JP3430547B2 - Valve system for 4-cycle engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system for a four-cycle engine in which a lift amount and a valve timing of an intake valve and an exhaust valve are variable according to an engine speed range.

[0002]

2. Description of the Related Art In a four-cycle engine valve operating device, a rocker shaft is rotatably supported in a cylinder head and has an eccentric portion eccentric to the shaft center.
A fixed fulcrum type rocker arm pivotally attached to the shaft part of the rocker shaft, a dynamic fulcrum type rocker arm pivotally attached to the eccentric part of the rocker shaft, and these rocker arms are respectively driven to open and close the intake and exhaust valves. There is a configuration provided with low-, medium-speed cams, high-speed cams, and the like having different cam profiles for valve actuation.

In the case of a four-cycle engine equipped with such a valve operating device, in the low and medium speed engine range,
By combining the low and middle speed cams and the fixed fulcrum type rocker arm, the engine performance is set to low and middle speed. Further, in the high-speed rotation range of the engine, the rocker shaft is rotated by the actuator and the fulcrum position of the dynamic fulcrum type rocker arm is changed, so that the high speed cam and the dynamic fulcrum type rocker arm are combined, The engine performance is optimized for high speed.

As described above, by selectively using the low / medium speed cam and the high speed cam, the engine output and torque characteristics are improved from the low / medium speed region to the high speed region, and the power band of the engine is widened.

FIG. 9 is a vertical cross-sectional view of a four-cycle engine 100 equipped with the valve operating device having the above structure. As shown here, if the engine 100 is a DOHC engine,
Two cam shafts 101IN and 101EX having low-, middle-speed cams and high-speed cams (not shown),
Two rocker shafts 102IN and 102EX
Are provided on the intake system side and the exhaust system side, respectively. The two rocker shafts 102IN and 102EX have
Eccentric portions 103 that are eccentric with respect to the axis are provided respectively. In this eccentric portion 103, an eccentric bush which is a separate component is used for the rocker shaft 102 by a pin or the like not shown
It is fixed to IN, 102EX.

The engine 100 includes a rocker shaft 1
A rotation angle regulation means 104 for regulating the rotation angle of 02IN, 102EX is provided. This rotation angle regulation means
For example, the bearing portion 1 of the camshafts 101IN and 101EX
Stopper bolt 10 screwed vertically from the 05 side
It is supposed to be 6.

Rocker shafts 102IN, 102EX
A positioning groove 107 is formed in each of the grooves in the circumferential direction, and the tip portion of the stopper bolt 106 is fitted into the positioning groove 107. Therefore, the rocker shafts 102IN and 102EX can be rotated at an angle until the stopper bolt 106 comes into contact with both ends of the positioning groove 107, and the low-, middle-speed cam and high-speed cam are in the middle of the rotation angle. Is switched.

By the way, the rocker shaft 102IN,
The displacement amount of the dynamic fulcrum type rocker arm with respect to the fixed fulcrum type rocker arm can be increased by increasing the rotation angle of 102EX (close to 180 °) or increasing the eccentric amount of the eccentric portion 103. Therefore, a large difference in profile between the low / medium speed cam and the high speed cam can be obtained, and a wider power band can be obtained.

As described above, the merit of having a large profile difference between the low / medium speed cam and the high speed cam is
In particular, it is remarkable on the intake system side, and on the exhaust system side, it is preferable not to increase the displacement amount of the fulcrum type rocker arm so much as to prioritize the reduction of the operating force of the actuator. Therefore, if the rotation angle and the amount of eccentricity of the intake system side rocker shaft 102IN are made larger than those of the exhaust system side rocker shaft 102EX, it is possible to achieve both expansion of the power band and reduction of the actuator operating force. .

[0010]

However, the rotation angle and eccentricity of the intake system side rocker shaft 102IN are
In order to make the rocker shaft 102EX larger than the exhaust system side rocker shaft 102EX, the length of the positioning groove 107 and the diameter of the eccentric bush forming the eccentric portion 103 are set to the rocker shaft 102I.
It is necessary to make N different from the rocker shaft 102EX, and the commonality of each component is lost. For this reason,
At the same time that the manufacturing cost of the engine 100 becomes high, the rocker shaft and the eccentric bush, which are slightly different in shape, may be confused and assembled into the engine.

