JPH0660708U - Camshaft - Google Patents

Abstract

(57) [Summary] [Purpose] Sufficient oil is supplied to the sliding surface between the cam and tappet. A camshaft 10 having an oil passage 10a formed in its axis and one end surface of the cam 11 are connected to a continuous portion 12 which is continuously formed by expanding a diameter of the camshaft from the camshaft to one end surface of the cam in a substantially conical shape. An oil hole 12a, one end of which opens in the vicinity of a predetermined position on the cam surface of the cam and the other end of which opens into the oil passage of the cam shaft
It has a structure in which at least one is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a camshaft particularly suitable for a push rod type valve operating mechanism.

[0002]

[Prior art]

 The engine valve mechanism is suitable for the purpose in consideration of the shape of the combustion chamber, the required speed range, the degree of freedom in designing the intake and exhaust holes, the space at the engine head, the serviceability of assembly, the weight, the manufacturing cost, etc. The most popular type is the overhead valve type, which makes it easy to design a compact combustion chamber and smooth intake and exhaust holes. Overhead valve types include push rod type, rocker arm type overhead cam, swing arm type overhead cam, direct drive type overhead cam, etc., depending on the cam position, rocker arm shape and presence, etc. It features high reliability and a high degree of freedom in designing the shape of the combustion chamber.

The push rod type is arranged above the cylinder head 1 as shown in FIG. 1, the substantially center is pivotally supported by the rocker shaft 2, and the lower surface of the tip 3a is in pressure contact with the upper end of the stem 4a of the valve 4. Rocker arm 3, a camshaft 5 arranged on the side of a cylinder block (not shown), a lower end abuts on a cam 6 via a tappet (valve lifter) 7, and an upper end is screwed on a base end 3b of the rocker arm 3. It is composed of a push rod 8 and the like that is in contact with the lower end of the attached valve adjust screw. As the cam 6 rotates, the push rod 8 is pushed up via the tappet 7 and the rocker arm 3 is swung to swing the valve 4. It is configured to open and close.

The tappet 7 is attached with a slight offset from the center line of the cam 6 as shown in FIG. 2, and the friction between the cam 6 and the lower surface (sliding surface) 7 a of the tappet 7 causes the cam 6 to move. By rotating the tappet 7, the lower surface 7a is evenly worn to prevent abnormal wear such as step wear. In order to rotate the tappet 7 effectively, the cam 6 has a cam surface slightly tapered (tapered cam), and the lower surface 7a of the tappet 7 is slightly spherical (spherical R tappet). ing.

[0005]

[Problems to be solved by the device]

 By the way, in the conventional push rod type valve operating mechanism, the oil that lubricates the sliding surface between the lower surface 7a of the tappet 7 and the cam 6 drips from the rocker shaft 2 through the push rod 8 and the tappet 7. Since it depends on oil and the oil transmitted to the tapet 7 scatters as the tappet rotates, the oil supplied to the sliding surface tends to be insufficient. Moreover, since the tappet 7 is arranged right above the cam 6, it is difficult to supply oil from the cam side to the sliding surface.

The present invention has been made in view of the above points, and in particular, a sufficient amount of oil is applied to the sliding surface between the cam and the tappet in the push rod type valve mechanism in which the tappet is arranged directly above the cam. It is an object to provide a camshaft that can be supplied.

[0007]

[Means for Solving the Problems]

 To achieve the above object, according to the present invention, a cam shaft having an oil passage formed in the shaft center and one end surface of the cam are expanded in a substantially conical shape from the cam shaft toward the one end surface of the cam. And a structure in which at least one oil hole communicating with the oil passage of the cam shaft is formed at one end of the connection portion, one end of the connection portion facing the predetermined position on the cam surface of the cam is opened. It was done.

[0008]

[Action]

 The oil supplied to the oil passage at the axial center of the camshaft is injected from the oil hole of the connecting portion to the vicinity of a predetermined position on the cam surface, and is supplied to the sliding surface between the cam and tappet. As a result, sufficient oil is supplied and lubricated on the sliding surface between the cam and tappet.

