JPS60178910A - Internal-combustion engine - Google Patents

Abstract

PURPOSE:To enhance the rigidity and reduce the weight of a cam bearing stand by having the bearing stand consist of yoke parts which are integrated with each other, a primary and a secondary separating wall parts which are perpendicular to each other, and a cylindrical wall part which defines an ignition plug engaging/disengaging hole. CONSTITUTION:A cam bearing stand 15 can be engaged and disengaged with and from a cylinder head and has a cam shaft, a rocker shaft, a rocker arm and so forth mounted thereon to make up an assembly of a valve tappet mechanism. The cam bearing stand consists of a yoke part 15a fringing the external periphery thereof, a primary separating wall part 15b having a bearing hole 39 in which the cam shaft is engaged and extending in the direction perpendicular to the cam shaft, a secondary separating wall part 15c which is perpendicular to the primary separating wall part 15b, and a cylindrical wall part 15d defining an engaging/disengaging hole 38 served for an ignition plug which is screwed on the cylinder head. The yoke part 15a, the primary separating wall part 15b, the secondary separating wall part 15c, and the cylindrical wall part 15d are integrated with each other, hence achieving high rigidity and reduction in weight.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine in which a cam bearing stand for supporting a camshaft of a valve train is removably bonded to a cylinder head.

In such an internal combustion engine, before the cam bearing pedestal is attached to the cylinder head, the camshaft, rocker shaft, rocker arm, etc. can be assembled to the cam bearing pedestal to form a valve train assembly. Although this has the advantage of being easy to disassemble and maintain, it has the disadvantage that the cam bearing stand increases the weight of the engine. Therefore, it is desirable for the cam bearing stand to be as light as possible while maintaining sufficient support rigidity for the valve train.

On the other hand, in recent years, with the trend toward higher engine output, the development of four-valve engines with one pair of intake and exhaust valves per cylinder has progressed. Because it is necessary to place the spark plug electrode in the center of the combustion chamber of each cylinder,
The spark plug is placed approximately on the axis of the cylinder. However, when the cam bearing pedestal is employed in such an engine, a removable hole for the ignition plug must be formed in the cam bearing pedestal, which causes a problem of reducing the rigidity of the cam bearing pedestal.

The present invention was made in view of such a technical background, and although it has a hole for attaching and detaching a spark plug, it has sufficient rigidity and
The internal combustion engine is equipped with a lightweight cam bearing pedestal (for the purpose of providing a residual quantity), and its characteristics include a frame portion that frames the outer periphery of the cam bearing pedestal, and a frame portion that frames the outer periphery of the cam bearing pedestal; a plurality of first partitions extending in a direction perpendicular to the axis of the camshaft and integrally connected to the frame; and a second partition intersecting these first partitions and also integrally connected to the frame. A bearing hole into which the camshaft fits is formed in the first partition wall part, and a cylindrical wall part defining an attachment/detachment hole for an ignition plug screwed to the cylinder head is formed in the first partition wall part. The first and second partition walls are integrally connected to each other.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.The internal combustion engine shown in FIG.
1, has C2. Since the structures of both cylinder rows C, , C2 are symmetrical, only the son left cylinder row C1 will be described.

A cylinder head 3 is superimposed and bonded to the upper surface of a cylinder block 2 having a cylinder 1 via a gasket 4. A piston 5 is slidably fitted into the cylinder 1, and a combustion chamber 6 is recessed in the bottom surface of the cylinder head 3 facing the piston 5.

The ceiling surface Y of the combustion chamber 6 curves around the axis g of the cylinder 1 or in the vicinity thereof. There are two ceiling slopes 7a and 7b that go down toward the roof line ridgeline, and one ceiling slope 7a has a pair of intake ports 8, 8, and the other ceiling slope 7h has the same. A pair of exhaust ports 9, 9]
(Open and close the intake ports 8, 8 and exhaust ports 9 and 9, respectively)
In each pair of intake valves 10.10 and exhaust valves 11.11 are provided in the cylinder head 3 with valve guides 12.12 and 1.
3.13 each is slidably supported. that time,
The intake valves 10 and 10 are connected to both cylinder rows C" with a plane P that includes the cylinder axis and IC and is parallel to the ridgeline as a boundary.
1.

On the side of the valley V between C'2, the exhaust valves ii, ii are arranged on the opposite side thereof, and both valves 10, 11 are inclined in mutually opposite directions with respect to the plane P.

As shown in FIGS. 2 and 4, an ignition plug 14 with an electrode facing the combustion chamber 6 is screwed onto the cylinder head 3, and this ignition plug 14 has intake and exhaust valves 10°, 10; 11, 11. It is arranged approximately along the cylinder axis Ac so that it is surrounded by.

A valve chamber 17 is formed on the upper surface of the cylinder head 3 by sequentially overlapping and bonding a cam bearing pedestal 15 and a head cover 16, and the intake valve 10.degree. 10 and the exhaust valve 11.
A valve train 18 is provided which provides opening and closing operations to the valve 11, and has the following configuration.

