JPH0146691B2 - - Google Patents

Abstract

PURPOSE:To increase the stiffness of cam holders by providing a stiffened frame in a frame form which is integrally equipped with an oil pipe, to the upper surface of the cam holders in a device where the cam holders are assembled on the upper surface of the plural number of shaft bearing pedestals so as to support a cam shaft rotatably. CONSTITUTION:The titled device is composed of the plural number of shaft bearing pedestals 20... which are arranged in parallel at certain intervals on the upper surface of cylinder heads 1, and of cam holders 21... which are installed over the shaft bearing pedestals, and a cam shaft 10 is rotatably supported between the shaft bearing pedestals 20 and the cam holders 21. And the cam holder 21 is connected with side walls 22 and 22 integrally. In this case, a stiffened frame 23 in a frame form including lateral frames 23a... is placed on the upper surface of the cam holder 21..., to which the lateral frames are closely contacted, and then is bolted (24) together. And the stiffened frame 23 includes an oil pipe 26 having sufficient stiffness provided integrally at the center enabling both intake and exhaust valves 10i and 10e to be lubricated through lubricating holes 27... which are formed on the lower surface of the oil pipe 26.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a support device for a camshaft in an overhead cam type valve mechanism of an engine. The present invention relates to a support device for a camshaft that is connected to each other.

(Prior Art) In an overhead cam type valve train for an engine, the camshaft is generally supported on its lower side by bearing stands arranged in parallel at intervals on the upper surface of the cylinder head, and the upper surface of the bearing stand is The upper surface side is supported by a cam holder assembled to each. The cam holder is removably fixed to the bearing stand with bolts. Conventionally, the cam holders were each independent.

However, the cam holder is a plate-shaped thing that is assembled almost perpendicularly to the cylinder head.
Since it is not possible to increase the thickness of the plate due to the limitations of the overall length of the engine, in a camshaft support device in which each cam holder is independent, the axial center position of each cam holder is determined by changes in the camshaft's load fluctuations, whirling, and cylinder head. They tend to shift due to thermal deformation, etc., making it difficult for the camshaft to rotate smoothly. For example, in engines equipped with many valves, such as the four-valve engine that has become common these days, in which each pair of intake valves and exhaust valves are provided in one combustion chamber, all the valves are When opening and closing operations are performed using a single camshaft, the reaction force applied to that camshaft becomes large, so to suppress the swinging of the camshaft, it is necessary to increase the rigidity of the cam holder or cylinder head. However, with the camshaft support device as described above, it is not possible to provide the cam holder and cylinder head with high rigidity.

For this reason, for example, JP-A-57-200648
As shown in the above publication, a camshaft support device has been proposed in which the upper portions of each cam holder are integrally connected to each other via a beam.
By doing so, the rigidity of the cam holder is increased, and the toughness against valve bounce can be improved.

(Problems to be Solved by the Invention) Incidentally, in an engine valve mechanism, it is necessary to lubricate the cam surface of the camshaft. For such lubrication, above the camshaft,
If an oil pipe is installed parallel to the camshaft and the lubricating oil is jetted from the oil pipe toward the cam surface, efficient lubricating oil can be supplied. Therefore, when connecting the upper part of the cam holder with a rigid member such as a beam as described above, as the rigid member,
By using such an oil pipe,
It is conceivable to increase the rigidity of the cam holder and to ensure efficient lubrication.

However, if this is done, the oil pipe, which is a rigid member, will be located at the center of the upper part of the cam holder. Therefore, it becomes difficult to process the camshaft bearing, which is constituted by the cam holder and the bearing stand of the cylinder head. In other words, each of the camshaft bearings must be finished with high precision and each must be positioned exactly on the same axis. A tool such as a reamer is passed through the end for finishing machining, but at that time, the length of the tool is long and the distance between the cam holders is large, so an intermediate bushing is inserted from above between the cam holders to guide the tool. It has become necessary.
In that case, if the oil pipe is provided in the center of the upper part of the cam holder, it becomes impossible to insert the intermediate bushing therein, and finishing machining of the camshaft bearing becomes extremely difficult.

The present invention was made in view of these problems, and its purpose is to increase the rigidity of the cam holder and cylinder head, and to efficiently lubricate the cam surface while improving the camshaft bearing. The purpose is to ensure that finishing processing is not hindered.

