JP2568846Y2 - Rocker arm support structure - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION This invention is relates to a structure for supporting a rocker arm which is swung by the camshaft in OHC engine.

[0002]

2. Description of the Related Art Overhead camshaft (OHC)
The engine uses a camshaft arranged above a cylinder as a driving means of a valve operating mechanism for opening and closing an intake / exhaust valve. Specifically, a cam driven to rotate in conjunction with a crankshaft is used. A shaft is provided on the cylinder head, and the rocker arm is swung by the rotation of the cam shaft, and the opening and closing operation of the intake / exhaust valve is controlled by the swing of the rocker arm. When this OHC engine is provided with a total of four valves, two each on the intake side and the exhaust side, a DOHC (double overhead camshaft) structure including two rocker shafts and two camshafts Is generally adopted (actual opening 63-
No. 147508). The reason is that, by arranging one rocker shaft and one camshaft as one set and arranging one set on both sides above the combustion chamber, the spark plug can be arranged between them and directly above the combustion chamber. This is because there is an advantage that a space can be obtained.

[0003]

However, in this prior art, since two rocker shafts and two camshafts are provided, the support structure for supporting both ends of each of the four shafts has a reduced number of parts. It is often complicated, and the workability of assembling also worsens.

Accordingly, an object of the present invention is to provide a rocker arm support structure in which the number of parts is reduced, the configuration is simplified, and the workability of assembly is improved.

[0005]

In order to achieve the above object, a rocker arm support structure according to the invention of claim 1 comprises:
And two rocker shaft for supporting the rocker arm so as to be parallel to each other, between these lockers shaft
A camshaft disposed below and extending from near one end to near the center of the rocker shaft in parallel with the rocker shaft, and a supported shaft formed at each end of the rocker shaft and the camshaft and supported by the cylinder head. A first support for supporting the supported portion formed at one end of each rocker shaft and the supported portion formed at one end of the camshaft on a cylinder head; A second support for supporting the supported portion formed at the other end on the cylinder head, and a third support for supporting the supported portion formed at the other end of each rocker shaft on the cylinder head. provided, the first
Or the third support is connected by a bridge portion to form an integral body
It has been.

[0006]

In the rocker arm support structure according to the first aspect, one end of a total of three shafts of two rocker shafts and one camshaft is supported by the first support, and the camshaft is supported by the second support. the other end is supported in, by the third support is supported the other end of the rocker shaft, the three supports are connected by a bridge portion
It is one thing. Therefore, three shafts
Extremely configuration because it can be supported at three places by one support
Can be simplified. In addition, lock above the camshaft.
Because the car shaft is located, the rocker shaft
Since the distance between them can be shortened,
The body can also be made smaller.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view of a valve mechanism of an OHC engine having a rocker arm support structure according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 1, FIG. 4 is a cross-sectional view of the IV-IV line of FIG. 1, FIG. 5 is a cross-sectional view of the V-V line of FIG. 1, and FIG. 6 is a VI-VI line of FIG. 7 is a cross section of the main part.
The cross-sectional views of the I-VII line are shown.

The overall configuration will be described briefly with reference to FIGS. An intake passage 3 and an exhaust passage 4 are formed in the cylinder head 2 of the cylinder 1 in FIG. 2, and two (only one is shown in FIG. 2) intake valves 5 are provided in the intake passage 3.
Two (only one is shown in FIG. 2) exhaust valves 6 are provided in the exhaust passage 4.
Is provided. Each intake valve 5 and each exhaust valve 6 are urged in a valve closing direction by two kinds of large and small valve springs 7 and 8, and face a combustion chamber 11 formed in a space above a piston 10 in a cylinder 9. .

At the upper part of the cylinder head 2, there is provided a support member 12 having a substantially sun-shaped flat shape as shown in FIG. The support member 12 includes a first support 13 extending vertically in the figure at the left end of FIG. 1, a second support 14 extending vertically in the figure at the center, and a vertical support 14 at the right end in FIG. And a third support member 15 extending in the same direction. The support members 13 to 15 are connected to each other via a bridge portion 16 having substantially the same shape, and have a substantially planar Japanese character shape as described above.

