JPS6220605A - Cam shaft of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable reduction of the size and the weight of a gear and a bearing, by a method wherein a cam shaft forms 3-split structure consisting of an intermediate member having a gear for driving and members at both ends each having a cam, and the members are axially coupled with each other. CONSTITUTION:A cam shaft 10 is formed such that a gear 11a for driving a cam shaft is formed integrally with the outer peripheral surface of an axially- extended intermediate part, and is formed with a hollow cylindrical intermediate member 11 having open end surfaces thereacross, and members 12 and 13 at both ends, positioned at both ends of the intermediate member 11, coupled with each other through axial press-in, and having plural cams 12a, 12b and 13a, 13b integrally formed. Journal parts 12c and 13c, engaged with ball bearings 14a and 15a of cam shaft holders 14 and 15, are formed on the one end sides of the members 12 and 13, respectively at both ends. Further, journal parts 12f and 13f, engaged with ball bearings 16a and 17a of cam shaft holders 16 and 17, are formed on the other end sides of the members 12 and 13, respectively, at both ends.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a camshaft for an internal combustion engine, in which a driving gear is provided on a camshaft body, and cams are provided at both ends of the driving gear.

(Prior art and its problems) In the conventional camshaft as described above, the camshaft main body is integrally constructed over the entire shaft length, so for example, the second camshaft
In the figure, the gear 1 is the gear attachment part 2 of the camshaft body 2.
If you try to attach the gear 1 to the cam 2b of the camshaft body 2.

2C, 2d, and 2e to connect the camshaft body 2.
It is necessary to attach it to the gear attachment part 2a. Therefore, when the inner diameter α of the gear 1 is larger than the dimension β of the maximum diameter part of the cam profile of each of the cams 2b to 2e, the inner diameter α of the gear 1 becomes a large diameter, and the inner diameter α and the gear mounting portion It is necessary to attach it via a spacer 1a to compensate for the difference with the outer diameter of 2a, and since the spacer 1a is required, this is disadvantageous in terms of the number of parts and assembly. Further, the outer diameter of the gear 1 also becomes large, and accordingly, the outer diameter of the camshaft body 2 also becomes large. Similarly, the ball bearings 3a and 4a of the camshaft holders 3 and 4 are attached to the journal part 2f provided between the cam 2C on one end side of the camshaft body 2 and the gear attachment part 2a, and the cam 2e on the other end side and the gear attachment. When attempting to attach the ball bearings 3a, 4a to the journal portion 2g provided between the cam 2b and the cam 2b.

It is necessary to insert and attach 2c, 2d, and 2e.

Therefore, the inner diameter γ of the ball bearings 3a, 4a is the same as that of the respective cams 2b~
When the ball bearings 3a, 4a are attached to the journal portions 2f, 2g of the camshaft body 2, the inner diameter γ of the ball bearings 3a, 4a and the journal A spacer 5.6 must be interposed to fill the difference between the outer diameters of the journal parts 2f and 2g, and the outer diameter of the journal parts 2f and 2g and the ball bearing 3a.
The difference in diameter between +4a and the inner diameter T is large, and in practice the ball bearings 3a+4a of the camshaft holders 3 and 4 are connected to the journal portion 2f of the camshaft body 2.

2g through the large-diameter spacers 5 and 6, respectively, resulting in problems.

In this way, in the camshaft with the conventional structure, the camshaft body 2, gear 1, and ball bearings 3 and 4 all have large diameters, so
The weight increases, and even if the rotation speed is the same, the larger the diameter, the faster the circumferential speed and the larger the capacity of the bearing.In the case of ball bearings, the balls become larger, and in the case of metal, the circumferential speed itself increases due to sliding. The oil lubricated surface has a large surface area, which increases sliding resistance, and at high speeds, problems such as adverse effects occur.

(Object of the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a camshaft for an internal combustion engine that can reduce the size and weight of gears and bearings, and has less horsepower loss due to cam drive. This is the purpose.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a camshaft for an internal combustion engine in which a driving gear is provided on the camshaft body and cams are provided on both ends of the driving gear. , the camshaft main body has a three-part structure consisting of an intermediate member provided with at least the driving gear and both end members provided with the cam, and the intermediate member and both end members are connected and fixed to each other in the axial direction. It is characterized by:

(Example) Hereinafter, one embodiment of the present invention will be described in detail based on FIG.

