JP2812241B2 - Cam chain guide device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a cam chain guide device for restricting a cam chain for a valve train of an internal combustion engine to a predetermined position.

[0002]

2. Description of the Related Art In an internal combustion engine using a cam chain for driving a valve gear, generally, a substantially linear chain guide is fixedly mounted on the tight side of the cam chain, and a chain tensioner is movable on the loose side. It is arranged together with the chain guide.

Here, a fixedly provided chain guide on the tension side is disposed along the outer periphery of the cam chain as shown in, for example, Japanese Utility Model Laid-Open Publication No. Sho 57-70545. It is firmly bolted to the end of the block. That is, the chain guide is fixed to the outer peripheral side of the cam chain of the cylinder block, and regulates the position of the cam chain only from the outer peripheral side.

[0004]

In the conventional configuration in which the chain guide is fixedly provided to the cam chain as described above, unless the rigidity of the chain guide itself and its supporting rigidity are set sufficiently high, torque fluctuation and the like will occur. And the cam chain swings considerably. In particular, if the support rigidity is insufficient, the chain guide itself tends to vibrate when strongly pressed by the cam chain, and it is not possible to sufficiently suppress the cam chain runout. The cam chain runout contributes to vibration and noise,
A large amount of lubricating oil may be scattered, which may have an adverse effect on blow-by gas processing.

However, if the rigidity of the chain guide and its supporting rigidity are set sufficiently high, the force applied to the chain guide surface of the chain guide acts on the cylinder block as it is. There is a problem that minute chain vibration generated in the chain is easily transmitted to the cylinder block via the chain guide, and as a result, noise is increased.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a cam chain guide device in which a chain guide is provided along a cam chain of an internal combustion engine and the chain guide is fixed to an end of a cylinder block. Above
The chain guide is made of synthetic resin and is in front of the cam chain.
Cover part and along the outer circumference of the cam chain
Ring-shaped cams that are erected from the side edges of the cover portion.
Band along a plane almost perpendicular to the chain motion trajectory plane
And a cover wall having a cylindrical shape.
It is fixed to the block and the back of the above guide wall.
From the end face of the cylinder block,
The flange portion is erected, and the back surface and the side wall surface of the flange portion are
Between the guide walls so that they contact each other when the guide wall is deformed.
A small gap is provided .

[0007]

According to a second aspect of the present invention, in the above-mentioned cover portion,
A guide wall is further provided along the inner peripheral side of the cam chain.

The invention according to claim 3 is characterized in that the flange portion
Characterized in that a chain cover is attached to the flange surface .

Further, in the invention according to claim 4, the chain guide is provided on a chain tension side where the cam chain is linearly formed along the side of the cylinder block, and the back surface and the support surface are parallel to each other. It is formed in a plane.

[0011]

In the above construction, the trajectory of the outer periphery of the cam chain is regulated by the guide wall of the synthetic resin chain guide. Here, the guide wall is usually the flange side wall at the back.
Since it is not in contact with the surface , even if a minute chain vibration is applied from the cam chain, it is interrupted here and the transmission of vibration to the cylinder block side is suppressed. On the other hand, along with the torque fluctuations, when pressed strongly guide wall as trying to move the cam chain is large, the back surface of the guide wall flange
It abuts against the side wall surface and is firmly supported here. As a result, excessive deformation of the guide wall is prevented, and consequently the cam chain run-out is restricted to a very small range. At this time,
The guide wall is located on the cover fixed to the cylinder block.
It is set up from the side edge, and the tip is a free end
Then, when the guide wall is pressed due to torque fluctuation or the like, first,
First of all, the guide wall tip should be
Abut on the base of the part. Therefore, the entry from the guide wall
The flange receives the force at its rigid base.
And the guide wall was in contact with the flange side wall
Minimizing noise caused by chain vibrations
Can be.

[0012]

According to the second aspect of the present invention, the displacement of the cam chain toward the inner periphery is also restricted.

According to the third aspect of the present invention, the flange is provided.
The chain cover is attached to the flange surface of the part,
A position distant from the flange surface that becomes the sealing surface, that is,
The tip of the guide wall makes strong contact with the base of the flange
Therefore, there is little effect on the sealing surface, and the sealing surface is designed
This increases the degree of freedom in design.