As shown in FIGS. 5 and 7, respectively, at both ends of the first support 13 and the third support 15,
A support hole 1 for arranging two cylindrical rocker shafts 17A and 17B in parallel with each other and inserting and supporting both ends thereof.
8 are drilled, and each rocker shaft 17A, 17
B has support holes 1 at both ends to be supported portions thereof.
8 and is supported in a erected state. Further, screw insertion holes 19 for fixing the rocker shafts 17A and 17B are formed in both ends of each of the first support 13 and the third support 15 so as to penetrate vertically. 17B, a detent hole 20 of substantially the same diameter corresponding to the screw insertion hole 19 is provided with the rocker shaft 1.
It is drilled at a location passing through the axis of 7A, 17B.

Incidentally, only the screw insertion hole 19 in FIG.
The rocker shaft 17B is formed at a position eccentric from the axis of the rocker shaft 17B, and an eccentric detent hole 20 is formed in the rocker shaft 17B correspondingly. And
As shown by phantom lines in FIG. 3, the fixing screw 21 is inserted through the screw insertion hole 19 and the rotation preventing hole 20 so that the cylinder head 2
The support member 12 is fixed to the cylinder head 2 by screwing into the screw hole 23 of the support base portion 22 of the support base portion 22, and the first and third support members 13 are fixed in a state where the rocker shafts 17A and 17B are prevented from rotating. , 15.

As shown in FIGS. 2 and 3, rocker arms 24A and 24B are rotatably fitted to the rocker shafts 17A and 17B, respectively.
As shown in FIG. 1, each of the rocker arms 24A and 24B is integrally formed with two valve drive arms 25 and one cam follower arm 26, respectively. A roller 27 serving as a cam follower is provided at the tip of the cam follower arm 26.
Are rotatably supported. As shown in FIG. 2, the roller 27 is in contact with a cam portion of a camshaft described later, and the distal end of the valve drive arm 25 is in contact with a shim 28 at the upper end of the intake valve 5 or the exhaust valve 6. I have.

As shown in FIG. 2, the rocker shaft 17
A, a single camshaft 29 having a length extending from the vicinity of one end (left end in the drawing) to the vicinity of the center of the support member 17B is provided.
The rocker arms 24A,
The shaft is supported in parallel with 24B. Therefore, the cam
The rocker shafts 17A, 1 are located above the shaft 29.
7B, the rocker shafts 17A,
Since the distance between 17B can be shortened, the first to third support members
13 to 15 connected by a bridge 16
Can be formed. This camshaft 29 has
As shown in FIG. 4, a driving sprocket 30 is fixed to a tip portion, and a positioning portion 31,
Journal part 32, exhaust side cam part 33, intake side cam part 3
4 and the journal portion 35 are integrally formed in this order.
As shown in FIG. 5, concave portions 36 and 37 having a radius of curvature matching the outer periphery of the journal portion 32 are formed on the first support body 13 and the support base portion 22 of the cylinder head 2 facing the one journal portion 32, respectively. The two concave portions 36 and 37 form a bearing surface that rotatably supports the journal portion 32. Similarly, as shown in FIG. 6, each of the second support 14 and the support base 22 of the cylinder head 2 facing the journal 35 at the other end has a concave portion 38 having a radius of curvature matching the outer periphery of the journal 35. , 39 are formed, and the two recesses 4 form a bearing surface for rotatably supporting the journal 35.

As shown in FIG. 4, the first support 13 and the support base 22 of the cylinder head 2 correspond to the positioning parts 31 provided in a state protruding in a direction perpendicular to the axial direction of the camshaft 29. Engaging concave portions 40 and 41 for rotatably fitting the positioning portions 31 are formed, and the camshaft 29 is axially positioned by the engagement between the positioning portions 31 and the two engaging concave portions 40 and 41. ing.

The rocker arms 24A and 24B are
As shown in FIG. 3, it is positioned in the axial direction by the elastic force of the spring 42 mounted on the rocker shafts 17A and 17B. When the shim 28 of the intake and exhaust valves 5 and 6 shown in FIG. Arms 24A and 24B are shown in FIG.
By shifting the spring 42 to the right in the drawing against the elastic force of the spring 42, the replacement operation can be easily performed.

