JPH0610101Y2 - Valve drive for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a valve operating device that opens and closes an intake / exhaust valve of an internal combustion engine via a swing arm by a cam that rotates in synchronization with the rotation of the engine.

(Prior Art) Generally, a valve train of an internal combustion engine has a shape of a combustion chamber, a required rotation range, a degree of design freedom of intake and exhaust holes, an assembly serviceability,
Although it is selected from those suitable for the purpose in consideration of weight, manufacturing cost, etc., these days, together with the demand for high-speed performance to the vehicle, while securing output performance, simplification of the valve train and cost reduction Is required.

As a conventional valve operating system for an internal combustion engine, for example, there is one shown in FIG. 4 (“Motor Fan March Issue”, Showa 6).
Released on March 1, 2000, see Sanei Shobo Co., Ltd.). In FIG. 4, 1a and 1b are first and second intake valves provided for each cylinder, and 2a and 2b are first and second exhaust valves similarly provided for each cylinder. Above the intake / exhaust valves 1a, 1b, 2a, 2b, a pair of cam shafts 3a, 3b are provided. One camshaft 3a
Is provided with a cam 4a for an intake valve, and the other cam shaft 3b is provided with a cam 4b for an exhaust valve. Also,
The swing fulcrums of the swing arms 5a and 5b swinging by the cams of the intake / exhaust valve cams 4a and 4b, respectively, are supported by the support member 6.
The swing arms 5a and 5b are slidably supported by a and 6b, and the intake and exhaust valve cams 4a and 4b are attached to the swing arms 5a and 5b.
The cam followers 7a and 7b which slide respectively are provided. Further, adjusting screws 8a, 8b are provided at the tip ends of the swing arms 5a, 5b, respectively, which come into contact with the valve shaft ends of the intake / exhaust valves 1a, 1b, 2a, 2b. Then, the swing arms 5a and 5b are slid by the cam force of the intake / exhaust valve cams 4a and 4b, so that the swinging force is applied to the intake / exhaust valves 1a, 1b and 2a through the adjustment screws 8a and 8b. , 2b, respectively, to open / close the intake / exhaust valves 1a, 1b, 2a, 2b. In addition, 9a and 9b are valve springs.
The arrows in the figure show the flow of intake and exhaust.

In this way, by opening and closing the first and second intake valves 1a and 1b and the first and second exhaust valves 2a and 2b with the swing arms 5a and 5b, respectively, the intake and exhaust valves are respectively separated. The cam and cam follower are halved compared to those operated by a swing arm of the body to simplify the valve operating system, reduce the weight of the valve operating system, and increase the maximum rotation speed.

(Problems to be Solved by the Invention) However, in such a conventional valve operating system for an internal combustion engine, since the cam follower is fixed to the swing arm, the friction between the cam and the cam follower increases and the fuel consumption is improved. However, the swing arm support structure is a shaft support structure, so that a shaft-shaped support member is required and the structure is complicated. In order to solve these problems, it is conceivable that the cam follower is rotatably supported in the shape of a roller, and the swing arm support structure is a spherical support structure. There was a problem that a new trouble occurred.

That is, when the swing arm has a spherical support structure,
Since the swing arm can swing not only in the swinging direction for opening and closing the valve but also in the cam axis direction, there arises a problem that the operation of the swing arm becomes unstable.

Further, in order to make the cam follower into a roller shape so as to be rotatable with respect to the swing arm, it is necessary to form a slight gap to some extent between the roller end surface of the cam follower and the swing arm. Actually, there is a gap to some extent between the cam follower and the swing arm due to manufacturing error or the like. Therefore, the cam follower
It becomes movable in the direction of its own rotation support axis and impacts the swing arm, resulting in problems such as a loud hitting sound and reduced durability.

Furthermore, in order to fill the above-mentioned gap, it is possible to make the above-mentioned gap as small as possible by tightening the dimensional control in the manufacture of the cam follower and the swing arm, but a new problem such as an extremely high cost occurs. To do.