Further, in the structure of the fourth aspect , the back surface of the guide wall and the side wall surface of the flange portion are opposed to each other in parallel, and the displacement of the guide wall is uniformly regulated at each portion.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the structure of the front end of an internal combustion engine 1 provided with a cam chain guide device according to the present invention.

The internal combustion engine 1 is mainly composed of a cylinder block 2 and a cylinder head 3. The internal combustion engine 1 has a DOHC type valve operating mechanism having a camshaft individually on each of an intake side and an exhaust side. The crank sprocket 4 and the intake side cam sprocket 5 at the front end of the engine
A cam chain 7 is wound between the cam chain 7 and the exhaust-side cam sprocket 6.

The cam chain 7 is housed in a chain chamber 8 formed over both the cylinder block 2 and the cylinder head 3. This chain room 8
On the cylinder block 2 side, it is formed in a shape depressed from the surrounding flange portion 9 and is covered by a chain cover 10 (see FIG. 5) fixed to the flange portion 9.
On the cylinder head 3 side, the cylinder head 3 is formed in a hollow shape penetrating vertically through the cylinder head 3 itself.

The cam chain 7 has a loose side on the left side in FIG. 1 and a tight side on the right side as the sprockets 4, 5, 6 rotate in the direction of the arrow. A chain guide 11 curved in a shape is provided. The chain guide 11 is configured to be swingable around a bolt 12 at the lower end. A chain tensioner 13 presses the upper end of the chain guide 11 inward, thereby applying an appropriate tension to the cam chain 7. doing.

The tension side of the cam chain 7 is substantially linear between the exhaust side cam sprocket 6 and the crank sprocket 4, and the chain guide 14 according to the present invention is provided here.

The chain guide 14 is made of a hard synthetic resin. As shown in detail in FIGS. 2 and 3, a cover portion 15 covering the front surface of the cam chain 7 and a first guide wall 16 along the outer periphery of the cam chain 7 are provided. Thus, a substantially L-shaped cross section is formed, and an extension portion 17 is formed on the back side of the first guide wall 16 at the lower end, and a first mounting hole 18 is formed here. The first guide wall 16 includes a motion trajectory surface of the cam chain 7, that is, a motion trajectory continuous in an annular shape.
It is molded in a strip shape along the substantially perpendicular to the plane to free plane. A substantially triangular extension 19 connected to the cover 15 is provided above the chain guide 14.
The second mounting hole 20 is formed so as to extend toward the inner peripheral side of the cam chain 7, opposite to that of the cam chain 7. A second guide wall 21 is formed on the upper portion of the chain guide 14 along one side of the extension 19 as shown in FIG. The second guide wall 21 is provided along the inner periphery of the cam chain 7, and has a straight intermediate portion and both ends 21a and 21b slightly curved outward. Note that the projecting height of the second guide wall 21 is relatively small as shown in FIG. Accordingly, when the chain guide 14 is mounted on the cylinder block 2, the cam chain 7 is easily guided between the two guide walls 16 and 21, and the mounting workability is improved. The first guide wall 16
Means that the middle part is also straight and both ends 16a, 1
6b is slightly curved outward.

On the other hand, as shown in FIG. 2, a first boss portion 24 having screw holes 22 and 23 is provided on the front end face of the cylinder block 2 corresponding to the chain guide 14.
And the second boss portion 25 is formed to protrude. Here, the lower first boss portion 24 is located on the outer peripheral side of the cam chain 7 and is formed to be continuous with the flange portion 9. Specifically, as shown in FIG. 1, the chain chamber 8 in which the cam chain 7 is accommodated is formed wider at a portion around the crank sprocket 4 than at an intermediate portion where the chain guide 14 is provided. The lower first boss portion 24 is disposed closer to the upper side in the wide portion. The upper second boss 25 is located on the inner peripheral side of the cam chain 7 and as close as possible to the upper end of the cylinder block 2.
The chain guide 14 is attached to each of the mounting holes 18 and 2.
The first boss portion 24 and the second boss portion 25 are coupled to each other by a stepped bolt 26 having a cylindrical portion 26a that fits into the first boss portion 24a. The chain guide 1 made of synthetic resin
In order to allow the thermal expansion in the longitudinal direction of No. 4, the lower first mounting hole 18 is slightly elongated.