Valve springs 19, 19 and 20.20 are respectively attached to the intake valve 10.10 and the exhaust valve 11.11 to bias them toward the closing side.

Intake valve io, almost directly above io, therefore cylinder axis A
At a position closer to the valley V side than c, a camshaft 21 that is interlocked with a crankshaft (none of which is shown) via a timing transmission is disposed parallel to the plane P. 21 connects the journal 21 to the cam bearing stand 15 and the bolt 22.
The bearing cap 24 is rotatably held between the bearing caps 24 which are connected by the bearing caps 23 and 23.

Disposing the camshaft 21 so as to be shifted toward the valley V side in this manner is effective in reducing the maximum outer dimensions of both cylinder rows CI + 62 as much as possible and downsizing the P' type engine.

As shown in FIG. 3, the camshaft 21 has a pair of intake cams 21Z corresponding to the intake valves 10.10 and exhaust valves 11.11.
, 21z and exhaust cams 21e, 21e, the intake cams 21i, 21i are arranged adjacent to the journal 21 on both sides thereof, and the exhaust cams 21e, 21e are further arranged on the inner and outer sides thereof.

Intake cam 21, 21? A pair of first cam followers 25.25 are interposed between the intake valve 10.10 and the head of the intake valve 10.10.

The first cam followers 25, 25 are provided with an adjustment bolt 26 at each base end, and a spherical end 26. z is rotatably engaged with a spherical recess 27Q of a support bolt 2γ screwed onto the cylinder head 3.

The first and second support shafts 28 and 29 are fixed to the cam bearing stand 15 with bolts 22 and 30, respectively.
8.29 is the intake and exhaust valve 10, 10; 1'1, 11
They are spaced sufficiently apart from each other with the axis Ap of the spark plug 14 in between, and are arranged parallel to the camshaft 21 . The first support shaft 28 near the intake valve 10.10 is connected to the intake cam 21.
>, , 211 is engaged with the second of the pair
The cam follower 31.31 is swingably supported, and the exhaust valve 1
A second support shaft 29 near 1.11 swings a pair of bell crank type rocker arms 33, 33 which engage with the heads of the exhaust valves ii and 1i through adjustment bolts 32, respectively. Support. A pair of 70-tube rods 34, 34 are interposed between the opposing surfaces of the second cam followers 31, 31 and the rocker arms 33, 33, respectively.

In addition to the aforementioned bolts 22 and 30 used to connect the cam bearing stand 15 to the cylinder head 3, a dedicated bolt 37 is also used.
is also used.

The cylinder head 3 and the cam bearing stand 15 have an ignition plug 14
A series of attachment/detachment holes 38 into which attachment/detachment tools are inserted are provided in an area surrounded by the two support shafts 28.29 and the surround of the deck/yellow 1-'' 34.34, and these attachment/detachment holes 38 It is opened to the outer surface of the head cover 16 through a partition tube 36 interposed between the bearing stand 15 and the head cover 16.

In this case, the two support shafts 28, 29 are spaced sufficiently apart from each other, and the two shafts 34, 34 are engaged with the exhaust cams 21e, 21e at the outer circumferential positions to ensure a wide space between them. The attachment/detachment hole 38 can be formed to have a size sufficient to allow the spark plug 14 to be easily attached/detached.

Now, the structure of the cam bearing stand 15 will be explained with reference to FIGS. 4 to 9. The basic shape of the cam bearing stand 15 is a rectangle that is long in the axial direction of the camshaft 21, and a frame frames the four sides of the outer periphery. a plurality of first partition wall portions 15 b that integrally connect the opposing long sides of the frame portion 15 a;
15b... and these first partition parts 15b, 15b.
. . and connects the opposite short sides of the frame 15a. It is composed of r. Each first partition wall portion 15b has a semicircular bearing hole 39 into which the camshaft 21 is fitted.
and a bearing boss 40. into which the support shafts 28 and 29 fit, respectively.
41 are formed, and the first partition portions 15b, 15A...
The attachment/detachment hole 38 is provided at each intersection between the ・and the second partition wall portion 15C.
A plurality of cylindrical wall portions 15ct, 15 defining ゜38...
d°". is formed. Thus, the cylindrical wall portion 15d is integrally connected to both the partition walls 15b and 15C.

Next, to explain the operation of this embodiment, during assembly,
First, the cam shaft 21 and the support shafts 28 and 29 are mounted on the cam bearing stand 15.
etc. are attached to form the assembly of the valve train 18. Next, the cam bearing stand 15, which is the base of this assembly, is superimposed on the two sides of the cylinder head 3 (pol) 22, 30.
．． 37 to bind. The rest of the assembly is carried out in the conventional manner.