The present invention has been made in order to solve the above problems, and does not impair the commonality of rocker shafts, eccentric bushes, etc. between the intake system side and the exhaust system side,
It is an object of the present invention to provide a valve operating system for a four-cycle engine, which is capable of varying the amount of displacement of the fulcrum type rocker arm, and which can prevent an increase in manufacturing cost of the engine and a mistake in each component.

[0012]

In order to achieve the above object, a valve train for a four-cycle engine according to the present invention is rotatably supported in a cylinder head and is eccentric with respect to its axis. A rocker shaft having a rocking portion, a rotation angle restricting means for restricting a rotation angle of the rocker shaft, a fixed fulcrum type rocker arm pivotally mounted on a shaft portion of the rocker shaft, and an eccentric portion of the rocker shaft. The fulcrum type rocker arm and the low and medium speed cams and cams with different cam profiles that drive the rocker arms to open and close the exhaust valve respectively The rocker shaft is provided separately on the system side to change the fulcrum position of the dynamic fulcrum-type rocker arm to rotate the low-, medium-speed cam and high-speed cam. In the valve gear of a four-cycle engine to divide have, the rotation angle of the rocker shaft, while maintaining the same in the air intake system side and the exhaust system side, the cam
A line connecting the shaft axis and the rocker shaft axis,
It is characterized in that the angle formed by the line connecting the rocker shaft axis and the apex of the eccentric portion is made different on the intake system side and the exhaust system side.

Further, the rotation angle restricting means for both the intake system side and the exhaust system side are provided for the respective camshaft axial centers and the rockers.
The lines connecting the camshaft axis and the rocker shaft axis are arranged at positions inclined in the same direction and at the same angle in the direction of rotation of the camshaft with respect to the line connecting the shaft axis. And the angle formed by the line connecting the rocker shaft axis and the apex of the eccentric portion is made different on the intake system side and the exhaust system side.

[0014]

According to the valve operating system for a four-cycle engine having the above-described structure, while keeping the same rotation angle and eccentricity of the intake system side rocker shaft and rotation angle and eccentricity of the exhaust system side rocker shaft, By changing the displacement amount of the fulcrum type rocker arm between the intake system side and the exhaust system side, it is possible to achieve both expansion of the power band and reduction of the operating force of the actuator.

Therefore, all rocker shafts, eccentric bushes, and other parts can be used in common, and it is possible to effectively prevent an increase in engine manufacturing cost and the replacement of parts.

An intake system provided in the cylinder head
Both rotation angle restricting means side and the exhaust system side, respectively
A line connecting the camshaft axis and the rocker shaft axis
On the other hand, by arranging the camshafts in the same direction and at the same angle with respect to the rotation direction of the camshaft, machining of the cylinder head becomes very easy, and the manufacturing cost of the engine is further reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a cylinder head of a four-cycle engine to which a valve operating system according to the present invention is applied,
2 is a vertical sectional view taken along line II-II of FIG. 1, and FIGS. 3 and 4 are vertical sectional views taken along line III-III and line IV-IV of FIG. 2, respectively.

This engine 1 is, for example, an in-line 4-cylinder D
This is an OHC engine, and in its cylinder head 2, an intake system side camshaft 3IN and an exhaust system side camshaft 3EX are rotatably supported. The camshafts 3IN and 3EX are rotationally driven in the A direction in FIGS. 3 and 4 by a crankshaft (not shown).