Further, as shown in FIG.
4, the back surface 16a of the first guide wall 16
And a small gap α is maintained between the flange portion 9 and the side wall surface 9a as a support surface opposed thereto. In addition, as shown in FIG. 1, they are opposed to each other over a relatively long range in an intermediate portion of the chain guide 14, and in the opposed portion, the back surface 16 a and the side wall surface 9 a are
They are formed on planes parallel to each other. Accordingly, transmission of the chain vibration from the chain guide 14 to the flange portion 9 is avoided, and at the same time, when there is an excessive input from the cam chain 7 to the first guide wall 16, the first guide wall 16 is moved to the flange portion 9. As a result, the first guide wall 16 is prevented from being excessively deformed.

FIG. 5 shows a state in which the chain cover 10 is mounted on the front end face of the cylinder block 2 in which the chain guide 14 and the like are accommodated as described above, and the mounting bracket 31 is further mounted thereon.

As shown in FIG. 1, the mounting bracket 31 has two upper and lower boss portions 32 and 33 formed on the flange portion 9 above the first boss portion 24 and the opposite side across the cam chain 7. Bolts 35 are connected to the boss 34 formed on the flange 9 at a total of three places. As shown in FIG. 6, the internal combustion engine 1 is mounted in a so-called horizontal state in an engine room 36 of an automobile, and two locations on the transmission 37 side are supported by mountings 38 and 39, and The end on the cam chain 7 side is supported by the mounting 40.
In FIG. 6, 41 indicates an intake collector, 42 indicates an air cleaner, and 43 indicates a radiator.

According to the configuration of the above embodiment, as shown in FIG. 4, the first guide wall 16 and the second guide wall 21 of the chain guide 14 are located along the outer periphery and the inner periphery of the cam chain 7, In addition, the front of the cam chain 7 is covered by the cover 1.
5 is covered. That is, the cam chain 7 is configured to surround the four sides of the cam chain 7 together with the wall surface at the front end of the cylinder block 2, and the position of the cam chain 7 can be reliably regulated. Therefore, the run-out of the cam chain 7 is extremely small, and noise, vibration and scattering of lubricating oil are suppressed.

In the above embodiment, the chain guide 14
The cam chain 7 extends over the tension side of the cam chain 7
It is fixedly supported on both the outer peripheral side and the inner peripheral side. Therefore,
The support rigidity of the cover portion 15 with respect to the cylinder block 2 is increased, and even when the cover portion 15 is strongly pressed by the cam chain 7, the vibration of the chain guide 14 itself does not easily occur.

In particular, as described above, the chain guide 1
4, the flange portion 9 side wall surface 9a faces the back surface 16a of the first guide wall 16 via the minute gap α.
In a normal state, minute displacement of the first guide wall 16 made of synthetic resin is allowed, and transmission of chain vibration from the chain guide 14 to the flange portion 9 is avoided. Therefore,
Noise due to minute chain vibration can be suppressed. At the same time, if there is an excessive input from the cam chain 7 to the first guide wall 16 due to torque fluctuation or the like, the first
Since the guide wall 16 is supported in contact with the side wall surface 9a of the flange portion 9, excessive deformation of the first guide wall 16 can be prevented. That is, the cam chain 7 can be regulated from the outer peripheral side with very high rigidity, and the deflection of the cam chain 7 can be suppressed to a minute range. And the above guide wall 1
6 is the side of the cover 15 fixed to the cylinder block 2
Standing from the edge, the tip is a free end
Therefore, as described above, the guide wall 16 is pushed due to torque fluctuation or the like.
When it is pressed, first, the tip of the guide wall 16 is
9 abuts against the side wall surface 9a, particularly the base of the flange portion 9
You. Therefore, the input from the guide wall 16 is transmitted to the flange 9
Will be received at the base where the rigidity is high.
When the guide wall 16 comes into contact with the side wall surface 9a of the flange 9
The noise caused by the chain vibration can be minimized
You.

