JPH09291803A - Valve system of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly insert a rocker shaft by using a coil spring capable of being easily manufactured. SOLUTION: In a valve system, end coil parts 20b, 20c positioned on both ends of respective coils for constituting a coil spring 20 to be inserted into a rocker shaft 14 are set to the diameter larger than that of the rocker shaft 14. An intermediate part 20a of the coil spring is set to such a diameter as to be brought in contact with the outer periphery of the rocker shaft, and the diameter of respective coils is gradually extended from the intermediate part 20 to both end coil parts 20b, 20c.

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 in which a rocker arm supported by a rocker shaft operates a valve body which opens and closes an intake hole and an exhaust hole formed in a cylinder of an engine.

[0002]

2. Description of the Related Art As is well known, in a cylinder head of a four-cycle engine, a valve operating device for opening and closing an intake hole and an exhaust hole of a cylinder is provided. As this valve operating device, there is one that causes a rocker arm to rotate and swing around a rocker shaft by a cam shaft held by a cylinder head, and the rocking moves the valve body up and down to open and close a cylinder intake hole and an exhaust hole. Are known.

FIGS. 6 and 7 are views showing a rocker shaft, a cam shaft and the like of a conventionally used valve train. In each figure, A is a rocker shaft fixed to a cylinder head B, and C is a cam shaft rotatably supported by the cylinder head B. A rocker arm D is rotatably provided on the rocker shaft A so as to correspond to a valve body (not shown) that opens and closes an intake hole and an exhaust hole of a cylinder. The rocker shaft A is provided with an oil flow passage A1 through which lubricating oil flows, along the axial direction, and an annular oil groove A2 is formed on the outer peripheral surface.
And a communication hole A3 (see FIG. 7) communicating with the oil flow passage A1 is formed in the oil groove A2. Then, the lubricating oil in the oil flow passage A1 flows from the communication hole A3 to the oil groove A2.
And is supplied between the rocker shaft A and the rocker arm D to maintain good lubricity of both.

A coil spring E is inserted through the rocker shaft A. The outer diameter of each coil of the coil spring E is substantially the same as the outer diameter of the rocker shaft A, and both ends of the coil spring E have a cylinder head B.
And the shaft insertion portion D1 of the rocker arm D, respectively. Due to the elastic force of the coil spring E, the rocker arm D is always in contact with the cylinder head B and is held in a fixed position in the axial direction. That is, the rocker arm D is held at a position where the cam shaft C opposes the cam C1, and the rotational movement of the cam C1 can be properly transmitted to the rocker arm D.

[0005]

However, in the above-mentioned conventional valve operating system for an engine, when the rocker shaft A is inserted into the coil spring E, it is formed at one end of the coil pulling E as shown in FIG. End winding part E1
After being caught in the oil groove A2 formed in the rocker shaft A, as shown in FIG.
The rocker shaft A and the rocker arm D may be caught between the rocker arm D and the rocker arm D via the end turn portion E1, and the rocker shaft A cannot be mounted smoothly. There was a problem.

Therefore, it has been considered that the oil groove A2 is not formed in the rocker shaft A but the oil groove D2 is formed in the shaft insertion portion D1 of the rocker arm D as shown in FIG. Grooves must be formed on the inner surface of the insertion portion D1, which causes a problem of difficulty in manufacturing. In addition, as shown in FIGS. 10A and 10B, the coil spring E
Although it has been proposed to form the shape of each wire ring into a non-circular shape, there is a problem that such a special shape wire ring is difficult to manufacture and stress is likely to be concentrated in a part.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and provides a valve operating device for an engine in which a rocker shaft can be smoothly inserted by using a coil spring which can be easily manufactured. It is an issue.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a rocker shaft having an oil flow passage for allowing a lubricating oil to flow therethrough and an oil groove communicating with the oil flow passage formed on an outer peripheral surface thereof, and the rocker shaft. A rocker arm slidably inserted through the shaft in the axial direction and the rotation direction, and a rocker arm that is fitted around the rocker shaft and is biased in the axial direction of the rocker shaft to a predetermined positioning portion. A valve spring of an engine having a coil spring to be brought into contact with the rocker arm, and rotating and rocking the rocker arm about a rocker shaft to operate a valve body to open and close an intake hole and an exhaust hole of the cylinder. In the device, the end turn portions located at both ends of each coil forming the coil spring are set to have a diameter larger than that of the rocker shaft. Together, set to a diameter which contacts the intermediate of the coil spring on the outer circumference of the rocker shaft,
Further, the diameter of each coil is gradually enlarged from the intermediate portion to both end portions.