Each of the camshafts 3IN and 3EX is provided with one low and middle speed cam 4L for each cylinder and two high speed cams 4H located on both sides thereof.
The low / medium speed cam 4L and the high speed cam 4H have different cam profiles. That is, the low and medium speed cams 4
The L cam profile has a shape that provides a valve lift amount and a valve opening / closing timing suitable when the engine 1 is operating in the low and medium speed rotation range, and the cam profile of the high speed cam 4H is the high speed engine 1 The shape is such that a valve lift amount and valve opening / closing timing suitable for operation in the rotation range can be obtained. Note that FIG. 3 and FIG.
In (A) and (B), the cam profile of the low / medium speed cam 4L is shown by a broken line, and the cam profile of the high speed cam 4H is shown by a solid line.

Below the camshafts 3IN and 3EX,
A rocker shaft 5IN on the intake system side and a rocker shaft 5EX on the exhaust system side are rotatably supported. The rocker shafts 5IN and 5EX are
2 on the intake system side and 2 on the exhaust system side of the cylinder head 2.
The books are pivoted one by one.

Fixed rocker type rocker arms 6A driven by the low and medium speed cams 4L are rotatably mounted on the rocker shafts 5IN and 5EX, one fixed cylinder type rocker arm 6A per cylinder. Two fulcrum type rocker arms 6B driven by high speed cams 4H are rotatably attached to both sides of the fixed fulcrum type rocker arm 6A.

As shown in FIGS. 5 (A) and 5 (B) and FIGS. 6 and 7, the fixed fulcrum type rocker arm 6A is directly pivotally attached to the shaft portions of the rocker shafts 5IN and 5EX to form a dynamic fulcrum. The rocker arm 6B includes rocker shafts 5IN, 5
It is pivotally attached to the eccentric portion 7 of the EX. The eccentric portion 7 includes, for example, an eccentric bush 8 and a pin 9 for the rocker shafts 5IN and 5IN.
It is fixed to EX.

The tip of the fixed fulcrum type rocker arm 6A is branched into two directions, and each branch end opens and closes an intake port 12 and an exhaust port 13 communicating with the combustion chamber 11 (see FIG. 3) of the engine 1. The heads of the valves 14 are in contact with each other. Here, four valves 14 are arranged in each combustion chamber 11, two for intake and two for exhaust. Each valve 14 is closed by the urging force of the valve spring 15.

Further, one fulcrum type rocker arm 6B
Of the fixed fulcrum type rocker arm 6A is abutted on one branch end of the fixed fulcrum type rocker arm 6A, and the tip of the other fulcrum type rocker arm 6B is abutted on the other branched end of the fixed fulcrum type rocker arm 6A. The contact point is set substantially on the axis of the valve 14. Incidentally, 16 and 17 are shims for adjusting tappet clearance.

The fixed fulcrum type rocker arm 6A is provided with a cam floor surface 18A, and the fulcrum type rocker arm 6B is provided.
A cam floor surface 18B is provided on the upper surface of the. The cam floor surface 18A can be pressed by the low and medium speed cams 4L, and the cam floor surface 18B can be pressed by the high speed cams 4H.

At the center of the upper surface of the cylinder head 2, for example, an actuator 21 operated by hydraulic pressure is installed. The actuator 21 has four hydraulic pistons (not shown) built therein, and a rack bar 22 extending outward is connected to each of the hydraulic pistons. Two of these rack bars 22 extend toward the intake system side and the exhaust system side of the engine 1, and a rack gear 22a is formed on the lower surface thereof. When the actuator 21 operates, the four rack bars 22 simultaneously expand and contract.

As shown in FIGS. 1 and 6, a pinion gear 23 is provided integrally with the rocker shafts 5IN and 5EX at the end on the engine center side, and these four pinion gears 23 are connected to the rack. The rack gears 22a of the bar 22 are meshed with each other. Therefore,
When the actuator 21 operates, the rocker shafts 5IN and 5EX are driven and rotated.

When the engine 1 is in the low and medium speed rotation range, the actuator 21 causes the four rack bars 22 to converge. Therefore, each pinion gear 23 is rotated in the O direction in FIG. 6, and the eccentric portion apexes 7a of the rocker shafts 5IN and 5EX are placed at the position shown in FIG. 5 (A). Then, the cam floor surface 18A of the fixed fulcrum type rocker arm 6A rises to the camshaft 3IN or 3EX side with respect to the cam floor surface 18B of the dynamic fulcrum type rocker arm 6B,
It is pressed by the low / medium speed cam 4L. Therefore, the valve 14 is opened / closed by the low / medium speed cam 4L, and the engine 1 is provided with the valve lift amount and the valve opening / closing timing suitable for the low / medium speed rotation range.