(Object of the Invention) Therefore, in the present invention, the cam follower has a roller shape, and in the valve operating device, the swing arm support structure is a spherical support structure, and a shim member is inserted between the end surface of the cam follower made of rollers and the swing arm. Provided is a valve operating device for an internal combustion engine, which is capable of simplifying a supporting structure of a swing arm by making the cam follower contact with a cam, and solving a problem caused by adopting a roller-like cam follower and adopting a spherical supporting structure. The purpose is to do.

(Means for Solving Problems) In order to achieve the above object, a valve operating system for an internal combustion engine according to the present invention is provided with at least one intake valve and at least one exhaust valve for each cylinder. In a valve operating system for an internal combustion engine in which the cam follower of the swing arm is in the form of a roller, one end of the swing arm is supported spherically and the other end is brought into contact with an intake valve or an exhaust valve. , The cam follower is rotatably supported by roller shafts whose both ends are supported by a swing arm,
A shim member, which is a separate member from the cam follower and has an outer diameter larger than that of the cam follower, is inserted between the cam follower and the swing arm so that the gap between the end surface of the cam follower and the swing arm is filled, and the shim member contacts the side surface of the cam. I am in contact.

(Operation) In the present invention, one end of the swing arm is spherically supported,
A shim member, which is a member separate from the cam follower and has an outer diameter larger than that of the cam follower, is inserted between the cam follower and the swing arm so as to fill the gap between the end surface of the cam follower and the swing arm, and the shim member contacts the cam.

Therefore, since the swing arm is spherically supported, the support structure of the swing arm is simplified and
The swinging of the swing arm in the cam axis direction is prevented by the shim member that abuts the side surface of the cam, and the operation of the swing arm is stabilized.

In addition, the movement of the cam follower in the roller axis direction is restricted by the shim member, and the shocking contact between the cam follower and the swing arm is prevented, so that tapping noise is prevented and durability is improved.

Further, the manufacturing error of the swing arm and the cam follower can be absorbed by adjusting the thickness of the inexpensive shim member, and the cost is reduced.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

1 to 3 are views showing an embodiment of the present invention, which is an example in which the present invention is applied to a four-valve engine.

First, the configuration will be described. In FIG. 1, 11a and 11b are intake passages for each cylinder, and in FIG. 1, since each part overlaps, only one set of intake system and exhaust valve on one side is shown. Intake valves 12a and 12b are provided in the intake boats of the intake passages 11a and 11b, respectively, and exhaust valves 13a and 13b are provided in the exhaust ports of the exhaust passages 14a and 14b so as to face the intake valves 12a and 12b, respectively. These valves 12a, 12b, 13a, 13b are normally biased in the valve closing direction by valve springs 15a, 15b, 15c, 15d. Since the intake side and the exhaust side have the same configuration, the intake side will be described with reference numeral i in the following description, and the exhaust side member having the same function will be denoted with the same reference numeral with the reference numeral e. To do.

A cam shaft 16i is provided above the intake valves 12a and 12b, and a cam 17i for the intake valve is formed on the cam shaft 16i. Further, the cylinder head 18 outside the intake valves 12a, 12b is provided with an end pivot 19i as a support member, and the end pivot 19i is connected to one end of the swing arm 20i. The other end of the swing arm 20i is the intake valve 1
The valve heads 2a and 12b are in contact with each other, and a cam follower 21i provided at an intermediate portion thereof is in contact with the intake valve cam 17i.

The seat portion of the end pivot 19i is formed in a spherical shape, and the swing fulcrum portion on one end side of the swing arm 20i facing the seat portion is formed in a concave spherical seat. Therefore,
The swing arm 20i swingably caps the spherical seat portion of the end pivot 19i, that is, is spherically supported by the concave spherical seat. The end pivot 19i extends by the oil supplied from the oil passage 22i formed in the cylinder head 18, and always maintains the clearance of the contact surface between the intake valve cam 17i and the cam follower 21i at zero. That is, the end pivot 19i has a function of automatically adjusting the clearance between the two. It should be noted that the position of the end pivot 19i may be adjusted by a screw, for example, without being limited to such hydraulic adjustment.

