are arranged on the rocker shafts so that the central portions of the rocker arms are swingably supported, and the rocker arms open and close the intake valves and exhaust valves provided for each two rocker arms. In addition, in a four-valve engine in which a plug is arranged in the center of the combustion chamber of the cylinder head, the two rocker arms on the intake side are arranged adjacent to each other and are located between the rocker shaft and the valve contact portion. Te, by connecting separate them rocker arms, the change mechanism which enables changing one of the valve operating characteristic of the two provided et al were the intake valve arranged, slippers intake side cam portion and the intake side rocker arm of the cam shaft part of, as well as arranged in a substantially central portion between the intake valves to the axial direction of the rocker shaft as a reference, the exhaust-side cam portion and exhaust-side rocker arm of the cam shaft Ripper portion, the valve operating characteristic changing function valve operating system for an internal combustion engine in the axial direction, characterized in that arranged outside of both the exhaust valves as the basis for the rocker shaft.