When the engine 1 is in the high speed rotation range,
The actuator 21 extends the four rack bars 22. Therefore, each pinion gear 23 rotates in the P direction in FIG. 6, and the eccentric portion vertices 7a of the rocker shafts 5IN and 5EX are placed at the position shown in FIG. 5 (B). In this case, the fulcrum position of the dynamic fulcrum type rocker arm 6B changes, and the cam floor surface 18B of the dynamic fulcrum type rocker arm 6B rises to the camshaft 3IN or 3EX side with respect to the cam floor surface 18A of the fixed fulcrum type rocker arm 6A, It is pressed by the high speed cam 4H. Therefore, the valve 14 comes to be opened / closed by the high speed cam 4H, and the valve lift amount and the valve opening / closing timing suitable for the high speed rotation range are set in the engine 1.
Brought to.

As shown in FIG. 4, the cylinder head 2 is provided with a rotation angle regulation means 24 for regulating the rotation angles of the rocker shafts 5IN and 5EX. The rotation angle regulating means 24 is, for example, the camshafts 3IN, 3E.
Rocker shafts 5IN, 5EX from the X bearing portion 25 side
Stopper bolts 26IN, 26 screwed toward the side
It is called EX.

On the other hand, the rocker shafts 5IN and 5EX are provided with positioning grooves 27 in the circumferential direction, and the stopper bolts 26 are provided in the positioning grooves 27.
The tip of IN, 26EX is fitted. Therefore, the rocker shafts 5IN and 5EX can be rotated only at an angle until the stopper bolts 26IN and 26EX come into contact with both ends of the positioning groove.

The length of the positioning groove 27 is the same for the rocker shafts 5IN and 5EX. Therefore, the rocker shafts 5IN and 5EX have the same rotation angle. Incidentally, in the present embodiment, the rotation angle is 140 °. The positioning groove 27 and the eccentric portion apex 7a
The relative positional relationship with the rocker shafts 5IN and 5EX
And are the same.

Now, with the camshaft axis C1 shown in FIG.
The line connecting the rocker shaft axis C2 and the rocker shaft
The angle θ formed by the line connecting the shaft center C2 and the eccentric portion apex 7a is different between the intake system side and the exhaust system side. That is, in the high speed mode shown in FIG. 4, the angle θ is, for example, 65 ° on the intake system side and 75 ° on the exhaust system side. In the low and medium speed modes (not shown), on the contrary, the intake system side is set to 75 ° and the exhaust system side is set to 65 °.

As described above, in order to make the angle θ different between the intake system side and the exhaust system side, the stopper bolts 26IN and 26EX, which are the rotation angle regulating means 24, are respectively provided.
The cam shaft axis center C1 and the rocker shaft axis center C2
Camshafts 3IN and 3EX for the connected lines
Are arranged in the same direction and at the same angle toward the rotation direction A. In this embodiment, the central axes of the stopper bolts 26IN and 26EX are respectively
The camshaft 3 is oriented toward the Kershaft axis C2.
Inclining in the rotation direction A of IN, 3EX by, for example, 5 ° each.

Since the rocker shafts 5IN and 5EX rotate in opposite directions to each other, when the angle θ is made different between the intake system side and the exhaust system side, the inclinations of the stopper bolts 26IN, 26EX are set as described above. The directions are the same.

FIG. 8 shows rocker shafts 5IN and 5EX.
FIG. 6 is a diagram showing the relationship between the rotation angle and the displacement amount of the fulcrum type rocker arm 6B. As is clear from this diagram,
When the rotation angle of the rocker shafts 5IN and 5EX is 0 °,
The displacement amount of the fulcrum type rocker arm 6B is zero. The rocker shafts 5IN and 5EX have a rotation angle of 180.
The amount of displacement of the fulcrum type rocker arm 6B becomes maximum during the rotation up to °.

