JPS6118007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve adjustment device for a multi-cylinder dual overhead camshaft internal combustion engine, and in particular to a valve adjustment device for a multi-cylinder dual overhead camshaft internal combustion engine, and in particular to a valve adjustment device in which a regular timing means for interlocking intake and exhaust valves is removed. The present invention relates to a valve adjusting device suitable for adjusting the valve.

One of the valve devices used in internal combustion engines, especially motorcycles or automobile gasoline engines, is
There is an overhead camshaft type. This has a dedicated camshaft on each cylinder head for operating the intake and exhaust valves, and an overhead camshaft that operates the intake and exhaust valves attached to the cylinder head via a push rod and a rocking arm. Compared to the valve type and single overhead camshaft type, which operate both the intake and exhaust valves with a single camshaft located at the top of the cylinder head, this type has the highest rigidity because the camshaft can be placed directly above the valve. Since it is less likely to cause valve surging etc. even at high engine speeds, it is mainly used in gasoline mechanisms for motorcycles and automobiles aimed at high performance.

An example of an internal combustion engine equipped with such a double overhead camshaft type valve device is shown in FIG. In the figure,
10 is a cylinder block; 12 is a cylinder head fixed on the cylinder block 10; 14 is a cylinder head fixed on the cylinder block 10;
16 is a piston that slides up and down in a cylinder formed in the cylinder block 10; 18 is an intake passage 20 formed in the cylinder head 12; 24 is an exhaust valve device for opening and closing between the combustion chamber 22 and the exhaust passage 26, which are also formed in the cylinder head 12; 28 is an exhaust valve device for operating the intake valve device 18; 30 is an exhaust valve camshaft for operating the exhaust valve device 24; 32 is a camshaft for connecting the cylinder head 12 to the cylinder block 10;
Numeral 34 is a bolt for fixing the cylinder head cover 14 to the cylinder head 12, and 36 is a bolt for fixing the camshaft cap 38 to the cylinder head 12.

As shown in FIG. 2, the intake valve device 18 and the exhaust valve device 24 have a valve body 42 that can slide up and down within a valve guide 40 inserted into the cylinder head 12, and a valve body 42 that is in contact with the surface of the cylinder head 12. a valve spring seat 44; a valve spring retainer 48 fixed to the upper part of the valve body 42 by a valve spring lock 46;
an inner valve spring 50 interposed between the valve guide 40 and the valve spring retainer 48;
, an outer valve spring 52 interposed between the valve spring seat 44 and the valve spring retainer 48 , and a valve seal 5 that maintains airtightness between the valve guide 40 and the valve body 42 .
4, a valve lifter 56, and the valve lifter 56
and a pad 58 inserted between cams disposed on the cam shaft.

Further, as shown in FIG. 3, cams 60 that come into contact with and press the valve lifter 56 of the intake/exhaust valve device are arranged on the intake valve camshaft 28 or the exhaust valve camshaft 30 depending on the number of cylinders. A timing gear 64 is meshed with a timing chain 62 for driving the intake valve camshaft 28 and the exhaust valve camshaft 30 in the same direction and at the same rotation speed in synchronization with engine rotation. 66 are fixed respectively.

On the other hand, in an internal combustion engine, the valve device is thermally deformed depending on the engine operating state, so there is a gap called a valve gap to prevent the valve from closing due to thermal expansion of the valve device. It is normal for intake valves to have a diameter of 0.1 to 0.4mm and exhaust valves to have a diameter of 0.2 to 0.5mm. If this valve gap is too small, the valve will suffer from poor airtightness during operation, while if this valve gap is too large, the valve device collision speed will increase and noise will increase. Therefore, this valve clearance needs to be adjusted within a predetermined range depending on the internal combustion engine.

Therefore, in the double overhead camshaft type internal combustion engine as described above, by changing the thickness of the pad 58 interposed between the valve lifter 56 and the camshaft,
The amount of protrusion of the tip of the valve body 42 into the combustion chamber 22 is changed to adjust the valve gap.