In the present invention, when the rocker shaft is inserted up to the middle portion of the coil spring, the middle portion contacts the outer periphery of the rocker shaft, so that the coil spring is held substantially concentric with the rocker shaft. As a result, the end turn portions located at both ends of the coil spring formed to have a diameter larger than that of the rocker shaft are held in a state of being separated from the outer circumference of the rocker shaft. It is possible to insert the rocker shaft into the coil spring extremely smoothly without being caught in the oil groove or caught between the oil groove and the rocker arm. Further, the shape of each coil of the coil spring is a very simple shape in which it gradually expands from the intermediate portion to both end portions, so that it can be easily manufactured.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 is an explanatory vertical cross-sectional side view showing an engine valve operating device and the like according to an embodiment of the present invention, FIG. 2 is an explanatory vertical cross-sectional side view showing the essential parts of what is shown in FIG. 1, and FIG. 4 is an explanatory exploded perspective view showing the shaft and the like, FIG. 4 is an explanatory plan view showing the rocker shaft and the coil spring shown in FIG. 3, and FIG. 5 is an explanatory transverse sectional view of what is shown in FIG.

In FIG. 1, reference numeral 1 is a cylinder of a four-cycle engine. A cylinder head 2 is provided at the upper end of the cylinder 1, and a cylinder head cover 3 is provided at the upper end of the cylinder head 2. A piston 5 connected to a crankshaft 4a via a connecting rod 4 is provided in the cylinder 1 so as to be movable back and forth. The intake hole 2a and the exhaust hole 2b formed in the above are opened and closed.

In the valve gear according to this embodiment, the intake and exhaust valves (valve bodies) 6 are formed by the valve springs 12 and 13 interposed in a compressed state between the upper retainers 8 and 9 and the lower retainers 10 and 11. 7 is always the intake hole 2a
And the exhaust hole 2b is kept closed, and the intake and exhaust valves 6 and 7 are pushed down against the valve springs 12 and 13 to open the intake hole 2a and the exhaust hole 2b, while the intake and exhaust valves 6 and 7 are opened. By releasing the pressing force applied to the intake / exhaust valves 7, the intake / exhaust valves 6 and 7 are returned to their original positions to close the intake / exhaust holes 2a and 2b.

The pressing and releasing operations of the valve are performed by the rocker arms 16 and 17. That is, the rocker arms 16 and 17 are rotatably supported by the rocker shafts 14 and 15, and the tip ends thereof come into contact with the upper ends of the valves, and the upper surfaces thereof are camshafts 18 and 19.
The cams 18a and 19a are in contact with each other. When the cam shafts 17 and 18 rotate in accordance with the reciprocating motion of the piston 5, the rocker arms 16 and 17 swing up and down around the rocker shaft according to the cam profile, and the swinging causes the valves 6 and 7 to swing. Is pressed and released to open and close the intake hole 2a and the exhaust hole 2b.

In this opening / closing operation, the cylindrical shaft insertion portions 16a and 17a of the rocker arms 16 and 17 slide on the outer peripheral surfaces of the rocker shafts 14 and 15 inserted therein, so that the sliding movement is smooth. In order to perform the above, lubricating oil is supplied between the rocker shafts 14 and 15 and the shaft insertion portions 16a and 17a by the structure shown in FIG. Since the rocker shaft 14 and the shaft insertion portion 16a provided on the exhaust hole 2b side are the same as the rocker shaft 15 and the shaft insertion portion 16a provided on the intake hole 2a side, the intake hole 2a will be described below. Only those provided on the side will be described as an example.

As shown in FIG. 2, the rocker shaft 14
At the central portion of the oil flow passage 14 extending along the axial direction.
a is formed, and the lubricating oil is supplied here. Further, on the outer peripheral surface of the rocker shaft 14, annular oil grooves 14b, 14b (see FIGS. 3 and 4) are formed at a position where the shaft insertion portion 16a of the rocker arm 16 is inserted. Furthermore, this oil groove 14
b and 14b, a communication hole 1 communicating with the oil flow passage 14a
4c and 14c (see FIGS. 3 and 4) are formed.
Therefore, the lubricating oil supplied to the oil flow passage 14a is
Since the oil flows out through the communication hole 14c into the entire annular oil groove 14b and then enters between the inner surface of the shaft insertion portion 16a of the rocker arm 16 and the outer surface of the rocker shaft 14, the rocker arm 16 rotates smoothly. To be done.

A coil spring 20 is inserted through the outer circumference of the rocker shaft 14. The coil spring 20 is interposed between one end surface 16a1 of the shaft insertion portion 16a of the rocker arm 16 and one end surface 2A of the cylinder head 2 in a compressed state. ,
The other end surface of the shaft insertion portion 16a is held in a state of being pressed against the other end surface (positioning portion) 2B of the cylinder head 2. That is, the rocker arm 16 is held at the position opposed to the cam 18a of the cam shaft 18 by the elastic force of the coil spring 20. 2 and 3
In the above, reference numeral 21 is a fixing screw for attaching the rocker shaft to the bearing portion of the cylinder head, and 22 is a cap for preventing oil from flowing out from the bearing portion.