As in this embodiment, the rocker shaft 5I
When the rotation angle of N and 5EX is set to 140 ° each, 1
The displacement amount of the fulcrum-type rocker arm 6B changes depending on where in FIG. 8 the rotation angle of 40 ° is provided. For example, even at the same rotation angle of 140 °, the displacement amount β2 in the range of α2 is larger than the displacement amount β1 in the range of α1 in FIG.

According to the present invention, the camshaft axis C
1 and the rocker shaft axis C2, and the rocker
The line connecting the shaft axis C2 and the eccentric portion apex 7a is folded.
When the formed angle θ is made different between the intake system side and the exhaust system side, the rotation angle range of the rocker shaft 5EX on the exhaust system side becomes close to α1 in FIG. Wearing fulcrum type rocker arm 6
The displacement amount of B is approximately β1. Further, the rotation angle range of the rocker shaft 5IN on the intake system side is similar to α2 in FIG. 8, and the displacement amount of the fulcrum type rocker arm 6B pivotally attached to the rocker shaft 5IN is approximately β.
It becomes 2.

Therefore, it is possible to bring a wide power band to the engine 1 by taking a large profile difference between the low / medium speed cam 4L and the high speed cam 4H of the intake system side camshaft 3IN. On the exhaust system side, on the other hand, it is possible to reduce the amount of displacement of the dynamic fulcrum type rocker arm 6B to reduce the operating force of the actuator 21. In this way, the displacement amount of the fulcrum-type rocker arm 6B is made different without changing the rotation angle or the eccentric amount of the rocker shafts 5IN and 5EX, and the expansion of the power band and the reduction of the operating force of the actuator 21 are made compatible. Therefore, the rocker shafts 5IN and 5EX and all the eccentric bushes 8 can be shared.

Therefore, the manufacturing cost of the engine 1 can be kept very low, and there is no possibility that the rocker shafts 5IN and 5EX and the eccentric bush 8 are erroneously assembled to the engine 1.

Moreover, the stopper bolts 26IN, 26
EX is cam shaft center C1 and rocker shaft
For the line connecting the shaft center C2, the camshaft 3I
Since the cylinder head 2 is arranged in the same direction and at the same angle with respect to the rotation direction A of N and 3EX, drilling and threading of the cylinder head 2 are very easy, and the manufacturing cost of the engine 1 is increased. Can be made even cheaper.

[0043]

As described above, the valve operating system for a four-cycle engine according to the present invention is rotatably supported in the cylinder head and has a rocker shaft having an eccentric portion eccentric with respect to the shaft center. A rotation angle regulation means for regulating the rotation angle of the rocker shaft, a fixed fulcrum type rocker arm pivotally attached to the shaft portion of the rocker shaft, and a dynamic fulcrum type rocker pivotally attached to the eccentric portion of the rocker shaft. The arm and these rocker arms are respectively driven and sucked,
Low and medium speed cams and high speed cams with different cam profiles that open the exhaust valve are individually provided on the intake system side and the exhaust system side, respectively. In a 4-cycle engine valve operating system in which the fulcrum position of the mold rocker arm is changed so that low-, medium-speed cams and high-speed cams are selectively used, the rocker shaft rotation angle is changed between the intake system side and the exhaust system side. While keeping the same, camshaft axis and rocker
The line connecting the shaft axis and the rocker shaft axis
It is characterized in that the angle formed by the line connecting the apex of the eccentric portion is different between the intake system side and the exhaust system side.

Therefore, while maintaining the same rotation angle and eccentricity of the intake system side rocker shaft and rotation angle and eccentricity of the exhaust system side rocker shaft, movement between the intake system side and the exhaust system side is performed. By changing the displacement amount of the fulcrum type rocker arm, it is possible to expand the power band and reduce the operating force of the actuator.

Therefore, all rocker shafts and parts such as the eccentric bush can be made common, the manufacturing cost of the engine can be kept low, and the rocker shafts IN and EX and the eccentric bush can be interchanged. There is no fear of being attached to 1.