As shown in the plan view of FIG. 2 (a), the swing arm 20i is connected to the retainers 23a, 2 of the intake valves 12a, 12b from the swing fulcrum portion.
It is formed to have a pair of substantially Y-shaped arm portions extending toward 3b. The valve heads are fixed to the retainers 23a and 23b via collets 24a and 24b, respectively.
The ends of the valve springs 15a and 15b are in contact with a and 23b.

The cam follower 21i includes a roller 26i and a needle 27i (cylindrical member) as shown in FIGS. 2 (a) and 2 (b),
It is configured as a roller-shaped so-called roller cam follower. The roller 26i is formed in a roller shape, and a substantially cylindrical needle 27i is provided between the roller 26i and the roller shaft 25i.
Is incorporated as a cylindrical member. The roller 26i is rotatably attached by a roller shaft 25i and a needle 27i in a cam follower housing 28i formed in the middle of the swing arm 20i. That is, the cam follower
21i is a roller shaft whose both ends are supported by the swing arm 20i.
It is rotatably supported by 25i. Also, roller 2
A shim member 29i is inserted between the roller end surface 30i of 6i and the cam follower storage portion 28i, and the gap between the roller end surface 30i and the cam follower storage portion 28i is filled with the shim member 29i. The outer diameter of the shim member 29i is larger than that of the roller 26i. The side surface of the shim member 29i on the roller 26i side is in contact with the cam side surface 31i of the intake valve cam 17i as shown in FIG. 3, and the gap between the shim member 29i and the intake valve cam 17i is kept small. Further, the roller 26i and the shim member 29i are formed with much higher hardness than the swing arm 20i, and wear due to contact with the intake valve cam 17i is reduced.

In FIG. 1 again, the intake manifold 32 is connected to the left side of the cylinder head 18 in the figure, and the exhaust manifold 33 is connected to the right side of the figure. The manifolds 32 and 33 form a part of the intake passages 11a and 11b and the exhaust passages 14a and 14b, respectively. A cylinder block 35 is connected to the lower part of the cylinder head 18 in the drawing through a gasket 34, and a piston 36 is slidably accommodated in the cylinder block 35. Further, an ignition plug 37 is provided on the upper portion of the cylinder block 35 in the figure so as to face the combustion chamber.
On the other hand, the upper part of the cam shaft 16i is covered with a cam bracket 38i, and both the intake and exhaust cam brackets 38i, 38e are further covered with a rocker cover 39.

Next, the operation will be described. For convenience of explanation, the intake side will be described, but the same applies to the exhaust side.

When the engine rotates, this rotational drive force causes the intake valve cam
17i is driven, the swing arm 20i swings via the cam follower 21i with the end pivot 19i as the swing fulcrum, and the intake valves 12a, 12b simultaneously open and close. At this time, the roller 26i of the cam follower 21i makes a point contact with the intake valve cam 17i, so that the friction between the cam follower 21i and the intake valve cam 17i is reduced. Therefore, it is possible to smoothly open and close the intake valves 12a and 12b while reducing wear of the cam followers 21i and the intake valve cams 17i, and it is possible to improve durability and reduce fuel consumption. Further, since the swing arm 20i is swingably supported by the end pivot 19i and the shim member 29i and the intake valve cam 17i are in contact with each other, the swing support portion can be simplified and the swing arm 20i can be moved. Movement is restricted only in the direction in which the intake valves 12a, 12b are opened and closed. Furthermore, since the end pivot 19i extends by hydraulic pressure, the clearance between the intake valve cam 17i and the swing arm 20i is automatically adjusted so that the clearance is always zero, and the adjustment screw can be omitted, reducing the maintenance man-hours. it can.

On the other hand, since the cam follower 21i is supported by the roller shaft 25i whose both ends are supported by the swing arm 20i, there is a gap between the cam follower end face and the swing arm 20i due to manufacturing error of each member. Are filled with shim members. Therefore, the movement of the cam follower 21i in the roller axial direction can be regulated by the shim member 29i, and the shocking contact between the cam follower 21i and the swing arm 20i can be prevented. Therefore,
It is possible to prevent hitting sound and improve durability of the cam follower 21i and the swing arm 20i.