By the way, the coil spring 20 in this embodiment is composed of wire rings having different diameters, as shown in FIGS. That is, the diameter of the wire ring 20a located in the middle of the coil spring 20 is
The diameter of the rocker shaft 14 is approximately the same as that of the rocker shaft 14, and the wire wheel 20a forms a contact portion that contacts the outer peripheral surface of the rocker shaft 14. The other coils are gradually expanded toward both ends, and the end turn portion 20 formed at both ends of the coil spring 20 is gradually expanded.
The diameters of b and 20c are maximum diameters. Therefore, the coil spring 20 has a drum shape in a side view and a spiral shape in a front view.

By using the coil spring 20 as described above, the work of mounting the rocker shaft 14 can be smoothly performed in this embodiment. That is, the mounting work of the rocker shaft 14 is performed by sequentially inserting the rocker shaft 14 into the bearing portion of the cylinder head 2, the coil spring 20, and the rocker arm 16. At this time, the coil spring 20 is Since both ends are formed to have a larger diameter than the rocker shaft 14, the tip end of the rocker shaft 14 can be inserted into the coil spring 20 very easily.

Further, when the rocker shaft 14 is inserted up to the intermediate position of the coil spring 20 or more, the coil wheel 20a at the intermediate position contacts the outer peripheral portion of the rocker shaft 14, so that the coil spring 20 is substantially concentric with the rocker shaft 14. Stabilizes at. Therefore, there is no possibility that the oil groove 14b of the rocker shaft 14 penetrating the intermediate position is caught by the front end turn portion 20c having a larger diameter, and the end turn portion 20c forms the oil groove 14b and the end surface 2B of the cylinder head 2. Since it is not caught between the rocker shafts 14, the rocker shaft 14 can be attached smoothly.

Further, the wire ring 20a at the intermediate position may be fitted into the oil groove of the rocker shaft 14, but since the wire ring 20a is inclined with respect to the oil groove 14 as shown in FIG. The portion that fits into the oil groove 14 is a very small portion of the wire ring, and it is extremely easy to escape from the oil groove 14b, so the insertion work of the rocker shaft 14 is not hindered. Further, since the coil spring 20 has a simple spiral shape, it can be easily manufactured, and since stress does not concentrate on a part during expansion and contraction, a stable elastic force is maintained for a long period of time. can do. The number, diameter, etc. of the coils of the contact portion and the end turn portion of the coil spring can be appropriately set and changed as necessary, and are not particularly limited to the above embodiment.

[0021]

As described above, according to the present invention, the end turn portions located at both ends of each coil forming the coil spring inserted in the rocker shaft are set to have a maximum diameter larger than that of the rocker shaft. Along with that, the middle part of the coil spring is set to the minimum diameter in contact with the outer circumference of the rocker shaft, and the diameter of each coil is gradually increased from the middle part to both ends.
The coil spring is not caught between the rocker shaft and the rocker arm when the rocker shaft is mounted, and the rocker shaft can be mounted smoothly. Further, since the coil spring has a simple shape, it can be manufactured very easily.

[Brief description of drawings]

FIG. 1 is an explanatory vertical cross-sectional side view showing an engine valve operating system and the like according to an embodiment of the present invention.

FIG. 2 is an explanatory vertical cross-sectional side view showing a main part of the one shown in FIG.

3 is an explanatory exploded perspective view showing the rocker shaft shown in FIG. 2 and the like.

FIG. 4 is an explanatory plan view showing a rocker shaft and a coil spring shown in FIG.

5 is an explanatory transverse sectional view of what is shown in FIG. 4. FIG.

FIG. 6 is an explanatory vertical sectional side view showing a main part of a conventional engine valve operating system.

7 is an explanatory cross-sectional view showing the rocker shaft, coil spring, rocker arm, and the like shown in FIG.

FIG. 8 is an explanatory diagram showing a state in which a coil spring is wound between a rocker shaft and a rocker arm.

FIG. 9 is an explanatory transverse sectional view showing another example of the conventional valve operating device.

FIG. 10 is a partially longitudinal explanatory front view showing another example of the coil spring in the conventional valve operating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 cylinder 2 cylinder head 2B other end surface (positioning part) 6 intake valve (valve body) 7 exhaust valve (valve body) 14 rocker shaft 14a oil flow passage 14b oil groove 16 rocker arm 20 coil spring 20a middle part 20b, 20c seat Winding part (both ends)

Claims (1)

[Claims] 1. A rocker shaft having an oil flow passage through which lubricating oil flows, and an oil groove communicating with the oil flow passage formed on an outer peripheral surface, and an axial direction and a rotation direction of the rocker shaft. And a coil spring fitted into the rocker shaft and biasing the rocker arm in the axial direction of the rocker shaft to abut a predetermined positioning portion. In the valve operating device for an engine, the valve body is operated by rotating and rocking the rocker arm around a rocker shaft, and the coil spring is configured in the valve operating device of the engine. The end turn portions located at both ends of each coil are set to have a diameter larger than that of the rocker shaft, and Set the intermediate grayed in diameter in contact with the outer periphery of the rocker shaft, and a valve operating system for an engine characterized by comprising gradually to expand the diameter of each wire wheels over the both end turn portion from the intermediate portion.