As shown in FIG. 1, the camshaft 10 of the present invention is a hollow cylindrical intermediate member 1 with both end surfaces open, which has a camshaft driving gear 11a integrally formed on the outer circumferential surface of an approximately intermediate portion in the axial direction.
1, and a plurality of (for example, two) cams 12a, 12b and 13a, 1 located at both ends of the intermediate member 11 and connected to each other by press-fitting in the axial direction, and on the outer peripheral surface.
3b are integrally formed with both end members 12 and 13.

The gear 11a is a gear (not shown) provided on the crankshaft of the engine via a chain or gear (not shown).
It is combined with

Journal portions 12C and 13c are formed on one end side of the both end members 12.13 through step portions 12d and 13d, which are fitted into ball bearings 14a and 15a of a camshaft holder 14.15, respectively. The other end side of the both end members 12.13 has a ball bearing of the camshaft holder 16.17, which has the same diameter as the fitting portions 1213 and 13e that are press-fitted into the fitting holes 11b and llc of the intermediate member 11, respectively. The journal portions 12f and 13f that are fitted into the stepped portions 16a and 17a are the step portions 12g,
13g respectively.

(Function) Both end members 12 and 13 are press-fitted into both ends of the intermediate member 11, but first, the ball bearings 16a of the camshaft holder 16 are inserted.
The journal portion 1 is inserted through the insertion portion 12e of the one end member 12.
2f and abut against the stepped portion 12g. The ball bearing 17a of the camshaft holder 17 is similarly inserted through the fitting portion 13e of the other end member 13, and brought into contact with the stepped portion 13g. After that, the insertion part 1 of the one end member 12 is attached to one end side of the intermediate member 11.
2e is press-fitted, and one end surface lid of the intermediate member 11 is brought into contact with the ball bearing 16a of the camshaft holder 16. Similarly, the fitting portion 13e of the other end member 13 is provided on the other end side of the intermediate member 11.
is press-fitted, and the other end surface lie of the intermediate member 11 is brought into contact with the ball bearing 17a of the camshaft holder 17.

In this way, the cams 12a, 1 formed on the camshaft 10
A ball bearing 16 having an inner diameter r' smaller than the maximum diameter dimension β' of each of the cam profiles 2b, 13a, and 13b.
a, 17a to the gear 11a of the intermediate member 11 and both end members 1
It becomes possible to insert and arrange them between the cams 12b and 113b of 2.13. The camshaft 10 includes ball bearings L6a, 17a of the camshaft holder 16.17 and camshaft holders 14.15 at both ends of the camshaft 10.
The cylinder head 18 is rotatably mounted on the upper end surface 18a of the cylinder head 18 by ball bearings 14a and 15a.

(Effects of the Invention) As described in detail above, the camshaft for an internal combustion engine of the present invention includes a driving gear on the camshaft body and a cam at both ends of the driving gear. a shaft body and an intermediate member provided with at least the driving gear or sprocket;
The present invention is characterized in that it has a three-part structure consisting of both end members provided with the cam, and these intermediate members and both end members are connected and fixed to each other in the axial direction.

Therefore, the drive gear can be integrally formed with the camshaft body, making it possible to use small gears and bearings with a small inner diameter, and the outer diameter of the camshaft itself is also smaller, making the overall size and weight lighter. In addition, the loss of driving horsepower of the camshaft can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of a camshaft for an internal combustion engine according to the present invention, and FIG. 2 is a longitudinal sectional view of a camshaft for an internal combustion engine according to the prior art.

Claims (1)

[Claims] 1. A camshaft for an internal combustion engine in which a camshaft body is provided with a driving gear and a cam on both ends of the driving gear, in which the camshaft body is connected to an intermediate member provided with at least the driving gear, and the cam is connected to an intermediate member provided with at least the driving gear. A camshaft for an internal combustion engine, characterized in that it has a three-part structure consisting of both end members provided, and the intermediate member and both end members are connected and fixed to each other in the axial direction.