When the engine is operated, the cam l1ll! 121 is rotationally driven by a crankshaft via a timing transmission (not shown). Then, when the intake stroke of the piston 5 is started, the peaks of the intake cams 21t and 21i are connected to the first cam follower 25.25.
are swung toward the intake valves 10 and 10, respectively, so
As a result, the intake valve 10°10 opens against the elastic force of the valve springs 19, 19, and the intake cam 2 opens at the end of the intake stroke.
Since the peaks 1i and 21L pass the first cam followers 25 and 25, the intake valve 10.10 is closed by the elastic force of the valve springs 19 and 19. During this time, an air-fuel mixture is drawn into the combustion chamber 6 from an air-fuel mixture generating device such as a carburetor (not shown) through the intake port 8.8.

When the piston 5 approaches the end of its compression stroke, the compressed gas in the combustion chamber 6 is ignited by the spark discharge from the spark plug 14, and the piston 5 moves to the expansion stroke. At this time, since the ignition plug 14 is located at or near the cylinder axis Ac, the flame propagation distance from the ignition point to each peripheral edge of the combustion chamber 6 is approximately equal, so the combustion time is shortened to the minimum and high output is achieved. is demonstrated.

When the exhaust stroke of the engine 5 starts, the exhaust cam 21
Since the peaks of g and 21g swing the second cam follower 31°31 towards the bushing rod 34.34, the bushing rod 34.34 is displaced and swings the rocker arm 33.33 towards the exhaust valve 11.11. As a result, the exhaust valves 11, 11 open against the elastic force of the valve springs 20, 20, and at the end of the exhaust stroke, the peaks of the exhaust cams 21e, 21N pass the second cam followers 31, 31, so that the exhaust Valves ii, ii are closed by the resilient force of the valve springs 20,20. During this time, exhaust gas is discharged from the combustion chamber 6 to the exhaust port 9.9.

During such operation of the engine, the cam bearing pedestal 15 is always subjected to a heavy load from the valve train 18, but the cam bearing pedestal 15 is exposed to the intersecting first and second partition wall portions 15h.

15C, and both corner walls 15b.

15,? Since it is reinforced by the cylindrical wall portion 15d and has sufficient rigidity, it can withstand the above load and continue to firmly support the valve train 18.

When attaching and detaching the ignition plug 14, the partition tube 36 and the attachment/detachment hole 3
This is done by inserting a special tool into the ignition plug 8, fitting it into the head of the ignition plug 14, and rotating it.

As described above, according to the present invention, a cam bearing pedestal is provided with a frame portion that frames the outer periphery of the cam bearing pedestal, and a plurality of shafts extending in a direction perpendicular to the axis of the camshaft and integrally connected to the frame portion. The cylinder head is composed of a first partition wall and a second partition wall that intersects with the first partition wall parts and is also integrally connected to the frame part. A cylindrical wall portion defining an attachment/detachment hole for an ignition plug screwed into the first and second
Since it is integrally connected to the partition wall, even though it has an attachment/detachment hole for the ignition plug, the cylindrical wall that defines the attachment/detachment hole can be effectively used to
The second partition wall portion can be reinforced, and as a result, a highly rigid cam bearing stand can be obtained, and since there is no waste material, it is lightweight. Therefore, the valve train can be firmly supported and the weight of the engine can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of the main parts of an internal combustion engine according to an embodiment of the present invention, Fig. 2 is a bottom view of the cylinder head in Fig. 1, and Fig. 3 is the cylinder head shown with the head cover removed.
4 is an enlarged plan view of the figure, FIG. 4 is a sectional view taken along the line iv-rv of FIG. 3, and FIG. 5 is a plan view of the cam bearing stand alone in FIG.
Figure 6, Figure 7, Figure 8 and Figure 9 are the vr - of Figure 5.
v-r line, Vll-■ line. -1111-1'llll line and IX-IX line sectional view. 14... Spark plug, 15... Cam bearing stand, 15a...
-Frame part, 15h...First partition part, i5C...Second partition part, 15d -Cylindrical wall part, 18...Valve train, 21.
・Camshaft, 25...1st cam follower, 28.29・
°1st °2nd support shaft, 31...second cam follower, 33
...Rocker arm, 34...Push rod, 3G.
・Partition tube, 38... Attachment/detachment hole, 39... Bearing hole, 40.4
1... Bearing patent applicant Honda Motor Co., Ltd. agent Patent attorney Ochiai i-:m... Figure 4Figure 2

Claims (1)

[Claims] In an internal combustion engine in which a cam bearing pedestal supporting a camshaft of a valve train is removably superimposed on a cylinder head, the cam bearing pedestal is connected to a frame portion that frames the outer periphery of the cam bearing pedestal, and a frame portion that frames the outer periphery of the cam bearing pedestal, and the camshaft. a plurality of first partition walls extending in a direction perpendicular to the axis of the frame and integrally connected to the frame; The bearing hole into which the camshaft fits is formed by ti.
iJ, characterized in that it is formed in the first partition wall and is integrally connected to the first and second partition wall parts, which are cylindrical wall parts defining an attachment/detachment hole for an ignition plug screwed to the cylinder head. internal combustion engine.