Further, the variation in the gap dimension between the end surface of the cam follower 21i and the swing arm 20i due to the above manufacturing error should be absorbed by adjusting the thickness of the shim member 29i by preparing a plurality of shim members 29i with different thicknesses that are inexpensive to manufacture. Therefore, in order to absorb the manufacturing error of the cam followers 21i and the swing arm 20i, it is not necessary to prepare a plurality of cam followers 21i having different sizes which require manufacturing cost, and the cost can be reduced.

When a step occurs due to an error in the machining accuracy of the valve shaft ends of the intake valves 12a and 12b, a rotational movement occurs in addition to the swinging movement about the end pivot 19i. At this time, since the shim member 29i having high hardness is inserted between the cam follower housing portion 28i of the swing arm 20i and the roller end surface 30i of the roller 26i, the gap between the shim member 29i and the intake valve cam 17i is regulated to be small. It is possible to suppress the rotational movement of the swing arm 20i about the end pivot 19i as a fulcrum while reducing the wear of the cam side surface 31i and the shim member 29i. Also, the roller end surface 30i of the roller 26i and the cam follower storage portion of the swing arm 20i.
Since the clearance between 28i can be adjusted with the shim member,
The axial movement of the roller shaft 25i of the swing arm 20i and the cam follower 21i, the rotational movement of the swing arm 20i with the end pivot 19i as a fulcrum, and the wear of the inner surface of the cam follower housing 28i can be further suppressed. Therefore, it is possible to stabilize the valve operating device by suppressing the occurrence of surges and the like, which is unlikely to cause bounce of the valve even in the high rotation range, and it is possible to reduce the wear of each member and to improve the performance and durability. Can be improved.

(Effects) According to the present invention, since the swing arm has the spherical support structure, the structure of the support part can be simplified as a result, as compared with the conventional swing arm having the shaft support structure. The structure of the entire device can be simplified.

Further, swinging of the swing arm in the cam axis direction can be prevented by the shim member that abuts on the cam side surface, and the operation of the swing arm can be stabilized.

Further, the movement of the cam follower in the roller axis direction is restricted by the shim member, so that the cam follower and the swing arm can be prevented from impactingly contacting each other, and the striking sound can be prevented and the durability can be improved.

Furthermore, the manufacturing error of the swing arm and the cam follower can be absorbed by adjusting the thickness of the inexpensive shim member, and the cost can be reduced.

[Brief description of drawings]

1 to 3 are views showing an embodiment of the present invention, FIG. 1 is a sectional view thereof, FIG. 2 (a) is a plan view of a swing arm thereof, and FIG. 2 (b) is FIG. FIG. 3A is a sectional view taken along the line II-II ′ of FIG. 3, FIG. 3 is a partial front view of the intake valve cam and cam follower, and FIG. 4 is a perspective view of an essential part showing a conventional valve operating device. 12a, 12b …… Intake valve, 13a, 13b …… Exhaust valve, 20i, 20e …… Swing arm 21i, 21e …… Cam follower, 25i, 25e …… Roller shaft, 26i, 26e …… Roller, 29i, 29e …… Shim member, 31i, 31e ... Side of cam.

Claims (1)

[Scope of utility model registration request] 1. An internal combustion engine having at least one of an intake valve and an exhaust valve for each cylinder, wherein the intake valve or the exhaust valve is operated by one swing arm, and a cam follower of the swing arm is a roller type. In the valve device, one end of the swing arm is supported spherically and the other end is brought into contact with an intake valve or an exhaust valve, and the cam follower is rotatably supported by roller shafts whose both ends are supported by the swing arm. And a shim member having a larger outer diameter than that of the cam follower is inserted between the cam follower and the swing arm so that a gap between the end surface of the cam follower and the swing arm is filled, and the shim member is brought into contact with the side surface of the cam. A valve operating system for an internal combustion engine, characterized in that