In the above embodiment, the chain guide 14
By disposing the second boss portion 25 supporting the upper portion on the inner peripheral side of the cam chain 7, the flange portion 9 on the side of the chain guide 14 whose position is determined along the trajectory of the linear cam chain 7 expands outward. Chain guide 1
The width of the cylinder block 2 in the portion where the cylinder 4 is arranged can be reduced. Also, interference between the upper second boss 25 and the bosses 32 and 33 for fixing the mounting bracket 31 is avoided. That is, as is apparent from FIG. 1, the bosses 32 and 33 for fixing the mounting bracket 31 can be formed near the cam chain 7, and the support point of the engine via the mounting bracket 31 is shifted toward the center of the engine. Can be secured. Then, the width of the chain cover 10 that covers the chain chamber 8 is reduced accordingly, and the amount of protrusion of the end of the cylinder block 2 to the side is also reduced. Therefore, it is possible to contribute to a reduction in size and weight of the entire internal combustion engine 1.

As is apparent from the above description, according to the cam chain guide device for an internal combustion engine according to the present invention, in a normal state where excessive input does not act on the guide wall, the guide wall is formed by the back flange portion. Since it is slightly separated from the side wall surface, even if minute chain vibration is applied from the cam chain, it is cut off here and the transmission of vibration to the cylinder block side is suppressed. Therefore, noise due to chain vibration can be reduced. On the other hand, when the cam chain tries to move largely due to torque fluctuation and strongly presses the guide wall, the rear surface of the guide wall abuts against the flange portion side wall surface , and is firmly supported here. Therefore, excessive deformation of the guide wall can be prevented, and the deflection of the cam chain can be reliably restricted to a small range. In particular, the guide
Since the tip mainly contacts the base of the flange,
Minimizes the noise caused by chain vibration when the
It can be kept to a minimum.

[0032]

Further, according to the structure of the second aspect , the displacement of the cam chain to the inner peripheral side can be restricted, and the position of the cam chain can be reliably guided.

Further , the chain cover is provided as in claim 3.
When installing on the flange surface, the flange
From the guide wall to the base of the flange away from the
Initial input is added, so there is little effect on the seal surface.
The degree of freedom in designing the sealing surface is improved.
You.

Further, according to the structure of the fourth aspect, the back surface and the support surface of the guide wall are opposed to each other in parallel, and the displacement of the guide wall is uniformly regulated in each part.

[Brief description of the drawings]

FIG. 1 is a front view of a partially cutaway front end of an internal combustion engine showing an embodiment of a cam chain guide device according to the present invention.

FIG. 2 is an exploded perspective view of the main part.

FIG. 3 is a perspective view showing the back side of the chain guide.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1;

FIG. 5 is a front view of the internal combustion engine with a mounting bracket mounted.

FIG. 6 is an explanatory diagram showing a layout in an engine room of the internal combustion engine.

[Explanation of symbols]

 2: Cylinder block 7: Cam chain 9a: Side wall surface 14: Chain guide 15: Cover part 16: First guide wall 16a: Back surface 21: Second guide wall

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 7/00-7/24 F02B 67/06

Claims (4)

(57) [Claims] 1. A cam chain guide device having a chain guide disposed along a cam chain of an internal combustion engine and fixing the chain guide to an end of a cylinder block, wherein the chain guide is made of synthetic resin, Cam chain
Cover that covers the front of the cam chain, and
So as to stand up from the side edge of the cover part and form an annular shape.
Along a plane that is almost perpendicular to the trajectory of the cam chain.
And a guide wall in the shape of a strip, and the cover portion is fixed to the cylinder block.
The cylinder block should face the back of the guide wall.
A flange portion is erected from the end surface of the lock, and a guide wall is provided between the rear surface and the side wall surface of the flange portion.
Small gaps set to abut each other during deformation
Cam chain guide device for an internal combustion engine, characterized by being. 2. The cam chain is provided on the inner peripheral side of the cam chain.
A guide wall along the
The cam chain guide device for an internal combustion engine according to claim 1. 3. A chain on a flange surface of the flange portion.
A cover is attached thereto,
3. A cam chain guide device for an internal combustion engine according to item 2. 4. The cam guide of the chain guide,
Chain tension straight along the cylinder block side
On the rear side and the flange
Note that the side wall surfaces are formed in planes parallel to each other.
An internal combustion engine according to any one of claims 1 to 4,
Chain guide device.