The valve clearance adjustment for this double overhead camshaft internal combustion engine is as follows:
Normally, during temporary assembly of the cylinder head on the production line (the intake and exhaust valve device, intake and exhaust valve camshafts, etc. are assembled to the cylinder head, and the intake valve camshaft 28 and the exhaust valve camshaft 30 are interlocked). The valve clearance is adjusted in advance in a state where the timing chain is not applied. In particular, when adjusting the valve gap using pads 58 having different plate thicknesses, it is currently almost always done during temporary assembly. However, during this temporary assembly, the timing chain was not applied, so when the valve clearance was measured and the pads were replaced to set the correct valve clearance, both camshafts were moved without interlocking with each other. As a result, the tips of the valve bodies may touch each other, causing the valve body to bend. This camshaft can be stopped at this position due to friction, and the valve body can be stopped at any lift position, but in the case of a single cylinder, both valves remain closed due to the reaction force of the valve spring. However, as the number of cylinders increases from 2 cylinders (180° crank) to 3 cylinders (120° crank) to 4 cylinders (180° crank), the amount of valve lift at the stable position of the camshaft increases. If one valve is lifted and the other camshaft is rotated freely, the valves may interfere with each other.

In order to avoid this, when designing an internal combustion engine, the intake valve device and exhaust valve device should be kept far apart, and under normal lift conditions, regardless of the valve timing condition,
It is possible to design a design that ensures that the two do not touch each other, but such a design would not only prevent the valve diameter from being large, resulting in poor intake and exhaust efficiency.
It cannot be applied to engines that are currently in production. It is also conceivable to remove the other camshaft when adjusting the valve clearance, but this poses a problem in that the camshaft must be installed and removed one by one, making the adjustment time-consuming.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional art, and provides a valve adjustment device for a multi-cylinder two overhead camshaft internal combustion engine in which valve gap adjustment can be easily performed without damaging the valves. With the goal.

The present invention interlocks both the intake valve camshaft and the exhaust valve camshaft, which is independent of the intake valve camshaft, with the same rotation amount and rotation direction, in a state where the intake and exhaust valves do not interlock with each other. A multi-cylinder two overhead camshaft internal combustion engine in which a possible interlocking means, a driving means capable of driving the interlocking means in a desired direction and a predetermined amount, and a regular timing means for interlocking these with intake and exhaust valves are removed. The above object is achieved by using a fixing means for fixing the cylinder head on the cylinder head of the cylinder head.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIGS. 4 to 6 show an embodiment of the valve adjusting device 70 according to the present invention on a cylinder head 12 of a multi-cylinder two overhead camshaft internal combustion engine in a pre-assembled state with the cylinder head cover and timing chain removed. It is shown in the fixed state above. The valve adjusting device 70 according to this embodiment has a base 74 fixed on the cylinder head 12 by a hexagon socket mounting bolt 72 that is screwed into a cylinder head cover mounting screw hole 68 formed on the cylinder head 12. and a single sprocket wheel 76 which is rotatably supported on the base 74 and can be engaged simultaneously with the timing gears 64 and 66 fixed to the intake valve camshaft 28 and the exhaust valve camshaft 30, respectively. Similarly, it is comprised of a gear 78 rotatably supported by the base 74 and capable of meshing with the sprocket wheel 76, and a ratchet handle 80 equipped with a ratchet mechanism that rotates the gear 78 in one direction. ing. In the figure, 32 is a bearing for rotatably supporting the sprocket wheel 76 on the base 74, and 84 is a bearing for rotatably supporting the gear 78 on the base 74.

The operation will be explained below. First, as shown in FIGS. 4 to 6, the valve adjusting device 70 is placed on the cylinder head 12 of the engine, and the camshaft 2 for the intake valve is
8 timing gear 64 and exhaust valve camshaft 30
When the timing gear 66 and the sprocket wheel 76 of the valve adjustment device 70 are in mesh with each other,
Mounting bolts 72 secure valve adjustment device 70 onto cylinder head 12. In this state, by operating the ratchet handle 80, the sprocket wheel 76 is rotated via the gear 78, and the intake valve camshaft 28 and the exhaust valve camshaft 30 are simultaneously rotated. The valve gap is adjusted at a predetermined position while rotating the device 18 and the exhaust valve device 24 in conjunction with each other. By using this valve adjustment device 70, the intake valve device 18 and the exhaust valve device 24 operate in conjunction with each other, so they do not interfere with each other regardless of the rotational state of the camshaft. , the valve clearance can be easily adjusted without damaging the valve. After adjusting the valve clearance, loosen the mounting bolt 72 and remove the valve adjustment device 70.
is removed from the cylinder head 12 and moved on to the next production process.