[0009]

Embodiment An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. In FIGS. 3 and 4, the cam shaft 10 is integrally formed with a cam 11 at a predetermined position, and the one end surface of the cam 11 is reduced in diameter toward the cam shaft 10 with a marginal edge 11a left. It is continuously provided by a conical connecting portion 12. In addition, after forming the conical connecting portion 12 on one end surface of the cam 11, the peripheral edge portion 11a may be formed by subjecting the peripheral edge of the connecting portion 12 to end surface processing.

The camshaft 10 has an oil passage 10a penetrating the axial center thereof, and a plurality of, for example, four small holes (hereinafter referred to as “oil holes”) 12a to 12d are formed in the continuous portion 12. ing. These oil holes 12a to 12d are formed in a radial shape and are inclined in the axial direction. One end of each of the oil holes 12a to 12d is located slightly outside the peripheral edge portion 11a of one end surface of the cam 11. The oil hole 12a faces the cam nose 11A of the cam 11, the oil holes 12b and 12d face the cam lift portions 11B and 11D, and the oil hole 12c faces the vicinity of the cam base portion 11C. Each of the other ends communicates with the oil passage 10a at the axial center of the cam shaft 10 at a position axially separated from the cam 11 from each of the open ends. That is, the oil holes 12a to 12d are formed in the axial direction from the oil passage 10a to a position slightly outward of the peripheral portion 11a of the cam 11. These oil holes 12a to 12d are small holes.

The cam shaft 10 is incorporated in, for example, the above-mentioned overhead valve type push rod type valve operating mechanism, and the tappet 13 is arranged directly above the cam 11 as shown in FIG. The oil passage 10a is connected to the lubrication system of the valve mechanism to supply oil. The camshaft 10 is rotationally driven in synchronization with the crankshaft, pushes up the push rod via the tappet 13, rocks the rocker arm, and opens a valve (neither is shown).

The operation will be described below. Part of the oil supplied to the oil passage 10a of the camshaft 10 is ejected from the oil holes 12a to 12d and is supplied to the lower surface 13a of the tappet 13 which is in sliding contact with the cam surface of the cam 11. On the other hand, a part of the oil that lubricates the rocker arm and the like flows down the tappet 13 along the push rod and is further supplied to the sliding surface between the lower surface 13 a of the tappet 13 and the cam 11. As a result, a large amount of oil is supplied to the sliding surface between the cam 11 and the tappet 13, and sufficient oil is supplied even during the cam lift where the surface pressure increases.

In the above embodiment, the case where the present invention is applied to the push rod type valve operating mechanism has been described, but the present invention is not limited to this, and it goes without saying that the present invention can also be applied to a valve operating mechanism of other structures. Is.

[0014]

[Effect of device]

 As described above, according to the present invention, sufficient oil can be supplied to the sliding surface between the cam and the tappet, and the sliding surface between the two can be satisfactorily lubricated. In particular, it is suitable for a cam shaft of a push rod type valve mechanism in which the tappet is arranged directly above the cam.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an overhead valve type push rod type valve mechanism.

FIG. 2 is an explanatory diagram showing a relationship between a cam and a tappet shown in FIG.

FIG. 3 is a perspective view of a main part of a camshaft according to the present invention.

4 is a sectional view taken along the line IV-IV in FIG.

[Explanation of symbols]

 10 camshaft 10a oil passage 11 cam 12 continuous installation part 12a-12d oil hole 13 tappet

Claims (1)

[Scope of utility model registration request] 1. A cam shaft having an oil passage formed in its axis and one end surface of the cam are continuously connected by expanding the diameter from the cam shaft toward the one end surface of the cam in a substantially conical shape. A camshaft, wherein one end of the camshaft is opened so as to face a predetermined portion of the cam surface of the cam, and the other end is formed with at least one oil hole communicating with an oil passage of the camshaft.