(Means for Solving the Problem) In order to achieve this object, in the present invention, a frame-shaped rigid frame that connects each cam holder to each other is removably fixed to the upper surface of the cam holder using tightening bolts or the like. At the same time, an oil pipe that is approximately parallel to the camshaft is integrally installed on the rigid frame. The oil pipe is provided with an oil supply hole that can inject lubricating oil toward the cam surface of the camshaft.

(Function) With this configuration, the cam holders are connected to each other by the rigid frame and the oil pipe, so that the cam holders have high rigidity also in the axial direction of the camshaft. In addition, by assembling the rigid frame to the cam holder,
An oil pipe is arranged above the camshaft. Therefore, the cam surface can be efficiently lubricated.

When finishing the camshaft bearing, a dummy frame without an oil pipe is attached to the cylinder head along with the cam holder in place of the rigid frame. Then, since the upper part between the cam holders becomes open, it becomes possible to insert the intermediate bushing therebetween, and it becomes possible to process it by the same method as in the conventional method.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

In the drawings, FIG. 1 is a perspective view of essential parts showing one embodiment of the camshaft support device according to the present invention, and FIG.
Figures 3 and 3 are a longitudinal sectional view and a vertical lateral sectional view, respectively, of the camshaft support device. Further, FIGS. 4 and 5 are a longitudinal sectional front view and a plan view of essential parts, respectively, of an engine valve mechanism equipped with the camshaft support device.

As is clear from FIGS. 4 and 5, the cylinder head 1 is provided with an intake port 2 and an exhaust port 3. These ports 2 and 3 branch into two intake valve ports 4 and 4 and two exhaust valve ports 5 and 5, respectively, and open into one combustion chamber 6. and,
These intake valve ports 4, 4 and exhaust valve ports 5, 5 are
They are opened and closed by a pair of intake valves 7, 7 and exhaust valves 8, 8, respectively.

A valve mechanism 9 is provided on the upper surface of the cylinder head 1. This valve operating mechanism 9 opens and closes each pair of intake valves 7, 7 and exhaust valves 8, 8 by a single camshaft 10 which is rotated in conjunction with a crankshaft (not shown). ,
The camshaft 10 includes valves 7, 7 and 8,
Intake cams 10i, 10i and exhaust cams 10e, 10e corresponding to the number 8 are provided.

Intake cam 10i and valve stem 7a of intake valve 7
A cam follower 1 is installed in a nearly horizontal direction between the end and the end.
1 is provided. This cam follower 11 is
Its base end is swingably supported by a spherical support portion 12a of an oil tappet 12 provided on the cylinder head 1, and swings up and down as the intake cam 10i rotates, causing the valve of the intake valve 7 to The intake valve 7 is opened by pressing the stem 7a downward against the valve spring 13.

Further, the intermediate portion of a cam follower 14 provided in the vertical direction comes into contact with the exhaust cam 10e. The lower end of this cam follower 14 is connected to an oil tappet 15 provided on the cylinder head 1.
It is swingably supported by a spherical support portion 15a. One end of a push rod 16 is connected to the upper end of the cam follower 14, and a bell crank-shaped rocker arm 17 is connected to the other end of the push rod 16.
The rocker arm 17 is swingably supported at its intermediate portion by a rocker shaft 18 parallel to the camshaft 10, and its rocking causes the valve stem 8a of the exhaust valve 8 to be pushed against the valve spring 1.
9 to open the exhaust valve 8.

A plurality of bearing stands 2 are provided on the upper surface of the cylinder head 1.
0, 20, . . . are arranged in parallel at predetermined intervals. Then, cam holders 21, 21, . . . are assembled on the upper surfaces of the bearing pedestals 20, 20, . There is.

As shown in FIGS. 1 to 4, the cam holders 21, 21, . . . are integrally connected to each other by side walls 22, 22 provided on both sides thereof. Further, a rigid frame 23 is attached to the upper surface of the cam holders 21, 21, . . . . This rigid frame 23 includes horizontal frames 23a, 23a,... which are in close contact with the upper surfaces of the respective cam holders 21, 21,...
A, 23a, . It is becoming more and more common. thus,
The cam holders 21, 21, . . . are connected to each other by a rigid frame 23 also on their upper surfaces. When assembled in this way, the camshaft 10 is fixed by each cam holder 21, 21,... and bearing stand 20, 20,...
Camshaft bearing 2 that supports the journal part of
5, 25, . . . are formed.