Further, in the valve train of the four-cycle engine according to the present invention, the rotation angle restricting means for both the intake system side and the exhaust system side are provided with the camshaft axial center and the rocker shuffle.
The line connecting the cam shaft axis and the rocker shaft axis by arranging them at positions inclined in the same direction and at the same angle toward the rotation direction of the cam shaft with respect to the line connecting And the line that connects the rocker shaft axis and the apex of the eccentric part are made different at the intake system side and the exhaust system side. It will be easier and the cost of manufacturing the engine will be lower.

[Brief description of drawings]

FIG. 1 is a plan view showing a cylinder head of a four-cycle engine to which a valve gear according to the present invention is applied.

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

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

FIG. 4 shows an embodiment of the present invention and is taken along line IV-IV of FIG.
FIG.

FIG. 5A is a diagram showing a state of a valve operating device in an engine low and medium speed mode, and FIG. 5B is a diagram showing a state of a valve operating device in an engine high speed mode.

FIG. 6 is a perspective view of a valve operating device.

FIG. 7 is a plan view of the valve gear.

FIG. 8 is a diagram showing a relationship between a rotation angle of a rocker shaft and a displacement amount of a fulcrum type rocker arm.

FIG. 9 is a vertical cross-sectional view of a valve train showing a conventional technique.

[Explanation of symbols]

1 engine 2 cylinder head 3IN intake system side camshaft 3EX exhaust system side camshaft 4L low and medium speed cam 4H high speed cam 5IN intake system rocker shaft 5EX exhaust system rocker shaft 6A fixed fulcrum type rocker arm 6B dynamic fulcrum type Rocker arm 7 Eccentric part 21 Actuator 24 Rotation angle regulating means C1 Cam shaft axis C2 Rocker shaft axis 7a Eccentric part apex θ The cam shaft axis and the rocker shaft axis are connected.
Connects the sloping line to the rocker shaft axis and the top of the eccentric part
Angle to fold with line

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Katsura Fukuyama 300, Takatsuka-cho, Hamamatsu-shi, Shizuoka Prefecture Suzuki stock company (72) Inventor Kunaki Ishibe, 300, Takatsuka-cho, Hamamatsu-shi, Shizuoka Suzuki stock company (56 ) Reference JP-A-3-271513 (JP, A) Actual development 2-112904 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01L 13/00 301 F01L 1/04 F01L 1/18

Claims (2)

(57) [Claims] 1. A rocker shaft that is rotatably supported in a cylinder head and has an eccentric portion that is eccentric with respect to the shaft center, and a rotation angle restriction means that restricts the rotation angle of the rocker shaft. Fixed fulcrum type rocker arm pivotally attached to the shaft part of the rocker shaft, dynamic fulcrum type rocker arm pivotally attached to the eccentric part of the rocker shaft, and these rocker arms are respectively driven to open and close the exhaust valve. Low-, medium-speed cams and high-speed cams with different cam profiles are individually provided on the intake system side and the exhaust system side, respectively, and the fulcrum position of the dynamic fulcrum type rocker arm is obtained by rotating the rocker shaft. In the valve operating system of the 4-cycle engine in which the low, medium speed and high speed cams are selectively used. , While keeping the intake system side and exhaust system side the same, the camshaft axis and rocker shaft axis center
And the line connecting them with the rocker shaft axis center and the eccentric part vertex
A valve operating system for a four-cycle engine, characterized in that the angle formed by the line connecting the two is different on the intake system side and the exhaust system side. 2. The intake system side and exhaust system side turning angle restricting means are respectively oriented in the rotational direction of the camshaft with respect to the line connecting the camshaft axis and the rocker shaft axis. By arranging them in the same direction and at the same angle, the angle between the line connecting the camshaft axis and the rocker shaft axis and the line connecting the rocker shaft axis and the eccentric apex The valve operating system for a four-cycle engine according to claim 1, wherein the intake system side and the exhaust system side are different from each other.