In this embodiment, the fixing means fixes the valve adjustment device onto the cylinder head using a cylinder head cover mounting screw hole formed on the cylinder head of a multi-cylinder two overhead camshaft internal combustion engine. Therefore, there is no need to provide any special fixing means, and the valve adjusting device can be fixed on the cylinder head very easily.

In the above embodiment, the means for interlocking both the intake valve camshaft and the exhaust valve camshaft was a sprocket wheel, but the interlocking means for interlocking the two is not limited to this, and could be a gear. It is also possible to use other interlocking means, such as.

Further, in the above embodiment, the driving means for driving the interlocking means in the required direction by the required amount was a ratchet handle equipped with a gear that meshes with the sprocket wheel, but the driving means is not limited to this.

In the above embodiment, the engine was a four-cylinder two-overhead camshaft internal combustion engine with a timing gear located in the center of the engine, which is often used in motorcycles. The scope of application of the present invention is not limited thereto, and it is clear that the present invention can be similarly applied to multi-cylinder dual overhead camshaft internal combustion engines for automobiles, in which a timing gear is generally disposed at the front end of the engine.

As explained above, the present invention provides a valve adjustment device used in a multi-cylinder double overhead camshaft internal combustion engine in which the intake and exhaust valves are adjusted without interlocking with each other. An interlocking means capable of interlocking both a camshaft and an independent exhaust valve camshaft in the same rotational amount and rotational direction, a driving means capable of driving the interlocking means in a desired direction by a required amount, and an interlocking means capable of interlocking both a camshaft and an independent exhaust valve camshaft; Equipped with a fixing means to be fixed on the cylinder head of a multi-cylinder two overhead camshaft internal combustion engine in which the regular timing means for interlocking has been removed, it is easy to adjust the valve clearance without damaging the valves. It has an excellent effect in that it can be used in many ways.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration around the valve device of a multi-cylinder dual overhead camshaft internal combustion engine to which the present invention is applied, and FIG. FIG. 3 is an exploded perspective view showing the intake and exhaust valve device, and FIG. 4 is a perspective view showing the camshaft and timing chain for the intake and exhaust valves.
A partially cutaway front view showing a state in which the valve adjustment device for a multi-cylinder twin overhead camshaft internal combustion engine according to the present invention is fixed on a cylinder head of a multi-cylinder twin overhead camshaft internal combustion engine. 5 is a top view, and FIG. 6 is a sectional view taken along the line - in FIG. 4. 12... Cylinder head, 18... Intake valve device, 24... Exhaust valve device, 28... Camshaft for intake valve, 30... Camshaft for exhaust valve, 56... Valve lifter, 58... Pad, 60... ...Cam, 62...
Timing chain, 64, 66... Timing gear, 68... Cylinder head cover mounting screw hole, 70... Valve adjustment device, 72... Mounting bolt, 74... Base, 76... Sprocket wheel, 78... Gear, 80... ratchet handle.

Claims (1)

[Scope of Claims] 1. An interlocking means capable of interlocking both an intake valve camshaft and an exhaust valve camshaft independent of the intake valve camshaft with the same amount of rotation and rotational direction; and a fixing means for fixing these onto the cylinder head of a multi-cylinder double overhead camshaft internal combustion engine in which regular timing means for interlocking intake and exhaust valves has been removed. A valve adjustment device for a multi-cylinder two-overhead camshaft internal combustion engine. 2. The multifunction device according to claim 1, wherein the interlocking means is a single sprocket wheel or gear that can mesh simultaneously with a timing gear fixed to the intake valve camshaft and the exhaust valve camshaft, respectively. Valve adjustment device for a two-cylinder overhead camshaft internal combustion engine. 3. The valve adjustment device for a multi-cylinder dual overhead camshaft internal combustion engine according to claim 2, wherein the drive means is a ratchet handle equipped with a gear that meshes with a sprocket wheel or gear of the interlocking means. . 4. The fixing means attaches the valve adjustment device to the multi-cylinder two-overhead camshaft internal combustion engine by using a cylinder head cover mounting screw hole formed on the cylinder head of the multi-cylinder two-overhead camshaft internal combustion engine. A valve adjusting device for a multi-cylinder two overhead camshaft internal combustion engine according to any one of claims 1 to 3, which is fixed on a cylinder head.