An oil pipe 26 is integrally provided in the center of the rigid frame 23. This oil pipe 26 has sufficient rigidity, and together with the vertical frames 23b, 23b, the cam holders 21, 21,
It is designed to function as a rigid member that connects...

Further, this oil pipe 26 is connected to the camshaft 1 when the camshaft 10 is assembled.
It is arranged to be located almost directly above and almost parallel to 0. As shown in FIG. 2, the lower surface of the oil pipe 26 has a number of oil supply holes 2 communicating with the internal oil passage 26a.
7, 27, . . . are formed. This oil supply hole 2
7, 27, ... are the intake cams 1 of the camshaft 10
It opens toward each cam surface of Oi and exhaust cam 10e. Furthermore, an oil supply hole 29 is provided at the end of the oil pipe 26, which is connected to an oil hole 28 formed in the cam holder 21 at the end, thereby connecting the oil passage 26a of the oil pipe 26 with the oil supply hole 29. It communicates with the inner surface of the camshaft bearing 25. As shown in FIG. 3, the oil passage 2 in the oil pipe 26
6a is connected to an oil gear gallery 32 in the cylinder head 1 through an oil introduction hole 30 formed at the end of the oil pipe 26 and an oil hole 31 formed in the cam holder 21 at the end. There is.

Next, the operation of the valve train mechanism 9 configured as described above will be explained.

When the engine is operating, the camshaft 10 is rotationally driven by the crankshaft. At the start of the intake stroke, the cam head of the intake cam 10i comes into sliding contact with the cam follower 11, and the cam follower 11 contacts the spherical support part 1 of the oil tappet 12.
Since it swings downward with 2a as a fulcrum, the intake valve 7
is opened against the valve spring 13. At the end of the intake stroke, the cam head of the intake cam 10i passes the cam follower 11, so the intake valve 7 is closed by the spring force of the valve spring 13. Also, at the start of the exhaust stroke, the exhaust cam 10
The cam head of e is in sliding contact with the cam follower 14, and the cam follower 14 swings in a direction to press the push rod 16 using the spherical support portion 15a of the oil tappet 15 as a fulcrum. As a result, the rocker arm 17 swings counterclockwise in FIG. 4, and the exhaust valve 8
opens against the valve spring 19. At the end of the exhaust stroke, the cam head of the exhaust cam 10e passes the cam follower 14, so the exhaust valve 8 is closed by the spring force of the valve spring 19.

During this period, the camshaft 10 has a pair of intake cams 10i, 10i and an exhaust cam 10e, 10 located between the camshaft bearings 25, 25.
The reaction forces of the valve springs 13 and 19 are applied to e. Also, oil tappet 12,1
Stress due to thrusting up in step 5 is also applied. Such a force is a force that tends to tilt the cam holder 21 in the front-rear direction, that is, in the axial direction of the camshaft 10. Further, due to this force, thermal deformation of the cylinder head 1, etc., stress acts to shift the mutual axis center positions of the cam holders 21, 21, . . . . However, each of the cam holders 21, 21, ... is connected to each other by the rigid frame 23 at its upper part, and is also integrally connected at both sides by the side walls 22, 22, so its rigidity is extremely high. It has become a thing. Furthermore, by assembling the cam holder 21 with such high rigidity, the rigidity of the bearing stand 20, that is, the cylinder head 1, is also improved, and the influence of thermal deformation is also suppressed to a minimum. Therefore, the cam holder 21
Even if the plate is thin, the camshaft 10
is definitely supported.

When the engine is running, lubricating oil is pumped to the oil gear rally 32 of the cylinder head 1 by an oil pump (not shown), and the lubricating oil is transferred to the oil hole 31 formed in the cam holder 21 at the end and to the oil pipe. The oil is introduced into the oil passage 26a in the oil pipe 26 through an oil introduction hole 30 formed at the end of the oil pipe 26. This lubricant is
Oil supply hole 2 formed on the lower surface of the oil pipe 26
7, 27, ... toward the cam surface of the camshaft 10, and is guided from the oil supply hole 29 at the end through the oil hole 28 in the cam holder 21 to the inner surface of the camshaft bearing 25 at the end. In this way, the cam surface of the camshaft 10 is lubricated by the lubricating oil falling from above, and the camshaft bearing 25 is also lubricated.