As described above, the camshaft 29 is set to extend from one end of the rocker shafts 17A and 17B supported by the first support 13 to the center near the second support 14. As shown in FIG. 1, a cavity 43 in which the camshaft 29 does not exist is formed in a portion surrounded by the second support 14 and the third support 15 and the bridge portions 16 on both sides connecting them. An ignition plug 44 is disposed in the hollow portion 43 at the center of the cylinder 1.

According to the rocker arm support structure of the above embodiment, the two rocker shafts 17A and 17B in FIG. 2 are provided with two intake valves 5 and two exhaust valves 6 each. (Single overhead camshaft) having a single camshaft 29 and a single camshaft 29
Achieved structure. And these three shafts 1
7A, 17B and 29 are supported at three places by the first to third supports 13 to 15 of the support member 12 shown in FIG. That is, the first support 13 supports one end of each of the rocker shafts 17A and 17B in a non-rotating state, and the one end of the camshaft 29 is rotatable together with the support base 22 of the cylinder head 2 in FIG. The other end of the camshaft 29 is rotatably held together with the support base 22 of the cylinder head 2 by the second support 14, and each of the rocker shafts 17A and 17B is supported by the third support 15 of FIG. The other end is supported in a detented state.

Here, the support member 12 includes first to third members.
Since the support members 13 to 15 are integrated with each other by the bridge portion 16, the number of components is reduced, and the assembling workability is improved. By the way, since the fixing screw 21 is not attached near the second support 14, the second support 14
The pressing force of the camshaft 29 due to is not so large. However, unlike the rocker shafts 17A and 17B to which an upward force is applied, the camshaft 29 has the valve springs 7 and
Since a downward force is mainly applied by the urging force of No. 8, there is no need to press with a large force from above, so the pressing force of the second support 14 on the other end of the camshaft 29 is sufficient.

[0019]

As described above, according to the rocker arm support structure according to the present invention, the structure provided with four valves has the SOHC structure and the two rocker shafts and one camshaft are connected. The first to third supports are supported at three places by first to third supports , and the first to third supports are bridge portions.
To form an integral support member.
Can be extremely simplified. Also above the camshaft
The rocker shaft is located at
Since the distance between the raft can be shortened, three support
It is also possible to form the integrated body small.

[Brief description of the drawings]

FIG. 1 is a plan view of a valve mechanism of an OHC engine to which a rocker arm support structure according to an embodiment of the present invention is applied.

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

FIG. 3 is a cross-sectional view of a main part along line III-III in FIG. 1;

FIG. 4 is a cross-sectional view of a main part along a line IV-IV in FIG. 1;

FIG. 5 is a cross-sectional view of a main part along line VV of FIG. 1;

FIG. 6 is a cross-sectional view of a main part along line VI-VI in FIG. 1;

FIG. 7 is a cross-sectional view of a main part along line VII-VII in FIG. 1;

[Explanation of symbols]

2 ... cylinder head, 13 ... 1st support, 14 ... 2nd support, 15 ... 3rd support, 16 ... bridge part, 17A,
17B: rocker shaft; 24A, 24B: rocker arm; 29: camshaft.

Claims (1)

(57) [Scope of request for utility model registration] 1. A and two rocker shaft for supporting the rocker arm so as to be parallel to each other, the central portion is disposed in its downward from one end vicinity of the rocker shaft parallel to the rocker shaft between these lockers shaft A camshaft extending to the vicinity, a supported portion formed at each end of each of the rocker shafts and the camshaft and supported by a cylinder head, and a supported portion formed at one end of each of the rocker shafts; A first support for supporting the supported portion formed at one end of the camshaft on the cylinder head; and a second support for supporting the supported portion formed at the other end of the camshaft on the cylinder head. comprising a body, a third support for supporting the supported portion formed at the other end of each rocker shaft to the cylinder head, said first Third support member are connected by a bridge portion Stone
Rocker arm support structure that is integrated .