When finishing the camshaft bearing 25, instead of the rigid frame 23 as described above,
As shown in FIG.
A dummy frame 33 that is not equipped with a cam holder is assembled onto the cam holder 21. Then, these are tightened to the bearing stand 20 of the cylinder head 1 with the tightening bolts 24, so that the state is similar to the actual assembled state. In this way, each cam holder 2
1, 21, . . . are open at the top.
Therefore, insert the intermediate bushing 34 from above,
Positioned between the camshaft bearings 25, 25,...
While guiding the tool 35, finish machining of the camshaft bearing 25 is performed in order starting from the end.

In this way, all camshaft bearings 2
When finishing step 5 is completed, tighten bolt 2
4 and remove the dummy frame 33 and cam holder 21. After the camshaft 10 is assembled onto the bearing stand 20, and the cam holder 21 and rigid frame 23 are assembled in this order, they are again tightened and fixed using the tightening bolts 24. In this way, the camshaft 10 is firmly supported.

Note that, as in the above embodiment, each cam holder 2
1, 21, ... are integrally connected to each other by the side walls 22, 22 on both sides, not only the rigidity of the cam holder 21 becomes extremely high, but also the Since it is a single part, it is easier to manage the parts and assemble the cam holder 21, but the rigidity of the cam holder 21 is sufficiently high just by connecting it to each other using the rigid frame 23, so it can be used when weight reduction is required. , its side walls 22, 22 can be eliminated.

Further, in the above embodiment, the valve operating mechanism 9 operates each pair of intake valves 7, 7 and exhaust valves 8, 8 by one camshaft 10.
It will be obvious that the present invention is not limited to this and can be applied to various overhead cam type valve mechanisms.

(Effects of the Invention) As is clear from the above description, according to the present invention, each cam holder is connected to each other by a rigid frame fixed to the upper surface of the cam holder, so that the cam holder and the cylinder head are connected to each other. Rigidity is increased and the camshaft can be strongly supported. Therefore, the valve bounce toughness of the camshaft and the toughness against uplift of the oil tappet are improved, and it becomes possible to maintain good valve operating characteristics.

In addition, since the oil pipe is integrated into the rigid frame, the oil pipe becomes a rigid member, and each cam holder is connected more firmly, and the oil pipe is positioned above the camshaft. As a result, lubricating oil can be efficiently supplied to the cam surface.

The rigid frame is removably fixed to the cam holder, so when finishing machining the camshaft bearing, the rigid frame can be removed to prevent the oil pipe from interfering with the machining. Can be done. Therefore, the workability is not impaired.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts showing an embodiment of a camshaft support device according to the present invention, FIG. 2 is a longitudinal cross-sectional view of the camshaft support device, and FIG. 3 is a view taken along the - line in FIG. 4 is a vertical cross-sectional view of a camshaft support device, FIG. 4 is a longitudinal sectional front view showing an example of an engine valve mechanism equipped with the camshaft support device, and FIG. 5 is a plan view of essential parts of the valve mechanism; FIG. 6 is a perspective view showing a state in which the camshaft bearing is being finished in the camshaft support device. 1... Cylinder head, 9... Valve mechanism, 10
...Camshaft, 10e...Exhaust cam, 10i
... Intake cam, 20 ... Bearing stand, 21 ... Cam holder, 22 ... Side wall, 23 ... Rigid frame, 2
3a...Horizontal frame, 23b...Vertical frame, 2
4... Tightening bolt, 25... Camshaft bearing, 26... Oil pipe, 26a... Oil passage, 27... Oil supply hole, 33... Dummy frame.

Claims (1)

[Scope of Claims] 1. A plurality of bearing stands 20, 20, ... arranged in parallel at intervals on the upper surface of the cylinder head 1, and cam holders 21, 21 assembled on the upper surface of the bearing stands 20, 20, ..., respectively. ,... A camshaft support device in an engine valve mechanism, in which a camshaft 10 is rotatably supported by; A frame-shaped rigid frame 23 that connects the camshafts 1 to each other is removably fixed to the rigid frame 23, and the camshaft 1
an oil pipe 26 that is substantially parallel to 0 and capable of injecting lubricating oil toward the cam surface of the camshaft 10;
A camshaft support device in an engine valve mechanism, which is integrally provided. 2. The camshaft support device according to claim 1, wherein the cam holders 21, 21, . . . are integrally connected to each other by side walls 22, 22 on both sides thereof.